Won't idle/lean condition
 

I haven't been able to get my 66 tri power with a clone center carb to idle. On high idle works fine but once the motor warms up and goes to the low side of the cam it stalls out. Covering the end carbs no vacuum leak detected but when the center carb is covered rpm picks up, to me indicating a lean condition. I have drilled the idle tubes +.003 and the idle restrictors same. There are no holes in the butterflies. The idle speed screw is already turned to far in. The idle air screws are 2 turns out, maybe turn in? Any suggestions?

Sounds like you covered the common problems already.

What is the idle speed before it begins to stall?

Have you tried turning the mixture screws out? Two turns is usually close, but I'd try turning them out at least another turn before you do anything else.

What is the original application of the clone carb?

An original 1966 A/T 389 center carb has .030" idle tubes, top idle air bleeds, .046" channel restrictions, .033" channel air bleeds and .057" idle air bypass in the throttle blades.

Many 1959-69 Pontiac 2G´s are close to these specs, but other makes are all over the map, lots of work to make them work properly but it can be done, "the impossible takes just a bit longer".

Tried the idle mixture screws all different settings. It will idle at 1,500 but when the idle speed screw is backed off it stalls out. There are no markings on the carb for me to guess it's origin. Tried several different venture clusters drilled to different sizes. It seems like a vacuum leak somewhere. I'm ready to pull the tri power off and put on a 4bbl of known performance. The tripower is an aftermarket aluminum intake and all I can think of is a flaw somewhere in the intake. What bugs me is sitting next to it is a 455 powered 64 vert with tri power and no problems.

Improperly machined repro intake manifold was the problem. Enough of a leakage at the bottom of runners got past the gasket to cause my problems. If buying one also check for water crossover match to the front cover. A friends would need near 2 o rings to seal, let alone casting flash inside and terrible manifold to head match.

Parts Place intake ?

Yes, thru the auction site. I don't know if I can get any compensation since it's been in my possession over a year. Friends is new, I would categorize it as a 2nd. Fitment and finishing bad.

Sad deal is the original PY Aluminum Tri-Power Intakes were perfect and the later stuff seems to have a lot of issues.

Tom V.

X-2...……...hard to find but I got one a few years back and had it ported by Dave at SD...….his reply.

Hi Rich

Sorry for any confusion but all the aluminum Tripower intakes that have come through the shop in the past had horrible core shift so they required welding. I have the intake matched up to the 1233 size gasket and there is enough material for sealing.

I ported the runners and cleaned up the plenum areas off each carb opening.

It’s the best aluminum Tripower intake I’ve ever seen so far.

Dave Bisschop
www.sdperformance.com