Overheating is an Understatement
 

I’m running a numbers matching rebuilt 327/365hp motor in my ’64 coupe that is consistently overheating. Heading out on a drive I start with a 5 min drive to the highway and cruise at 60 mph. 15 min after that the needle climbs over 210 deg. This isn’t an issue of simply running hot, because it will continue over 210 if I don’t stop and it’s hard to completely enjoy a car that has a 20 min driving range. The temp grows consistently and only once did I let it go over 210 deg to puking (240+). That was a mistake I’ll only make once so to protect this motor.

I have gone through all the FAQ and Sticky threads on this forum and am at a dead end. References are listed in the links at the bottom for what I read through. The most helpful was John Hinckley’s article titled “Early Corvette Cooling”.

To follow Mr. Hinckley’s checklist:
Coolant – 50/50 mix with Water Wetter
Radiator – 6 years old aluminum Griffin that has been flushed regularly, is clean of debris, and has good flow. 20 deg of cooling when idling in garage (180 top, 160 bottom)
Expansion Tank – Filled exactly half way to the “Fill Cold” line
Water Pump – High flow replacement
Thermostat – New, tested 160 deg. (I know 160 vs. 180 is irrelevant)
Radiator Cap – 16# (13# used with same result)
Lower Radiator Hose – New and reinforced
Fan Shroud and Seals – All stock and accounted for
Fan and Clutch – Clutch fan working properly. Replaced with solid racing fan and got same result. Half-in/half-out
Temperature Gauge and Sending Unit – Verified accurate with IR gun
Ignition Timing – Total timing set to 34 deg results with a base timing of 12 deg. Less advanced timing provided the same result in temp.
Engine Bore – 4.06” diameter

I’ve had the car for two weeks and would like to “watch the scenery while cruising instead of the temperature gauge” so any input is much appreciated.

Thanks,
John

Reference material:
Overheating / Cooling FAQ - http://forums.corvetteforum.com/1558302870-post3.html
Barry and Linda’s Vette Tech Section - http://lbfun.com/Corvette/Tech/vettetech.html
Still boiling hot but there is light. - http://forums.corvetteforum.com/c1-a...post1561445673
66 corvette over heating - http://forums.corvetteforum.com/c1-a...r-heating.html

The car did puke the one time he let it go above 210 as indicated in the first post - he has a genuine overheating problem - not faulty instrumentation IMO. He also verified readings with I/R temp gun.

OP has done all the logical, correct things to troubleshoot. I'll be interested to see what others may say on the topic.

"The temp grows consistently and only once did I let it go over 210 deg to puking (240+)."

Were you pulled over and stopped, or driving when this happened..??

EDIT BELOW


Kind of a dumb question...your heater core..is it new and free of blockage...do you have your hoses on correctly...

What's the build history on the motor? Fresh rebuild, recent rebuild, or original? What coolant was in it when you bought it? Aluminum or cast pump? Aluminum or original heads? See my post on the 66 overheating big block - excessive corrosion build up. If all else has been ruled out, a blockage is likely.

IMHO I would add the following to the list:

Run a distributor vacuum advance, (if your not already), this will help
Remove the two block drain plugs and power flush the block
50/50 mix of distilled water and antifreeze

This should be an interesting post...

Does your griffin rad have tanks on each end? If so,That might be your problem!

As soon as your griffin goes under load, it can't handle the extra BTUs.:mad:

Get a proper exact re-production radiator from DeWitts. That will cure it. $700-900 Later.:thumbs:

Elaborate more on High Flow pump.

I have found the best pumps are GM factory, or NAPA replacement pumps. The after-market performance pumps seem to not flow water well at low RPM. Not sure what RPM range your overheating is in

Doug

You didn't mention if this was a new build, or if the problem has always been there, or if it just started. The overbore isn't helping, but .060" shouldn't be too much

Doug

Ya, the "high flow" can pump coolant so fast it doesn't have time to do a heat exchange.

