I am experiencing rough running under load and recently, some knocking at about 3000 rpm. My newly rebuilt engine has about 9.7:1 compression ratio with the stock iron cylinder heads.
Cam is a Comp Roller 33-000-9. This is one step up from an OE or "towing" cam. Idle quality is good, 650 RPM. I measured valve lift and they are all identical.
I did a dry compression test and found 7 cylinders at 170psi, 1 at 180. Wet compression all at 180.
Initial timing is 10 degrees BTDC. Using that as my zero, I measure centrifugal timing to be as follows:
RPM OE Rec'd This setup
800 .5-1.5 2
1000 3.5-4.5 8
1600 5.75-7 19
2800 8.25-9.5 24
4000 10.75-12.75 24(max)
Vacuum advance at 1000 RPM
In Hg OE Rec'd This setup
8 2-5 0
10 4-7 3
15 5.5-8.5 4
20 5.5-8.5 4
Cam is a Comp Roller 33-000-9. This is one step up from an OE or "towing" cam. Idle quality is good, 650 RPM. I measured valve lift and they are all identical.
I did a dry compression test and found 7 cylinders at 170psi, 1 at 180. Wet compression all at 180.
Initial timing is 10 degrees BTDC. Using that as my zero, I measure centrifugal timing to be as follows:
RPM OE Rec'd This setup
800 .5-1.5 2
1000 3.5-4.5 8
1600 5.75-7 19
2800 8.25-9.5 24
4000 10.75-12.75 24(max)
Vacuum advance at 1000 RPM
In Hg OE Rec'd This setup
8 2-5 0
10 4-7 3
15 5.5-8.5 4
20 5.5-8.5 4
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