340 x heads

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Muad'Dib15

Muad'Dib15

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So yesterday I found out that my 360 has a set of x heads on it. I don't know the date of casting on them so don't know who to sell to if I sell them. But I haven't had any luck finding anything about them. As far as I can tell, they are pretty much exactly like the J, O, U heads but without hardened seals and 2.02 valves instead of 1.88s. So what do I need to know about these heads? rocker ratios, amount of lift possible without machining the seats, porting tips, any weird thing about them that is different than other LA SBM heads? Answers would be greatly appreciated.
 
from factory...stock non adjustable rockers rated at 1.50..but probably somewhere around 1.45...and probably everyone is different...

lift...from the factory...springs are limited to about .500 lift....

yes..they are pretty much the same as the rest of the J, O, U, Z heads...
 
So anything that can be done to those heads apply to these as well? Like specs and stuff?
 
yes, I would say if your going to chop a set find some 915's that are more plentiful. find someone doing a resto for the x's as they were only made a couple years.
 
By the time and money you throw into these heads, you could've bought yourself a set of RHS heads, and for a few hundred bucks more you can get a set of eddy (60779) heads. Ask me how I know.
 
Rocky_JS said:
yes, I would say if your going to chop a set find some 915's that are more plentiful. find someone doing a resto for the x's as they were only made a couple years.
Click to expand...

uh, 915 J heads right? Not the 915 BBM heads? :p And RHS no longer has the heads. Indy is now the only company who makes them, and those prices are on par with the eddy heads.
 
O.K. After all that what are a set of "X" heads that need to be gone through worth? I would gladly trade my 915 "X" heads to somebody that has a set of "J" heads with 2.02 intakes that don't need any work.

Jack
 
I've read that the 69 340 had X heads with flame hardened 2.02 valves and the matching 69exhaust manifolds had the largest diameter dumps at about 2.25 .
Today those heads would need hardened seats installed and probably guides too.
Someone building a correct 69 340 might want them.
 
Muad'Dib15 said:
uh, 915 J heads right? Not the 915 BBM heads? :p And RHS no longer has the heads. Indy is now the only company who makes them, and those prices are on par with the eddy heads.
Click to expand...

Correct, casting 3418915 are J, U, and O heads. here is a comparison and once cut it negates what the X head had in stock form. http://www.moparmusclemagazine.com/...opp_0001_360_engine_head_porting/viewall.html


Coyote Jack said:
O.K. After all that what are a set of "X" heads that need to be gone through worth? I would gladly trade my 915 "X" heads to somebody that has a set of "J" heads with 2.02 intakes that don't need any work.

Jack
Click to expand...

The X head casting number in question is 2531894. I believe there is another head with a small "x" on it which came on a 318? these are not the heads in question.
 
Rocky_JS said:
The X head casting number in question is 2531894. I believe there is another head with a small "x" on it which came on a 318? these are not the heads in question.
Click to expand...

I will have to have a look when I get home. I am pretty sure mine have the 915 number and a large X beside the spark plug holes. I will take pics when I look at them.

Jack
 
I stand corrected Rocky_JS, Mine are "X" heads but they do not have the 915 part number they have the 894 part number.

Jack
 
894's are nice heads in stock form, but not to butcher. good for someone doing a resto and number matching, they were used in 68-9 and some 70 340 models along with the 915's.
If I were looking to open up a set I would find good 915's with 1.88's and cut the seats for 2.02 that will eliminate any valve sink.
 
Why not cut them up? I guess that's my main question. My dad is telling me to just go for it as they flow well to begin with and porting will only help. And it's cheaper than trying to find newer heads. This is a budget build, I'm using what I got.

Also, Rocky what's the point of that link? All they did was work on the 360 heads until they exceeded the 340s. If you put that amount of work in the 340s they'd flow the same. I got the engine for $500 with the heads on there. I'm not blowing money on it if I'll get the same result for less money.
 
Why? if they are good, fresh, uncut heads they can bring some good money. 915, or 587's can be picked up cheap and are fairly common.
Cheaper? I beg to differ, the difference will be a good bit of the "budget" needed to finish the heads without out of pocket expenses.
perhaps I think to much.
just trying give some insight. good luck with what ever you decide to do! =)
 
I would have to put nice X heads on the market too. Purists will rebuild a that matching number 340 block punched .060 over rather than replace it. When they need a head they'll pay for it. Just like the 340 exhaust manifiolds and other 340 correct parts that carry a supply and demand premium.
 
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