Compression test results on new engine, help
#1
Compression test results on new engine, help
New rebuilt engine. Fully built engine.
Anyway, I had a track day about 2 weeks ago. car was fine. last 2 runs it had a miss fire while idling. mmmmmm ba ba bammmmmmmba ba bammmmmmmmba ba bammmmmmmm bababa
you get me. While drive full ***** i didnt feel the miss at all.
So I went home and put the car away.
last night I did a comp test just to make sure i didnt have a mechanical or serious type of issue. Maybe just a lose wire or some dumb ****.
Anyway, cyl 123 all at 180. Cyl 4 at 160!!!!!!!!!!!
WTF guys/ I am just looking for ideas of the tops of your heads.
I will be having a leakdown test done by my machinist next week.
i just wanted some of your ideas before I even go to the shop. I am fukken pissed and sad. I dont much a budget left for fixing ****..
I hope its a simple valve issue that will be quick, easy, and cheap to fix..
Anyway, I had a track day about 2 weeks ago. car was fine. last 2 runs it had a miss fire while idling. mmmmmm ba ba bammmmmmmba ba bammmmmmmmba ba bammmmmmmm bababa
you get me. While drive full ***** i didnt feel the miss at all.
So I went home and put the car away.
last night I did a comp test just to make sure i didnt have a mechanical or serious type of issue. Maybe just a lose wire or some dumb ****.
Anyway, cyl 123 all at 180. Cyl 4 at 160!!!!!!!!!!!
WTF guys/ I am just looking for ideas of the tops of your heads.
I will be having a leakdown test done by my machinist next week.
i just wanted some of your ideas before I even go to the shop. I am fukken pissed and sad. I dont much a budget left for fixing ****..
I hope its a simple valve issue that will be quick, easy, and cheap to fix..
#2
Try a wet test. Small amount of oil into cyl. 1/3 of an egg cup. Crank over with plugs out to blow out excess and recheck comp. If it's a valve issue you'll see next to no diff. If cyl issue the extra oil will have helped seal any blow by and figure will be higher.
Malcolm
To get a better comparison repeat with one of the other cyls.
Malcolm
To get a better comparison repeat with one of the other cyls.
#11
What Alta said ^ IF yes, then pull your cam cover, look at all the valve areas at the cam lobes. IF they look OK, then try rotating the crank by hand slowly while watching (and listening) the action at the lobes.
I had a shim crack on a shim-under-bucket - but all that did was keep the valve from opening all the way. Amazingly the bucket kept all the shim pieces captured instead of letting the bounce around the head. But shim parts could easily hold the valve open and the OE shims are good candidates for cracking or spitting out with the abuse you're giving them.
I had a shim crack on a shim-under-bucket - but all that did was keep the valve from opening all the way. Amazingly the bucket kept all the shim pieces captured instead of letting the bounce around the head. But shim parts could easily hold the valve open and the OE shims are good candidates for cracking or spitting out with the abuse you're giving them.
#12
Thanks for all of the replies again guys.
99 head
Engine was cold.
No plugs in any cylinders.
throttle was closed.
oil looked fine, but I am going to check again.
I did not over heat. water and water wetter also looked fine..
The engine has 2 competitions and 1/2 day at a practice event. So not much time
The engine was heat cycled on the dyno. It didnt overheat.
I will look into the comp test with oil this week/end
I will also take off the valve cover to check the lobes and shims
99 head
Engine was cold.
No plugs in any cylinders.
throttle was closed.
oil looked fine, but I am going to check again.
I did not over heat. water and water wetter also looked fine..
The engine has 2 competitions and 1/2 day at a practice event. So not much time
The engine was heat cycled on the dyno. It didnt overheat.
I will look into the comp test with oil this week/end
I will also take off the valve cover to check the lobes and shims
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