Does anyone know what part number heads should be on an original 383 2 bbl engine? I'd like to swap cams at some point, but I would think I should do some work on the heads. I'd assume that the stock heads aren't the best for a larger cam, as the motor is a low compression 383. Would you guys recommend using "906" heads instead of the stock 2bbl heads? I have a set laying around on a blown motor. If the top end on that motor is good, I suppose I should use those heads.

Thanks.

What year? 68-70 383 2 bbls had 906 heads.

Yes, 1968. That's interesting. I would've thought that the low compression motors would have had different heads compared to the HP motors.

Your engine should have 906 heads

I'd still be better off by doing some head though, compared to just swapping cams, right?

The cam I'm looking at is a Comp 21-223-4 I think. Is this too much for a stock 2bbl motor which now has a 4bbl setup?

Big blocks all ran the same heads. There were pretty much only a few substantial design differences between the different kinds of heads. 906's are no better than any other of the open chamber big block heads. Some would argue they are worse than the 70's heads because at least the 70's heads came with hardened valve seats. Doing head work or picking up a set of aftermarket heads is always a good idea. Flow is flow, so better flowing heads will make more power with a given cam.

Quote:

---

The cam I'm looking at is a Comp 21-223-4 I think. Is this too much for a stock 2bbl motor which now has a 4bbl setup?

---

That cam is the XE268H. Don't call it the 21-223-4, most people don't know off hand what what means, but the letter/number cam grind designation for comp's line of cams is much more familiar to most than the part #.

268H is about the most cam I would want to run in a street 383. It'll be a great street/strip cam with a lopey idle. Do a search, some member posted a vid of his 383 with the XE268H a while back. If it's the 4sp car in your sig that this motor is in, and you have 3.55 or numerically higher rear end gears, IMO this will be a good cam for you.

Thanks for the information. Yes, it's the same car. It's a 4 speed with 3.91 gears.

Thanks again.

if you are going to spend money on stock iron heads either find a set that someone is selling that is upgrading to alum heads or get a set of closed chamber heads , preferably 915's , though you could get by with 516's that have bigger valves and porting .

As said, Ma Mopar used the same heads with the 2bbl & 4bbl cars. However, It's really hard to make compression in a 383 with open chamber heads. If you're willing to spend the money on rebuilding a set of heads, I'd go find myself a set of 516's (closed chamber), then spend the extra money to cut in a set 1.74 exhaust valves. You'd then have a decent set of heads that would probably get you to somewhere around 9.25:1 compression with your existing bottom end. Use .020 shim style head gaskets when you re-assemble. You're going to need compression to be able to realize the potential of the larger cam.

Many thanks again for the information. Maybe I'll get lucky and find a set of 915's or 516's at Carlisle for cheap.

Well, I guess I'll look around for the 516's then. What would a fair price be? I'm clueless here on this one.

Thanks.

about 50 bucks , for the PAIR ...

That sounds good in theory. Somehow I doubt though that I'd find a set that cheap.