I realize this is probably an old subject, but i just want some clarification on the subject. I have a 73 block and 73 heads. I am planing a rebuild. Is there any problem with me buying an engine kit for a 70 to bump up the compresion ratio. I realize that the heads and block are of the 8.5 to 1 variety, but the pistons from a 70 should bump up the ratio right? Are there clearance issues or anything i should know before i screw up? It's a daily driver that needs a new heart. I just want that extra little kick. I know I wont get the same ratio as a 70 350-4, but it is an improvement right? TELL ME PLEASE. Give me some suggestions guys. you are the experts. Let me know. Thanx in advance.
Th 68-70 pistons will give you a nice increase in compression. Shaving a little bit off the heads or block will help also. If you get a high comp kit, make sure it is for 70 and not 68/69 as the lifters are different. Unless you are running a .500+ lift cam, you should have any interference problems with the valves. You may have to run higher octane gas or less timing but otherwise you will be good to go. Dan
Not all '70 350s had 10.25:1 comp. You need to make sure you are getting the hi-comp pistons to achieve 10.25:1. These will not come in the garden variety rebuild kit. But yes, it will improve hp. The pistons are the only difference between the hi-comp and low-comp engines.
