jt1 Posted August 28, 2008 Share Posted August 28, 2008 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 Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted August 28, 2008 Share Posted August 28, 2008 great PICTURES and a well done thread! BTW the cam we used to get the best results with in the past on retro Z28 builds was a crane 110921 flat tappet solid lifter http://www.cranecams.com/index.php?show=browseParts&action=partSpec&partNumber=110921&lvl=2&prt=5 best with the manual trans and 4.11-4.56 rear gears in a light car. you might find this interesting http://www.camaro-untoldsecrets.com/articles/crossram.htm the offy intakes still available and twin 600 cfm carbs tend to work great...but theres been lots of improvements in things like roller rockers and intakes since then, and a very similar built 383 is almost certainly going to be faster http://store.summitracing.com/partdetail.asp?autofilter=1&part=OFY%2D5893&N=700+115&autoview=sku http://store.summitracing.com/partdetail.asp?part=OFY-5903 http://store.summitracing.com/partdetail.asp?part=OFY-5902 Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted August 29, 2008 Share Posted August 29, 2008 i was wondering how long it was going to take someone to recommend a belly button 383. I'd take a high winding 302 over a 383 anyday. The sound alone would be worth it! yeah! that sound might be nice, but it tends to loose a bit of its seductive nature when you find your watching tail lights a bit to frequently....we found that out rapidly, want a bit of both,charicteristics, build a 377 (350 crank in a 400 block) but again, the guys that had a 400 block soon found that a properly built 406-421 stroker tended to out run the 377, about the same peak hp but more mid and low rpm tq as the cylinder head and cam technology advanced the ability to feed and use those extra cubic inches proved that added displacement tends to have advantages. 35 years ago the heads and cams available would barely feed a 327-350 displacement at 5500-7000rpm,to make max power, we have made big improvements since then in head flow and valve control. lets say your average well thought thru 383 will make 1.1 hp per cubic inch and a well designed 302 makes 10% more hp per cubic inch 383 x 1.1=421 hp 302 x 332hp plus 10%=365 hp, your still 56 hp lower and that makes a differance THERES EVEN A LARGER DIFFERANCE in useable tq Quote Link to comment Share on other sites More sharing options...
HarrisonTX Posted August 30, 2008 Share Posted August 30, 2008 Great man! I have been piecing mine together for years, and just got my parts out of the machine shop. I went with a small journal 327 block, and a small journal 283 crank. I have some ProComp H-beams (NEEDS arp rod bolts) and some JE pistons, the last of 2 sets left in America i was told. The only thing im missing, is a cam grind, and a carb. I have some solid roller lifters, i just need to figure up a cam. Please let me know what you pick, and how it turns out. Im going to run a super t-10 4 speed, or a TKO 5 speed, right now i have 3.90 gears for the car. Like i said, i just got the parts outa the machine shop, and im dying to piece it together!!! I commend you for not running a 383 Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted August 30, 2008 Share Posted August 30, 2008 Crane used to make a really neat solid roller that went by the TR series. 250/260 .600/.615 110LSA that really worked well in 302 327 engines. I don't see that anymore. Those heads will work pretty well on that engine as well but lack any real airflow for larger displacement IMO. The 302 will rpm about 800 to 1000 rpm higher than stated rpm ranges as they are typically based on 350 cubic inches, at least that is my experience. A grind in the 250 to 260 range and lift around .600 will be pretty stable IMO. The LSA will determine your powerband and I typically prefer a 106 to 108 however you may like something different. Quote Link to comment Share on other sites More sharing options...
Jerminator96 Posted August 30, 2008 Share Posted August 30, 2008 Excellent thread John, looks like a well documented build. I love that you can build a decent motor most from parts just laying around, someday maybe I'll be that lucky. I started a 302 build once, but then came across a good deal on a 3.25" crank so I decided that it would be nice to have the extra cubes at the expense of a little RPM. Then I got a good deal on a 400 block so I decided that a 358 would get me my RPM back with more cubes and more power. Then I found a good deal on a 4" crank and 4.155" bore JE pistons with carrillo rods and decided that while I'm at it I ought to build a big nasty 434. Then I couldn't find a decent deal on the heads I wanted so I got bored with the project and sold it. So more power to ya when you finish this one. Quote Link to comment Share on other sites More sharing options...
HarrisonTX Posted October 3, 2009 Share Posted October 3, 2009 Any news on this? I cant wait for updates. Of corse, my third deployment has stopped any progress on my build. Still need a solid roller cam grind. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted October 3, 2009 Share Posted October 3, 2009 http://www.crower.com/misc/cam_spec/cam_finder.php?part_num=00425&x=34&y=3 heres a decent choice in a solid roller cam for that application but talk to the crower tech guys Quote Link to comment Share on other sites More sharing options...
jt1 Posted October 4, 2009 Author Share Posted October 4, 2009 Project is still in the works, but has slowed. I hit a major snag when I found the valves on the 292's were too short to allow the installed height I need for the cam I want. So, this was gonna require new valves and retainers, $$$$$, totally defeating the what-I-had-laying-around concept. About that time I blew a head gasket on the 358 in my Z, and a head gasket swap turned into a major rebuild with a bore, new pistons, new main cap, and new rods. This diverted some attention from the 302, but that sub-project is nearing an end, so hopefully I'll get back on the 302 pretty soon. John Quote Link to comment Share on other sites More sharing options...
saxfiend1967 Posted October 5, 2009 Share Posted October 5, 2009 also look at a herbert ch7 its almost identical to the crower I have one ground on 106 center. doug herbert.com Quote Link to comment Share on other sites More sharing options...
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