Hey guys…..A few questions that I have after extensively looking up a lot of Engine Quest Magnum LA bolt pattern / Magnum head swaps on the net.

My current engine is a J headed 360 chamber size from what I read is 71cc chamber. The short block has a stock 3.58” stroke, zero deck, speedpro pistons 4.030 / 10cc, felpro1008 head gaskets yielding a .39 compressed size. Crane 272 advertised duration cam.

So on a comp ratio calculator the present setup yields 9.18.

I check out the Engine Quest magnum LA and from what I can find on the net its 62CC so we are now looking at a 10.33 comp ratio.

In the Tech page the LA/Magnum write up, the guy says he is using a 268 mp cam (pretty much the same as mine) and 10.6 comp ratio and it runs fine on 92 pump gas.

Question #1: I think that’s a pretty high pump gas compression ratio but are the magnum combustion chambers that good that this is ok?

Other general questions not mentioned:

Question #2 Head gaskets: 360 or magnum?

Question #3 Spark Plugs: 360 the same as magnum, anything special?

Question #4 Pushrods: As I am using the LA rockers found on the EQ conversion head, do I still need those special 7.625 length pushrods, (MP Part number: 5007477 or the summit chromemoly brand that was mentioned)? If so is that due to a possible head height difference? I also don’t need the oiling type pushrods for pedestal rockers as I am not using them, so is there a solid version of this pushrod (I don’t think it matters though).


Question #5:
Dealers for OE 318B heads: I have seen them mentioned here on Moparts. That Clearwater Cylinder Inc (on EBAY# 370124447607) sells them 700 a set, Carolina Machine engine (CME) and that fast 4 speed guy. Are they ok dealers?

Question #6: Some people state the LA valve covers may work on the Magnum; if so what gasket is good for this?

Question #7 (Last one). I got 340 manifolds, somebody suggested on moparts some remtek or whatever gaskets kept it sealed up as there is a port mismatch.

A lot of question I know…sorry.

Thanks
Sean

1) you should be, IMHO...very efficent chambers
2) Using stock 360 head gaskets works fine
3) Magnum spark plugs use 5/8" heads as opposed to the 13/16" on LA heads. I just used the magnum plugs for a 96 ram van which is what I got my heads off of...working well so far
4) I used the summit pushrods on a stock deck height block with a set of heads that had not been machined in any way, I had the other ones in first and I didn't think they had enough preload. I believe this length only really applies with the stock rockers you DO need hollow pushrods because there are no oiling holes in magnum heads!!! they would not have any oil otherwise!
5)can't answer this one
6)They do, I'd use aluminum valvecovers only though. I used the plain cheapo cork ones without issues
7)I never had an issue with leaking on my headers

(1)yes (2) either (3) different (4) Dont know & dont buy ANY pushrod until you mock up your setup & measure (5) dont know (6)not sure which LA gasket is the best (7) people have had good luck with remflex & mr gasket ultra seals I believe(in that order) but I dont know part #'s but I will add that when I put an 83 318 into my 65 dart w orig 273 logs the parts house had 2 sizes of ex gaskets(the ones with the silver corrugated surface on one side) & it took the smaller ones) (7A) this is a free deal there is no limit on Q's(as long as they are all in the same thread )

Hey Goldduster,

The EQ 318B conversion heads USE the LA rockers so I assume the heads must be drilled to accept oiling from the block. Unless the hollow pushrods squirt so much oil up there it will replace the shaft oiling system.

Sean

Hey Rapid Robert,

On the exhaust gaskets am I buying the magnum gasket to use on the 340 LA manifold or the other way around?

thanks
Sean

Dang....

I am 100% incorrect. I think I need a remedial reading class.

Thanks for clarifying that for me. Looks like something else I have to buy.

Also...if I am going this far shouldI just get a magnum manifold. I had my old one milled to fit the heavily decked block and shaved heads.

Which brings up another question. If someone had their block decked which intake style will take up the mismatch better, the verticle bolt type magnum or the LA style?

Thanks
Sean