Steve59

Just got back my dual 4's rebuilt by Bob Kunz. Magnificent job. I should have taken before and after pics. These carbs are museum quality.

If it ever warms up around here, I'm planning on pulling the single 4 intake and replacing it with the dual 4. That doesn't seem to be much of a problem but my question has to do with the distributor. I current have a vacuum can advanced dist that has a Petronix III in it. I want to reuse it with the new duals, will I have enough room to reinstall it and time the engine? It looks awfully tight back there with the coil, intake runners etc.
Steve

Frankie the Fink

I run the same setup with a complete Pertronix distributor installed with vacuum advance....it'll fit. It'll even fit if you want to cobble together a PCV system.

Decide now if you'll use F/I gaskets to block off the intake heat runners; I would.

If you 'clock' the distributor as shown you'll have no problems; the timing will adjust, the vac can will not hit anything and the shielding will fit

Steve59

Frank:
Thanks for the pic. Looks mighty crowded back there. I will do what you did. Also, I am planning on using the "block off" gaskets on the intake although I've used the regular ones on my 1x4 for almost 40 years without a problem.
Steve

DZVette

Steve
I run mine like Frank's is setup. That vac fitting is in a tight spot on the rear carb. I used the 755 fitting from Paragon to get the vacuum for the advance unit. The nipple screws out of the fitting so that you can get a wrench on it. Tighten it up and orient it so that you can screw the nipple in. The fitting shows in the pic below along with the numbered plug wires.
Dave Z

Frankie the Fink

If you use the Paragon fitting for the vac advance as DZvette had done; you'll have no problem. My PCV setup required me to drop the rear carb fitting below the rim of the distributor where it was hitting -- so things got a little complicated

MikeM

I believe you'd be about as well off using the stock dual point and speeding up the timing curve instead of having all that stuff crammed back there in one spot.

Frankie the Fink

Sure - if you run at WOT all the time....

I'm down with that...

devildog

Steve,
Pleased to see you are joining the most elite Corvette group...2x4 WCFB Carb Club. A couple of suggestions to add to the usual fine advice from Dave, Frank, and Mike:

1.Do not forget you have a vacuum port on the back of the front WCFB, the California Corvette's had an RPO for a PCV (no draft tube) that was fitted to the FRONT carb. No need to fight putting PCV port on rear WCFB

2.Frank loves his Petronix vacuum distributor; however, I combined Mike and Frank's suggestion. I use my original Delco dual point Mallory distributor with a Petronix module replacing the points. It is very drivable and got good mileage 20MPG highway with no vacuum when I had the 283 in it (now I have a 400 DART and mileage is reduce a little).

Petronix has a module that emulates the dual points used on Corvette, Chevy FI and Stude Hawks & Avanti.

3.For sure block off the heat passages on the intake gaskets, most gaskets come with little metal plates.

4.Be sure to use an extra insulator under the WCFBs to stop the heat transfer to the heavy base on the carbs. I recall Frank made some from a polymer, I used 1/4" oak plywood (gasket was templet to cut). I have no vapor starting problems even in our Texas heat.

Plywood spacers are an old racers trick and great for 'bench racing' over beer conversation.

Runs and starts (even hot starts) like it was EFI.

5.Buy a $75 digital timing light with RPM readout to do a 'LARS' tune to be sure you have optimized the ignition advance.

6.Ask what jets and metering rods are in the rear WCFB, I find using a larger metering rod in the rear WCFB to increase the A/F ratio a bit makes for better performance. But, do 1 - 5 first and we can play with A/F later.

Joe

Steve59

Guys thanks for all of the advice and especially the pics. As to the technical aspects of the carbs (jets, etc), what ever Bob Kunz put in them is what I'm going with. I'm not that technically competent when it comes to the finer aspects of the WCFB's.

I will be using the block off gaskets on the intake . Kunz said that that should be enough to keep the carbs cool, but personally, if I ever find 1/4" phenolic spacers, I'd really like to use them.

I want to use my vac advanced distributor because it's already set up with the Petronix III, so It's just a pullup and then reinstall.

Frankie the Fink

OK. WCFB carb heat insulators (phenolic) are now available off-the-shelf:
http://dashman.net/product.html?id=203 but a little pricey.

Second, if you block off the intake heat passages the wire open the passenger side exhaust heat riser or replace it with a spacer, or, when the engine is cold; the exhaust has no where to go on that side !

Third, if you tell Mssr. Kunz what you're running he will set up the carbs at, or near, perfection...make sure you insist on the anti-stall bushings too !

Frankie the Fink

Far be it from me to dispute JohnZ, but the '61 AIM is misleading in this regard. It kinda implies, IF, its a 2x4 setup that the front (FRT in the drawing) carb gets the PCV valve.

My setup is currently run to the front carb....works fine

wmf62

John
will it work if connected to the front instead of the rear, with no detriment?
Bill

MikeM

If your driving style is such that the front carb never or rarely opens, you have lost the benefit of the PCV system. Carb has to be open at least under part throttle to pull out the gases.

JohnZ

Frankie and Joe, you're absolutely right - I missed the "front carburetor" note in the diagram in Noland's book (I don't have the '61 A.I.M.). I'll delete my erroneous post.

Y0GI

Yes, but: "Includes free gaskets, nuts, and washers." (!) Such a deal!

Yogi

Frankie the Fink

Errr...that would be a "no". Just like with vac advance...that rear fitting is pulling full manifold vacuum below the throttle plates; regardless of which carb it is on.

I use that fitting with a vacuum gauge, at idle, to set carb mixture...on both my '61 and '63 WCFBs...
Full crankcase scavenge at idle is one of the benefits of the PCV over the road draft tube

MikeM

Yeah, that sounds right.

Steve59

My passenger side heat riser has been wired open for 35 years and is probably frozen open by now. I'm also still running the road draft tube and will continue with that for a while. I told Bob what I was running and have the carbs back, so whatever is in them, I'm going to run with.

Frank, I do have one additional question about those spacers. The dual quad manifold has that weird open hole set up, what Kunz described as "Siamese" intake holes. Will the spacers that you referenced above work with that "Siamese" set up?

Frankie the Fink

Properly sized 4 hole spacers should work fine; even on the "figure 8" manifolds...prob a little add'l air turbulence but those manifolds feed into 4 distinct holes sooner or later anyway as that's how the base of the carb is configured.

HOWEVER, I would hold off on the spacers until you confirm you need them. With the intake heat risers blocked off you may be fine already. I wound up removing my spacers after that change because I no longer had hot restart/perc problems

If you notice my extra long carb mounting studs in my last picture post -- that is because I removed the spacers and never went back to the shorter studs

MikeM

I would not plumb the PCV to the front carb because when NOT running progressive linkage, that end of the engine is already running leaner than the rear cylinders so why introduce the calibrated vacuum leak in that end of the engine that is already a little leaner.