Question on 915 heads Options

[41DodgeCoupe]

I got a line on a couple of rebuildable 915 heads on Craigslist. I understand that 915 heads came with 1.60 exh and 1.74 exh depending on performance options.

Are the valves measured across the face or across the seat?

BTW, he wants $200 for the pair for 1.74 exh. Is that reasonable for 915 heads?

George

[moparman1972]

I'd say $200 is reasonable for a set of 915's, especially if they're HP heads.. Anyone else?

[BombFactory]

The exhaust valve size depends on what application the head is (i.e. if it is a standard 383/440 head or a high performance head). The 915 retains the closed chamber of the 516, but has updated and better ports. Even if it has 1.60" exhaust valves, 1.74" valves can be machined in. Depending on your engine configuration, you may not need a larger exhaust valve to begin with.

The valve size is measured across the face of the valve, so the overall diameter, not the seat. I think $200 is an extremely reasonable price for a usable pair of 915s, especially if they are 1.74" exhaust. There is a lot of mythology about B block heads (i.e. some people swear that late 70's 440 heads are superior), but a lot of this came about due to the fact that the late model 440 heads had hard seats and were an easy swap for earlier soft seats when unleaded fuel became standard. In reality, for most carbureted engines, smogger heads are garbage compared to a set of 915 heads due to the smogger open chamber and port configuration. The 915, from all the literature and flowcharts I've seen, is the best factory head produced for B blocks. Racers took many out of circulation, and the rest have come back to us a Honda Civics, so they are hard to find. If you don't buy them, pass on the contact info to me will ya!

[tggodfrey]

The exhaust valve size depends on what application the head is (i.e. if it is a standard 383/440 head or a high performance head). The 915 retains the closed chamber of the 916, but has updated and better ports. Even if it has 1.60" exhaust valves, 1.74" valves can be machined in. Depending on your engine configuration, you may not need a larger exhaust valve to begin with.

The valve size is measured across the face of the valve, so the overall diameter, not the seat. I think $200 is an extremely reasonable price for a usable pair of 915s, especially if they are 1.74" exhaust. There is a lot of mythology about B block heads (i.e. some people swear that late 70's 440 heads are superior), but a lot of this came about due to the fact that the late model 440 heads had hard seats and were an easy swap for earlier soft seats when unleaded fuel became standard. In reality, for most carbureted engines, smogger heads are garbage compared to a set of 915 heads due to the smogger open chamber and port configuration. The 915, from all the literature and flowcharts I've seen, is the best factory head produced for B blocks. Racers took many out of circulation, and the rest have come back to us a Honda Civics, so they are hard to find. If you don't buy them, pass on the contact info to me will ya!

Are you sure? The 915 head was a closed chamber version of the 906 head.

200.00 is a steal especially if they are untouched. The hp head was only used in 67 so you can imagine how hard it can be to get your hands on a head that was only used one year!

[BombFactory]

Tggodfrey, please clarify, as I'm not sure what you are asking. What are you asking if I'm sure of? You are correct--although I'm reversing your order--that the 906 is an open chamber version of the 915 with the same port configurations; the 906 actually shows slightly better flow than the 915. However, the 915's smaller volume combustion chamber and its subsequent geometric design yields far superior combustion characteristics than the 906's and later castings' open chamber design. To match and exceed the 906's slightly higher flow numbers, a little porting needs to be done to the 915. The open chamber heads are stuck with poorer combustion designs that cannot be fixed, while the 915 can be brought to better flow numbers with machine work. This is why, in my opinion, and the opinion of a lot of old school racers, the 915 is the best oem head to get your hands on. Regardless of whether the head has 1.60" standard or 1.74" HP exhaust valves, the 915 was only produced in 1967, so, with the modern ease of getting larger valves and cheap machine work, both heads are worth about the same; it's not the valves that make these heads special, its the port and closed chamber configuration that no other oem head has.

[67Mopar]

I have to agree with the Bomber here...
If I had a set of 906, 452 & 915 heads sitting on my bench, and only one block to mount them on, my eyes would be fixed on that set of 915's, knowing that with just a little extra effort they would make an ideal set of heads for a Stock or Magnum style build.

Come to think of it, I actually have a set of the old close chamber heads in my shop... can't remember which ones however.... I'll have to have a look the next time I get home.

[tggodfrey]

I dont know where in my post you got the idea I was questioning the 915 head. In fact i have a pair sitting in my attic with SS 214 181 valves so I am familiar with the desire of the heads.

The post I quoted was stating the 915 was the same as a 916 head.......I am not aware of a 916 head ever produced so i was asking if the individual posting meant the 906 heads. the 906 head is very close to a 915 head but with a closed chamber as you already stated.

Did this place turn into an import board..........

[BombFactory]

I dont know where in my post you got the idea I was questioning the 915 head. In fact i have a pair sitting in my attic with SS 214 181 valves so I am familiar with the desire of the heads.

The post I quoted was stating the 915 was the same as a 916 head.......I am not aware of a 916 head ever produced so i was asking if the individual posting meant the 906 heads. the 906 head is very close to a 915 head but with a closed chamber as you already stated.

Did this place turn into an import board..........

Maybe it's just me, but you didn't make yourself clear the first time. Let me first say that my quote of a 916 is a typo; I meant 516. I'm not exactly sure how your original post of "Are you sure? The 915 head was a closed chamber version of the 906 head" asks any kind of question about what casting I'm talking about (the 915 or 906), as "are you sure" questions the whole quote which contains many different ideas. For all I knew, you were asking me if I was sure a valve is measured across the face or if I was sure the 915 head is superior--which is how I got the idea you were questioning the 915's superiority. Furthermore, I never said the 915 was the same as the 516 (916 typo). I said, "The 915 retains the closed chamber of the 916 [516], but has updated and better ports." I merely give my friendly opinion here, but it would have been much easier to converse if your question was a complete sentence of "Are you sure the 915 is the same as the 916, because I've never heard of a 916 head? Did you mean the 906?" Or it could take us four posts a piece to figure out one sentence