has anybody ever mounted carbs directly to the heads. i'm starting to do rough work on what it will take but i would like to know if someone has done it yet

Alfa 33's with the flat fours (1500cc or 1700cc) used carbs on each head. Only they had more of a EA82t style head, two inlets. You'd need to build custom manifolds and a custom linkage for choke and throttle. Other then that you might need a jointing pipe (made from alloy I would recommend, not rubber) between the two manifolds to normalise vacuum between the two. Just a lot of fabrication work. And you will need two new carbs. Some webers would do the trick!

 

 

I have the standard EA81 dual carb setup we got here in Aus. Uses about 20% more fual and gives about 10% more power. This setup will alos bolt onto a EA82 I believe with no troubles. But you'd be looking at $300 for the manifold and another $100 on shipping :-\

It was done on vintage JDM EA81 race engines. There's pictures in the USMB galleries. It's no different than VW dual carb setups - you just need to rout the coolant passage from one head to the other. Everything else is the same as any other dual carb engine. The carbs have to be syncro'ed, and VERY carefully tuned. And you do need a vacuum pressure equalizer hose.

 

... you will want to use the EA82 MPFI heads - they flow better. And you'll need to change the cams, and possibly the compression. Probably best to just start with an EA82 MPFI for it's higher comp. anyway.

 

GD

you just need to rout the coolant passage from one head to the other.

And also do something for a thermostat housing and radiator hose.

i like this idea.. (the whole dual carby method)

 

but has anyone ever given a thought to using sidedraft carbs??

 

i only ask because with my Zcar heritage, its what im most familiar with anyhow. I know it may seem sorta dumb to make everything flow that way when we have the flat engine, but im curious.

Downdrafts are superior for this application - you don't want the air taking a 90 degree turn. That's the whole point of mounting them on the heads is to get rid of the turns and twists of the manifold, and eliminate the heat of the coolant passage.

 

GD

2 issues to consider. The first is that the shorter intake length will raise the intake's optimum RPM considerably; not a bad thing if everthing else is modified for, say, a 6-8k RPM torque peak. The second is that the stronger induction pulses will make the jetting richer than it would be as a single carb feeding more cylinders. Not too much of an issue with Weber/Solex/D'ellOrtos, where one is expected to tune for such conditions, but might be difficult on lesser carbs.

i'm good at finding overcomplicated solutions to simple problems...hears my goal i'm looking for peak power between 2500 and 6500 and i figured this would be the best way to do it. i'm also looking for improved throttle response but what i'm looking for i think would be beyond a single Weber

SPFI, and change the cams.

 

Your engine already makes peak power in that range, so that leaves throttle response - SPFI FTW.

 

GD

i was hoping to leave this one carbed, its one of the few things my dad and i can still do together (i'm 22 now and its getting a bit harder), but thanks everyone for your responses