Can someone explain how worn valve guides would create an rapidly fluctuating vacuum signal on a vacuum gauge?

thanks

Worn guides will not let the valve head seat directly on the valve seat, thus causing a mismatch on the faces. Thus not sealing properly. Remember that the motor is basically an air pump.

Thanks DoubleD!

Have you checked the compression on each cylinder?

Every time that I have observed a rapidly fluctuating gauge I have had a burned valve or bad seat. May not be the case here but worth a compression check. A broken valve spring will do the same thing.

ive had th same symptoms for a year and i did do a compression check last year. all where 190-200 psi.

did a leak down test too...and that came back fine too. a vacuum leak or bad guides might still pass both tests, right?

is there a way to test the valve springs without taking everything apart?

thanks