mickatbp

Hi all,

I have a number of 1960 to 63 WCFBs at home plus one 1960 WCFB restored that I was going (am going to use on a single WCFB manifold - carbi rejected for a 327) BUT I've seen that you can buy a correct dual quad manifold for less than $300. I've also noticed that you can buy a clone dual quad with manifold for about $2000 fully restored and you can get a carbi restored for about $200ish and a linkage kit for about $70 and a fuel line kit for about $50............SO the questions.............. how much more juice does a dual set up suck compared to a single wcfb in normal running? Considering I can probably build a dual quad set up with what I already have for about $500.

I know that the dual quad setup uses a progressive linkage setup...........so does that mean during normal running only the primary throats of the primary carbi are feeding the engine and under mild accelaration the primary carbi secondaries open and if you give it a gut full of throttle the secondary carbi primaries and then secondaries come in to play............OR .......... are the both primaries of the dual quad always feeding fuel into the engine and only the secondaries are progressive.

I also assume 2x4s are jetted differently than a 1x4 (with the 1x4 having larger jets).......... is this correct? So if I convert two 1x4 carbs to a 2x4 I'll have to rejet them?

I'd like to know from someone who has driven similar C1s, one with a 2x4 setup and one with a 1x4 set up............ was there much difference in fuel consumption vs power and is the upgrade worth the effort?

Basically, how much more will it cost me to run the car with a 2x4 set up in miles per gallon comparison with a 1x4 and how much more horse power can I expect to achieve with a 2x4 set up.

I know the 1x4 looks cool, the 2x4 fantastic and the FI 'smokin hot' (but economically out of my reach).

Oh by the way I'm running a 327

Thoughts please

P.S. I may be in the market for a 2x4 manifold!!!!!

92GTA

My '56 had a 2x4 setup on it when I purchased it. I drove it that way for about 6-7 months before going back to the original 1x4 configuration. I'll also say my car still has an aftermarket Isky cam, a little more aggressive than the Duntov cam, that was installed in 1965 with the 2x4s.

I can't comment on the mileage (who owns/drives these with that in mind ) but I can tell you the power difference was very noticeable. I was running hotter plugs and still having fouling issues and idle was erratic driving in town during the summer (the carbs probably needed a rebuild). I always got a TON of great comments at shows with the 2x4s. It seemed like throttle response was more instant with the 2x4s, it for sure did use more gas, but then again it's allot more fun to nail the throttle with the 2x4s I think with a 327 they would scream! 2x4s on a 265 seemed like overkill to me but it was fun as hell.

If you don't care about being factory original, by all means go 2x4! From a performance standpoint I regret going to a 1x4 but my goal is factory original.

devildog

Michael,
I have run 2 x 4 WCFB's for 40+ years and 200,000 miles on my 61.

With a 3:36 ratio differential, I routinely got 18-20 mpg cruising at 70-75 mph.

With the progressive linkage you can easily adjust (shorten) the threaded rod if you want to be a bit more aggressive to actuate the front carb sooner. The front PRIMARY will open before the rear SECONDARIES. The front carb is closed until you more fully accelerate.

You can get a 2 x 4 manifold on eBay for usually $200-250. ? shipping to AUS ????

You dont need to change the jetting, the air-fuel ratio should be the same in either application 1 x 4 or 1 x4. However, the there are some slight differences in the WCFB's for 1 x 4 vs 2 x 4 set ups.

In the Service Manual for the C-1 Corvettes is a page with all the different models of WCFBs, configurations of the jet and metering rod.

I am out of the country so I can not scan you the page but Frank has a library full of WCFB info...he is a good guy about chiming in on WCFB issues.

I use a little smaller jet than what the original specs are. The original specs yield about a 13 A/F ratio...I try to get to about 14 A/F. If you can make TF30-P engines run, you will have fun with WCFB's

You will not see much difference in MPG using one vs. two. If you kick-in the front carb you will use a bit more fuel, BUT have a lot more fun!

