[2+2=421]

I have a 66 2+2 421 tripower car, tripower worked great as it was restored by Mikes tripowers several years back. I just had the engine rebuilt, put 1968 #16 heads with forged dished sealed power pistons and a comp cams xe268h cam, long branch repro exhaust manifolds etc. now when i go around a corner the car is dying out temporarily untul it gets fuel or something. Is this due to the car using more fuel with the bigger cam and more HP? Or is it just coincidence and a float or jetting problem? Car never did this before the rebuild. I may have 40 miles on the rebuild.. any suggestions please?
Thanks
Andy

[1969GiPper]

Originally Posted by 2+2=421

I have a 66 2+2 421 tripower car, tripower worked great as it was restored by Mikes tripowers several years back. I just had the engine rebuilt, put 1968 #16 heads with forged dished sealed power pistons and a comp cams xe268h cam, long branch repro exhaust manifolds etc. now when i go around a corner the car is dying out temporarily untul it gets fuel or something. Is this due to the car using more fuel with the bigger cam and more HP? Or is it just coincidence and a float or jetting problem? Car never did this before the rebuild. I may have 40 miles on the rebuild.. any suggestions please?
Thanks
Andy

Left turn? Right turn? Or both?

[Simple Man]

How much fuel is in the tank? Filters clean?

[geeteeohguy]

Suspect a low float level in the center carb. Classic symptom.

[2+2=421]

Left turn

[2+2=421]

Fuel half tank, new filter, ran fine on old motor a month ago

[2+2=421]

Ok, i tgought once the float was set it really couldnt get altered, not true your saying?

[Radman]

Hard turn or gentle turn? Right, left, or both. First think float in center carb as someone else suggested. Other thought is wiring moving and shorting the ignition.

[1969GiPper]

Originally Posted by 2+2=421

Left turn

It may not be a running out of gas, it may be a flooding condition causing a momentary stumble. Could be caused by a sticking needle in the seat, an incorrect float level or a seat that has become lose and started to unscrew from the air horn. I had the seat loosen in the front carb on my 65 setup.

[geeteeohguy]

Originally Posted by 2+2=421

Left turn

I'll say it again: classic case of low float level. The discharge jet is on the left side at the bottom of the float bowl, and is the first thing to run dry on a left turn if the float level is off. I would first eyeball the wiring at the bulkhead connectors near the steering column in the engine compartment, then I would drive the car and see if it dies on RIGHT turns. If all ok, the next step is to pull the top of the center carb (5 minute job) and verify the float level and float drop.

[2+2=421]

Well, I rebuilt carb, reset float 3 times, put a phenolic plate on it and it still chokes out on left turns. I am embarrased to say but i fixed it,, the ground strap from drivers side head to the upper control arm was a little lose and had dirt and grease between th3 strap button and the bolt, causing intermittent shorts making me think it was fuel.. weird thing is i checked both ground straps for being secure and they were..but i didnt wiggle side to side the one under the rubber flap on the A arm.. once i wirebrushed the holearea, cleaned the braided strap and reattached nice and tight no more problem.. what a lesson..thanks all

[geeteeohguy]

Originally Posted by 2+2=421

Well, I rebuilt carb, reset float 3 times, put a phenolic plate on it and it still chokes out on left turns. I am embarrased to say but i fixed it,, the ground strap from drivers side head to the upper control arm was a little lose and had dirt and grease between th3 strap button and the bolt, causing intermittent shorts making me think it was fuel.. weird thing is i checked both ground straps for being secure and they were..but i didnt wiggle side to side the one under the rubber flap on the A arm.. once i wirebrushed the holearea, cleaned the braided strap and reattached nice and tight no more problem.. what a lesson..thanks all

Thanks for the update! Sometimes it turns out to be the dumbest/simplest thing. Glad it's fixed.

[Greg Reid]

I'm trying to keep up here, so help me...How does a loose chassis-ground cause the engine to cut out?
I could understand it if there was part of the ignition system shorting to ground or something like that but I'm not understanding he loose ground cable causing the problem described.
???

[Old Goat 67]

The problem would be properly described as "intermittent open circuit".

Remember the circuit has to have a complete path to function properly. The ground side is half of that.

[Greg Reid]

I don't doubt it Charles and I know what you're talking about...It's just that I've have driven these old cars with the battery completely taken out of the car once it's running. Considering that we have several parallel ground paths in the circuit, it would surprise me if one ground strap caused the car to go dead.
Not arguing with ANYONE, just trying to understand how that happens.

[Old Goat 67]

That kinda surprised me also.

[Simple Man]

Originally Posted by Old Goat 67

The problem would be properly described as "intermittent open circuit".

Remember the circuit has to have a complete path to function properly. The ground side is half of that.

It would seem, that the rest of the grounds weren't doing their job, if the one mentioned caused the problem.

[Greg Reid]

Exactly guys. My analogy was a bad one though once I thought about it. The battery only needs to be grounded to the block and starting equipment. All the other stuff does rely a lot on the body and chassis grounds but one loose one causing the car to cut out tells me that the o.p. needs to shore up all those grounds under the hood.
Might be replacing the shifter cable pretty soon.

[Dick Boneske]

Why is it that so many problems with Tripower Pontiac engines blamed on the carburetors? Functionally, the center carb is identical to the single two barrel versions, but you almost never hear people complain about carburetors being the problem with those engines.

This reminds me of the 1970's and 1980's when synthetic oils first were used. Any time an engine failed, if synthetic oil was in the crankcase, that was pointed at as the cause. I can't remember is it was Jon Havens or Jon Hardgrove who said "90% of carburetor problems are electrical." That may be a bit extreme, but the above thread is one example of that syndrome. Just some food for thought.

[mgarblik]

Originally Posted by Greg Reid

I don't doubt it Charles and I know what you're talking about...It's just that I've have driven these old cars with the battery completely taken out of the car once it's running. Considering that we have several parallel ground paths in the circuit, it would surprise me if one ground strap caused the car to go dead.
Not arguing with ANYONE, just trying to understand how that happens.

I think you make a good point here. In order for the OP to have the problem he described, multiple grounds have failed, by design. He fixed the one that he found, which is great because the symptom is resolved. However, when he has some spare time, I would go through and clean all the under hood ground straps in a similar way. These kind of issues can really wear you out. Glad it's fixed.