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the low compression is weird but very balanced and I don't know your dynamic cr.
a lot off advice, hope you find it.
the all eight issue is why I went with intake
What should cranking compression be on a sbc? Everything I ready is 130+ you are good. The engine CR is 9:1. My fear is I have glazed the cylinder walls from idling it trying to figure out what the overheating issue was.
Rings will seat. Comp test will end up at 200 psi with throttle open. That 140 psi is low for broke in rings.
Your gonna like it. Drive it.
Stop looking in the mirror.....................
Did I read/understand right, only 5 miles on the engine?
That is a lot of oil for just a few miles.
Did you get new valves and guides?
I would retorque the heads and intake, clean the plugs, then drive it hard for a while. As long as it doesn't overheat, it probably won't do any damage, unless the rings are too tight, which doesn't sound like it.
Good luck.
Lots of modified C3s.
Too many variances in these cars to call "what is normal" cranking C.R.
Dished pistons, domed pistons. And also, when the Intake valve closes as the piston is rising. The cam profile dictates some of the compression test results.
Your numbers look fine. What can cause abnormal numbers between test is not so much a wide-open throttle but rather battery condition. The last cylinder tested gets the least amount of cranking amps.
Always start with a freshly charged battery and keep the charger on while testing.
What should cranking compression be on a sbc? Everything I ready is 130+ you are good. The engine CR is 9:1. My fear is I have glazed the cylinder walls from idling it trying to figure out what the overheating issue was.
Cr is fairly verible, depends on cam, pistons, etc. May or may not be your rings. Oil on the rings could come from the top or the bottom.
Lots of cars run well with your readings.
What should cranking compression be on a sbc? Everything I ready is 130+ you are good. The engine CR is 9:1. My fear is I have glazed the cylinder walls from idling it trying to figure out what the overheating issue was.
depends, like mentioned.
150 is pretty average.
175 is beginning of good performance.
hell I have a 10.5 c/r pumping 225
125-130 low
not knowing I assumed 145 was balanced and sealed.
I have been down rabbit holes because I was stuck on an idea and missed the real issue.
Did I read/understand right, only 5 miles on the engine?
That is a lot of oil for just a few miles.
Did you get new valves and guides?
I would retorque the heads and intake, clean the plugs, then drive it hard for a while. As long as it doesn't overheat, it probably won't do any damage, unless the rings are too tight, which doesn't sound like it.
Good luck.
Yes only about 5 miles of driving. Heads were gone through and only one exhaust valve required replacement. New comp seals were installed. Going to be raining here for the next several days... in the mean time I will retorque everything and inspect the intake runners with borescope.
Yes only about 5 miles of driving. Heads were gone through and only one exhaust valve required replacement. New comp seals were installed. Going to be raining here for the next several days... in the mean time I will retorque everything and inspect the intake runners with borescope.
Valve guides?
Depending on how many miles on the old valves, they could definately have excessive clearance to the old guides.
Even so, I doubt worn valves/guides would leak that much oil in ALL cylinders.
Hopefully retorqueing will fix it.
OK, so I was able to mess with the car tonight. The intake bolts took about 1/8 of a turn before the wrench clicked. I was able to snap some pictures of a couple intake runners. Deffinately looks like there is some oil in there. I decided to look into the cylinders as well. Is this typical for the oil to be in one place? Also, not a fan of some of these vertical lines. Could that be the root cause of my issue, scored cylinder! How could I verify this? You can see the cross hatch very well, so maybe these lines are nothing really? Do the cylinders look glazed?
The scoring is Any or all of the following...
Rings not deburred after gapping...There is an Awful lot of scoring for just this....
Cylinder Bores not chamfered and polished at the bottom....Causing scuffing
Dirty environment during rebuild...
There is also over heating and poor lubrication...
I think I'd pull the oil filter and see how much metal is in it...
Did you add oil to the cylinders as part of the compression test? There was a lot on top of that one piston...
I’ve read that moly rings tend to do that especially if heated when broken in. I’ve always just used Hastings cast rings in my builds. That scoring looks serious, if it continues I’d use some bon ami.
