1963 Fuel injection woes
 

Thanks all for your suggestions on my SWC fuel injection problem. To recap, a barn car of sorts that barely ran... Timing is now correct, but I still can't get it to idle once the thermostatic choke comes off the cam. It just dies quietly. While the choke is still on the cam idle is 2200rpm.

I have set the idle mix and idle speed to the suggested values and adjusted up and down with no apparent effect. I think I have all of the open ports plugged.

Any ideas?

If it won't idle, there is no way to properly adjust the idle fuel and idle speed controls. It's a chicken and egg problem. But let's back up from the idling problem and look at a larger picture:

How long has the car been sitting? When was the FI unit last rebuilt? What was replaced? Who did the work? And most important, has the unit ever worked properly since being rebuilt?

Jim

idle
 

Check the Vacuum can at distributor. The stock ones dont like to idle on the SHP cars. Get a generic B28 from NAPA or check the unit with a vac guage. Duke williams has written alot about it on this forum, try searching it? It worked for my 340 hp car.

Boyan

The car had been sitting for about 10 years when I bought it last fall. I took the gas tank out and purged all of the gook from the fuel lines. I replaced the fuel filter, plugs, plug wires other consumables. I don't think the FI unit has been rebuilt. I have resigned myself to having it rebuilt. I'll try Boyan's suggestion of a new vacuum can.

Thanks for the tip!

1963 fuel injection cars do not have any vacuum advance at idle speed. They operate off venturi vacuum.

Mike's observation is spot on.... '63 FI units supply ported vacuum only to the VAC and this means there is NO vacuum advance at idle. So, changing VACs won't solve anything.

If the unit has truly never been rebuilt, then a non-idle condition could be anything..... an inflexible main diaphragm, sticking spill valve, a failed cranking signal valve, and on and on..... None of these are fixable by do-it-ur-selfers.

A rebuild by a competent, honest rebuilder will address all these potential issues, and more.

Jim

:iagree:That's the one that I would check first....followed by ALL of the other diaphrams for cracks.

My mistake...........I was just referenceing a similar problem with my 340 hp car that did not want to idle. Obviously, I need to brush up on my FI stuff....

Thanks for correcting me,
Boyan

Gene,

Jim is one of the best fuel injection restorers. Take his advice and save yourself time and money.

You can eliminate the cranking signal valve by starting the engine, then pinching off the vacuum hose leading to it. If the engine continues to run, you've likely found at least one of the problems.

I finally got a chance to try pinching the cranking signal line, and the rubber hose is rock hard and un-pinchable. I took a slew of photos and will post them once I figure out how to do it.

Since I will likely have this thing re-built , the next question is, where are the experts? Jerry Bramlett is in Mobile. Where is Jim Lockwood? I live north of Philadelphia.

John Degregory is located in Greenberg, PA. He is one of the best FI guys.

724 832 3786

replace the hose and try the 'pinch' thing. the hose is only standard vacuum hose available at any parts place by the inch/foot.
Bill

I live in northern California. PM sent.

Jim

Totally agree. I would give him first consideration.

I recommend Williams Repair, Sidney, Ohio, Cell 937 726-7914. He does all the fuel injection repairs for the Corvette Dealers etc. in Ohio.

Hi Allen aka Gene jockey, The old fuel injection units don't last forever you know. You said you have a barn find car. Hopefully the critters didn't build a nest inside you air meter and plenum. Man do they do the damage.
If your rubber hose is hard a rock one might expect all the rubber on the entire FI is in the same state.
Diaphragms: Rarely do you see them cracked. But you sure do see them aged. You are taking a chance running this engine you know. You could easily hydraulic lock the engine and then goodbye some rods or the entire block.
Got your call yesterday. Will return it after Panera Bread breakfast.
I live near about 5 hrs from you.
Meanwhile don't know where all the 63 Fi's are coming from. Sure I love to do them as I have had my 63 FI coupe since late 70's. Known as the Little White Car (LWC) I put this in there for the Michael dude looking in here from IN.
Anyhow I have probably restored more 63 Fi's than any other year. Reason being is that Rochester Products made at least 3000 of them.
In 1975 old Jon Blanchette said the production qty was 3022 with 91 service units. On my notes I crossed that number out and came up with 2610 63's. I don't really know how many were made and I will tell you that RP didn't know either. Frank Sciabica from RP once told me not to believe the productions numbers you read as the fuel injection business was a nightmare and paper work was not organized as it should be.
Are you going to Spring Carlisle Don??? Talk to you later, John D.
P.S.
One more thing is this. It's a whole new ball game with fuel injections (and carbs) today guys. Ethanol has caused this. Expect your cars to run at least 10-15% leaner with wonderful ethanol in them. Calibrating the units with ethanol is almost a waste. Now if you can get some good 100LL or some really hi-octane fuel then you will have something. But don't expect your FI to run like a clock and have boo coo power with ethanol in it. Sluggish it will be. The same as your late model.
Luckily we have all the components today to update the FI units for ethanol. Like I said that doesn't make them run any better but at least they won't be leaking and causing fires from key rubber parts failing.

