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Author Topic:   sbc head info needed
MBoyd55
Dirt Newbie

Total posts: 3
posted February 05, 2005 11:47 PM  
Hello to all. I just recieved a set of 354434 305ci 2.02 60cc heads. I understand that the bigger valves are generaly a good thing but being off a late 70's 305 makes me wonder.
Can anyone give me a idea how these would preform on a 350, flat top motor, 4412, roughly 500lift cam.
Also can anyone explain how the CC's effect performance and compression ratio. Thanks to all that give me some head schooling. Boyd

racin78p
Dirt Freak

Total posts: 333
posted February 06, 2005 02:32 AM  
The biggest problem with the 305 heads you have is the intake runners don't flow really well. You can get 'em ported, but the money spend on them is debatable. Can you run after-market heads? There are much better offerings that way. Be advised that you CAN over "flow" a motor by putting on too big of a intake runner (cc) head. Basically, the bigger the intake runner, the more flow into the chambers and the more power you can develop. Stay around 200cc. As fas as combustion chamber size (cc), the smaller they are, the more compression you'll get. BUT beware that you might get into valve clearance problems with too small of chambers. Cam specs have alot to do with this also. People have written books on this subject and I don't want to write one now. What you end up with depends on your track rules and your budget. Whatever you do, be sure to check valve to piston clearance to be safe.

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racin78p
if it ain't fun, then don't run

MBoyd55
Dirt Newbie

Total posts: 3
posted February 06, 2005 08:32 AM  
Thank you for your help, We have to run a factory head and no Fuelie, humps, angle plugs and a hand full of performance castings gm produced (wissota MW Mod rules)
So i might as well find a better flowing 1.94 head and be just as good your saying.

No tampering with the chambers what so ever but if i read the rules right we do not have a compression or valve size rule. Thanks for your help.

BTW, i dont think clearance is a issue here with these heads, owner i got from ran a much larger lift than i am. BOYD

midmod34
Dirt Maniac

Total posts: 119
posted February 06, 2005 10:37 AM  
mw mod rules state 9.5 compression and it is almost impossible to get 202 valves into the heads with the 1/4 inch rule

[This message has been edited by midmod34 (edited February 06, 2005).]

MBoyd55
Dirt Newbie

Total posts: 3
posted February 06, 2005 12:01 PM  
Yes, i read that 9.5 after i posted. I should have read closer. Your saying its imposible to put 2.02 in a 1.92 head without passing the 1/4 inch cut rule.

Ok so back to my ??. Do i have anything to gain by using these 305 2.02 heads.

Does anyone have their opinion of the best legal head/valve combo if them 305's are not advisable. Thanks to all so far.

midmod34
Dirt Maniac

Total posts: 119
posted February 06, 2005 06:51 PM  
lok at the dalr matheson story at homerunengines.com they had brand new castings from gm that didnt pass the 1/4 inch rule. best heads to use that ive heard of for a chev is the 601 there is also a casting in the 450 range that works well not sure on the specific number.

midmod34
Dirt Maniac

Total posts: 119
posted February 08, 2005 06:19 PM  
talked to a couple of guys about the chevy hheads preferably are the 487x then the 601's

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