My trusty 318 • The Dodge Challenger Message Board

by **Joel** » 22 Jul 2001 7:23

Yes Dave, I am sorry. A few of you began to to talk about valvetrain, so I tried to take advantage of the moment to ask a question/problem I seem to be facing. I am not sure just how much Ray, the original guy who started the work on my who quit to go work at Arco, an oil refinery here in in the most northern part of Washington state. I don't know I Ray was keeping record of all the work he was doing to my engine, you see. So knowing just how much he took off the heads, but I am sure that he didn't take so much of the heads that I would have had to have the intake manifold shaved too, but exactly how much is that? How much will this bump up my compression? I want to get as much compression as I can possibly get, so would it be worth to get Mopar Performance shim type gaskets? If Ray did not take enough of the heads off to have to shave the intake, should I still be worried about shortening the pushrods too?

It seems, at least to my knowledge, that the highest compression pistons I can get is 9.0:1. Do you know if I can get higher compression pistons some where else other than from Mopar Performance?

by **Jack T** » 22 Jul 2001 23:05

Regarding the trusty 318...... I have one with 175000 miles on it and since it will need a rebore and therefore new pistons, can it be bored out to be a 340? Are there pros and cons I should be aware of? What about the heads? Hopefully I'm in the correct thread here..... My apologies if I'm not.

by **Joel** » 23 Jul 2001 12:25

If what Dave has been telling me, YES YOU ARE IN THE WRONG THREAD!!!!!! No, I am just kidding
Jack T!!! If what Dave has told me is correct, the only thing that makes the 340 different from the 318 is that it has been.....lets see now what does my shop manual say...it says that the 318 has a bore of 3.91" and the 340 shares the same cank, but the 340's bore is 4.040" so it is 13hundredths larger than the bore of the 318. Now common knowledge tells me that the 318, 340, and the 360 are all on the same block, but all three have different respective heads. The water jackets in the block should be the same, right Dave? SO no, Jack T, you sould not have many problems boring the 318 out to the sweet number of 340, or at least to my knowledge. For sure you will need a cam, heads, and pistons that are for a 340 though.

Uh, Dave you can correct me in any areas that I may have missed and or any that I have mentioned that maybe incorrect.

by **Joel** » 23 Jul 2001 12:44

Jack, don't let anyone convince you that the Chrysler A-engines are JUST nice and all, they are THE best set of small blocks out there. Oh yeah, don't let Dave talk you into buy a bigger block, okay Jack? Small blocks are best for touring races anyway, you know. Having a big block in the straight-a-ways is one thing; having a big block on winding roads is another. Any experienced touring racer can tell you that cornering with a big block, no matter how well the suspension is built, is no match for a small block in the corners.

by **dave-r** » 23 Jul 2001 12:58

I don't think they are cast the same at all. The most you should bore a LA engine is 30 thou over. You can go to 40 thou but that is pushing it.

by **Joel** » 02 Aug 2001 20:17

If they don't share the same block Dave, I am kinda curious to as why machinists, mechanics, and died hard Mopar fans that I have heard and talked to, all say that the LA engines share the same block. I know that it sounds like I am questioning your better judgement, but my tone of voice would indicate that I am truly baffled. Could you, if you have an answer, sort this out. I want to be absolutly sure about this, because I don't want to give someone any information that may be false.