FC3S Murray's never ending build.

NoDOHC · 09-14-2009, 10:40 PM

I used a piston compression tester, I got 115 psi pulses on all faces at 5000 miles. (I got about 100 at 500 miles). Total compression (check valve in) was a tick over 120 on both rotors. I think the piston tester works just fine, I don't understand your low readings.

By chance, did you try dumping oil down the spark plug hole and trying compression test again? (you should gain ~5-10 psi) If you gain a lot more, I guess more break-in is in order.

I premixed for the first 200 miles and then quit mixing after that until 5,000 miles, when I started mixing again.

FC3S Murray · 09-15-2009, 12:25 PM

Quote:

Originally Posted by NoDOHC

I used a piston compression tester, I got 115 psi pulses on all faces at 5000 miles. (I got about 100 at 500 miles). Total compression (check valve in) was a tick over 120 on both rotors. I think the piston tester works just fine, I don't understand your low readings.

115 psi pulses? Man I was seeing 55 psi and I heard the average(via rotary ressurection) was 30-35 psi for each consecutive pulse. ?hmm

I am not worried until I hit 1500 miles.

NoDOHC · 09-29-2009, 09:35 PM

Quote:

Originally Posted by FC3S Murray

115 psi pulses? Man I was seeing 55 psi and I heard the average(via rotary ressurection) was 30-35 psi for each consecutive pulse. ?hmm

I am not worried until I hit 1500 miles.

Hey, I figured this out! My Compression tester pushes right into the port (no hose). I went to Silver86's the other day and we compression tested his engine, we got 45-50 psi bounces with his gauge (with a long hose). We tried it on my '91 and got 65 psi pulses.

I feel stupid, the difference is the amount of air to compress in the hose going up to the compression gauge. I should have thought of this before.

The '91 gets 110 psi on his gauge (so don't feel at all bad about 55 psi).

Just thought I would clear this up.

09-14-2009, 10:40 PM	#1
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin Posts: 855 Rep Power: 18	I used a piston compression tester, I got 115 psi pulses on all faces at 5000 miles. (I got about 100 at 500 miles). Total compression (check valve in) was a tick over 120 on both rotors. I think the piston tester works just fine, I don't understand your low readings. By chance, did you try dumping oil down the spark plug hole and trying compression test again? (you should gain ~5-10 psi) If you gain a lot more, I guess more break-in is in order. I premixed for the first 200 miles and then quit mixing after that until 5,000 miles, when I started mixing again. __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic)