Compression test on my ‘90
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 2,238
Likes: 4
From: Milan
Compression test on my ‘90
I want to do a compression test on my ’90. Before to start I need to know :
I need to unplug the others spark plugs? Example If I’m doing the test in the #1 plug hole I have to unplug 2,3,4,5,6,7,8 spark plugs?
I need to disconnect some electrical thing??? (distributor…)
The TB must be open??
Others suggestion are welcomes (such values in psi) knowing my engine is new (4000 miles).
Specs are in my signature and yes, the block and the heads are ‘resurfaced’. (camshaft is stock).
Thanks
-Beppe-
I need to unplug the others spark plugs? Example If I’m doing the test in the #1 plug hole I have to unplug 2,3,4,5,6,7,8 spark plugs?
I need to disconnect some electrical thing??? (distributor…)
The TB must be open??
Others suggestion are welcomes (such values in psi) knowing my engine is new (4000 miles).
Specs are in my signature and yes, the block and the heads are ‘resurfaced’. (camshaft is stock).
Thanks
-Beppe-
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
Re: Compression test on my ‘90 (conv90)
It's best to REMOVE all the other plugs so the engine can spin over at a descent spped during the compression test.
The 'book' sez to have the TB wode open but in the real worls it doesn't matter so don't worry about that.
Depending on your compression and camshaft you should see in the range of
110-180 lbs on your gauge. The MAIN thing is for the compression reading to be within 10% of each other from cylinder to cylinder.
A 'differential compression' tester is the best but you can do it with a common compression gauge.
Good luck and you can always direct questions back to this forum. There are a lot of really smart and talented folks on here that can answer your questions.
The 'book' sez to have the TB wode open but in the real worls it doesn't matter so don't worry about that.
Depending on your compression and camshaft you should see in the range of
110-180 lbs on your gauge. The MAIN thing is for the compression reading to be within 10% of each other from cylinder to cylinder.
A 'differential compression' tester is the best but you can do it with a common compression gauge.
Good luck and you can always direct questions back to this forum. There are a lot of really smart and talented folks on here that can answer your questions.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Compression test on my ‘90 (conv90)
Before running a compression check:
-remove a spark plugs
-pull the red wire from the left side of the dist
-pull the two fuel injector fuses
-block the throttle open (or hold accelerator down when cranking)
The insert the gauge, crank for 4 revs, note psi on 1st crank & final psi.
BTW, good luck getting the testor into #8 cylinder!
-remove a spark plugs
-pull the red wire from the left side of the dist
-pull the two fuel injector fuses
-block the throttle open (or hold accelerator down when cranking)
The insert the gauge, crank for 4 revs, note psi on 1st crank & final psi.
BTW, good luck getting the testor into #8 cylinder!
