Compression check gone POSTAL!! 231 237 What should it be???
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From: Ohio
Compression check gone POSTAL!! 231 237 What should it be??? Let me start by telling you my problem. I upgraded froma 224 228 cam and a crappy set of heads to the pp 5.3 and the texas speed 231 237 cam. Car seems to run very well is responsive no popping had a 12.8 to 13.0 AFR on the dyno but only made 400rwhp. This was weird seeing how I made 392 with the crappy heads and 224 cam. I have been chasing the wanted HP fpor a while now.
I did a compression check on all cylinders and the results are really messed up.
1- 180
2 - 210
3 - 210
4 - 215
5 - 230
6 - 220
7 - 165
8 - 210
What's up with that? I cranked all cylinders untill pressure stopped rising. I thought this cam should only be about 165..
I also did a leakdown all cylinders were under 8% with most being under 4%.
Any ideas what could cause this? OR what it should be?
I have a set of Harlan Sharp Roller Rockers torqued to 22ftlb's. I did check preload as the directions said and I got between 1/2 and 3/4 turn of preload before hitting 22ftlb's Heads are unmilled and I'm running a stock length pushrod.
Thanks Rob
I did a compression check on all cylinders and the results are really messed up.
1- 180
2 - 210
3 - 210
4 - 215
5 - 230
6 - 220
7 - 165
8 - 210
What's up with that? I cranked all cylinders untill pressure stopped rising. I thought this cam should only be about 165..
I also did a leakdown all cylinders were under 8% with most being under 4%.
Any ideas what could cause this? OR what it should be?
I have a set of Harlan Sharp Roller Rockers torqued to 22ftlb's. I did check preload as the directions said and I got between 1/2 and 3/4 turn of preload before hitting 22ftlb's Heads are unmilled and I'm running a stock length pushrod.
Thanks Rob
I recently did a compression test on my car with the TR230 cam.. I wasn't aware that the actual compression changed based on the cam..
My numbers were:
1-150
2-150
3-150
4-150
5-145
6-150
7-145
8-150
Does this mean that my 5 and 7 cylinder are jacked?
I'm not tryin to highjack your thread. I'm confused also..
My numbers were:
1-150
2-150
3-150
4-150
5-145
6-150
7-145
8-150
Does this mean that my 5 and 7 cylinder are jacked?
I'm not tryin to highjack your thread. I'm confused also..
Thread Starter
TECH Enthusiast
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Posts: 535
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From: Ohio
No your fine thats what they should look like. As long as they are with in 10 psi of each other your good. Those numbers are determined by the amount of overlap a cam has. yours probably has some good over lap to have numbers in the 150 range. Overlap is the amount of time both the intake and exhaust valves are open at the same time. Mine should as well. But for some reason I dont. Thats what confusing me.
Rob
Rob
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Im new to the board so ill say hey first off. Im pretty sure this is not your 1st comp test just wondering did you disable the fuel to prevent fuel wash down to produce different readings? Did you keep equal cranking times? Tried another comp. guage? If all is correct have you added a small about of oil to the cyinder to see if pressure goes up? If it does you may have a ring seal issue. Just a few thoughts. Later
It seems you may have gone from one set of crappy heads to another. There are alot of pp 5.3 guys making under 420 with that cam. Are you an auto or an m6? You should have had the old set of heads and the new set of heads flow checked to see the difference in the cfm. before installing them to eliminate that as the cause. I hope for your sake it is something to do with preload, wrong size pushrods etc... and not the heads. Good Luck.
Thread Starter
TECH Enthusiast
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From: Ohio
Thanks for the reply. Yes I've done a few. I cranked each cylinder unitl the pressure stopped going up. This was about eight crank rotations. Yes I did disable the fuel pump. I only tried the one guage but this one worked fine last year on this car. I can try to get another just to be sure. The leak down tells me the rings are ok. So no need for oil in the cylinders. I was hoping to lower the pressure anyhow not raise it. The high number tells me that the valves aren't opening correctly too soon too late not enough who knows. Just not right I believe my pressure should be in the 160's.
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From: Fat Chance Hotel
Originally Posted by LEATHL_WS6
Let me start by telling you my problem. I upgraded froma 224 228 cam and a crappy set of heads to the pp 5.3 and the texas speed 231 237 cam. Car seems to run very well is responsive no popping had a 12.8 to 13.0 AFR on the dyno but only made 400rwhp. This was weird seeing how I made 392 with the crappy heads and 224 cam. I have been chasing the wanted HP fpor a while now.
I did a compression check on all cylinders and the results are really messed up.
1- 180
2 - 210
3 - 210
4 - 215
5 - 230
6 - 220
7 - 165
8 - 210
What's up with that? I cranked all cylinders untill pressure stopped rising. I thought this cam should only be about 165..
I also did a leakdown all cylinders were under 8% with most being under 4%.
Any ideas what could cause this? OR what it should be?
I have a set of Harlan Sharp Roller Rockers torqued to 22ftlb's. I did check preload as the directions said and I got between 1/2 and 3/4 turn of preload before hitting 22ftlb's Heads are unmilled and I'm running a stock length pushrod.
Thanks Rob
I did a compression check on all cylinders and the results are really messed up.
1- 180
2 - 210
3 - 210
4 - 215
5 - 230
6 - 220
7 - 165
8 - 210
What's up with that? I cranked all cylinders untill pressure stopped rising. I thought this cam should only be about 165..
I also did a leakdown all cylinders were under 8% with most being under 4%.
Any ideas what could cause this? OR what it should be?
I have a set of Harlan Sharp Roller Rockers torqued to 22ftlb's. I did check preload as the directions said and I got between 1/2 and 3/4 turn of preload before hitting 22ftlb's Heads are unmilled and I'm running a stock length pushrod.