Joe

Plasticman

Joe (as usual) is right on!

Running a 355 with dual Carter 500 Comp. AFBs (no chokes) on an Offenhauser intake manifold & headers, and typically see 16-17 most of the time, and have seen 23-24 on the open road. However, I do have a 3.55 rear with a .73 overdrive. And yes, you know when the 2nd carb kicks in!

If I go for short drives, the mileage goes down the toilet due to the evaporation of the fuel vaporizing in the carb bowls just sitting in the garage. I can smell the gas in the garage for the next 2 days, and by the 3rd day, I have to fill the carb bowls (longer crank times) to re-fire it. No carb leaks (these are not Holleys!). If I restart the engine within a day or 2 it fires right up. Just something to deal with when running ethanol laced fuel.

Plasticman

mickatbp

Good comments so far..........keep em' com'in

I also believe that the 57 and earlier carbs had the choke on the throttle body not the carbi base so using one of these earlier bases would also make the clone less noticeable......... will one of the earlier bases fit to a later throttle body? (I was also thinking of just cutting off the choke plate on the later base and attempting to replicate the sand casting texture) I asked earlier if the carbs were die cast alloy or cast aluminium as I'd planned on welding up the choke shaft holes in the airhorn but is was suggested that the easiest option was to turn down an aluminium rod and glue it in place with metal set/bond and then finish flush with the inner and outer surfaces of the airhorn .......... any other suggestions for this? You often see the apparent 'original' dual 2x4s for sale on ebay etc and either both have chokes or the second carb has had the choke shaft and butterfly removed but the shaft holes are very apparent........so much for original 2x4..........usually followed with the statement "I don't know anything about these early carbs" but they seem to know what a correct pair should sell for.

I know original can be important but mine is pretty far gone when it comes to original.........so I've decided original components and options that were offered in 1960 is good enough for me. I want it to look period correct but not necessarily accurate for what mine was when it roled off the assembly line..........Does that make sense?

With some added safety such as disc brakes and added economy and usuability with a 5 speed.

Economy is not that important but I don't want to go crazy either, 91 octane is $1.52 a litre (and 98 octane about $1.80) over here at the moment and one of my mates has a a big block in his Ford and gets 6mpg........I can't do that .......... for me that is just a bit too inefficient and I do want to drive it.........and drive it eventually!

Frankie the Fink

I've run a 1X4 on a 1X4 manifold; 2X4s on a 2X4 manifold, and a 1X4 on a 2X4 manifold (yes it's possible -- see pic). I've also run the one year only 1956 WCFB dual quads, the "real deal" 270HP dual quads and now "mutt" clone dual quads. The clones, strangely enough, have proven to be the most "streetable" and immune to percolation.

FUEL CONSUMPTION:

The beauty of the progressive linkage on the dual quads is that you have fairly granular control over when things happen. I can cruise on the back primary bores all day long and gradually pull in the secondaries, then the front carb primaries and finally the whole shebang with the front carb's rear secondaries. I would bet that running along gently on a dual quad is essentially the same as babying a single carb...with the difference that the fuel distribution is different across the cylinders somewhat. I haven't measured lately but with my 5-spd overdrive and clone carbs I've seen 18-20 miles per gallon (and a tad higher in a couple of cases) on interstates. I can put that number in the toilet sitting at city stop lights or putting my foot into the carbs.

Soooo...you CAN get close to the same mileage with either setup if you drive like a "Nancy boy" all the time. That won't happen because the endorphins released when you floor a dual quad car demand that you do it at least once in a while....

PERFORMANCE:

Typical WCFB flows 384cfm...so two of them (in THEORY) can flow 768cfm...however that is VERY dependent on the rear flappers in the carbs, your cam and other vacuum characteristics of the engine. Yes...you can reconfigure WCFBs nearly any way you want...some have 2-step metering rods, some 3-step rods -- springs for the vacuumeters vary depending on the carb and jets can be diddled with.

