We've all heard about the legendary 302. High winding motors that revved forever and made horsepower all out of proportion to their displacement. I've mostly run larger engines, except for an old dirt car I bought once. It had a 302, and I ran it a while till it met an untimely end, and was jerked for another motor. My current 355 is about to need freshening, so I decided to freshen up the 302 for a couple of reasons. The first is to see how well the small motor runs while I freshen the 355, and the second is to play with E85 some. The 355 is a 10:1 pump gas motor, so not well suited to E85. This 302 is a high compression engine, which supposedly works well with E85. So the old 302 was drug out of the chicken coop and the cleanup begins. The basic plan is to freshen it up, using mostly stuff I've got laying around in the way.
Teardown was interesting. Do you think I ever floated the valves?
The block is a 010 K block, which began life in a 73 Blazer. It's noticeably different from usual 010 blocks.
While not spectacular, it's one of the better sbc blocks I've sonic tested.
The block was baked, lightly honed, squared, fitted with Pro Gram caps, ARP studs, and new cam bearings, oil restrictors, and plugs. Also clearanced for a double roller chain.
Notice anything missing? A lot of work for only a couple of pounds off the front of the car. I probably wouldn't do this again.
Cleaned up the rear main cap oil passage, a good mod IMO.
A genuine GM large journal 3" crank, which had to be turned to clean up. It was wet magged to check for cracks and passed with flying colors. Notice the chamfer on the rod oil holes. I don't know if that is factory or done in a previous build. Somewhere, there is a Camaro guy who wants this crank.
Crank end play checked out at 0.007.
The stock rods had seen a lot of abuse, due to a bad driver. I decided to replace them with Comp Products chinese Ultralight rods. These are rated to 600hp, but were mainly chosen because they're light at 585 gms, so only a minor rebalance would be necessary. They are nice looking pieces, using 7/16" ARP 8740 capscrews. My machinest checked them out and honed three big ends a little bit, since they were a little tight for his taste.
Stock GM pistons. Both them and the bores had some wear, so I juggled them around to match the pistons and bores. I wound up with between 0.0075 and 0.008 piston to bore clearance on all cylinders. A little loose by modern standards, but OK with these old style forged pistons. Net dome cc is 15.3, a nominal 12:1 dome.
I used file fit Speed Pro moly rings, 1/16-1/16-3/16. Since the bores had a little taper, end gap was checked at BDC. 0.020 top. 0.022 second.
Previously I had used a pliers-type ring compressor, which pretty much was a PITA. I bought one of the tapered ring type for this build, and it works great, highly reccomended.
Deck height wound up at -0.008 to -0.009.
The mains were torqued to 70/65, rods to 60. Main clearance was 0.0028, rods 0.0025 with ACL bearings.
That pretty much wraps up the bottom end, on to heads and cam. The heads will be a vintage set of 292 angle plugs which have a light cleanup. They flowed 240/186 at 0.600 lift, I'll post more on these later.
I have a couple of cams laying around I may use, or I might buy a new one, I'm on the fence. I'd like to hear some suggestions for the cam. It will be a solid roller.
The whole combo is a race only 302, 12.2 compression, the above heads, performer rpm intake, MSD ignition, 1 3/4 long tube headers with h pipe and full exhaust with race bullet mufflers. It will be used in a straight drive 2700# road race car, turning from 3500 to 7500 rpm, so it needs a wider torque curve than a drag motor. Let me know what you think.
John