Funfer2 go to cobraautomotive.com they have sandcast reproductions of the original valve covers available.

First up, what engine capacity, compression ratio, and camshaft?

Something else is going on here, either carbs are synced well enough OFF IDLE, or needs the third hole for progression.

A 70 idle with 85 air?

double post

393 stroker engine Schneider racing hydraulic roller 4022W 238/248@0.50,112 degrees

Can't tell you the compression ratio but it runs well on high octane pump gas.
This engine ran like a striped ass ape on my speed demon carb.

Nothing against Jim Inglese, he has been around a LONG time.

But something is not right with this setup.

The mixture screws should only be about 3/4 to 1 turn out from seated, if the idle circuit calibration is correct.

Your cam is not overly wild, so it should idle quite nicely, once set correctly.

Have you synched the carbs with a synchrometer?

How far open are all the butterflies to get the engine to idle?

It idles nicely it is only when the maintain speed is reached that the studded occurs. We bumped the emulsion tubes up and the problem got worse. So evidently too much air. Now he is shipping a lower air emulsion tube and we shal see.

Oops the sync has been done and the butterflies are closed at idle.

What emulsion tube do you have now, and what tube is Jim going to send you?

Butterflies closed at idle? or open by 1/4 turn?

Sorry for the long delay but I have not been able to get the site up for a while.

He is sending me a 75 emulsion tube for the idler circuit. The butterflies are closed at start until I give it some throttle. The mix jets are open about 1 turn to 1 1/4.

We'll wait to see what arrives from Jim.

Emulsion tube should be Fxx (F2 - F20 etc).

What is your current emulsion tube, F7?

The current tubes had 120 stamped on them but he had soldered closed the 120 hole and drilled a .85mm hole. Now I am closing off his 85mm hole and drilling 75mm holes in them.

Hopeful to get them drilled today and try tonight.

I think your referring to idle air holder that your re-sizing for .75 from .85 idle air holder.
Emulsion tube is what is found holding your main fuel jet and main air jet.

Carmine thanks for the correction, I am still a student in learning mode lol.
However I did plug the .85 and drilled it for a .75 and here is what I found. The hesitation at speed was still there while the huge bog down when I put my foot in it was gone.

If I took the idle mix screws to 1/2 open the hesitation was better but the throttle response was defiantly worse while idling in the garage and quickly bumping the throttle.
Throttle response liked having the mix jets opened more.

By accident I did find that if I cover the air intakes on any of the rear two carberators that would be all four rear air inlets one at a time the rpms pick up.

Do the same to the front two carberators and it would either slightly go down in rpm or try to die.

Sounds like the rear carbs are lean at idle.

Can you post as much detail as you can about this whole combo please?

Engine and capacity, camshaft profile, compression ratio, ALL carb details - main jet, emulsion tube, air corrector, main venturi, idle fuel and air sizes, pump jet, pump exhaust.

Gary

Ok talking with my buddy who does engines he told me to go home and put some propane into the oil fill and see if the engine rpms pick up. His comment was if the angles of the new intake manifold did not seat correctly on the bottom with the head for whatever reason this would show that was the case.

I really hope this does not work. ��

I think your buddy is on the right track. I was having problems with my webers when I first put the engine together, nothing seem to work, backfiring on drivers side only on de-cel. Finally decided to put 4 barrel set up on, and while doing that, noticed uneven intake surface on drivers side head. Smoothed it out by hand with a file and installed 4 barrel and problems were gone. Intake gaskets couldn't seal the way it was. When I pull the engine I'll have the heads surfaced, and try the webers again. It's the kind of challenge I like !

Ok I am not an engine builder etc and know enough to be dangerous, but this one is beyond me by a mile.

Any help here would be appreciated.

So the rear 4 air intakes on my Weber’s when covered appear to pick up a little rpm and not stumble the engine as the front 4 did.

So I put about 30 seconds worth of regulated propane in the oil fill spout to attempt to see if I had an intake gasket leak on the bottom of the intake as the top has yielded no indications of a leak on top with carb cleaner sprayed everywhere.

So the engine did not care at 30 seconds and there was no increase in rpms. Now here’s where it gets interesting.

I wondered if I was putting enough volume of propane in the cavity so I ran the hose over number 8 air intake and the rpms jumped right up. But the test yielded that the rear 4 numbers 7,8,3, and 4 all increased when the hose ran over them.

However numbers 1,2,5, and 6 all stumble and want to kill the engine when the hose is ran across them?

How Is it possible for 1/2 of the engine to want one thing and the other to want something else? The idle jet holders are all the same jets and air bleed hole size. I can tell you that even when I had my Demon carb on the engine the rear mix screws did not get the same response the front ones did.

On the Weber’s I can screw the mix screw all the way in on the rear 4 sets and it does not even stumble but the front 4 will almost kill the engine with the same adjustment.

Sorry but totally at a loss here and could use some advise.

Thanks
Kirk

Sounds like the rear carbs are open too far in relation to the front.

What did you use to balance the carbs?

Know nothing about webers but is it not possible that some of your cam lobes have been wiped?

I used a velometer to balance the air flows so I know the air is correct. That was also my next concern was the cam lobes?