"Temperature Gauge and Sending Unit – Verified accurate with IR gun"

No question is a dumb question at this level of desperation.

I have not looked into the heater core or hoses. I'll check it when I get home, but it sure pumps out hot air well when I'm trying to keep the temp low.

bypass it for now and check. Correct? Did you check to see if there is any fuel in the water? Or anything coming out the tailpipes?

I'm already running a distributer vacum advance, but just in case will double check it's functionality.

I'm already running a distributer vacuum advance, but just in case will double check it's functionality.

There are bulges on each end that may be the tanks you're describing.

It's a painted versio of this:
http://www.griffinrad.com/images/rad_images/6-00061.jpg

I don't know much about the pump. The only reason I know it's high flow is because it says so on the engine rebuild docs.

I'm overheating in all rpms. Idle in the garage up to cruising at 80 mph (3k ish).

The motor was rebuilt in 2001 but non of the documentation indicates the mileage. Somewhere between 32k and 60k isn't the best indicator.

I've heard of that and it made me wonder.

If it's idling and not even driving, wouldn't a drop in temp from 180 to 160 be a good indicator of the heat exchange rate? 20 deg isn't great but I wouldn't think it's all that bad for sitting in a hot garage with minimal air flow.

Bypass is a good idea to eliminate one more possible issue.

When I flushed the coolant there was no fuel or oil in it.

Exhaust looks good too. Maybe running a bit rich, but that's better than lean for heating issues.

If after you troubleshoot your problem it leads to your radiator this is the best place to go:

http://www.dewitts.com/collections/c...inum-radiators

Dennis

If it overheats at idle, it isn't a radiator capacity issue. If it overheats at speed, it isn't from lack of airflow (not a fan problem.)

You still didn't say if this prob just started or not, but I think your water pump failed, or you have some blockage keeping water from the radiator.


If the problem just started, did you change something, or did it unexplicably appear?


You are not getting too fast of water flow, especially if the problem just started.

You said the Tstat works, you just changed it? is it opening fully?

Doug

Thanks Dennis. Would you suggest sticking with the motor driven fan or converting to electric (4139063M) ?

I have owned the car for only two weeks and the issue has been there the whole time. Now I know why the seller only wanted to meet after 730 at night. Other things like a 160 deg thermostat, 16# radiator cap, lockout tab on clutch fan, etc. lead me to believe that this issue has been around for a while.

The Tstat opens fully. Checked it in the kitchen first.

Good input Doug. Thanks

This may sound off the wall, since you've stated that you are running a #'s matching 327/365 engine, but, have you checked the block to make sure it is a 3782870 and not a 3858180. The 8180's were used in conjunction with the 2870's, but, had much thinner cylinder walls. If the overbore of .060" is done on an 8180, I'd be a little worried. Just a thought. :eek:

If you could post a few pics of your engine bay so we all could see your set up that could help. Do you still have the fan shroud and the seals for example. Is the fan correct or some aftermarket flex fan? Original distributor with full time ported vacuum? Just a few more specifics and we should be able to narrow this down a bit.

Dennis

Possibly a head gasket leak or cracked head. A block tester kit will verify if so, many shops offer this service, shouldn't cost too much, ot just buy your own, they are not expensive.

I would eliminate combustion gasses into the coolant first, then investigate things like water pump. The 16# cap is a combustion gas clue.

You can also leave the cap on loose (first notch) and drive the car and see if problem continues, releasing the gases into the air should slow or eliminate teh overheating, especially if you have a 160* Tstat.

Doug

What if Bubba put a reverse rotation water pump in? You would probably need to pull the pump to inspect the impeller.

Electric fan is just another fix to try and solve a different problem. You DON'T have an airflow problem, anything over 20 MPH, and you don't need a fan at all for cruise conditions.

Ah, the old meet at night trick. Kinda like the car is already warmed up when you get there to look at it trick. There is something being hidden, the question is, what?

Doug

:iagree:

:iagree:

Let's hope is only a couple hundred dollar fix and not a couple thousand dollar fix.

