My 302 is in top shape inside and out, I would say less than 6000 miles on the rebuild... Can I update the cam,lifers and springs without doing another rebuild on the motor ? I just want something a little more on the lopey side just for fun, not for racing... Yes I know that this is a crazy reason for a change but I want to do it anyway...lol... Note: I have a set of stock heads with screw down rockers I Will use as well...
You can change the cam and lifters like you want, gotta pull the balancer, timing cover, dist, intake, fuel pump and valve covers. You can also change the springs without removing the heads, by either using compressed air to hold the valves up, or filling the cyl with heavy string or light rope to do the same thing.
Before you choose a cam, you need to first find out what your compression ratio is. Lopey cams generally don't work well with low compression ratios (less than 9 to 1) And piston heights (with flat tops)vary with 302's, not to mention the 72-76 302 pistons had huge dished centers that when combined with 1977-85 heads yeilds a sub 8 to 1 ratio.
Well It's a bone stock block with a std bore and the original pistons, crank and rods out of my 74 grabber... I don't know what the compression ratio was in a 302 in 1974 but I'm thinking its not very high... Maybe I should build my other block and put matching parts though out the motor.... It was a nice thought...lol...
Yea, you should. Your comp ratio is right at 8 to 1, if not lower. Especially if those aren't the 74 heads
My other block is a 74 too, so is it OK to build a simple 306 out of it ? better pistons and rods with either gt40 or edlebrock e heads I'm thinking 10to1 or 11to1 max... then match a cam to that and my c4 with 2800 stall that is already in the car...
Building the other block is fine as long as it's a good block (not already overbored, cracked, etc) Choose your pistons wisely, you're looking for only those flat tops with as close to a 1.620" pin (compression) height as possible. I say this because 302 flat top pin heights range from 1.585 to 1.620, so they're not all equal and that .035 difference can change the comp ratio by a full half point.You may also want to have the block's deck surfaces milled too, but do this after boring and checking the assembled height of the piston/rod combo, this is to assure that the piston comes as close to a zero deck (flush with the block's deck) as possible. These mid 70's blocks supposedly have slightly taller decks (by .020) than earlier and later blocks. To get to a 10-11 to 1 ratio, you'll need the pistons at zero deck and 54-58 cc chambered heads. Not doing your homework, this can knock the ratio down a full point or two by picking the wrong pin height and combustion chambers that are too big
