small block head question

[70nos340 barracuda]

i am tryin to learn more! thanks for reading and any help. i have a 340 and have always heard about the "x" heads, i think they r 2.02's ? i have the others 1.88 , from what i have seen on here they r worth a bunch of hp or am i wrong? and r they worth tryin to find and the $ or just rebuild mine to these specs, mine are in good shape but i always want more hp! what is the best way to go on my limited budget. and is it worth waiting for aluminum heads? thanks

[360 'CUDA]

I think the Eddies have it all over any of the old heads but it's not like I ever ponied up the loot for them either 

Those big valves do get pretty close to the piston 

[dimples]

X and J heads are so close.......it doesn't matter which one you have. The X'es cam e with 2.02's, the J's came with 1.88's........

[Green Drop Top]

X and J heads are so close.......it doesn't matter which one you have. The X'es cam e with 2.02's, the J's came with 1.88's........

X's came with 2.02's but so did MANY J heads (as well as U heads, O heads, and others that were blank) later J heads went to the smaller valves but nothing else changed much, it's simply a matter of adding the bigger valves and unshrouding them. If you have the money Edelbrock aluminum heads are a good long term investment because they can be ported easily and repaired if broken. You will actually make more power with an iron head due to thermal efficiency (all other things being equal) but if you build and engine with aluminum heads in mind you'll have a bad boy small engine that's reliable and cost effective, especially if you use a 4.0 stroker crank.

[dimples]

Not to start a argument, but I have never seen a 2.02 J head, from the factory, and Chrysler said they didn't make one either. I only know of one other guy who claims they came with 2.02's........Rumblefish knows who.

U,O heads, didn't either.

[moparnut]

Not to start a argument, but I have never seen a 2.02 J head, from the factory, and Chrysler said they didn't make one either. I only know of one other guy who claims they came with 2.02's........Rumblefish knows who.

U,O heads, didn't either.

Yes they did in 70 for the J heads,I have a set in my shop.Casting 3418915.You can look at another discussion on these.
 http://www.cuda-challenger.com/cc/index.php?topic=21782.0
http://www.cuda-challenger.com/cc/index.php?topic=22199.0


2465315 273 1964-65 1.78 1.50
2536178 273 1966 1.78 1.50
2658920 273 1967 1.78 1.50
2843675 273 1968-69 1.78 1.50
2658920 318 1967 1.78 1.50
2658234 318 1967 1.78 1.50
2843675 318 1968-74 1.78 1.50
3769973 318 1975-83 1.78 1.50
4027163 318 1977-86 1.78 1.50
4027593 318 1977-84 1.78 1.50
4323302 318 Fast Burn 1985-86 1.78 1.50
4323345 318 Police 1983-86 1.78 1.50
2531894 340 1968-70 2.02 1.60
3418915 340TA 1970 2.02 1.60
3418915 340 1971-72 1.88 1.60
3671587 340 1973 1.88 1.60
3418915 360 1970-72 1.88 1.60
3671587 360 1973-74 1.88 1.60
3769974 360 1975-76 1.88 1.60
3671587 360 1976 1.88 1.60
4027569 360 1977-86 1.88 1.60

[dimples]

ALl I saw, was some ad from Ebay saying "Factory machined 2.02 J heads"..............You cant throw the T/A head into the J head category either.
J head 340's, came with 1.88 valves. (Excluding the T/A's)

3418915 340TA 1970 2.02 1.60

According to your list, I am right.

[Green Drop Top]

Well, I suppose I should have been clearer in my post, but here goes.

 All 3418915 heads were the same castings, the ONLY difference was the factory machining done before valves were installed, since T/A heads were 915 castings and had 2.02 valves in them they qualify IMO, I have seen LOTS of J heads with 2.02 valves installed, some appeared factory but I can not authenticate that because they were'nt taken off of virgin original factory built engines by myself.
 

When you compare a 3418915 casting to a 2531894 you will be hard pressed to find any decernable differences, the 915 head is basically a superceeded casting number to the 894.

So, the bottom line, which is a better head? Niether IMO, they are virtually the same with 2.02 valves installed (regardless of who installed them, the factory or someone else down the road). All the hoopla and high prices that go with the X heads is just a bunch of hype. The only reason I'd even bother to seek out X heads would be if I needed them for a correct resto on an early 340 car.

[moparnut]

ALl I saw, was some ad from Ebay saying "Factory machined 2.02 J heads"..............You cant throw the T/A head into the J head category either.
J head 340's, came with 1.88 valves. (Excluding the T/A's)

According to your list, I am right.

http://www.autohobbydigest.com/tables.php?03_Head-Casting-Numbers
That casting doc was somewhat decieving I should have used to one above,there were in fact 202 J heads in 70 and maybe 71/72.I saw the ones I have pulled right from the motor with all original miles on a 70 cuda vert numbers car that a buddy cloned into a hemi cuda vert to sell 3 years ago.It was obivious the heads were never removed or rebuilt.Did you read all the posts?Chryco will testify there are factory 202 J heads.
3418915    1970    340     T/A 6bbl     2.02" 1.60"     
 3418915    1971-1972    340     J-heads    2.02" 1.60"     65cc - 73cc 

[70nos340 barracuda]

ok thanks guys i guess my question was answered , don't really need to find x's just rebuild mine with bigger vavles or get aluminum if i have the money? right! and yes i plan to build a stroker small block not sure witch way to go yet.

[tactransman]

and yes i plan to build a stroker small block not sure witch way to go yet.

Go with the aluminum heads if you can afford it, easier on the pump gas with a higher compression ratio too.

[dimples]

OK, here's what I got.

69 340, it had 894's, 2.02's........(Of course)
(2) 71 340, both have 915's, both have 1.88's, one was a 4 speed car engine, with a steel crank.
(1) 72 340, 915's, 1.88's
And a set of heads, off of a 73 340, 587's, 1.88's...............
A 71 car 360, 1.88's, and a 72 truck 360, has 1.88's

All of the info I can find, tells me the only 915's with 2.02's were T/A's..........please point me in the right direction to a link, or info, so I can quit arguing with myself!

[moparnut]

I did a couple posts back
http://www.autohobbydigest.com/tables.php?03_Head-Casting-Numbers
http://www.autohobbydigest.com/tables.php?03_Head-Casting-Numbers
http://www.autohobbydigest.com/tables.php?03_Head-Casting-Numbers
http://www.autohobbydigest.com/tables.php?03_Head-Casting-Numbers
http://www.autohobbydigest.com/tables.php?03_Head-Casting-Numbers
http://www.autohobbydigest.com/tables.php?03_Head-Casting-Numbers
There I made it so you cant miss it

[dimples]

I saw it on the net, so it must be true!   

According to CHRYSLER, and all of the CHRYSLER info I have, non TA 915's had 1.88's. I have never seen a 915 with 2.02's, other than ones I KNEW were tamperd with. Autohobbydigest.com is not a factory source of info, I should have been more clear.

[dimples]

Digging further, Mopar did sell 2.02 J's, but they were not installed in production vehicles.
This is from Mopar themselves.