The Ford Barn - View Single Post - Questions regarding idle on early Y-block

scicala · 07-17-2015, 07:51 PM

"Sal,
What would a good idle vacuum be? About 20? I haven't had a gauge on one recently enough to remember.
Thanks."

Hi dmsfrr,

It will vary from engine to engine, but on a stock Y-Block in good condition I would expect to see from 17" to almost 20" of vacuum. I recently worked on a '54 Mercury 256 that was just rebuilt and good running that only had 17.5". I think the camshaft differences from year to year may account for the variation. Hard to say.

Sal

07-17-2015, 07:51 PM	#4
scicala Senior Member Join Date: Jun 2010 Location: Detroit suburb, MI Posts: 3,706	Re: Questions regarding idle on early Y-block "Sal, What would a good idle vacuum be? About 20? I haven't had a gauge on one recently enough to remember. Thanks." Hi dmsfrr, It will vary from engine to engine, but on a stock Y-Block in good condition I would expect to see from 17" to almost 20" of vacuum. I recently worked on a '54 Mercury 256 that was just rebuilt and good running that only had 17.5". I think the camshaft differences from year to year may account for the variation. Hard to say. Sal