TRI-POWER IDLE ISSUES
 

JUST INSTALLED AN ALUMINUM TRI-POWER INTAKE ON A 462 PONTIAC,( KRE ALUMINUM HEADS). I USED MY ORRIGINAL (HOME-RE-BUILT) FRONT AND REAR CARBS FROM A 4 GEAR 1965 GTO.( I CENTERED THE THROTTLE BUTTERFLYS. REF DAG123) THE CENTER CARB IS A BRAND NEW (RE-BUILT) FROM XXXX. I COULDN'T USE MY ORRIGINAL 1965 CENTER CARB. IT HAS A SMALL BOLT PATTERN AND THE MANIFOLD HAS A LARGE BOLT PATTERN.



I TRIED TO START THE CAR BUT COUDN'T GET THE ENGINE TO IDLE. TURNED THE IDLE SCREW TO MAX BUT STILL NO IDLE : JUST START AND DIE. I CAN GET SOMETHING LIKE AN IDLE IF I CONTINULLY FIDIGET WITH THE FOOT FEED BUT 3000 / 4000 RPM IS NOT A STREET CAR IDLE.

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PREVIOUS TO THE ALUMINUM TRI-POWER INSTALL, I HAD AN ALUMINUM (EDELBROCK) INTAKE AND HOLLEY 780 (LIST 3310). THE CAR RAN JUST FINE WITH THE HOLLEY. IN FACT, (BACK IN THE DAY), MY '65 GTO RAN JUST FINE WITH THE IRON TRI-POWER BEFORE I REMOVED IT : 30 YEARS AGO.




SO, I CALLED XXXX AND WAS TOLD THAT MY (HYDRAULIC ROLLER) COMP CAM (224* TO 230* DURATION) WAS'NT PRODUCING ENOUGH VACUUM TO ENGAGE THE IDLE CIRCUITS IN THE CENTER ROCHESTER 2 BARREL. SUPPOSIBLY, I HAD TOO MUCH DURATION IN THE CAM. THIS EXPLANATION SEEMS NOT TO BE LOIGICAL. WITH A BIG CID ENGINE THEIR SHOULD BE PLENTY OF VACUUM THROUGH THE SMALLER 2 BARREL ROCHESTER AS OPPOSED TO THE 2 FORWARD BARRELS OF THE HOLLEY.




BUT, I STILL HAVE AN IDLE PROBLEM. ANY IDEAS ? ? ?
:confused:

I have a KRE-headed 462 with a Comp hydraulic roller cam with 236/242 duration and it runs just fine with a stock '66 tripower setup.

Make sure your end carb butterflies are sealing tight at idle, if they are open AT ALL it is a huge vacuum leak and it will never idle.

Do your end carbs have idle circuits? That could also be a problem, tripower end carbs don't have idle circuits so I'm thinking those would have to be blocked off too.

Just block off the rear and the front carbs with either plates or make thick gaskets with no throttle bore holes for the end carbs and regular mounting holes. Disconnect the secondary linkage. If the engine idles of you had a air leak on the secondary carbs.

If you still have the issue with the front and rear carb air flow blocked, then the center carb is not calibrated properly. The engine should run fine only on the center carb.

Tom Vaught