big block head castings

[gipperco]

So I have a question that maybe someone can verify for me. I have a 66 383 that has head castings of 2406518 I recently head that this was the worst head that Mopar ever made that I should think of upgrading to a 2780915. Has anyone else heard of such a thing. I have new springs, valve seals on them averaging about 110PSI on compression. It has new cam, lifters, push rods, timing set. nothing was done to the lower end at all other then the looked at to make sure the bearings were still ok.

 

[moper]

What you have are "516s". That last digit is a 6. Those heads have a fairly bad exh port, and a flat intake port. They come with 1.65 exh valves IIRC, and have issues with core shift. In stock form, I wouldnt expect much from them other than to help keep the comression up. I have two sets in service now that make 480 and 500 crank hp after a performance rebuild and midium port work. About a stage 2 porting job. They respond like any other head. Favorably with improvement, unfavorably with cheap work and parts. 110psi for a stock lower end and stock parts is on the low side of OK IMO. If they are all close to 100, I wouldnt sweat it.

 

[gipperco]

the lowest I had was 105 and that was on just one of the holes. it seems to run ok and it is for a driver and an occassional trip down the 1/4. It has headers, performer dual plane manifold, 600 Edlebrock carb.