StreetSleeper
Well-Known Member
If you already had engine blocks, even both heads to choose from to begin with, which head is better either for moderate street performance and which head is best for a max performance build?
Which head/combustion chamber is better for performance? Speed master aluminum LA or aftermarket magnum iron head?
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Newbomb Turk
Well-Known Member
None of those heads are for a max performance build.
You need to define your terms differently.
There are some pretty nice magnum heads out there but the trouble is they came on Mopar crate engines or other sources and are no longer available. A friend has a set on his 408 based engine that runs 10.70’s. (2.05 valve). Edelbrock, Speedmaster, ProMax, TrickFlow, etc can be made to go a lot faster. But all require extra work. As did the magnum heads on my friends build. But like it says above more info is needed
TT5.9mag
Two atmospheres are better than one
Which head is that? Most of the crate engines I’m aware of used either;
Cast iron magnum head
Cast iron magnum R/T head
Aluminum edlebrock magnum head
He’s told me probably 4 times and all I know is it was a better magnum head that was on factory crate engines and is no longer available. The short side excited my fingers. Kinda like a W2 only different.
Newbomb Turk
Well-Known Member
Were those actually magnum heads? I had two sets of those with the improved exhaust port but I didn’t think they were magnums.
My buddies are for sure magnums. I’ll text him to see what model. We already had our phone chat time. Lol
PRH
Well-Known Member
I’d rather port on the aluminum heads.
Newbomb Turk
Well-Known Member
Might be a good idea to tell us which pistons you plan to use.
furrystump
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For all out, one of the newer aluminum castings. The best between the OEM castings? Shaft mounted rockers or stud mounted. Shaft is more stable. Closed or open chambers? Pretty sure there are available pistons that can help the open chamber. In the end, I wouldn’t sink a dime into a cast iron head if I wasn’t required to.
StreetSleeper
Well-Known Member
Either KB-107 or Speed Pro H116cp
Cam would be smaller than comp cams XE 268 for the street build
StreetSleeper
Well-Known Member
StreetSleeper
Well-Known Member
Both of the mentioned heads are closed chambers, each with either shaft or stud mounted lifters-they are price comparable entry level when replacing heads on a SBM.
I meant available new.
StreetSleeper
Well-Known Member
Just the Chinese repo with a few engine quest heads and an occasional RT set popping up for a quick second at the different marketplaces either under $2K usually sir.
I've used both those pistons and I would recommend the Speed Pro. No special ring gap requirements.
TT5.9mag
Two atmospheres are better than one
Thanks, that was definitely the cast iron magnum R/T. They were a magnum style head with W2 influence. @Brian Hafliger at IMM is currently evaluating a set for me now. I’ll post what he finds.
TT5.9mag
Two atmospheres are better than one
rebelcaptain
Active Member
Mentioned were Edelbroor Performer, TrickFlow, Speedmaster and ProMax heads. What about the 1970 and 71 stock 340 heads with the large 2.02 valves? Are any of those aftermarket heads better/worse? The literatures says "increased performance". Performance doesn't necessarily effect gas mileage. What's the story?
Don’t ask me about gas mileage. It’s a subject I never cared about or studied. As far as going quick yes an X or J head can be made to go fast, real fast. My street car ran 11.82 with them back in the 1970’s and that was with junk parts. A friend has a set running 9’s with small valves but it’s a drag only car.
Out of the box Speedmasters are close to equal to X's or J's. Did I read that somewhere or am I completely wrong?
Out of the box Speedmaster heads are in the 250cfm area. I’m betting a J or X head can be made to flow better than that but be prepared to pay a handsome price. I could do a set for free (or close to free) and I’m not even interested.
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