Also, when you did the compression test, was the engine warmed up and did you hold the throttle wide open while cranking? If not, try it again with the throttle held open. That can make a surprisingly big difference.
Also, when you did the compression test, was the engine warmed up and did you hold the throttle wide open while cranking? If not, try it again with the throttle held open. That can make a surprisingly big difference.
I don't think the throttle was open. Why does that make a difference? I don't know too much about this stuff!
You need unrestricted air flow or your readings are useless. I bet you will see a big difference if you do a test again with the throttle wide open.
If the throttle is closed, it may not get enough air to avoid pulling a vacuum in the intake manifold while cranking. If there's a vacuum, the pressure of the air before compression is lower and you're still compressing it the same amount, so the compression reading will show lower.
So how did this turn out?
noddaz said:So how did this turn out?
Good enough that I didn't bother rebuilding the engine.
Ran the car as-is in a number of races from 2017-2019. Even squeezed in one last race before COVID hit in 2020. Compression is now 135 psi and very even (+/- 4 psi) across all four cylinders. Minimal blow-by in the catch can. Makes decent power and pulls all the way to the 8k redline. Won regional championship for my class, which isn't saying much since there's like 3 guys in the class LOL ... but still.
The boat anchor "race engine" is back at the shop ... a different one this time. Making plans to build this one properly.
Hey y'all I'm dealing with stuck rings in my LB7 DMaxx (see my other post for the storyline). I presume pulling the injectors and pouring MMO is the next step?
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