Technical Dual Carb Flathead Manifold Question

We're gonna use two carbs on our 37 flattie and want to be able to mount the generator in the stock position. Here's the question;

What is the difference in performance (if any) between an elevated slingshot style manifold (the carbs sit atop a wye that converges in the center of the manifold) vs. an Offy style manifold that has one carb centered and the second carb behind it?

Does the longer distance for the fuel to travel somehow affect the acceleration response?

Thanks for any help.

 

Almost all traditional sources credit the super duals with greater power, with the fairly tall medium rise type like Offy and Edelbrocks rated as having best overall performance...
I believe this is covered by actual dyno work in JWL's book, but for some reason I have not bought that yet. JWL is a person who never ever says anything not exhaustively tested on dyno and flow bench...

 

The long manifold would have more ram effect like the sixties Chrysler Sonoramic with ram manifolds or the late model fuel injection jobs. Doubt it would make a noticeable difference on your car.

 

Depending if you have a regular twin carb manifold this may suit you application better. We have an Almquist "Y" adapter on our 32 with no long runner issues at all as the heat risers are still in the original single carb manifold. But beware that these "Y" risers may cause hood clearance issues with tall aircleaners. The front 97 carb just clears the rear bolt on the generator by a couple of business card thickness. You will need to fabricate a carb linkage.

 

Longer runners move peaks downward, where stock flathead needs no help...the lowest manifolds like Fenton reputedly have reversion issues.
Main reason for the close-coupled manifolds was that putting a super dual on a flathead is a PAIN that requires multiple adaptations...move generator, probably have to figure out a new way to run a fan, get longer studs for the new generator, back to the store for new belts, now the wiring doesn't reach, etc. There was a serious market for the easy way once, when someone wanted to hotrod his daily driver and needed a way that did not lead to all sorts of issues followed by walking to work on Monday because he was out of parts, out of money, and the damn thing still wasn't all figgered out...

 

Im running the Offenhauser reg dual ( the one that lets you use the stock gen position) with dual 94s on two inch risers on my '37 and I love it!

 

Thanks everybody.

Bruce Lancaster, I agree with you. The set-up we bought with our engine calls for modifications everywhere and the end result isn't any better.

Slick Willy, that sounds great. neither of the two 94s we have have the stock throttle control at the bottom to allow the stock throttle adjustment attachment. Is it a big deal to take out that rod on our old carb and put it in the new carb or will we need a press?

 

I've been looking for a two-carb manifold that has enough space for an alternator mounted up front for my 60hp. Marvin

 

I'll let you know what we get Marvin CT.