When you get them tweaked however the enormous wow factor, fun and acceleration gain on a 2X4 setup makes that the overwhelming choice for me and the gas consumption is a secondary issue.

Who has a choice in restoring a part of a Corvette and if their budget and originality criteria permits says, "....Oh Yeah - please give me the low performance option. Thank you very much." ??

toms silver 60

You can set them up internally and externally in almost infinite combinations to ring your chimes, but there will be a great temptation to step on it which will totally blow your mileage. The previous posts all have valid info.
If you are just doing local stop and go driving, you're pretty much screwed with regards to making valid mpg comparisons on any changes, other than staying out of it or not. That will show up real quick!
30+ years of driving my 60 to work on a 50-100 mile daily trip was great opportunity for doing mileage test loops. Factors include gas tank fill procedures, size of air cleaner, disconnecting secondary or carb linkages, blanking off carbs, jet/spring/rod changes as well as your normal tuneup tweaks.
Recommend you find a good 100 mile test loop with minimal stop/go driving, get your baseline, install new setup, repeat, see what happens providing you keep your foot out of it! Then tweak as desired.
Remember there is a good 1-3 gallons difference capacity in how you fuel your car which makes a major factor in calculating mileage. That is why you need to use a good half tank or more when checking mileage.

Oh Yeah, get those extra carbs. One carb is ok, two are great and three are even better! Bling is cool!

devildog

Michael,

When you install your 2 x 4 WCFBs, be sure to use an insulator to keep manifold heat from vaporizing the carb fuel. Makes hot start easy like you had EFI.

Frank uses a phenolic spacer/insulator, real WCFB men use wood



I just used the gasket as a pattern to cut out 1/4 inch plywood.

Joe

mickatbp

Yeh I'v seen those phenolic spacers. What about those question re. the different carbi bases ie. earlier carbs with choke mounted on the throttle body vs later mounted on the base and compatability and blanking off the choke shaft holes in the top of the secondary carb. I must be a 'Nancy Boy' because I was going to get me some of those phenolic blocks.............do they really make that much difference? Is the a 2x4 manifold that I should be chasing (part number wise) and any specifics I need to make sure are fitted or not broken.

Also what about those powerpack / double hump heads?

Ta

devildog

You want 3739653 as in picture 1957-61 (there is a different one for a few 1956 2 x 4).

You can put 2-3 gaskets as an insulator. These WCFB's have smaller bolt pattern than the common later carbs...I do not think you can buy spacers, Frank had his made I think.

The power packs (diamond on end) were the ones in 1960, but use the double humps 461's because they flow a little better. If you get new heads, buy aluminum which flow much better

Joe

MikeM

Based on what I remember from almost 50 years ago.......................,

A 2X4 setup on a 240 hp, 265 '56 Bel Air was worth a lot of noise and about a car length plus in a quarter mile drag race.

A 2X4 setup on an other wise stock 327/340 engine vs a single WCFB was worth some noise and a solid two car lengths in a quarter mile drag race.

As I remember, the car was also quicker with the two WCFB's than it was with a single AFB on a cast iron intake manifold.

I was doing some experitmenting at the time. The car also ran as well with the 2X4 WCFB's as it did with a four barrel Holley on aluminum hi rise.

I don't understand all this stuff about carb spacers, percolation, dry float bowls and hard hot restarts. I can let my 327/250 hp engine sit for 2-3 weeks after parking it hot and it fires right up. Not so with a similar 327/300 hp engine with AFB though.

Frankie the Fink

I did make mine; however an eBay vendor has recently started offering these:
http://cgi.ebay.com/ebaymotors/WCFB-CARTER-HEAT-BLOCKING-SPACER-1-4-BEST-GRADE-MADE-SAVE-CARB-/180723231279?pt=Motors_Car_Truck_Parts_A ccessories&hash=item2a13f1aa2f

This product could be easily modified for the dual quad figure-8 pattern if desired. However, I always tell folks to block of the intake manifold heat riser passages first to reduce/stop percolation and then do the spacers if that didn't do it.

