What is the normal compression on a 1995 RRC 4.2. My mechanic said I have 142-147 on the cylinders. Just checking what most people find they have. The truck has 196,000miles on it. Maybe its time for a diesel conversion.
What is the normal compression on a 1995 RRC 4.2. My mechanic said I have 142-147 on the cylinders. Just checking what most people find they have. The truck has 196,000miles on it. Maybe its time for a diesel conversion.
That's a narrow range so rings and valves are likely fine. That is lower than I usually see. Around 180psi. When's the last time you put a timing chain on it?
You might want to check your compression gauge.
Why do you say that?
I don't think I see them that high. I figured his 145 was pretty good. But then I usually just do cylinder leak down tests anymore.
Buddy the rods are a little longer on the 4.0 vs the 3.9 and the cam is advanced a few degrees so maybe a 4.0 will read a little higher than a 3.9. Comp ratio is still the same. It's been so long since I've had a real 3.9 that I don't remember. I'd expect a 4.2, just like a 4.6, to have similar readings as the 9.35:1 4.0. Now on my 4.6 with 4.0 pistons I'm seeing around 215 psi
225 psi on mine, but I have aftermarket pistons on my 4.6.
Might want to go by this advice. One of the main things to keep in mind is difference between cyl readings. If varies less than 20% rather normal.I don't think I see them that high. I figured his 145 was pretty good. But then I usually just do cylinder leak down tests anymore.
Sounds like a similar build. I did the crower 229 cam. A 228 might have a little higher psi. Which did you do?