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Discussion Starter #1
Hey guys, I told you before that I found out that my 67' Biscayne appears to have a 307 in it (block casting number- 3970020). I found tonight that I appear to have some powerpack 283 heads on it as well lol. The numbers come as follow: 3884520 GM 4 T^-(big triangle lol) 0238-(may be 0288). These heads appear to be about 60cc chambers from what I gather online and 1.72/1.50 valves. Do you think these heads could support up to 300hp with a 1.94 intake valve? Anyone have any experience with these as I personally do not. Any help would be great!
 

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Hey guys, I told you before that I found out that my 67' Biscayne appears to have a 307 in it (block casting number- 3970020). I found tonight that I appear to have some powerpack 283 heads on it as well lol. The numbers come as follow: 3884520 GM 4 T^-(big triangle lol) 0238-(may be 0288). These heads appear to be about 60cc chambers from what I gather online and 1.72/1.50 valves. Do you think these heads could support up to 300hp with a 1.94 intake valve? Anyone have any experience with these as I personally do not. Any help would be great!
They can support hp 300 with a good valve job, our 283 NHRA stocker held the record at 12.57 @ 104.70 in O stock automatic, which is a 65 chevelle wagon with a 283 in it, at 3570 pounds which shows about 313 HP at crank which is what I saw for observed HP on my dyno. Now intake flow was about 169 cfm @ 28 inches with the 1.720 valve unported due to rules, its seems they go in the 190s for flow with a 1.940 valve with minor porting. Hope this answers your question.
 

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Thanks alot!! Since these heads are already on the car I was thinkign of leaving them, just swapping valve springs and camshaft. I have a 4bbl aluminum q-jet manifold and carb to go on, hoping for mid 200's or so hp wise(the closer to 300 the better) and looking for some good low end torque. I was going to get some 416 heads but I'm trying to keep the engine part of this project on a budget since the motor is in such good shape. I don't see the point in swapping it or going crazy at this time.
 

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416 heads are cheap man....

I got ripped off on my first set but my boss gave me my second set

Ill give you the first set if you pay shipping. but one of the valve guides is messed up and you would have to spend 30 dollars to get a false guide put in. ....
 

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I wonder how much shipping would be lol.
 

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The mph though is the real give away. I see guys in high 13's running 104. He's probably hooking like crazy and has some really high (numerically) gears. A buddy of mine was running [email protected] putting down 276 at the tires in a 94' Z28
 

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The mph though is the real give away. I see guys in high 13's running 104. He's probably hooking like crazy and has some really high (numerically) gears. A buddy of mine was running [email protected] putting down 276 at the tires in a 94' Z28
Actually we never where able to get the car to leave like we wanted to, needed more converter testing, 60 ft was 1.72 but we were looking for 1.69 104.7 should net a mid 12.4 but the car held the O/SA record for a few years, Cal Method bought the car and raced it before building his C/SA Nova 402 375 HP car.
 

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Discussion Starter #10
sounds like a sweet set up. You think with the x4262h cam with the PP heads, q-jet aluminum intake and carb would make around 250-270 or so?
 

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sounds like a sweet set up. You think with the x4262h cam with the PP heads, q-jet aluminum intake and carb would make around 250-270 or so?
I have no experiance with that type of combination so I couldnt say, but 250 dyno HP seems reasonable. I wouldnt use the 416 heads, the runners are to big for a 307 plus the heat crossover going into both exhaust ports bothers me, stick with the 520s, It was a long time ago but Ive done a 350 with 520s ported, solid flattappet, 11.1 comp, 450 dyno [email protected] 6500 rpm, 70 nova ran 11.30s @ 116, car showed about 390 Hp going down the track, which tells me the car and drive line needed some work.
 

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Cool thanks for the info. I'll probably just clean up the 520's when I do a cam swap (valve jobs, new springs/seals etc). I'm more interested in the torque it'll make but would like t get at least 250 out of it hp wise for the time being. Of course I'm not one to leave anything alone so down the road my goal will be much higher :devil:
 
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