If you set the air/fuel mixture with a air/fuel meter, it won't be lean or rich.

Little red car (LRC) runs like a clock with plenty of power on 89 octane E-10!:D

Did somebody take your seat at Panera Bread?

Sorry Michael, You are incorrect. Impossible to have a correct setting aka constant setting throughout the entire range of operation with ethanol. Impossible may be a strong word but this time it's correct.

I see you have hit the lottery. Yeah I thought you only used 87 octane.
Whew!!!!! Later as I am outta here.
:smash:

Looks like a drive by shooting to me!:lurk:

VP Racing fuel or Union 76 Race gas works for me.......one of the benefits of living just 10 miles from MSR Cresson:D

John
Frank was the guy that taught me what i know about FI, is he still alive?
Bill

I have been hoping someone will explain this one to me. What does E-10 have to do with it?

Well, I got some new hose, and did the pinch thing, and it made no difference. A re-build is the next step. Had a nice chat with John DeGregory. I'll see him, and maybe some of you all at the Spring Carlisle show.

Next time you talk to him, have him explain post #19 to you and then pass it on to me.

PS, I'm sure he'll do a good job on your FI unit!

Somebody? Anybody?

:D:lurk:

:iagree: John's a good man. You won't regret having him work on your FI.

Jim

Well Mike,
I'm not an FI expert, got one that I can make run OK, but I surmise that it would'nt make any difference whether we are talking about FI or a carburetor-- Anytime you are running a fuel that has a different gram weight /cu ml., which ethanol contains, for instance, .789 grams / cu ml. versus gasoline, which has only .680 gr./ml., you can see that alcohol (ethanol) is much denser. Without going into a (very) lengthy discussion on the properties, advantages/disadvantages of ethanol, a simple explanation would be that it takes a lot more ethanol to do the same job an equal amount of gasoline will do. That is why cars set up to run straight methanol/and or ethanol for that matter, require jets larger on the order of half again as large. Since there are only a few selections for nozzle sizes available on the Rochester FI units, I think that is probably what John meant.

Thanks but John indicated that a proper air/fuel ratio curve could not be maintained over the operating range of the engine because the fuel was E-10 instead of straight gasoline.

That would imply it could be maintained at certain rpm but not all rpm.

I don't believe nozzle size is the issue here, if there is an issue? Fuel delivery is controlled by nozzle size, spill valve and pump output.

He also implied that the fuel curve couldn't be maintained with E 10 but could be with other fuels. What's up with that?

Thanks for your answer and I am no expert on the stuff either.

This is true- but the fuel being discussed is E10, only 10% ethanol.

How can you be 15% lean when you only have 10% ethanol? Does this mean the ethanol is totally inert, plus some?:D

Mike
here's my .02...the liquid output of the Rochester is going to be the same whether it is water or gasoline or alcohol; and, given that it takes more ethanol to generate the same energy as gasoline; and, if the power stop is not changed, then the ethanol fuel would be leaner across the range. mechanical FI doesn't have an O2 sensor to adjust mixture, it just senses air flow which tells the spill valve what to allow to the nozzles.

BUT, if the power stop AND the rod length to the diaphragm is adjusted to allow more fuel in relationship to air flow AND a O2 analyzer is used to do the setup, then i would think the original stoichiometry could be attained. the standard tuning methods are out the window...
:cheers:
Bill

I think you are agreeing that there should be no problem getting a correct fuel curve, across the board with E-10?

:iagree:, i think it will take an O2 analyzer to dial it in; a Kent Moore manometer wouldn't have a prayer....
Bill

Instinctively, this would seem to be true. Adjust the ratio lever stops as Bill describes and you'd expect the leaning effect of ethanol would be negated.

I think what John D. was referencing is related to a discovery Jerry Bramlett has recently made about the difference between pump gas and racing gas.

The following is a quote lifted from Jerry's excellent and comprehensive web page which addresses the issue:

Before Jerry drew this conclusion he did very good science to repeatedly verify the results he was getting. While I can't explain what's going on, I do believe Jerry's conclusions.

