327 SB Chevy compression test results..help?
1972 Corvette engine issue
I just did a compression test on my 327 and came up with F 1: 151 2: 0 R 3: 151 4: 164 O 5: 140 6: 160 N 7: 150 8: 145 T The 327 is a 1968 and has around 60,000 since last rebuild, heads were rebuilt at the same time. This was back in 1975 though. I did the compression test with the engine at running temp, then when I got the zero reading I did a wet test with oil in that cylinder. The wet test did not improve the compression so I know it's not rings. I found out I have a collapsed lifter on that cylinder, the other one for the same cylinder was feeling "soft" when I pushed on the rocker arm. Any tips or advice you guys have would be appreciated... |
Originally Posted by 1972Stingray4Speed
(Post 1579951606)
1972 Corvette engine issue
I just did a compression test on my 327 and came up with F 1: 151 2: 0 R 3: 151 4: 164 O 5: 140 6: 160 N 7: 150 8: 145 T The 327 is a 1968 and has around 60,000 since last rebuild, heads were rebuilt at the same time. This was back in 1975 though. I did the compression test with the engine at running temp, then when I got the zero reading I did a wet test with oil in that cylinder. The wet test did not improve the compression so I know it's not rings. I found out I have a collapsed lifter on that cylinder, the other one for the same cylinder was feeling "soft" when I pushed on the rocker arm. Any tips or advice you guys have would be appreciated... |
Too much of a difference bet 8 and 5 as well. Try the oil trick in the others and see if you get different readings. If so, it's time for a leak down test. That will help you isolate the leak(s) better.
Without the benefit of that info, I would guess your exhaust seats are pounded out. That old of an engine doesn't have hardened exh seats. They don't like unleaded gas. It may be time for a new set of heads and valvetrain. |
Originally Posted by Ben Lurkin
(Post 1579951950)
Too much of a difference bet 8 and 5 as well. Try the oil trick in the others and see if you get different readings. If so, it's time for a leak down test. That will help you isolate the leak(s) better.
Without the benefit of that info, I would guess your exhaust seats are pounded out. That old of an engine doesn't have hardened exh seats. They don't like unleaded gas. It may be time for a new set of heads and valvetrain. |
Originally Posted by 1972Stingray4Speed
(Post 1579952708)
I have a new lunati cam part # 07102. I plan on getting my heads rebuilt as well as new lifters. The one lifter on the right side on front side #2 came apart when I took the rocker arm and pushrod pressure from it. That and the spring on that same lifter is broken in two places... I think I found the problem. Question I keep asking myself is why did both of those parts break on the same valve..
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Originally Posted by 1972Stingray4Speed
(Post 1579952708)
I have a new lunati cam part # 07102. I plan on getting my heads rebuilt as well as new lifters. The one lifter on the right side on front side #2 came apart when I took the rocker arm and pushrod pressure from it. That and the spring on that same lifter is broken in two places... I think I found the problem. Question I keep asking myself is why did both of those parts break on the same valve..
With regards to your heads, consider a set of vortec heads instead of rebuilding yours. For about the same money, the vortecs will give you a lot better performance. |
Originally Posted by Ben Lurkin
(Post 1579953565)
Broken spring? What 63 Mako said. . . It really doesn't take much to bend a valve.
With regards to your heads, consider a set of vortec heads instead of rebuilding yours. For about the same money, the vortecs will give you a lot better performance. |
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