Lima compression results

[cbr600rx7]

So I had a few seconds today to spare (rare for me) so I decided to do a compression test. I ran the motor for about 90 seconds before shutting her down and pulling the coil pack plugs and fuel pressure relay. I then hooked a set of jumper cables to the F150 to keep the battery charged and cranked each cylinder for about 3-5 seconds each. The results kind of shocked me as each cylinder showed 150-160 psi. I tested each cylinder two times just to be sure. I have used this same compression tester on other engines and this is the result I typically get on motors with just over a 9.0 to 1 compression ratio. I think my truck is supposed to have around a 9.2 to 1 CR so this would be very healthy for a motor that I assume has 230,000+ miles. I don't know the mileage because it had a 5 digit cluster in it when we purchased it. It has rolled over once since then however since it showed only 79,000 on it in 2009 and it was 16 years old at the time I think it's safe to say it's gone around more then once.

 

[RonD]

Numbers look good

 

[tomw]

(in Vermonter voice Ayup.

Good compression. The Lima will last a long time if not abused, fed & watered, and somewhat regular oil changes. Not as zoomy as the duratec DOHC replacement, but nontheless a good steady engine. It can be 'awakened' with porting, tuning, cam, etc, but will do pretty well just left alone. My siblings & I have probably had a dozen between us, and all have been pretty good.
When I have done compression tests, I usually just crank the engine while listening, and watching the gauge. Most times, the pressure will maximize after about 4 cycles, maybe 5-6, but I really don't pay attention that closely. I have yet to figure out why the compression doesn't show up 'max' on the first go-round. Any ideas?
tom