Hi everyone, looking for some advise on choice of heads to use on my 283 im rebuilding, 283 has forged .60 domed piston isky cam 1800 to 5500 rpm, im looking at using 305 stock heads as budget get little low, i figured i would get pretty good compression with them. Any suggestion or advise welcome. Cheers Andy
As cheap as the aftermarket heads are for a SBC, its hard to justify spending the $$ on getting a set of stockers rebuilt. $649 gets you Summit part # SUM-152123 cast iron 2.02 heads that are better than the old double humps. Or #SUM-162109 for $879 is the aluminum version. I spent MANY hours last summer porting my BBC heads. I'm proud of my work but after spending $450 at the machine shop to get new valve guides and a thorough rebuild after all that, I think I should have worked a few side jobs to pay for a new set with modern technology. I would have been "a head", pun intended! SBC's are cheap to build. No wonder so many dudes run them. Oh yeah and there's no sound like a 283 or 327 winding up to the moon! Good luck!
I was just going to say, if you're putting bigger valves or "different" combustion chambers on a 283 be CAREFUL. Tough to fit all that in that small bore, especially if you have domes on those pistons and run any lift at all.
Buy my power pack heads I have in the cl***ifieds. That will get you the compression with out sacrificing flow that the 305's would cause. Plus it's old school and they are ready to run. r
I have an 80 over 283 in my 62 nova. When I built it, Dart heads were brand new at close to a g. I put double humps with 2.02's, ported with 7/16 screw in studs. With guides, some new valves and clean up it was close to the Darts. It has the comp cams 292H cam in it. Has no low end but pulls to almost 7k.. can the 305 heads and get something that flows, even if its an old set of reworked fuelers or something. Anything from 72 on in SBC is barely good for anchoring a boat.
The '416 and '601 L-69 305 HO heads flow about like the old 461 "Double Hump" heads on the intake side, a little weaker on the exhaust side but a die grinder, dual pattern cam or 1.6 rockers on the exhaust can help that. They have 58/60 cc chambers and 1.84 intake valves. In the 1800 to 5500 range they'd be excellent for a 292 ( .060" over 283 ). The standard 305 2 bbl. heads? Good door stops or Winter ballast and right now worth about $50...... a ton. Just noticed your location, 305 HO heads might be a little hard to come by but if you CAN find a set they would work well.
http://www.jalopyjournal.com/forum/showthread.php?t=302087 http://www.jalopyjournal.com/forum/showthread.php?t=242405 http://www.jalopyjournal.com/forum/showthread.php?t=204736 http://www.jalopyjournal.com/forum/showthread.php?t=45615 heres some reading material
thanks for all the imput, been taking to engine recon guy today says compression he thinks will be around 12, being that its a weekend famliy rod my wife can drive i need to get it down to run on unleaded gas and to be good weekend family rod. It will be going in 51 pontiac coupe, am i on the right track by thinking i need to be looking at smog heads with a 76cc chamber, dont get me wrong i like it to get up and go, but also for my wife and kids when old enough to be able to turn the key with no troubles. Im going to run a early tri power setup, offenhauser intake and three 2g rocks
The cam you're planning to use needs a static compression ratio of 8.75:1 minimum to 10.0:1 maximum. The domed pistons are killin' you. Even if you manage to crutch the motor with big chambers and get the SCR down within range, flame propogation across the chamber will be horrid and there's no way to get a good squish in the chamber with that big dome in the way.
12 to 1 in a daily driver........... OUCH. I wasn't thinking clearly last night, 'fridaynitedrags' is correct that combo is not going to work well. It will "work" but it will be FAR from optimum. What cam are you running and is that 1800-5500 range in a 283 or a 350? Without some more info and knowing what octane ratings are available in NZ I'm going to say you need to be at around 9.5 to 1 static compression to pull this off. A set of flat tops with 4 valve reliefs, 58cc chamber heads (305 HO's) and a quench distance of .046 will put you at roughly 9.3 and have far better flame travel. All the flow in the world isn't any good if you can't get it all burned evenly. That should run easily on 87 Octane or possibly a little less.
hi guy ditching the piston, got some flat top 0.60 to run on this build around 9 comp. cheers for all the advise
You'll be glad you did. Don't know what drivetrain or vehicle this is gong in but in a 3,000 Lb. or lighter vehicle with a 5 speed or 200-4R auto and some 3.73 gears it would get good mileage and be a real blast to drive. Would still do respectable in something 3500 Lbs. or so.
The Jalopy Journal