There is nothing to understand about percolation in these carbs...it happens a ton. I get several emails during each week asking about spacers and how to stop percolation.

jdk971

mpg on these old engines is always the foot. jmho jim
ps i would not worry about it. have fun

mickatbp

Yeh, I've seen these spacers......should this 'nancy boy' go for a 1/4 or 1/2 inch thickness (I'm too weak to carve out some ply)? How does this go with hood gap (especially the 1/2 inch) as I've heard some say they've damaged their air cleaner from closing there hood ........... is this even possible

Frankie the Fink

I, and several others on here, are using the 1/4" spacers that I made out of phenolic with NO hood clearance problems. Thicker than that and you will have clearance issues. To test, install the spacers and then put some modeling clay (child's play dough if you want) on the front of the hood and close it SLOWLY and see how much space is indicated by the test material. The other thing you will need is carb mounting studs that are 1/4" longer...they aren't hard to find and I got mine at a local parts outfit. Finally, I put nylon washers under the carb mounting nuts to reduce heat transfer at those points as well.

Between the spacers and blocking off the intake manifold heat riser passages my fuel bowl temps (confirmed with I/R temp gun) dropped about 25-30 degrees and percolation stopped.

mickatbp

These heat riser passages in the manifold (manifold that I don't have and haven't seen one in the flesh) are easy to see and identify - Does someone have a picture?

I must admit that even with the 1x4 my garage stank from petrol fumes for quite a few days after I parked it - the boss was not happy as the garage is attached to the house and our bedroom is above it............ was not at all happy!!

I think I'll get the 1/4" spacers........... how do I need to modify these for a 2x4 setup?

Thanks guys, all of the info so far has been really helpful.......... Frankie the Fink is a fountain of knowledge (as are the other guys) but Frank-T-F has helped me out on many occasion with his straight forward advice.

Frankie the Fink

Here are the heat riser passages circled on my car. All of the major Corvette vendors have the fuel injection intake manifold gaskets that block off these passages (about $30 USD)

This has the metal plate that blocks off those risers. You may find when you block these off that you car doesn't have any more percolation issues so you could stop there with any more modifications (e.g. spacers) although they won't hurt.

You could use the spacers on eBay "as is" or, if you want the figure-8 pattern to match the manifold take an old manifold-to-carb gasket and mark out the figure 8 on the spacer then CAREFULLY cut it out with a jig saw or hacksaw (phenolic is tough stuff; so cut the "hardest" material for your tool's blades that you can find). Even better contact the eBay seller and ask him if HE will modify the spacers and sell them to you.

The fuel smell which is 99% eliminated on my car can be from a multitude of causes. Vented fuel cap (it should be non-vented) bad or missing gas tank cover gasket, blocked drain line under the gas cap filler door, bad weld on gas tank metal filler neck....more stuff too. But, one thing at a time.

Thanks for the compliment....I do bumble around and hit on a solution that works once in a while and I certainly try to share it.

JohnZ

If you block off the heat riser passages, make sure you either wire the heat riser valve open, gut it, or replace it with a spacer; otherwise the right bank exhaust gases have nowhere to go at cold start.

Frankie the Fink

Very true...you also might not like the change in the exhaust note as this mod changes the harmonics....a crossover pipe between the exhausts on each side restores the sound (just like the fuel injected engines have) !!! My crossover was $85 installed at the local muffler shop.

mickatbp

Good, I have the crossover tube on my system. Can I leave the heat riser out all together or is the exhaust tube length such that it or a spacer must be used? I live in Queensland and where we are we only get the lightest frost for about one week in winter and the rest of the time the weather even in winter is quite mild so cold (freezing cold) starts are not really an issue.