Testing for Vacume Leaks

[chuckbrandt]

When assembling a new engine or working on a running engine with problems, is there a way to effectively test for vacume leaks on an assembled engine. Could you close the valves and block off the carb flange and use a leakdown tester? If so how would that work? Is it reasonable to expect it to hold a vacume before it's run or does it have to go through some heating cooling cycles first?

Thanks, Chuck

[Bob Putnam]

The "classic" method for checking is a piece of fuel line - one end held to the ear, the other probing likely leak spots. Nowadays, we're much more sophisticated . We use an unlit propane torch blowing around likely spots. When the idle changes, you've found the spot.

Hopefully.

[chuckbrandt]

I had heard the propane trick on another forum too. I wonder if it would find a leak underneath like in the lifter valley side? Anyway, thanks for the tip.

Chuck

[ohekk]

Like the propane technique, I've used a spray can of starting fluid and listen for increase in RPM.