I just installed a three duece setup on by 350 small auto. When I slip into gear it goes to pieces and will die out when I brake. no vacuum leaks, good timing and spark, 2500 stall. 17 lbs vacuum at idle, 14 under load. please help!
Sounds like a vacuum leak I had the same issues with my tri set up, no apparent leaks anywhere ,gave in and resealed every thing and problem solved.Hope it helps.
Are the outboard carbs closed when the throttle is at rest? It seems the biggest problem that folks have with "three deuces" is the secondary carbs don't shut completely or seal tight at idle. Only the center carb should be slightly open at idle.
Try this. Unhook the end carbs, make sure the end carb butterflys are shut, spring them shut, whatever, see if it still does it.
My bet is the end carbs. They are just big vaccum leaks waiting to happen. One of the tricks is to use JB weld ,or similar stuff, to build a little shelf for them to seal against. There are better multi carb guys on the board than me so I'll let them explain what I'm talking about. Dick York (dickster27) did mine and they work great. Try blocking off the end carbs and see how it runs.
If you have the correct bases on the end carbs they won't have idle mixture screws. My J2 Olds did the samething. The throttle blades weren't sealing to the base and created a vacum leak
I have a vintage speed set up and my outer carbs wernt sealing at the butterflies either... Went arount with spray and couldn't find it either.. Blocked the carbs off with rags over the tops and noticed an inprovement.. Then took them off and made block off plates... Ran a million times better.. Then rebuilt the outer bases problem solved... For now?
What kind of carbs are you using? Are they junkyard fresh or have you done any rebuilding or modifications to them? Are you using a mechanical or vaccum advance distributor?
Give me a call and I'll help you solve your issues. I'm sorry, but if try every suggestion here you will have worn your carbies out before they are adjusted correctly. 317-417-3202
Hey have you looked at the power valves? I know when running multiple Holly 94's on a Flatty you have to lower the power valve size to accomidate the drop in vacumm in a multiple carb application. Just a thought.
When the car is at idle cover the tops of the two end carbs. If engine speed changes your vacuum leak is the throttle plate(s) not sealing. Simple fast test for something that is very common. Been through it. And if the throttle plates are leaking you will never get your system to run right. Take Dickster27 up on his offer.
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