Jim

I'm seeing more and more FI units that have had inexplicable nozzle changes.... a recent 283 unit with 327 "X" nozzles was one, a '62 unit with un-marked, sewer-pipe Z+++ nozzles was another.

A Kent-Moore manometer wouldn't have any way to detect or to deal with such inappropriate changes. Neither would anyone's Seat-Of-The-Pants-O-Meter.

These days, regardless of fuel, the ONLY way to accurately dial in an FI unit is to use a wide band O2 gauge.

Jim

Jim
not only the lever stops but i think also the position the lever floats at between the stops. getting it to 'float' in a slightly richer position will richen the mixture at light load conditions and across the range. the economy stop and the power stop are the extremes.
:thumbs:
Bill

Jerry's findings puzzle me too.... :willy:

I read Jerry's conclusions, I just don't know how he got there and I want someone to explain how he drew those conclusions. Besides, his remarks just draw a differenece between racing gas and E-10. Doesn't say you can't adjust for one or the other and that is the issue as far as I'm concerned. John D and others thinks the sun rises and sets on 100 LL. Jerry B says if you don't want to put racing gas in your car, he doesn't need your business and 100 LL makes little difference.

Nothing against Jerry. Smart, meticulous guy.

WTF?

I don't have any of the problems Jerry and John mentions mentions. No more so than what was normal in 1963. I haven't burnt any pistons, fouled any plugs, etc., etc.

So, somebody tell me why you can't get a linear fuel curve with E-10?

dumb old me had no problem at all with E10 in the winter, i just used the old seat of the pants 'lean it til it surges, then back it off til it goes away; then read the plugs', but come summer no amount of tinkering would keep it from stalling... the only thing that made it civilized was a mix of 112 racing gas and 93 E10 (boy, did it ever smell goooood; i had forgotten that sweet exhaust smell...)

but, it was too expensive; so the Rochester went in a box and y'all know the rest of the story.
Bill

ps: now have a smooth top doghouse, another thing i had forgotten was how much smaller the runners were in the ribbed top plenum...

http://i42.tinypic.com/30wwnxt.jpg

http://i42.tinypic.com/2zqsq6f.jpg

Bill,

Under all normal driving conditions, the ratio lever rides firmly against the economy stop. The manifold vacuum "window" within which it can float between the two stops is very small.

On my '60, for example, which has the correct enrichment diaphragm spring, the transition to the power stop begins when manifold vacuum drops to 9" Hg and is complete before the vacuum has reached 6" Hg.

I might be able to float the ratio lever if I were pulling a fairly steep grade in 4th gear at moderately slow speed and if I had a sensitive throttle foot. It'd be an effort, though.

Jim

thanks Jim, i guess i've slept one too many times...
:o
Bill

Naw, you're just still infatuated with your Rochester (E)FI system. And I'm more than a little envious.

Jim

Jim
if it wasn't for the summertime problems i'd still be using the Rochester; ...as dinosaurs go, it's a simplisticly beautiful beast...
Bill

just think of the 'fun' things we could have done if we had stayed in the Columbia area...

i wonder if Bob Stafford is still alive.....
Bill

Life as I've known it on earth would certainly have been different if I had stayed in Columbia. I don't believe it would have been better. The left coast has been really good to me.

I don't think Bob would be more than about 70-ish, would he? He ought to still be kicking.

I bought my first FI unit from him back in '78. It was a screwed up '57 unit (is that redundant?:D) and I'm sure he knew that. I certainly didn't.

After I muddled through my first FI rebuild, not really knowing what I was doing, the unit actually worked and worked well.

One evening Bob was at my house and I casually turned the key to start the engine with his former FI unit on it. When the engine lit off, and settled into a nice idle, the instant astonishment that registered on his face was just priceless.

Jim

I read his piece but I'm unsure if Jerry drew any conclusion other than E-10 and racing gas behaved differently.

I don't believe it says anywhere that a proper fuel curve cannot be maintained. He did say there was a difference between the two fuels but exactly how much wasn't mentioned.:thumbs:

What he said is that the two curves cross in two places. That means that at least one of them is non-linear and that they certainly aren't parallel, able to be made concurrent by a stop screw adjustment.

Mike what’s your obsession with E-10, are you heavily invested with E-10 stocks, an agriculture farmer, or just put it on your cereal in the morning?

rustylugnuts :confused2:

Yes, I understand that part of it but it's implied not only is there a difference between race gas and E 10 it's also said that E-10 can/will cause serious engine damage such as burnt pistons, fouled plugs and blown head gaskets. That "difference" sounds very significant to me if true.