The fan is a clutch and I've also used a rigid racing fan, but I'm not certain about the distributor.

Here are the only engine pics I have at this time:

http://s22.postimg.org/sm0luscyp/3_L...bb7d8715bf.jpg
http://s23.postimg.org/kz73s5v4r/3r6...463a4e1b30.jpg

I know that the water is flowing correctly because the lower hose is 20 deg cooler than the upper hose.

Hang in there. Post some pics for us we can sort it out.


Dennis:cheers:

Kits are only $25 bucks so that's not bad. Although I doubt that's the case. I haven't seen any oil in the water or water coming out of the tail pipes. Never hurts to check though.

I had a leaky headgasket/overheat problem once, and never had eitehr of those symptoms. It was a minor gas leak, car would over heat and puke coolant.

Doug

Here is some additional reading from just a few days ago. Same year as yours.
http://forums.corvetteforum.com/c1-a...g-problem.html

Dennis:cheers:

Good opinion Miguel! Years back when building Hot Rods with lots of miss matched parts we would occasionally have to put a man made blockage of some sort into a cooling system due to too fast a flow threw the Radiator. Last time I mentioned this in a Thread, Barry, of Barry and Linda Fame ridiculed me for suggesting such a thing. Experience teaches us some things that Slide Rules contradict!
If I were the OP, I'd remove the Therm. and drive the car just to observe the result. Next I'd try filling threw the upper Radiator Hose and the Therm. Housing Port.. Never know, could be an Air Trap somewhere. (I know, highly unlikely). All Diagnosis Testing can be done with plain tap water for convenience. Keep us posted so we all learn something new. Al W.

Any chance the last owner painted it himself and clogged all of the fins?

Although not as good as a DeWitts repro, that Griffin radiator, in good condition, has plenty of capacity for your car's engine. My bride's track car runs this radiator which cools a 377 in full song lap after lap. On-track coolant temps have never gotten above 180.

That said, you might want to run your hand all around the front of the core to ensure that the whole radiator is participating in cooling the engine.

Jim

Kiss
 

Borrow a rad pressure tester and test the system for leaks . Check it cold first, then warm it up and pump it up again .
My guess would be a cracked head or a head gasket and
the pressure test will show you if it has either one .

Bill

The OPs radiator looks like the proper unit. But I bet it's been visually restored. But is old and clogged. That's what mine was like when I bought the C2.

Cooling issues on the hwy means the rad is likely toast.:yesnod:

Don't dis regard this note by Toddalin, the impellers in the pump look so much alike that it has happened many times to many people. If I find one water pump with the reverse rotation impeller installed I would ask for a pump with a different date code to replace it. In manufacturing if one is made wrong the odds are the whole run is done wrong so start with another manufacturer or a different date code produced on another day to get you away from this issue.
You can rule this out by checking flow, harder than most cars to check on a vette, you can't just open the rad cap and look in at flow. I am thinking you would probably need to create a site glass or container that could receive coolant from your heater hose feed line and somehow tie back in and complete the circuit so you could watch flow while running your engine. Maybe someone has created such a tool already and can help?
Your statement about having a hot heater core does indicate you have flow but is it enough?
On engines I have dealt with that had head gasket leaks causing overheat you had both overheat and the radiator would pressurize blowing fluid out the cap even before the temp was in the overheat zone. You could make these drive fine temporarily by drilling a hole in the Rad cap to relieve the combustion pressure in the radiator.

What happens if you park it hot while running and run cool water over the radiator, maybe a mist from a spray nozzle? If you have flow in the engine the cool mist approach would quickly pull heat out of your radiator and your temp gage should drop instantly. If it does not drop you have a flow problem or blockage.

If a reverse rotation impeller is installed but is turned in standard rotation it does not pump coolant backward, it will flow coolant but at a much slower rate with far less pressure. Rather than cupping the fluid and directing it in the right flow direction it slices through the fluid more like a knife going through water compared to a spoon going through water.
That may be an exaggeration but I hope it helps understand what happens.

