Okay, this post is a little premature because I still haven't determined if my cam timing is off a tooth. But lets assume that my timing is 100% correct.

Having just done an engine swap, can anyone think of any possible reasons I might have a vacuum leak? What would be the most common causes?

Almost eveything from my original engine (which was running great) has been swapped over. The reason it seems I might have a vacuum leak is that the car could not run unless the PCV valve was plugged. This was determined when the valve cover was off. Not sure how it would behave when plugged into the cover, but I'd assume similarly. Is there a constant flow of air through the valve cover when it's on or does it create a vacuum?

I am not using EGR/Vacuum Amplifier. All that stuff on the carb is blocked off. No OSAC either. Just straight to the distributor on that. No power brakes or anything like that either. It's a very simple setup. I AM using the canister setup but I don't think that should matter.

When we ran the car after the engine swap and checked it with the timing light, the TDC mark was WAY in the before. Like somewhere between 30-40 degrees. Maybe more. The distributor might be advanced a tooth, but we couldn't get the car to run on the previous tooth.

I will post back tonight when I get out of work and finally figure out once and for all whether my cam timing is correct. But, in the meantime, can anyone offer food for thought on my possible vacuum situation or majorly advanced timing mark?

THANKS!!

-Matt

Any time you assemble a gasketed joint (carb to intake, intake to head, intake to exhaust, exhaust to head, exhaust to pipe…) you run the risk of creating a vacuum leak. Also, did you use the 1973 intake manifold, or the '72? If the '72, is it out of a California car?

The engine should happily run with the PCV valve on the end of its hose whether or not it's plugged into the valve cover. Answer to your question is "continuous flow".

The vapour cannister itself won't cause a vacuum leak unless it is badly damaged, but the purge line needs to be hooked up correctly. Double-check your carb ports to make sure you haven't accidentally hooked something up incorrectly or blocked off the wrong port; carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download.

Focus on one thing at a time; get the cam timing right, then the ignition timing, then go from there.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Hey Dan! It's good to hear from you, been a while. I'll take this opportunity to tell you again how wonderful the carb has been that you sold me! Kept my car running strong even with low compression.

I swapped the complete intake/exhaust assembly from the '73, but I must admit, I did re-use the manifold gasket I ordered from that Australian company you recommended. It might be shot at this point. I'm going to have to order another one. I might try replacing it (temporarily) with one of the ones that came with my engine gasket kit.

Tonight I'm going to determine my cam position once and for all. Then I'll put everything back together and double check that everything is hooked up right. I'll post back with my results.

THANKS!!

-Matt

Glad that carb is working well for you. Me, I never re-use manifold gaskets. The odds of it sealing properly are minimal. The '73 intake is fine, was wondering if maybe you'd wound up with a California '72 intake (w/floor jet).

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一期一会
Too many people who were born on third base actually believe they've hit a triple.