Thanks Rob
#7 ain't right. maybe try again. otherwise i'd say bad valvejob/valve or they just aren't closing on #7, since you said leakdown was ok.
#1 ain't looking to good either.
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TECH Enthusiast
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From: Ohio
Mike heads seem to be fine. Thanks for the bash. plus heads would not cause these types of readings. Last heads flowed in the low 280's these in the low 300's
Car is an M6.
As I stated earlier I did a leakdown and all cylinders were fine.
Sure guys are making under 420 but I've yet to see anyone post compression test readings like these. Something is wrong and its not the heads. II'm gonna try the stock rockers tomorrow and see if that makes a differance.
Rob
Car is an M6.
As I stated earlier I did a leakdown and all cylinders were fine.
Sure guys are making under 420 but I've yet to see anyone post compression test readings like these. Something is wrong and its not the heads. II'm gonna try the stock rockers tomorrow and see if that makes a differance.
Rob
Thread Starter
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From: Ohio
Tech old setup was 190 or so across the board. But this cam is susposed to have more overlap and is susposed to be in the 160 range. 7 and 1 are closer to what all cylinders should be.
as for trying again I did all cylinders 2 times and did 7 and 1 four times because I couldn't believe it.
as for trying again I did all cylinders 2 times and did 7 and 1 four times because I couldn't believe it.
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From: Fat Chance Hotel
Originally Posted by LEATHL_WS6
Tech old setup was 190 or so across the board. But this cam is susposed to have more overlap and is susposed to be in the 160 range. 7 and 1 are closer to what all cylinders should be.
as for trying again I did all cylinders 2 times and did 7 and 1 four times because I couldn't believe it.
as for trying again I did all cylinders 2 times and did 7 and 1 four times because I couldn't believe it.
Was there excessive carbon buildup on the pistons in the cylinders that were high?
Never heard of this one...normally I'm looking for the low cylinder(s) ( because something's wrong) not the abnormally high
Last edited by technical; May 4, 2004 at 10:13 PM.
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Might be a bad lifter or cam lobe Could be that you have a cam lobe problem or a bad lifter to me. Sometimes a new cam is defective and is not hardened correctly, or it was installed with out enough lube. After 15 minutes of running a cam lobe could get wiped out. Check the lift on the bad cylinders and some of the good ones with a dial indicator gauge. If the lift is a lot lower on the bad cylinders this would indicate a bad cam lobe, Or possibbly some of your lifters may have gone bad or collapsed. Did you reuse the old lifters? If they are old I would have replaced them. Also check the rocker arms to see if they are to lose, worn etc.
Hope this helps
Hope this helps
If your using comp or crane lifters 1/2 to 3/4 may be a little too much preload on some. I do 1/4 to 1/2 on the aftermarket lifters. As stated above, could also be a flat lobe or dead lifter. Was the cam degreed in at installation or just dot to dot?
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From: Ohio
Originally Posted by StickSS
Could be that you have a cam lobe problem or a bad lifter to me. Sometimes a new cam is defective and is not hardened correctly, or it was installed with out enough lube. After 15 minutes of running a cam lobe could get wiped out. Check the lift on the bad cylinders and some of the good ones with a dial indicator gauge. If the lift is a lot lower on the bad cylinders this would indicate a bad cam lobe, Or possibbly some of your lifters may have gone bad or collapsed. Did you reuse the old lifters? If they are old I would have replaced them. Also check the rocker arms to see if they are to lose, worn etc.
Hope this helps
Hope this helps
I always use assembly lube when assembling and engine or changing lifters cam etc. I covered the cam with assembly lube before installing it.
I also agree I think the cam is ground wrong. I find it hard to believe that 6 lifters went bad. The motor only has 16k on it so I just reused the old lifters. I will get a dial indicator and check that out. rockers are all still tight and look good.
Thanks Rob
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From: Ohio
Originally Posted by strokedls1
If your using comp or crane lifters 1/2 to 3/4 may be a little too much preload on some. I do 1/4 to 1/2 on the aftermarket lifters. As stated above, could also be a flat lobe or dead lifter. Was the cam degreed in at installation or just dot to dot?
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From: Fat Chance Hotel
Originally Posted by LEATHL_WS6
Tech Nope all cylinders had the same amount of buildup which I removed.
Sorry for all the quick posts, but this one is real interesting...just trying to brainstorm some ideas.
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From: Ohio
No problem Tech.
I tried those cylinders 4 times each so I doubt the hose was in wrong 4 times. I'm going to re run the test again tonight with a different gauge and see if I get the same results. Then I'm going to put the stock rockers back on and test it again.
Real intresting but driving me nuts.....
Rob
I tried those cylinders 4 times each so I doubt the hose was in wrong 4 times. I'm going to re run the test again tonight with a different gauge and see if I get the same results. Then I'm going to put the stock rockers back on and test it again.
Real intresting but driving me nuts.....
Rob
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From: Fat Chance Hotel
Originally Posted by LEATHL_WS6
No problem Tech.
I tried those cylinders 4 times each so I doubt the hose was in wrong 4 times. I'm going to re run the test again tonight with a different gauge and see if I get the same results. Then I'm going to put the stock rockers back on and test it again.
Real intresting but driving me nuts.....
Rob
I tried those cylinders 4 times each so I doubt the hose was in wrong 4 times. I'm going to re run the test again tonight with a different gauge and see if I get the same results. Then I'm going to put the stock rockers back on and test it again.
Real intresting but driving me nuts.....
Rob
Sometimes a bad valve guide can do this as well ie Leakdown would look ok, but during compression the valve would rock and loose a little pressure. I'd hate to think that since they are new heads. Good luck tonight, let us know.