Yet another example of why even reading the question and answer forum makes my blood boil.


The main problem is a simple one. The fact that his timing was set a bit aggressive, and that he has a 160 degree thermostat and that the engine is undercarbed merely just aggravated it a little.

The engine has a MANIFOLD VACUUM LEAK. Plane and simple. You guys should have picked up on that in that the idle is inconsistent, and increases the more he drives and the engine is run longer while being so lean and the chambers get hotter and angrier, and also for the fact that he had the base timing pretty well up there, yet the vacuum was only 11 inches.
That lift and duration of camshaft in a split pattern with that compression should pull at least 15-16 inches of vacuum, and that would be with not too terribly much timing and the idle set lean (i.e. a bit of a worst case scenario for idle conditions).

Those who replied to the post before me must be the same group that called me stupid for mentioning a vacuum guage as the thing to have if someone were to get only one tool period for timing and tuning a carbuerated engine.

The original poster even expressed a concern about his phenolic spacer possibly not having a uniform sealing surface, and you guys didnt pay attention.

Ok, so original poster: I would like to offer you some actual help here. Get rid of that phenolic spacer, or buy a new one if you are unsure about it.
Remove and reseal the intake using ultra black RTV on every bit of sealing surface all around the bottom side of the valley pan gasket, and around every bit of port sealing surface on the top side of it. Also put RTV on the threads of all of your intake bolts, and torque the bolts properly at 35 ft lbs or there abouts. THEN you may retime your engine, and THEN you may redo the fuel mixture, and THEN check the manifold vacuum with a vacuum gauge and if it is still low and incosistent, ckeck anythign else that may be privy to said vacuum; whether it be the vacuum Tee on the intake, brake booster, nippled off ports on the intake or carb, PCV valve and hose, etc.

I hope the best for ya man. Get that top end resealed. I don't care if its a new motor. If you didn't build it, then why would you believe that the intake and valley pan weren't tossed on there more or less dry, etc?

Rant off, and guys, get your heads out of the clouds of complicated custom engine runability theory.