Help Identifying a 392 HEMI for sale

RustyRatRod said
That's actually true. The 54 and up 331 and 354 heads are the best. They are actually more of a true Hemi design. The 392 heads are actually the worst besides the tiny round port 51-53 331 heads. Because of how the intake ports are curved more downward, because the 392 is a tall deck engine and rather than make the intakes different, they extended the intake ports which makes the intake ports on the 392 heads much less desirable. The hot ticket is putting the 392 size valves in the 331 or 354 heads.

Depends on what you're doing with them. Gene Adams said all the heads, '54-'58, flowed about 225cfm in stock form. When you start porting them is when the difference comes out, the ported 54/55 heads do better.

And it's all relative. Even the 51-53 331 heads in stock form probably flow about as well as stock small block heads in stock form. Certainly better than the factory 318 heads did. You wouldn't use them for a big horsepower build, but even a stockish 331 build with better compression numbers would put out decent power with them.

An excerpt from "Racing the early hemi, by Gene Adams" Racing the early hemi, by Gene Adams – Alkydigger – Technical Info

"I’m going to talk about cylinder heads first, as they are the most important part of making horsepower. This is probably the least understood aspect of the early hemi engines. One would naturally think that the last and largest of the early hemi’s, the ‘57-‘58 392, would have the heads with the most potential. This is not true, and the ‘56 354 head is not much better. The ‘54-‘55 331 passenger car and some industrial heads have far mor air flow potential for racing. These heads actually have bigger ports. The reason for this is not completely understood. Rumors and some sources say that the later heads were made smaller for improved low end torque to haul the larger and heavier cars that they were used in. This is the reason the aftermarket manufacturers of aluminum heads copied the 331.

The stock valve sizes from ‘54 through ‘56 were the same with 1.940″ intakes and 1.750″ exhausts. The 392 has 2.00″ intake and 1.750″ exhaust valves. All the heads in stock form flow about 225 CFM maximum. With all out porting and big intake valves, the ‘54 and ‘55 heads can be make to flow as much as 15% more than the ‘56 – ‘58 heads. In total flow numbers, the ‘56 – ‘58 will flow 305 – 315 CFM, and the ‘54 – ‘55 will flow 360 – 370 CFM. When casually inspecting these heads, the differences are not readily apparent. The intake port at the opening is the same, but on closer inspection, one can see a significant difference next to the valve guide area. The ports in early heads are much taller, at 1.675″ as compared to the later heads which are 1.410″, and start tapering to the smaller size immediately from the port opening. The way the water jackets are cast, the late heads cannot be opened up to the size of the early heads. The 331 heads allow the advantage of a much larger valve, as large as a 2.200″ intake. Keep in mind, these high flow numbers are without brazing, welding, or epoxy. One of the mistakes that was made in the ‘60’s with the hemi’s was installing huge exhaust valves at the expense of the intake size, which caused over scavenging. A popular size was 2.0625″, and in some cases even 2.125″ exhaust valves, which was counterproductive. In some instances when this was done, the exhaust out flowed the intake by a great deal. I was guilty of using a 2.0625″ valve myself, not knowing any better at the time. The ideal valve size is 2.125″ for blown and 2.200″ for unblown intakes and 1.800″ for all exhausts."