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figulaz
01-23-2014, 10:07 PM
I figure I'll make this look like an ASE cert question:D
A 92 super coupe auto (with a 94 long block) holds vacuum steady at idle just at or around 19 hg per the factory gauge. It is basically stock w a late model blower. A nearby 93 super coupe 5 spd holds vac at 22-23 hg also with alate model blower but with a dual IC, headers and overall better exhaust. Both cars are at sea level. Is the higher vac due to
A. better exhaust scavenging
B bigger IC
C. different cam profiles (94 profile for the auto and 93 for the 5spd)
D. the lower vac due to inferior engine condition
E. yet another firkin mystery vacuum leak on the 92
F.its in range don't worry about it.

820
01-24-2014, 06:50 AM
Vacume gauge reads different.

figulaz
01-24-2014, 12:12 PM
good idea. I should cross check with a hand held vac gauge.

S_Mazza
01-24-2014, 01:22 PM
I say answer F!

decipha
01-24-2014, 08:44 PM
theres no way its pulling 22+ in of vac at a stock 700rpm idle

that gauge is screwed

bowez
01-25-2014, 12:55 PM
Well not impossible... I'd agree gauge is bad. Considering 25 is the max that these engines could produce.

SC34
01-26-2014, 04:19 AM
My 91 and 93 appear to read different. ..I believe due to how the gauge needle is put on the pin it goes on. Shut off both engines and see where the neeedles set with no vacuum being applied. Bet they're different, mine are..

figulaz
01-28-2014, 10:15 PM
My 91 and 93 appear to read different. ..I believe due to how the gauge needle is put on the pin it goes on. Shut off both engines and see where the neeedles set with no vacuum being applied. Bet they're different, mine are..

Could be. I got a mighty vac gauge and the 92 that read just under 20 on the gauge had a slightly shaky needle at 18. The 93 5spd reading well past 20 on the factory gauge was rock steady at 19

SuperCoupe007
01-29-2014, 01:54 PM
Could be. I got a mighty vac gauge and the 92 that read just under 20 on the gauge had a slightly shaky needle at 18. The 93 5spd reading well past 20 on the factory gauge was rock steady at 19


Both seem within range. Glad you were able to check it.

Maybe during the next meet you can bring that handy tool and I can check my actual VAC. Mine shows a steady 13 or so at idle :p

820
01-29-2014, 02:07 PM
With a shaky steady needle you may have some wore valve guides. with an intermitten shaky needle you may have sticky valves, lifters, ignition miss, or a big hairy camshaft. in any case unless you have that bad cam there may be a slight problem.

figulaz
01-31-2014, 01:34 AM
Both seem within range. Glad you were able to check it.

Maybe during the next meet you can bring that handy tool and I can check my actual VAC. Mine shows a steady 13 or so at idle :p

I'd be happy to! I just need some tires for road trippin.

figulaz
01-31-2014, 01:40 AM
With a shaky steady needle you may have some wore valve guides. with an intermitten shaky needle you may have sticky valves, lifters, ignition miss, or a big hairy camshaft. in any case unless you have that bad cam there may be a slight problem.

It was slight and steady but just enough to bug me a bit. I figured worn guides as it is a junkyard 94 long block.

SuperCoupe007
01-31-2014, 01:33 PM
Just a suggestion. How about taking a short video with your phone and upload it to YouTube.

Maybe it wont help solve the issue, but just so everyone sees what you see.