Carter Thermoquad on a 350

[BlouDon]

I bought my truck with a Holley 1850.

The engine did not idle happy and I was convinced, based on fuel consumption, that it was running pig rich.

I had a spare Carter Thermoquad (the cousin of the Rochester??) lying around that came of some Mopar 440, which I had fitted to and tuned on my Jensen Interceptor (also fitted with Mopar 440).

I know the Carter has a very poor reputation but I recon its the Rolls Royce of 4 barrel carbs.

The elegance of the TQ is that, after removing the air filter:

• Idle mixture can be tuned by hand;
• Primary mixture can be tuned with a small flat screwdriver;
• Secondary mixture can be tuned with a smallish long nose pliers.

My SBC was fitted with the Chevrolet Performance 10185063 spread bore intake manifold which allowed me to bolt the Carter straight on, using a 3mm (1/8") self made cork gasket - which also has gasket running down the middle of the carb over the seperator. Only trouble is that I have no choke operation - yet.

This carb improved matters a lot but I was still not happy. Anyway, I had to repair an intake manifold coolant leak above #8. The Felpro gasket kit I had, also included EGR, blanking plates to reduce the EGR ports with smaller round openings. In our hot climate I would have preferred complete blocks, but there we are.

Since I had the intake manifold off, I noticed that there were round openings in the bottom of each plenum about 8mm (5/16"), allowing exhaust gas back into the plenums. These I also blanked off by tapping 12mm thread into them and installing bolts with Loctite 272 thread locker.

All this has improved matters significantly. She now idles nice and steady and really sounds happy at part throttle.

Next project: Out with TH400, in with 700R4.