Lot of good ideas being thrown out here and while this can get very old in a hurry just hang in there and work through each of the cooling system elements. Assuming this is not a timing issue which sounds like you have ruled that out it comes down to the cooling system. I will throw my .02 in here if for no other reason than to reaffirm what others have already said.

I also think you have a water flow problem not a air flow problem as Doug has stated. If I was troubleshooting this I would first rule out any internal pressure problems using a pressure tester. Next I would remove the T-Stat and drive the car to see if this made any difference. Next on my list would be to replace the non stock water pump with the correct GM pump.

Keep good detailed temp notes using the IR gun during this whole troubleshooting process and post those numbers so we can get a feel for what’s going on and when. I look forward to staying with this thread as I like troubleshooting hard problems like this. For what’s it worth I don’t think that Griffin radiator is causing your problem if working properly which as you stated it seems to be.


Coolant Flow

The coolant enters the block through the water pump at the front of the block on each side, it flows through the block to the rear then up to the heads and flows to the front where it inters the intake, both sides meet where the t-stat is and flows to the radiator.

Great input everyone.

It looks like I have my work cut out for me to check off all these new suggestions. In addition, I had a new discovery last night. After going back and double checking the timing, I noticed that the Base Timing and the Total Timing fell close to spec as before. The part that stuck out is that there is no change when the vacuum advance is connected. That's the first step in the process.

Going back on your comments, here is my action item list that I will be starting tonight:
1. Replace vacuum advance mechanism and verify functionality. Test drive.
2. I.R. Gun different areas of the radiator to look for inconsistencies.
3. Replace water pump with one from Napa (OEM pump from Zip or somewhere will replace Napa part if pump is issue). Possibly run flow pressure test in addition. Test drive.
4. Block Test for combustion gases in cooling system.

Make sure your vac advance is hooked to full manifold vacuum.

Good find. I would stay on this until it is corrected. Be sure you are connected to full time vacuum AND you vac can is doing it job. Check the springs and weights in your distributor as well. Are they working freely? I think you are on to something here.

Dennis:cheers:

Also remember that when it comes to timing;

Initial + Vacuum + Mechanical = Total Degrees

When you change out the Vac Cann also check to make sure the mechanical fly weights under the rotor cap move freely and that you have a spring on each weight. I had a dist on a 74 Vette where the mechanical fly weights were rusted in fixed position.

Never mind, Dennis beat me to this.

The timing numbers I found on the forum per Corvette News for the 327/365 are:
10-14 deg at idol with vacuum advance disconnected and plugged
34-38 deg above 2500 rpm with vacuum advance disconnected and plugged
26-30 deg at idol with vacuum advance connected

I'm searching for pictures that clearly illustrate the proper connection location for full vacuum.

simple enough, just pull hoses off, with the engine at idle, until you find one that is sucking in air; this will work for your vacuum advance.
Bill

Do a pressure test ! It is free and easy . Unless you don't want to know if you have a crack or a bad head gasket.

Bill

As noted your dist vac should be hooked up to full manifold vacuum.
People are posting this because your Carburetor will have Manifold vac ports and Ported Vac ports.

Hook a Vac gage up to the available ports, at idle Manifold vac will pull the most vacuum.
Probably a constant 15 inches or so at idle, crack the throttle while running and Man Vac drops until the engine reaches a steady speed again and then it will rise again.
Ported vac is nearly zero at idle and increases with RPM.
Make sure you hook up to Manifold Vac. It makes a huge difference.

think of this as a speed vs heat transfer test; in reverse...

set the a/c fan in your car on high and feel the outlet temp; then turn it down to successively lower speeds and feel how the air temp feels colder. this is because the air flowing through the evaporator is slower and has more time to transfer the heat.
Bill

I think of the high flow water pumps this way.

GM spent time/money developing the best flow rate pump for the SBC. It's the same pump flow rate for all of them.

Why try to re-engineer the thing?