I just haven't experienced those problems in many years of running E 10in my cars, including Rochester FI, garden tractors, boats, and any number of small engines. So while I don't doubt there could be some difference in the characteristics of the fuels (even though I have no idea why) as stated, I'm curious as the the extent of the difference.

Not putting words in Mike's mouth, but he's probably as sick and tired of the rehashed myths and misunderstandings (AKA BS) as I am.

As it turns out, the info above about the mixture 'going 10-15% lean' was based on use of E85 fuel (85% ethanol) and not E10. :ack:

Mike & Mike
i tried E85 in my, as Jim calls it, (E)FI and didn't see any difference; but a few folks told me that it was a BAD thing to do and could cause problems to the fuel system and other parts.

at this point i have no clue as to what fuel or even what else this thread is about...
:willy:
Bill

My interest was this. DeGregory made a statement way back that you couldn't get a satisfactory air/fuel curve using E-10 as a fuel and it did not matter whether it was Rochester FI or a carburetor.

No facts or documentation were provided. Just a statement and then a "goodbye"!

As an aside here, one rebuilder uses a chassis dyno and racing gas to calibrate his units, the guy from Pennsylvania uses "who knows what" method but I'm reasonably sure it's not a dyno. Yet, both these guys turn out rebuilt/refurbished fuel injection units that seem to run well under most conditions and that includes using 93 E-10 gasoline.

I don't care anything about a comparison between E-10 and any other fuel. I'm just trying to learn something.

All I want to know is why/how? So far, I'm still searching for the answer(s).:thumbs:

There may be some light at the end of the tunnel. The piston aviation industry is working on a no-lead substitute for 100LL with some success at least at a small scale. The big 550 CI turbocharged mechanical fuel injected engines run at 35-36 inches Hg manifold pressure. However, they've been at this for quite some time. We have the same concerns, especially with the compatibility of seals and gaskets with ethanol. We'll see...

E85 got tossed in there somewhere/somehow...

:iagree: i never had any problems (other than summer heat perc) using E10 93 with the Rochester on a 70 LT1...

so i'll hush, and listen; and hopefully learn something too

:lurk:

Bill

Sounds like he showed you the picture of the bent connecting rod!

i saw the pic and know it can happen; but i don't understand how it has anything to do with ethanol.... but then i have never had a anti-siphon/hydrostatic lock problem EXCEPT with the 80 Pontiac Bonneville with the 350 diesel they had at the time...

but i digress... i promised to hush...
:willy:

What set off my BS detector was the statement way up above that engine would run lean by 10-15% when using E10. This makes no sense.

In an extended conversation over on the VH board, a further statement was made by the same poster in support of the above claim, that the stoichiometric ratio of ethanol blended gasoline was 10:1 vs. the value of pure gasoline which is 14:69. For reference, pure ethanol is 9:1. The contention was the Rochester FI unit could not be calibrated to accommodate such a fuel. This is probably true HOWEVER-

E10 actually has a stoichiometric value of about 14.16 and E85 has a value of around 10:1.

This means that the 10-15% 'the sky is falling' value was based on use of E85 and not E10.:ack:

The units may suffer from hot start problems when using E10, but this is most likely due to percolation of gas formulations have an unacceptable Reid vapour pressure, but that's independent of the presence of ethanol. Pure gas can be just as susceptible.

I'm not convinced that anyone here knows enough about E10 pump gas, racing gas, 100LL, or syrup, for that matter, to make definitive and/or generalized statements about how each performs in the extremely variable conditions FI Corvettes are driven in. (well...maybe we can say that syrup will perform lousy)

Each car is different, each fuel blend is different, each climate is different, each driver is different, and each FI unit/engine is set up differently. The matrix is huge and unwieldily.

My experience with 63 FI cars in Michigan will be totally different than Florida, Washington state, or California, as the fuel blends and weather conditions are completely dissimilar.

I've found that in Michigan my FI cars run great on racing fuel, good on 100LL (or premium pump with no alcohol), and awful on 10% alcohol pump gas. Others say different. OK, I believe them.

You'll NEVER sort this out globally, so decide for your car alone: run the cheapest stuff that keeps your idle smooth and isn't hard to start when hot.

Me, I run racing gas, 'cause I've tried them all in two different cars and the results are the same.

amen... this was my experience in Florida too...
Bill

This wasn't the issue but, thanks.

Maybe a local chassis dyno shop can shed some light on the issue.

You're welcome, Mike, but my earlier post really does comprehend the issue.

It would be nice to come up with a fuel/air curve for E10 pump gas, but frankly E10 is not one mixture, it is a different mixture every time you purchase it. There are hundreds of hydrocarbons in pump gas and oil companies vary the components and their percentages, as they so choose. All they have to do is vary the percentage of one component for Winter and the volatility changes dramatically, as does performance in a FI engine.

