The Stovebolt Site Forums The Shop Area Engine Shop Rochester B Insulator

I have read some of the posts on the Model B but still cannot solve the sooty plugs and dark smoke from the tailpipes.

I have a 56, 235 bored .040, new pistons, head redone, new hydraulic lifters, new coil, correct distributor .....
Has about 1000 miles.

I've rebuilt and tried three different model B and the same problem still exists. Polished the power piston, put in a new .058 jet. All springs and the 2 balls are in.

The gasket and insulator match, and look like the one on the top right [URL=http://www.thecarburetorshop.com/Chevygasket.jpg][/URL] in the pic posted by carbking.

The gasket does line up with the power piston hole on the throttle body and the insulator. I don't think that is the problem.

The throttle body has a second hole drilled at an angle, but this hole is covered by the gasket and the insulator does not have a hole for it either. Is this correct or do I have the wrong insulator.

If not what is causing the soot? Any suggestions?

Sounds like either you the weld plugs in the underside of the main body are loose and leking gas, or you may have a vacumm leak. Check all hoses, Dist. Vac. Adv. diaphram, choke pulloff diaphram and check the throttle shaft for play. If there is excessive wear on the throttle plate bore between the throttle shaft and bore you will have a vacumm leak and run rich. Check out my website, www.ClassicFastCars.com Thanks, Mark Greeno,

go to www.classicfastcars.com. there is a carburetor repair link there that I found very useful.

On the throttle bodys with two holes it is only necessary to have one of them exposed to vacuum.

Are you sure you have the timing advanced enough?

I'm not sure if the timing is advanced, but I have it set at the ball. Is there a better setting?

I had the 51-52 distributor and just removed it and installed the correct distributor. I saw your earlier post about the gear material being different and decided to change the dist. Thanks for the info.

When I "goose" the engine pretty hard and quick, is when I see the black smoke. After 10-15 minutes brand new plugs, 45's, are black.

Vacuum advance works fine, new intake manifold sleeves at the head, wiper vacuum at manifold closed.

Not sure if it is a car or truck engine, block casting 3837004, date Nov 3 55, stamped T56Z, head 3836848, if that makes any difference for parts or settings.

If the flywheel/bellhousing is from a 216 engine the ball is in the wrong place. Try timing it with a vacuum gauge and turn the distributor to get the highest vacuum reading at idle.

Curt B.

Good point Curt. That's a possibility because the intake & exhaust manifolds were a 216 and had no sleeves on the intake.

Never did vacuum timing but I'm about to learn. I'm guessing it's the vacuum at the wiper connection on the intake?

Right now, pump the gas once, turn the key and it starts faster than I can let off the starter even after setting for 4 days.

Is a 216 flywheel different than a 235 or is the pointer just in a different location or both. Anyway to tell the difference between the two.

216 flywheels have a different number of teeth so it's necessary to keep it when using the foot starter and correct motor mounts in pre 1955 trucks. The ball position is different on the 235 flywheel as well due to timing differences between the 2. Hook the vacuum gauge to the intake where the wipers go and try the following:

http://www.centuryperformance.com/vacuum.asp

Good luck,
Curt B.