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snod83 03-04-2004 01:12 PM

283 heads on a 350
Hey everyone, I am new here and I stumbled across this forum with google. I am just wondering if it is a good idea to use 283 heads on a 350 bored .030? I am wanting to have around 10:1 compression and I have full forged internals, roller cam, and I want to run about 150 horse nitrous. I just don't know if I should stick with the bigger combustion chamber 350 heads, or smaller 283. Also will 202 valves fit into a 283 head? The ones I have are from a 67 Malibu, and they have the soft seats.

Thanks, any suggestion would be great!!


killerformula 03-04-2004 01:40 PM

You may be able to get the valves to fit with some cutting, but that doesn't always improve flow. In fact, in some of the later 1.94 heads an increase in valve size without porting actually hurt the flow numbers.

283 heads are not a good idea on a 350. They will increase your compression, but they'll kill your overall horsepower by seriously constricting your flow at anything above probably 3000 RPM, so you'll make no power with them. Compression does not equal power, its only a necessary component for lots of airflow/fuel mixture. If you don't get any more mixture into the chamber, overcompressing the normal amount of fuel/air charge will likely create nothing but some pre-ignition, pingng and detonation.

If you're planning on using N20, you want to make sure you don't have a crazy amount of compression anyway, 9 or 9.5:1 is probably plenty depending on your intake runner size and cam. BTW they make N20 specialty cams too, check out

Hope that helps-


machine shop tom 03-04-2004 02:28 PM

No, No, a thousand times, no! 03-04-2004 02:44 PM

I'm with Tom, you would be taking an expensive step BACKWARDS!

bowtienut 03-04-2004 03:13 PM

no, a large door is no good if you have a small hallway.

snod83 03-04-2004 06:06 PM

Thanks Guys! Just wanted to make sure, I have heard of people using 305 heads, so i just had a thought! I have both 283 and 350 heads, and I believe the 350s are 64 cc so I will go with those! I just wanted to make sure! Thanks for the quick replys... especially the no no no! coming from a guy that has machine shop in the name, i will definetly take that as a great answer!!! haha... so as far as the 202 valves go, should I do a 350 head, or look for another combination? I am open to suggestions!

Thanks again guys!!


Man, not to get off topic but its crazy that all you guys are from michigan!! thats amazing, I am a Indiana native, but I am in Flint going to school, good ole General Motors Institute! (now Kettering U. unfortunately).. Thanks for the help again!

MI2600 03-04-2004 08:53 PM

What casting # 350 heads do you have? It would also help to know what pistons you have, flat top domed, or dished.

Asked another Michigander, whose son is a Kettering grad.

snod83 03-04-2004 09:07 PM

Well, I am not sure of the casting numbers, I will know this weekend, they are at home, in indiana. I have flat top, 30 over forged trw sealed power pistons, I have a comp cams nitrous roller cam, custom grind (don't know specs off hand), and I have forged internals, a great intake, single plane edelbrock, and a NOS sniper kit, adjustable from 50-150. I am putting a 700r4 tranny to it and I have a 4.10 posi 10 bolt in the car. Its all going into a 78 nova (yeah, the ugly boxes). I'll let you guys know the casting numbers for more advice sunday night!

Thanks again!


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