My point is that maybe E10 sometimes works in FI engines, so more power to those of you who use it. In attempting to make that stuff work for everybody, every time, though, you're facing an impossible task. If you insist on trying, that's fine, I wish you luck, but the odds are stacked against you.

As it stands, though, I'd rather not stall at lights and have trouble re-starting, a situation I always see with E10 and never see with any racing fuel.

This is taken from post #17 and this is what I have issue with:

"Calibrating the units with ethanol is almost a waste."


Stalling at stop lights and hot restart problems are not a calibration problem. That is a Reid vapor pressure problem.

This poster led us to believe that you can establish a linear fuel curve with racing gasoline but even with minor tweaking for the leaner E-10 mixture, the mixture would not be stable and run a parallel curve to the racing gas and saying that it's a waste of time to calibrate with E 10.

I disagree. The only way I know that could happen is if the specific weight of the fuel (whichever one you choose) would vary throughout an air/fuel calibration.

That could possibly happen on a chassis dyno where underhood airflow doesn't represent actual road conditions and could conceivably cause fuel to vaporize in the fuel spider while calibrating. Otherwise, once you establish a fuel curve with one fuel, an alternate fuel should run a parallel curve to the first fuel.

So ask yourself, if calibrating with E 10 is a waste of time, just how do these guys that fix these things for a living do it, knowing full well that many of their customers use E 10? Well, we know one that uses a chassis dyno, we know some use the Kent-Moore manometer method and I'm sure there's other ways to do it. You even have one guy that says racing gas is the only way to run these things. Others swear by 100 LL. Others like myself have little/no problem with E-10.

No argument from me that racing gas or AV gas will make a FI run smoother when they get warm or hot retarts. The reason is obvious and it has nothing to do with E 10, it has to do with fuel vapor pressure.

My only issue is the statement that "calibrating a Rochester FI with E 10 is a waste of time.

I just read your original post stating this car sat for over 10 years. My 61 FI sat for over 25 years.
I did not want to take a chance and run the FI without rebuilding it and I didn't know how the engine was going to run. So I changed the fuel tank, replaced all rubber lines and the metal fuel line.
Then I removed the FI unit and installed an old manifold and carburetor that I knew was OK. This way I could set the engine up and drive it for a few months to get the ‘bugs’ out while I rebuilt the FI unit.
My thinking was if the engine ran good with the carb set-up and it didn’t when I installed the FI, then the trouble had to be in the unit not the engine.
This worked out perfect for me. I didn’t want two unknowns.
Joe

my FI sat, on the car, for 17 years and was never started during that period; just drove it into the car and parked it... the FI gods must have been smiling on me as, when i finally got around to it, i figured the fuel pump would be corroded beyond all use. i had put a marine gasoline stabilizer in the gas and maybe that is what 'saved' me as i expected to see the same kind of mess one often sees when they take the top off a carb that has set with fuel in it...

well, i pulled the plugs, squirted WD40 into each cylinder and the fuel pump and let sit over night, changed oil, installed new plugs, and with a new battery started it right up WITH 17 YEAR OLD GAS....

but this was back when gas was leaded, the real thing..

not sure i would be so lucky today...

Bill

BTW, Joe, congratulations on your aircleaner fix...
:thumbs:

Bill-

Your story reminds me of a car that I looked at back in 89, really nice 70 LT1 4speed car. Pulled the gas cap, and it looked like grape jelly!
Yes Sir, would you like that on whole wheat or plain?:rofl:

Efi
 

Bill- PM sent

I bought a 63 fuelie 4 years ago that had been in storage since 1969. I sent the unit to Ken Hansen to have it restored. He rebuilt it and then installed it on his 63 and drove it 2 weeks. It has performed perfectly since then. His price was very reasonable and turn around time was 3 -4 weeks. His shop is in western Tenn. Shop phone num. is 731-783-0815. Good luck , Dave

What kind of gasoline do you run in it. Just curious.

Thanks for the kind reply. That unit was calibrated with pump gas and yes it had the percolation problems at idle on a hot day. With all my units I recommend using racing fuel when ever possible, 100LL as a second choice. I also recommend fine tuning the unit with a dino. I too am amazed at Jerry's findings with the repeated dino testing with different fuels. In my opinion the only way to get a unit totally dialed in is with the use of a dino.

I also think its only fair to post Jerrys complete analysis which was posted on his web site:

Until November, 2011, I used pump premium gasoline for all my road testing and calibration work. Occasionally I'd get a bad tankful at some station and have to replace it with a different brand, but that happened only once or twice a year. Unfortunately, I consider those years the "good ol' days". Today the pump premium sold here in Mobile is unacceptable for use in Rochester injected Corvettes. Now I use undiluted racing gas exclusively in my test cars.

