What are the vacuum specs?
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Tuned
Joined: Nov 2009
Posts: 264
Likes: 0
From: Sherman Oaks California
What are the vacuum specs?
Hi everybody,
Do any of you know what are the normal vacuum specs for a 1986 302? I get 17 inches in idle & 14 inches in drive...Should it drop that much?
Thanks
Do any of you know what are the normal vacuum specs for a 1986 302? I get 17 inches in idle & 14 inches in drive...Should it drop that much?
Thanks
Mountain Pass
Joined: Jul 2010
Posts: 105
Likes: 1
From: Honolulu, HI
I'm not sure on the specs myself, but I pull 19-20 (closer to 20) inches at idle and and roughly 18 during drive (cruise control on @ 55). Just did this test a few months ago.
Mine's a 1985 302 with Feedback carb.
Mine's a 1985 302 with Feedback carb.
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
17 at idle in neutral is low. Good is ~20 at idle. However, many things can impact the vacuum. One is late ignition timing - but if you have a computer on yours, as you probably do unless you've changed the system, you don't have any way to change the timing.
Next is low idle speed. Too low an idle speed drops the vacuum, and really kills it when you drop the tranny in gear.
Another is vacuum leaks. Again, the computer will be trying to compensate (assuming you have one), but there is just so much it can do at idle. Check your hoses for cracking, splits, etc.
Beyond that, you could have a bad cam. I did. Gave me all sorts of problems, including but certainly not limited to low vacuum. Or, a clogged up catalytic converter.
As for 14 in gear, a 3 in drop isn't too bad. Get the neutral # up and you'll be ok.
Next is low idle speed. Too low an idle speed drops the vacuum, and really kills it when you drop the tranny in gear.
Another is vacuum leaks. Again, the computer will be trying to compensate (assuming you have one), but there is just so much it can do at idle. Check your hoses for cracking, splits, etc.
Beyond that, you could have a bad cam. I did. Gave me all sorts of problems, including but certainly not limited to low vacuum. Or, a clogged up catalytic converter.
As for 14 in gear, a 3 in drop isn't too bad. Get the neutral # up and you'll be ok.
