Small world 335
Thread Starter
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Laughing Gas
Joined: Jan 2006
Posts: 883
Likes: 7
From: New-brunswick,Canada
Small world 335
I recalculate my scr and dcr. Static 8.7 and dynamic 7.5 on 400 with iron head 64 cc. I talked to the rebuilt shop guy today for rebuilt my aussie head and he said i should go with a bigger cam and better pistons than original .030 over. Since my cam and pistons are already install i dont want to go back. Cam is not a problem to change. He said bigger cam less detonate?? pistons are press fit and have to buy new pistons again. I'm learning (i'm telling you guy's ! This is my first rebuilt but not the last one. I have to deal with what i have now!) I also call United Engines and Machine co. to ask them what was my piston head volume:15.5 cc. He said he know an expert guy who makes pistons. he said I have a phone # TIM MAYER!?!?!. I was SUPRISE. I wish to knew him before. The guy from U E and M co said IF i got with the proper geometry i should not have problem with those pistons as long as the 400 don't detonate with my set up i should be ok. I don't want to break everyting the first day. It a light FORD street car with high rear end. Edelbrock 600 ,performer 400 ,straight up double roller,crane cams roller rocker arms, new stock oil pump,new oil shaft ex-256h.
I'm on a tight budget but it's for street weekend and maby strip for fun to see how it's go. PLEASE HELP !
I'm on a tight budget but it's for street weekend and maby strip for fun to see how it's go. PLEASE HELP !
Posting Guru
Joined: Jul 2007
Posts: 1,355
Likes: 1
7.5 dcr is a good to go, dont be worried about detonation, and yeah you should use better pistons and a higher cam on your light vehicule as i recomended you before, this cam youre using will give you exsesive torque but will hold you back on your mid range..... you could go up a bit in your cam choice and mille your heads to keep up the dcr if you dont wantb to tear down your engine.... oh and yes a bigger cam the lower dcr on a given scr.....
Thread Starter
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Laughing Gas
Joined: Jan 2006
Posts: 883
Likes: 7
From: New-brunswick,Canada
something i dont understand ?? what cause detonation. high scr or dcr? i thing it's the static ?
The guy from the machine shop said it will be better to use my stock converter since it's a ton of torque at low rpm and used high gear ratio.
The guy from the machine shop said it will be better to use my stock converter since it's a ton of torque at low rpm and used high gear ratio.
Posting Guru
Joined: Jul 2007
Posts: 1,355
Likes: 1
scr is the space calculated and dcr is the real operating copmpression ratio, the cam afects this due to overlaping and valve opennings, check this out:
http://www.empirenet.com/pkelley2/DynamicCR.html
to calculate your stuff use this :
www.edyno.com
http://www.empirenet.com/pkelley2/DynamicCR.html
to calculate your stuff use this :
www.edyno.com
