vacuum question

[broker-len]

4 cylinder plymouth--------------motor rebuilt    pistons and valves     head shaved and new gasket------timed with the plug on the head then used vacuum method                       the gage is 15 lbs and all over the place     run very ruff     I think I checked compression and it was OK  how to check for vacuum leak at manifold---  SHOOT OIL  ????? GET EVERY THING DIRTY ???????----------------------ANY THOUGHTS    ??????

[cahartley]

WD40 works perfectly and doesn't leave a mess.

[Digger914]

Rubber hose off the end of a good old fashion propane torch, not the self igniter type, will keep everything clean, let you get into all the tight places and provide a little gas that can be sucked in by a vacuum leak.

[Ltc4748]

I use water in a spray bottle to check vacuum leaks, it makes a peculiar sound when you find a leak. if the vacuum gage is bouncing radically recheck the valve adjustment. Make sure if it is to be done hot or cold you follow procedure. Valves that are adjusted too tight will cause a vacuum gage to bounce.