I have also never seen the lack of vacuum advance (by itself) in a midyear Corvette make any difference in the running temperature of the engine unless it's at very low speeds. And that's assuming the cooling system is in proper working order. If something else is wrong, all bets are off.

I don't know what's wrong with the OP's engine but I'm in with the group that says low or no coolant flow.

I suggested to somebody here, may have been Toddalin, to put a clear pastic section in his top radiator hose to check flow, lack of flow or direction of flow. He did it and found his problem, I think. One of those guys from the left coast.

You could do the same thing by pulling the thermostat housing, remove the thermostat and see which way the coolant flowed. That's kinda' messy but it'd work.

Mike
OP said the temp differential inlet to outlet is 20* (outlet being lower), so if it is flow related it would have to be a velocity problem
Bill

Yes, I know. I waited until post #56 to say anything as I'm not sure we're working off exactly accurate information.

This is what I'm keying on: "I start with a 5 min drive to the highway and cruise at 60 mph. 15 min after that the needle climbs over 210 deg. This isn’t an issue of simply running hot, because it will continue over 210 if I don’t stop".

In my experience, either his coolant isn't flowing or his cooling system isn't full. You really have to work at it to get an engine that hot, that quick.

Thats fine with a factory rad. On the other hand, if you install a larger capacity rad, the higher volume pump is fine.

Another thought. What would be the temperature differential if his water pump was not circulating anything?

Just gravity flow like a Model T?

Good question. I would think the temp differential would be higher though with the coolant sitting in the radiator that long, but that's just a guess.

I was thinking maybe the system is not full to capacity, but I would think any air pocket would have been burped out after a few heat cycles. If he pulls the thermostat, the coolant level should be right there at the t-stat.

A failed water pump would go a long way to explaining it, but I doubt the shaft would break. Could the impeller fall off the shaft? Belt so loose that it's slipping?

:cheers:
Gerry

http://www.mtfca.com/discus/messages...tml?1284480432

http://www.fordbarn.com/forum/showthread.php?t=73662

and then there is this...

http://www.arrowheadradiator.com/14_...utomobiles.htm

Bill

Doesn't this suggest that moving water slowly does not allow it to pick up heat when steam forms an insulating layer? I'm thinking that the quart of water floating on top of the molten lead wasn't moving very quickly.

Fast moving coolant (or turbulent) might prevent the steam pockets from forming, no?

:cheers:
Gerry

In the 1990's we used to manufacture Carter Water Pumps then we picked up Sealed Power and TRW Water pump business so we had a lot of water pump exposure.
Things I saw pump related that caused overheat issues.
1. Pump with impeller that did not have enough interference fit on the shaft, the belt turned the WP pulley but did not turn the impeller inside. NO Flow.
2. Pump with reverse rotation impeller installed by mistake No Flow
3. Pump with OEM Design that required a Positive displacement plate on the impeller sold without the positive displacement plate installed causing low flow overheat issues.
Heavy Duty engine Water Pumps usually had a Positive displacement pump, these did not pump more water but pumped with more pressure so they could maintain flow in high heat environments. Like a 327 in a Dump Truck pulling a hill that takes several minutes at wide open throttle, these work engines expose the block to more heat for extended periods and positive displacement pumps worked, change that engine to an automotive water pump and they would burn up the engine doing the same work.

5. Most automotive pumps use a simple paddle wheel impeller, it slaps at the coolant as it rotates keeping it flowing, in low demand applications this works fine.
Some aftermarket companies add a disc to the back of the impeller making it function more like a positive displacement pump without adding the extra weight and mass of a true heavy duty pump. These actually improve flow considerably, not faster flow but positive displacement flow so the pressure stays more uniform cold or very hot and this helps.
Water Pump sales in the late 90's were all exiting the USA and moving to China and we chose to exit the business in the late 90's so all this info is old but may still apply.
Let us know what you finally find.

I'd remove the block drain plugs, power flush it then replace the pump with the stock cast iron pump. This is a cheap next step to remove potential blockage then rule out the pump. Check your heater hose configuration as well. I'm running with a similar replacement radiator, the Bosch stock style pump, 50/50 mix, 180 thermostat, and the bypass from manifold to pump top. 327/365 bored .040 over. Never overheats even in the garage on a hot day.