On a '57 - '62 unit, make sure there is an air gap between the top of the spider hub and the bottom surface of the plenum.


Modern pump gas can cause FI running problems throughout the RPM range. You're probably familiar with the poor idle caused by percolation (boiling) of pump gasoline in the distribution spider. You may not have heard about the problems it causes during cruising and at high rpm though. Those problems are a little tougher to detect.

It took four hours on the chassis dyno for me to understand the Air / Fuel ratio differences between running modern pump gas and true racing gas. I was in shock by the end of that test session. I found that pump gas burns much leaner at idle (below 1,000 rpm) and high rpm (above 4,000 rpm) during hot weather than racing gas. Oddly, pump gas burns richer than racing gas at legal cruising speeds (30 to 70 mph). This means that although your car will run on pump gas, it won't run its best. In the summer your idle will be rough after the engine is fully warm, and you'll foul spark plugs more frequently while cruising. This also means sustained engine operation (many minutes) at very high rpm (above 5,000 rpm) with pump gas could burn a hole in a piston or a head gasket on a hot day.

Here's my opinion why modern pump gas doesn't calibrate properly in old Rochester FI units. Gasoline is a mixture of many components. These components have different physical characteristics. Some are "light ends", and vaporize at relatively low temperatures at atmospheric pressure. This fact isn't apparent when you see the published vapor pressure of gasoline because it's an average for the entire mixture.

At idle, the distribution spider is only pressurized to 0.25 pounds per square inch. This is very near atmospheric pressure. A significant portion of modern pump gasoline will vaporize inside a hot spider hub at such a low pressure. This causes the Air / Fuel mixture at the nozzles to go lean. It may not be lean enough for your seat-of-the-pants gauge to detect, but I can certainly see it going lean using the dynamometer control panel instrumentation.

The high speed lean-out is caused by a similar, but different, vaporization problem. All pumps need a certain amount of feed pressure on the suction side to maintain liquid flow at the design pumping rate. If this feed pressure (called "Net Positive Suction Head") is less than required by the pump design, the incoming liquid will partially vaporize into bubbles. It's called "pump suction cavitation" when this happens. Bottom line: a pump that doesn't have enough Net Positive Suction Head will not flow as much liquid as it should.

The amount of Net Positive Suction Head is determined by the height of the liquid feeding the pump suction side and the physical properties of that liquid at pumping temperature. Hot modern pump gasoline less than 3" high in the fuel bowl doesn't provide squat for NPSH. I can see exactly when gear pump cavitation starts while watching the dyno control panel. On a hot day, it can occur as low as 4,000 rpm under full acceleration load. It only gets worse as the rpm's climb. By 5,000 rpm, cavitation can cause a mixture as lean as 18:1. That's lean enough under load to hurt some engine parts if you don't take your foot out of it.

Pump gas burning richer than racing gas while cruising is not a big shock to me. After all, octane rating is often indirectly related to volatility. Because it is more volatile, I believe modern pump gas burns more efficiently than racing gas at relatively low engine compression ratios. Running slightly rich while cruising won't cause any major problem. It may foul spark plugs a little sooner than running the right A/F ratio, however.

You can run 100LL Aviation gasoline, but it won't help much. Those special gasoline additives sold at auto parts stores don't have any significant effect either. Neither does the additive sold at swap meets that is 99% kerosene. I've tried the thick, one-piece, plenum to baseplate gasket too. It was no help. Insulating the gas line from the engine fuel pump to the FI fuel meter makes things worse. The best course is to just run 100% racing gas. I use the VP brand with a 110 octane rating, but other brands of racing gas would probably work just as well. I tried cutting it 50% with pump premium to save money, but the running problems were still there.


Regards
Ken Hansen

Rochester FI's had perc problems when they were new. No such thing as E 10 back then. That's what DeGregory said that E 10 was the problem. I think not. I think it's the reid vapor pressure of the fuel.

No question, racing gas will smooth one out for all the mentioned reasons. Racing gas isn't supposed to cause these problems, that's why it's called racing gas.

DeGregory says you can't properly calibrate a Rochester FI with E 10. I guess that's because of Jerry's dyno findings. On the other hand, I'm not sure that a chassis dyno comes close to duplicating airflow over the engine and keeping that fuel system cool opposed to running the car on the road.

How do you calibrate your FI units? Manometer? Dyno? Do you use racing gas? What does the customer use for fuel if you have it set up for some other fuel?

