Fiend car shows 16.5-17 in/hg at idle. is this okay or should he do a compression check?

 

should be closer to 20-22 in/hg at idle.

 

That's a little on the low side, but not too bad.

 

sound good to me...

i have a b16 8.5:1..
i have the same number

 

i was wondering the same thing, during the day i idle about 700, and see about 16, at night i see idle speed 1k, and about 18. on 10.5:1

 

The answer to this Q is really dependent upon your friends setup. I have a stock hatch...I could throw in a cam with some overlap and watch my vaccum @ idle drop a few inches (I'm pulling about 19-20" on 150k mile motor).

But your readings look decent, etiher way.

 

It depends on your elevation. Here in Az at approx 1000-ish feet I see 21 in/hg regularly. I'm guessing at sea level I'd see something more like 23 maybe, and at say 5000 feet it might only be the 15-16 inches of mercury that your friend is seeing. Check your altitude first, if you' re below 3500+ feet, check the vaccum lines.

This is all assuming he's got a honda engine, I would assume others would be the same but I'm not really sure,

Ryan P.

 

I think it verys from engine to engine. I've had 3 engines in my car. 1st had 20 in/hg. 2nd out of automatic had 15 in/hg. 3rd rebuilt 1st engine has 19-20 in/hg.

 

Could be the gauge, especially if it an Autometer.