Good morning everyone. I was able to get a few things done last night and left with some more items eliminated and some more questions.

First, the Block Engine Test came back negative (Image 1), so that's a relief. Ran the motor up to 190 deg so the thermostat was open and flowing. Checked fluid levels and then temps in the rad hoses to verify circulation. Set the tester in place of the rad cap and pumped the bulb for a minute. Glad to see it remained blue.

Second, I replaced the vacuum advance mechanism (Image 2). It matches the one spec'd out in one of Lars' articles and was the recommended replacement from Napa as well. After getting everything back together I still have no vacuum advance on my timing. 34 total and 16 at idle regardless of whether the vacuum is attched or not. The arm on the advance seems to take a significant amount of suction to move. I tried testing it with my mouth (as one YouTube vid demonstrated. guess I don't have 16-18 in. Hg in me. Insert joke here) and it wouldn't budge. It makes me question if the vacuum from the carb (Image 3) has enough to move it. More questions.

This weekend I plan to replace the water pump with a cheap unit (if there is one in town) to see if the current one is the issue. I'll also go through the rad with the I.R. gun to map out the temp differential across it.

Thanks again for all the great input.

Image 1: Block Test Results
http://s17.postimg.org/6kleb86xb/20130710_202616.jpg

Image 2: Vacuum Advance Mechanism
http://s22.postimg.org/527qdla29/20130710_202015.jpg

Image 3: Vacuum line from carb to advance
http://s15.postimg.org/3sk5x7gnf/20130710_174307.jpg

If vacuum to the dist continues to be an issue, remove the plug at the back of the manifold as seen in you pic, and adapt a fitting for attaching the dist vacuum. It will be the most direct you can get. :cheers: Dennis

:iagree: try it...; if that doesn't move it there is something wrong with your distributor
Bill

OK, you got a 2818 Holley Carb so disconnect the rubber vacuum line from the vacuum advance and connect a vacuum gauge to the steel line coming out of the carb and post the reading you get at idle.

If you have a Mityvac you can connect it to the vacuum advance and see how many inches of vacuum (Hg) you need to pull the canister to full advance.

You might have a stuck or jamming breaker points plate in the Dist.

Agree. He said he applied oral vacuum and he couldn't move it. Oral vacuum should easily move that plate. It shouldn't take but about 3" vacuum to make it start to move.

As a side note, make sure someone hasn't stuck a ball bearing inside the hose to block vacuum from going to the can.

Oral vacuum didn't move the arm on the vacuum advance (new and old) at all when applied directly to the vacuum advance mechanism.

Did you suck on the vacuum advance with it uninstalled? You should see the arm move.

Yea. It was done on both while they were uninstalled.

Maybe it's already been mentioned but in case it hasn't...the #2818 carb has the vacuum advance connection up on the metering plate, above the throttle plates, so there won't be any vacuum signal coming through at idle to the vacuum advance canister. You'll only see vacuum when the rpm increases . If you're actually testing at an elevated rpm and still no signal, there is a blockage somewhere, or maybe the canister is defective?
Mike T.

Use a Mityvac, can't imagine you have 2 bad vacuum advances.

2818 vacuum port
 

Mike are you saying that the vacuum port on the Holley 2818 is "ported" vacuum instead of full vacuum?

I came across an older post from another website where BarryK was discussing this very topic.

Seems that while the original 2818-1 carbs were full vacuum ports the later service replacement units were changed to ported vacuum.

If true could explain why there is no vacuum at idle.

just depends if the port is above the throttle plate(ported) or below the throttle plate (full vacum)

Unless the #2818 is built different than all the other Holleys I've seen (and that is a possibility), any time I see the vacuum port being used is not located on the baseplate or at least the lowest portion of the carb body, then I usually assume the connection is intended as a 'ported vacuum'. I expect the guys with the #2818 will chime in soon and let us know for sure.
Mike T.