Not picking on you. Just curious.

PS. Haven't seen you on VH's in a couple of years.

seeing how weather has a BIG influence on richness/leanness. considering that the rochester has no way adjusting the AFR like EFI does, humidity and temperature has a GREAT deal of influence on AFR and performance and only seasonal tuning will mitigate it... heck, even underhood temps at different driving scenarios will affect AFR..

i know for a fact that the FI ran/runs better in the winter than in the summer

Bill

I don't see how it affects a Rochester FI anymore than a carburetor and I agree that underhood temps can/do affect performance and that is one of my points.

An EFI system is completely oblivious to any of these conditions. Mostly!

I can understand that there can be differences in different batches of E 10 due to different concentrations of the ethanol. 8% vs 10% would make some difference. How much, I have no idea but I would speculate it would be on the order of 1%.

I DO understand that the FI high pressure pump cannot pump vapor and I understand that low vapor pressure fuel can vaporized in the spider lines. By the same token, I think these conditions can be heightened by lack of cooling airflow while using a stationary chassis dyno.

In other words, I don't believe what I'm reading here that you CANNOT calibrate a proper fuel curve on either a carburetor or Rochester FI using E 10 for a fuel. Maybe not on a chassis dyno but certainly on the road, using an O2 sensor.

I purchased an air/fuel meter for just such this purpose a few months ago. I tried it out on the highway with the O2 sensor in the tailpipe. Got some screwy readings I think because it was in the tailpipe. When I get to it, I'll put the bung in the exhaust pipe, just downstream from the manifold and look for more stable/accurate readings. If I can get these readings within reason, I think I'll try the chassis dyno just for s...s and giggles to see if the results are the same.

In any case, I can't believe the air/fuel mixtures would go that far out of bed.

One local chassis dyno operator (25 years experience) I consulted on this scoffed at the idea that a fuel curve for E 10 wouldn't run parrallel with any other fuel.

If I get ambitious, I guess I'll find out.

Mike
i agree with you, my point was that there are things other than the formulation of gas that affect performance; temp & humidity being 2.. and they can be BIG factors. heck, even altitude.. none of which the rochester can accomodate
Bill

Don't feel bad. Only a handfull have the fuel injection down.:yesnod:

If you have never had one? No need learn.Not exactly a common item now days.:thumbs:

I am just a bystander on this one.

You have strayed from my issue with this thread. DeGregory says that carbs and FI's can't be properly calibrated with E 10.

I just happen to think that' s a bunch of baloney.

Also lot's of hysteria over E 10 eating up fuel system components. I have a '65 Corvette that still have the original carb/fuel pump on it. Never touched and still working well.

'66 327/350 fuel pump original. Still working well.

63 Rochester FI. Ran on leaded gas until 1980. Switched to E 10 for another 10 years and was running okay until I tore it apart to find out why it was still running well.

Got two more Rochester FI's that have been running for 5-6 years, no latest rubber or anything. Runs fine. Plugs down't foul. Pistons don't burn. I mean, WTF is the problem?????????????

i prefer 'ricocheted' rather than 'strayed'..
:cheers:
Bill

You have no commercial incentive to convince people that the sky is falling? :eek:

63 fuel inj.
 

WE have 93 oct. with no ethanol here in Greenville S.C. and i add an additive that i buy from Jack. It has been running great since I got it back from Ken Hensan 4 years ago. Dave

Absolutely none. You mean that's why there could be a difference of opinion?

:D

Are we talking about what type of fuel can run smoothly on today's Ethanol fuel in an early performance engine or what's the best type of fuel that matches maximum performance of when our engines were new?

I totally agree it depends on ambient temperatures, altitude, and humidity. Here in Florida, June & July 98 to 100 degrees an 11.0:1 and higher compression ratio engines with the older Rochester fuel injection runs better on aviation, or racing fuel than any fuel containing Ethanol period.

If I could run Ethanol the performance would suffer without a doubt, so why use it! If you run your Corvette to achieve good gas mileage without any concerns to performance, I say sell it...... and buy a Honda!

rustylugnuts :cool:

If you are addressing me, the issue didn't have anything to do with what runs best, how hot it gets, how cold it gets, whether it's Rochester FI or a carb, gas milage or other related things that obviously went right over your head while you were trying to get your foot in the door on this thread.



Go back and read posts #17, 18 and 19 again and maybe you'll figure it out.

My last post on this subject.:leaving:

remove the fuel meter top cover, flat sand it on a piece of window glass using 320 wet or dry paper. when you get it flat, then tighten it back on in a star pattern (like wheel lugs). Had same problem in a '63 many years ago, this solved the vacuum leak.

