Thread: 302 chevy

Tweet

I have a 302 chevy engine, budget is important as always, my question is if I bought a 383 short block, could I use the the 302 heads on it?

Yes. What heads do you have on the 302? Stock ones could hamper the output of a 383 so bad that you might wonder why you bought the short block.

Old tech and a step backwards using those heads,with good flowing aluminum heads you could have a bigger power gain and a large increase in flow for a decent amount of cash.

Agree, they'll fit but why would you invest in the stroker short block only to choke it down? I think it was Tech who said just the other day, "...fifty year old technology in those heads..."

Hey Craig - welcome to CHR.

If you have genuine 302 parts, you could certainly e-bay them as there are always folks looking for the real thing to do a period correct restoration for a Z-28. I have to agree with the above posts, i.e., the heads are old and the technology has come a long way since 1968. A 383 needs to breath to be effective and the stock 302 heads will hamper that process.

My 2 cents,
Glenn

Originally Posted by glennsexton

Hey Craig - welcome to CHR.

If you have genuine 302 parts, you could certainly e-bay them as there are always folks looking for the real thing to do a period correct restoration for a Z-28. I have to agree with the above posts, i.e., the heads are old and the technology has come a long way since 1968. A 383 needs to breathe to be effective and the stock 302 heads will hamper that process.
My 2 cents,
Glenn

I agree. Pro-filer 195's with 72cc chambers, flat-top pistons with compression height of 1.425", ~7 cc's of valve relief and zero block deck with a 0.040" head gasket will yield a 10.0:1 static compression ratio and a 0.040" squish, perfect for pump gas with aluminum heads.
http://www.profilerperformance.com/r.../sbc-23-degree
Use this retrofit roller cam together with genuine Howards retrofit hydraulic roller lifters....
http://www.summitracing.com/parts/hrs-110885-08
and produce an 8.76:1 dynamic compression ratio. The motor will want a genuine 10" converter that stalls at ~2500 rpm's and some numerically-steep rear gears.

Use an Edelbrock Performer RPM 7101 intake manifold (or Holley 300-36 or Weiand 8016 or Professional Products Typhoon 52021). Motor will operate with any carburetor, but will make the most power with a 750. Keep fuel pressure at 5 psi at the carb inlet. More pressure than that can overpower the needle and seat in the bowl and allow the fuel pump to blow raw fuel into the intake manifold. Use 1 5/8" diameter headers with an X or H pipe immediately after the collectors. Headers with flange thicknesses of less than 3/8" can curl up from heat of combustion and spit out the exhaust gaskets, so choose good quality headers if you don't want to be foolin' with them all the time. Use a 14" x 3" or 14" x 4" air filter arrangement so the motor can breathe.

With good quality machine work and careful attention to detail in assembly, this motor should easily produce 425 hp and 450 ft/lbs of torque.

.

If you have real 302 heads they will have 2.02/1.60 valves and will bolt on and should work pretty well on the 383. You will possibly leave some HP on the table compared to after market heads but it shouldn't be a dog by any means.

As far as the budget goes, if the heads are ready to bolt on it it is definitely a viable option.....if they need everything (seat, guides, springs, valves, milled etc) then you are probably money ahead with aftermarket heads, especially for what those heads should bring to a restorer.



.

Do you have the casting numbers of the heads? In 1967, two different cylinder head castings were used on the 302 engines, 3917291 and 3890462. Both heads used 2.02/1.60 valves. 1968 used casting number 3917291 but there’s a very subtle tell-tale - the 1968 heads have a water temperature sensor, the 1967 heads do not. The 291 castings have a slightly larger combustion chamber volume than the 462 castings – 64cc versus 63cc. The exact combustion chamber measurement of a perfect 291 casting is 63.995cc. 1969 engines used head casting number 3927186. Still have 2.02/ 1.60 valves but in1969 the heads were drilled and tapped to accommodate the new alternator mounting position. All three numbers have the camel-hump stamping on the end of the head. All three were also used on HP 327 engines as well.The 186 castings are most sought after – typically fetching $1,000 - $1,500 a pair depending on the condition.