Attached is a picture of a 65 327/350hp I restored a few years ago, the 2818 carb on this car was a correct dated (1965) carb and the vacuum line is hooked up the same.

This car NEVER ran over 180 degrees while I owned it.

The 2818 IS different than other Holleys - it has NO vacuum ports in the baseplate - the only vacuum port is in the right side of the primary metering block (fed internally from the baseplate), and on original metering blocks, that port is full manifold vacuum. On later re-issue versions, they changed the metering block, and that port became a "ported" vacuum source. There's also a full manifold vacuum source on the driver's side of the main body, but it's for a 90* restrictor fitting for the PCV hose. :thumbs:

So, if the original poster's carb is hooked up correctly and not providing vacuum from that port, then it's probably a later version? Seeing as there are a number of early Vette engines that didn't originally come with vacuum advance pods, 62Jeff's 340 horse 327 comes to mind, and they weren't prone to overheating, the lack of a vac pod shouldn't be a death sentence for overheating/.
Mike T.

Vacuum Advance Can
 

Hey guys, I guess nobody noticed what I did. The vacuum advance can he got was a B1, which takes 16-18 inches of vacuum to fully pull in. A 365 HP engine will only develop that much vacuum going downhill with no throttle opening. Not that this is why his vacuum advance is not working, but it won't work properly even if he gets it working. To the original poster---you need a can with B28 or 236 stamped on it, and if I'm right, they have been discontinued. Somewhere in the back of my mind, I read that Rock Auto still has a few,but I'm not sure.

I had a sneaking suspicion about this exact thing. The vacuum is there but not exactly up to pulling a golf ball through a garden hose.

May I redirect this thread back to the original issue? :cheers:

he is the OP, so it's his thread to discuss whatever he feels is relevant to his issue.
:cheers:
Bill

Unless you have really, really thin cylinder walls, i would say water pump, since it isn't a head gasket type problem.

NAPA pumps are about $50, last time I checked. GM pumps from Chev used to be about $12 last time I bought one, but I am dating myself.

Inexpensive fix, and not hard to do.

FWIW, for peace of mind, when i bought a '72 a few years ago, i replaced the water pump, had the alternator rebuilt (matching numbers type thing), and had the starter rebuilt, for peace of mind, as the WP felt funny turning it by hand, and so did the alternator. The dizzy will be next. One persons motor rebuild is not the same as another persons, often, the old worn out peripheral items go right back on a rebuilt motor.

Doug

C'mon Doug, we're supposed to be talking about vac cans and such
unless the OP wants otherwise...:rock:

To those of you who lovingly cling to the notion that a vacuum advance or lack of it is causing your overheating problem, I offer this very unscientific test I ran today just because of this thread.

First, I have a 327/360 FI engine that is built to stock spec. The initial advance was set about seven or more years ago when I built this engine at 12* initial. I didn't check to see how much centrifugal I had. Didn't seem important to me. The '63 FI engine does not have full manifold vacuum on the distributor. Only venturi vacuum. I haven't check the timing since I put the engine in the car but if the timing has changed, it can only get slower as the points wear and the gap closes. The timing can't get faster. I do have the VC 1810 cannister on the engine like the OP is supposed to have.

I have no idea how old my radiator is. I don't know what my coolant level is as I haven't checked it in five years or better. The radiator didn't look new when I bought the car 10-11 years ago. I have a stock clutch fan and I have no idea if it's been rebuilt, only that it blows air. I have a 160* thermostat in the engine. I also know as verified by IR gun that when the temp gauge shows in the middle of the 180* mark, the engine is actually running about 185*.

So, today, I do a test. It's 83*. Bright sun. I totally disconnect the vacuum advance hose from engine vacuum.

I start off and drive three miles to the highway. Temp gauge shows the needle is just about a needle width above the mark before 180. That would be about 160*. I continue down the highway, driving somewhat aggresively and with a couple spurts up to 90 mph. The temp gauge is still about a needle width above the mark before 180*. In other words, it's at it's normal temp, even without the vacuum advance being hooked up.

So about five miles down the road, I stopped and let the engine idle after the aggresive driving and the temp gauge finally crawled up to about the "1" on the "180" on the gauge and then it stopped. I let it idle for about ten minutes and the gauge didn't go any higher. At that point, I hooked up the vacuum advance and drove back home. On the return trip, the temp gauge fell back to the same spot as with no vacuum advance which would be about 165*/`170*.

You guys are chasing your tail trying to blame lack of spark advance on your overheating problem and the guys that are foisting this myth on you should cease and desist.

If you want to argue about what I posted, start another thread and I won't be on it. I would agree that higher ambient temps would result in different results but nothing to cause a problem.

:D

I never thought I'd hear myself saying this, but I tend to agree with MikeM on this.

Tebok, if you find that fixing the vacuum advance fixes your problem I will be very happy for you, but it never affected my temperature enough to note. It would take some doing to cause the temperature to rise over 240. I think you're going to eventually find a problem in the cooling system.

:iagree: Mike, I am glad we gave you a reason to go drive your toy, hope you had a great time. I do think the vacuum advance can make a difference in a borderline situation, 105 day maybe stop and go traffic but not in the situations reported by the OP and tested by MikeM. Looking forward to the answer on this one. :cheers:

I'm baffled by the OP's issue and out of ideas - which is why I quit posting early on. But I do agree with MikeM. Vac advance may make some marginal change in temp...but nothing on the order of the problem the OP is having. I changed my 283ci from its original dual point mechanical advance only dizzy over to a Pertronix III with vac advance (using FULL manifold vacuum, not PORTED) and saw no difference in running temperature at all.

this thread has been interesting.....a great post was when the block check was offered as a diagnostic for combustion gasses....always overlooked and sooo simple to do before one starts chasing his tail after the usual checks have been made...jmo....:rock:

:iagree: The only small block car I have with vacuum advance is my 64 and only because it is bone stock. My 62 with a blown 413 CI small block has no advance. Nothing. The inside of the dist. is empty. It runs off a crank trigger. All the dist. dose is direct spark to the plugs. I run the stock shroud and fan. Never go's over 180.

My 66 has a mild soild lifter 327 with cross ram webers. There is no vaccum ports. Stock Corvette dist. with no can at all. No room for it if I wanted one. Stock fan and shroud. Cars runs at 170 and I have been driving that one since 2006.

Point is the lack of a vaccum advance can will not make your car over heat. The kind of temps the OP is stating points to a major flow problem or cracked head or heads. But it is not the vaccum advance.

Brian G.

This has been a great thread for those of us without the problem. The OP has undoubtedly gotten a lot of good advice. Whatever the problem turns out to be it appears there was a problem in the vacuum advance of his car. Let's say he first threw a new DeWitts radiator in there and reported back that all the temp problems disappeared as so many do. Vacuum advance problem would then be covered up and still not right. So I see this as all being good in the end. OP will get it right in the end and may have corrected some other problems along the way. Good job guys.

Dennis:cheers:

It's been suggested several times. I would remove the thermostat. Takes just a couple of minutes to get that out of the equation.

I agree. As I said in another thread I've even seen them installed upside down!

Again, good morning and happy Friday everyone.

The level of quality responses could not be better. I thank you all for that.

So on to today’s update. The distributor was removed and tested last night and indeed modified the advance at just over 16 in Hg. The vacuum provided from the carb and manifold at idol were the same and were in the ballpark of 8-10 in Hg. So there you go. A replacement B28 advance and you can check that off the list.

Back to cooling.

This weekend I will be replacing the water pump and removing the thermostat for testing.

I'm running out of options so hopefully that's the end to this tale.

:iagree: I couldn't agree more. Good work guys.

I have not read this thread from the start, but one thought. Have you drained coolant, and refilled? I had a car that ran hot, ended up being an air bubble of sorts......damn thing just needed to be burped!