| Re: cylinder heads and compression ratios |  | ||
| Re: Re: cylinder heads and compression ratios -- Ken Merring | Post Reply | Top of thread | Maverick Message Board |
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Posted by: Fred H 01/18/2002, 07:49:19 |
:=My engine has a compression ratio of 8.1:1 (its a '77) and i feel that it is too low to get good performance, but I am not sure. DOes anyone have an opion that would help me figure out whether or not this is low. Also, what size of combustion chambers are you guys putting in your 6 to 8 swaps. The shop manuel i have says mine are between 67-70cc is this correct? If I mill the heads is it possible to raise my compression to about 8.5:1 to 9.0:1 ?
................................ 289/302 heads with 53cc +/- chamber plus some milling will give close to 10.5 cr on the 77 block. Have the rocker studs replaced with the 3/8" screw-in studs and push rod guide plates. The use non-rail rockers and your set to use any cam. Th casting # C3AZ, C60Z, C70Z,/ C80Z ************************************************************* Dave, 10.5:1 is safe for daily driving if you do not go crazy with ignition timing and and run premium gas. Some will tell you it is too much for a daily driver but I know form personal experience several times over that it is not (but I would not want to go much higher without mixing) Detonation is what you will need to avoid. If he is going to go the cheapest possible route and plans on building a relatively mild motor (6500 rpm or so) then aftermarket rail rockers , pressed in studs (the studs can be pinned for extra safety, although not necessary in my opinion), and stock pushrods (assuming geometry is correct). However, if the budget allows, I agree in that the screw in stud and guide plate set up is ideal. I was assuming that he is working on a budget and that his cam selection would be limited by lack of compression and whether or not the heads will be ported. |
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