How to pressurize the intake to check for leaks?
05-09-2008, 11:46 AM
#16
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05-09-2008, 12:54 PM
#17
Under the Lift
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The 928 stock valve timing is non-overlap, so there should not be any open valves. I.E., if intake valves are open, exhaust will be closed, so leakage is minimal and pressurzing is feasible.
05-09-2008, 06:32 PM
#18
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Thanks everyone for the suggestions!
Schocki - that is the same 2" x 3" adapter I purchased. I had difficulty getting it to fit over the MAF. Did you have to modify it in any way?
Andrew - thanks for reminder to turn the pressure down. 100 psi would probably blow the side air boxes off or worse!
Mike - I HOPE we do not need the fire extinguisher!
Schocki - that is the same 2" x 3" adapter I purchased. I had difficulty getting it to fit over the MAF. Did you have to modify it in any way?
Andrew - thanks for reminder to turn the pressure down. 100 psi would probably blow the side air boxes off or worse!
Mike - I HOPE we do not need the fire extinguisher!
05-09-2008, 06:55 PM
#19
Team Owner
Hey Adam i made a smart remark but after reading this I am going to assume that you have a supercharger installed?,
Anyway I was only joking around and the fact that you might have a leak is possible, so I guess its a good idea to check, goodluck with your car, Stan
Anyway I was only joking around and the fact that you might have a leak is possible, so I guess its a good idea to check, goodluck with your car, Stan
05-09-2008, 07:04 PM
#20
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this is silly, as you have so many ports that are open. (ie in the TB, in the plennum etc)
However, the easy way to do it, is to pull all the air out, (ie run the car in idle) then you are running at near 17"hg vaccum. all you then do is spray carb cleaner all over the place to see if the idle picks up. if not you are sealed.
mk
However, the easy way to do it, is to pull all the air out, (ie run the car in idle) then you are running at near 17"hg vaccum. all you then do is spray carb cleaner all over the place to see if the idle picks up. if not you are sealed.
mk
05-09-2008, 09:19 PM
#21
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Mark,
I have done what you have suggested on non-928 motors, but on the '85/'86 the side air boxes take up alot of room under the hood and make it difficult to locate vacuum leaks in situ using this method.
When I purchased the car last Fall, as a parts car, it started and ran - but rough. Mike (Frye) and I found several sources of vacuum leaks and mis-routed lines. Since there was so much wrong with the vacuum aspect of the motor, I want to eliminate vacuum leaks as a source of poor performance before I fire it up again after the many hours Mike and I have devoted on this car.
Should I fire it up and hope for the best?
I have done what you have suggested on non-928 motors, but on the '85/'86 the side air boxes take up alot of room under the hood and make it difficult to locate vacuum leaks in situ using this method.
When I purchased the car last Fall, as a parts car, it started and ran - but rough. Mike (Frye) and I found several sources of vacuum leaks and mis-routed lines. Since there was so much wrong with the vacuum aspect of the motor, I want to eliminate vacuum leaks as a source of poor performance before I fire it up again after the many hours Mike and I have devoted on this car.
Should I fire it up and hope for the best?
05-09-2008, 09:20 PM
#22
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Lube the big rubber. It's still really tough to get on. I made one that looks just like schoki's. I took the MAS off, fitted the testing gizmo, then put the MAS in.
WSM calls for ~5psi pressure. At that pressure finding a leak is an art and/or luck and/or due to location of the leak.
I wish I had a smoke machine. But, they seemed wAy pricey when I checked.
WSM calls for ~5psi pressure. At that pressure finding a leak is an art and/or luck and/or due to location of the leak.
I wish I had a smoke machine. But, they seemed wAy pricey when I checked.
05-10-2008, 03:02 AM
#23
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Thanks everyone for the suggestions!
Schocki - that is the same 2" x 3" adapter I purchased. I had difficulty getting it to fit over the MAF. Did you have to modify it in any way?
Andrew - thanks for reminder to turn the pressure down. 100 psi would probably blow the side air boxes off or worse!
Mike - I HOPE we do not need the fire extinguisher!
Schocki - that is the same 2" x 3" adapter I purchased. I had difficulty getting it to fit over the MAF. Did you have to modify it in any way?
Andrew - thanks for reminder to turn the pressure down. 100 psi would probably blow the side air boxes off or worse!
Mike - I HOPE we do not need the fire extinguisher!