Geratol........ Yep!

rustylugnuts :lurk:

Gas
 

It is a bit scary to see how much info and opinion surrounds Rochester FI systems. My unit is at DeGregory's for refurbishing. In taking it off of the engine I was surprised to find that I had to remove the FI unit to get the valve covers (cast aluminum) off since the FI legs overlap. Seems like a design flaw. If you want to set the valve lash, you have to remove the FI!
Anticipating getting my FI unit back, I'll need new gaskets. Who makes/sells good ones? The lowest level gaskets on my engine are a sexy blue.

This is the golden age of Rochester FI.

More is known about these units now than at any other in their existence. Also, the reproduction and replacement parts currently available are far higher quality than what GM used to produce.

.

John is a good man. He'll take very good care of your FI unit.

True and not true. If the bottom of the piezometer ring and of the venturi cone ring are ground flat, it becomes possible to remove the driver's side valve cover.

Jim

On the fuelie. Did the factory recommend setting lash while running, like the carbed solid lifter motors?

tis a shame that it is no longer the golden age of gasoline.....

at the most all you would have to do is to remove the air meter from the plenum: 4 nuts.

my memory is now fuzzy, but you might only have to remove the piezometer ring
Bill

...........just remove the ring, not the whole unit, don't 'GRIND' any thing

..........I set mine cold

Just to be clear, I don't advocate grinding off the bottom of the ring. It was, however, a common modification back in the day. It is a way to get valve cover clearance.

I'm not entirely sure I'd even recommend a do-it-ur-selfer remove the piezometer ring. I've just seen too many creative ways an FI unit can be screwed up by well-meaning but inexperienced tinkerers.

Jim

pull the whole air meter then... :)
Bill

Yes. Same engine, same cam, same procedure in the Shop Manual. :thumbs:

Ethanol effects
 

Ethanol will dissolve the resin in fiberglass tanks and the galvanizing in standard fuel tanks! That is why they they do not sell it for aircraft or marine use. In addition, ethanol evaporates at 173 degrees, which is why it is NOT recommended for the Rochester Fuel Injected engines. You can buy 100% gasoline at various outlets: http://www.pure-gas.org

Excellent!

hmmmm..... I see no new information or questions; is there a reason this thread was resurrected?
Bill

Well here's a question that a quick read provided no answer to...Where can I get new parts for my '63 fuel injection? Are the injectors still available anywhere?

By "injectors" I assume you mean nozzles. What makes you think you need new ones? Originals don't go bad.

Jim

True-not much to ware out. I had my nozzles out and cleaned them-some mighty small innards there! My original manual suggests changing them if one is plugged--I get that was the old days but would be nice to have a source if one existed.
This is my first meeting with a fuelie so I'm thankful for any help and advice you can offer. I've replaced the drive shaft and got the wobble pump working after is sat for 20+ years; then checked the flow through the spider connection, bolted it back on and fired it up.
The car starts ok, sometimes better than others, idles pretty dependably, and runs well enough to drive. The problem is when I jump on the throttle. Hesitation and jumpy is the best description I an offer.
If that suggests a reparable problem or a place to start, I'd love to hear your comments.
Plugs, points and wires are all new but I haven't touched the timing.
Thanks--Steve

The shop manuals do a pretty good job of describing FI repair, given the body of knowledge available back in the day. They don't reflect modern thinking based on 50+ years of experience, though.

Unless Bubba has had his incompetent hands on a set of nozzles, all they ever need is disassembly and cleaning. (I use an ultrasonic cleaner to sanitize the metering orifice discs and the screens.) The worst thing which tends to happen is the nozzle top splits where the tube ferrule seals. Replacement nozzle tops are readily available and inexpensive.

So your FI unit has a wobble pump? Must be an early '63. Wobble pumps were short lived and aren't nearly as robust or as simple as the gear pumps which preceeded and succeeded them.

The hesitation you note could be due to the unit being mis-adjusted, from the diaphragms being old and stiff (especially if they are 20+ years old), ignition problems, clogged fuel passages..... any number of things. Without seeing the unit, I'd just be guessing to diagnose it from long distance.

The bottom line and your take-away is that your FI unit can be made to perform as new.:thumbs:

Jim

IIRC, one of the nozzles in my spare set is missing a screen.... :willy:
Bill

A fellow brought his '57 fuelie to me with the complaint that the engine had a miss and got really poor fuel economy.

After determining which cylinder wasn't firing, and ruling out ignition, I pulled the nozzle..... the metering orifice disc was gone!

Did I mention his fuel economy was poor?:ack::rofl: