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killer sperm
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2,852 Posts
Are you kidding? You need to spend some time studying engine builds on this forum. Oh yeah, welcome to the forum. Also you may wamt to take a minute to introduce yourself.
 

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1,700 Posts
If you are coing to 10.25:1 it would be in your best interest to look into cams that can handle it , stock ones and stock heads would not be the optimum combo.
 

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82 Posts
Got C.R.

About 9-1 or 9.3-1 would be the max c.r. you want to run with stock cams .You will have to work with your jetting and ingition to get it right.
Choosing C.R. then building around that Is kinda like the "completion backwards theroy" Works O.K. but you gotta do it twice.
All good builds start from the ground up as a package, a group of components desiged to work together.
If you have some 10.5-1 pistons (you got cheep or whatever) and cannot afford cams,carb and exhaust. Save them for later or swap them for some flat tops.
The problem is that at 10.5-1 with stock cams there is not enough valve overlap to bleed off some of that cylinder pressure.And detionation rears it's ulgy head.
All that happens with a performance cam is that the intake valve closes later Because the cylinder does not build pressure untill the intake valve closes this effectively reduces the cranking pressure.That is a simplifcation of what goes on But is the root of your problem.It is all about the combinations,getting the heads.cams,intake,ing and exhaust to work together.
 
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