magnums & A bodies exhaust fun(not)

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braveseal

33 years with Mopar!
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While I'm no stranger to A bodies or mechanical work,Putting a magnum into an A body does have its exhaust problems.
Bought a 68 valiant with a 360 magnum,older one before they got smart and went back to more normal exhaust port opening(magnum r/t) with aluminum heads and the strange exhaust port shape that no one makes headers or exhaust gaskets for (not for cars anyway) so now I have to make header gaskets and modify standard LA series headers to fit.

Having made a template for the exhaust gasket for the odd port shape,I now will transfer that to the header flange and have the flange welded up,then grind the weird a** shape into the flange openings.I'll probably have to weld the outside of the tubes up because it may break out.
Then after all that is done,I still have to make header gaskets,either out of dead soft alum(if I can find some) or out of copper or regular exhaust material.....fun huh?
anyone want to buy a low mileage 360 magnum with fresh heads??!! :angry4:
 
?????

Standard LA headers or exhaust manifolds bolt up to the magnum head with no problem and seal fine with standard LA gaskets, I put a magnum headed 360 into my 68 Barracuda and have Hedman A-body headers on it. I also have several buddies with magnum crate motors that are using off the shelf headers intended for LA motors.

The exhaust port has less of the corner lopped off (i.e., more rectangular) but LA gaskets don't intrude into the port and didn't require any modification. I am using Felpro #1423 header gaskets. The sealing ring on the headers also contacts the surface of the head with no issues regarding the port shape.

Are you sure your engine doesn't have one of the mopar race heads on it? They are the only ones with a different exhaust port configuration that requires special headers.
 
dgc333 said:
?????
Standard LA headers or exhaust manifolds bolt up to the magnum head with no problem and seal fine with standard LA gaskets, ...
Click to expand...


Actually, his statement:
" ... with a 360 magnum,older one before they got smart and went back to more normal exhaust port opening ... "

- Sounds to me more like he's saying that the older 360's have the non-standard port openings. Curious - 'W' heads? Even they have off the shelf headers available though - just not iron manifolds.

~Bill
 
but whit W series or race heads the bolt pattern should be diferent aswell

got any pictures`?
 
Bill,
All factory magnum head castings are the same there was no design change. The R/T magnum head is identical externally but has some internal port modification to improve flow. The only thing they made available with the R/T magnum head was a version with LA intake bolting provisions, so you can order it either way.

If braveseal can't mount LA headers to the head then he does not have a magnum head on the engine. Plus he indicates that the heads are aluminum which would indicate they are not magnum heads. Only the aftermarket R/T head is availabel in aluminum and that was just released in the past year or so.
 
Reading this fellow's post, it sounds like he has W-5s or some other pain in the neck W-series head.
Why anyone would want to pay the $$ to run those things on the street, where you hardly use their potential, is beyond me.

Mark.
 
heres the head..#P4532900
fill too large,can;t upload
While LA headers will bolt up,they won't seal because the port
shape is totally different.
not retangular,but more square wil flaired corners
 
heres the port opening

mag head.jpg
 
ha! not using it on the street??
The dart I owned had a Barton W2 roller engine,.642 lift,4600 ATI conv,
and although I didn't "use" it much on the street....It sure was fun!!
made alot of big blocks look sick!
 
dgc333 said:
Bill,
All factory magnum head castings are the same there was no design change. The R/T magnum head is identical externally but has some internal port modification to improve flow. The only thing they made available with the R/T magnum head was a version with LA intake bolting provisions, so you can order it either way.

If braveseal can't mount LA headers to the head then he does not have a magnum head on the engine. Plus he indicates that the heads are aluminum which would indicate they are not magnum heads. Only the aftermarket R/T head is availabel in aluminum and that was just released in the past year or so.
Click to expand...

I thought I had basically the same question you had; namely, that since all A-engine headers should fit all non "W" type A-engine heads, why kind of non-standard heads does he have?

The only difference was that I took him to mean that he thought (not me) older A-engine heads would not accept off-the-shelf headers.

~Bill
 
braveseal said:
heres the R/t head right out of the cat
Click to expand...

This picture looks just like factory iron magnum heads (and is the same for all factory heads from 92 to when they stopped magnum production in 02/03). I have had two sets, one from an early 90's engine and a set from a 99 engine which are on my 360 and LA exhaust stuff fits fine. As I mentioned before not as much of the corner is knocked off in the two center ports as an LA head but in either case gaskets and headers fit both.

The previous picture I have never seen a head that looks like that and have no idea what it is.
 
when you compare the LA header openings to the ports on these heads...the LA opening is about 3/4 of an inch longer(top to bottom) than the port opening on these heads,So if you use an LA gasket..that much of the head port(3/4) has nothing to seal against,and the sides of the ports are blocked 1/8 by the header flange cause the head ports are slightly wider...
 
the first pic is my head and the one after, I got from a m.p. parts seller The ports are the same,.Thats what I have.The last pic (r/t head),..the port opening would work with the LA header........S**T!
 
You certainly have something strange there. The ports are definately different shaped than the LA/Magnum port. With Mopar being on them I would think that there would be some info available about them.
 
Those ports look like ones I've seen on W-8 or W-9 heads.
MP makes special kit to adapt them to the standard header flanges, IIRC.
Or maybe it was that MP sold the flanges to weld to the headers?
I forget.

I'll bet you thought you were getting a helluva deal on some cheap aluminum heads at some meet and they were likely MP closeouts that you'll have a hard time finding replacement parts for, much less accessories like headers.

Mark.
 
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Looking in my 01 MP catalog, I see that funky ex. port shape you are talking about. The old part number is P4876624. Doesn't mention anything about not matching up to stock ex. pattern. Does say "Uses single production exhaust flange pattern". Whatever that means. The chart says it is suppose to be a standard ex. port shape. :scratch:
 
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