360 Build ?'s

bushwackertn

First if all I'd like to say Hi, to you all. And thank you for having this board, for people like me to come to for help and advice. :t: O.K., to start out with, my son is soon to turn 16, and I gave him my 79 CJ-5 a couple of years ago. It has a 360 in it. We recently got another 360 to build. We are wanting to build a strong engine with-out going to crazy. This Jeep will be running in a local mud-sling compt. I'm wanting to bump up the compression some and go with good cam for what we are going to be doing with it. We already have a Performer Intake, and a 750 cfm Performer Carb. We also have a set of 291 heads off of a 70 390 on the way. I have been doing research on installing 343 flat-top pistons in the 360. But I can't find any real detailed info. about doing it.I have talked to an engine builder about this, and he said the first thing that we need to do is to see what it will take to clean the cylinders up and then get the pistons. After that he said that we will install the crank and and make up a rod that will allow us to slip the wrist pin in without pressing it in, to check the deck height on all cylinders. To see how much the block deck needs to be cut down. Do any of you know if this needs to be done, I have read some post talking about (0 deck height) on here. Is this needed with using the 291 heads? I'm also considering installing the valley oil line. And I'm confused with cam selection, the mud-sling is timed from point "a" to point "b" I think the pit is around 300 ft. And you start out from a dead stop, any input for a good cam would also be helpful, The engine builder that I talked to said it would be best to go with a solid lift cam, but all the profiles for solid lift cam's seem to be in a higher RPM range than I think we need. Input please???? Also, do we need to do any port work to the heads or will they perform well with stock ports. The heads will have to be shaved down due to some pitting on the mounting surface. Also wanting to run a set of roller rocker's, allot of talk about push rod length though, that confusses me 111!!! Well if any of you want, I need the help and I'm willing to listen to your input on this. Thanks....

jeepsr4ever

You want solid midrange is what I am hearing. 343 pistons will yeild 12-1 compression in a 360 with 52cc heads (IIRC) This is pretty high and I wouldnt run them with those heads. I would look for a set of 10.5 and under compression pistons with those heads and run a cam that has a nice intake and exhaust duration for that range and a nice lift at around .500 for the exhaust and just over .490 for the intake. The comp Cam XE256H is very close to that and is a good choice. With the range your working in 2300-5800 a valley line or smaller hole cam bearings should be used with a deep sump extra capacity oil pan and no need for a crank scraper at those RPM's. Make sure you use a rev limiter or you will cause damage. You will want bushed pins like you machinist reccomended and have those rods balanced. you can build some really nice power with this type of setup and if its put together right it definately wont let you down. Thats my .02$ other will chime in soon Welcome aboard :t:

bushwackertn

Thanks, for the Welcome. :t: And thanks again for the advice also, what would happen if I used the small hole cam bearings, and the valley oil line would there be a problem with that? Also we have a set of 58cc heads that have already been worked: new valve guides, valves ground w/new seals, and stiffer springs for the use of a performance cam (got the springs from maddog racing) these heads were also milled down just to clean them up for trueness. Should we use these heads on the engine with the 343 pistons? I was thinking that we would have like 10.2:1 compression with the 291's and the 343 pistons 111!!! The valves do not have a three angle valve job done on them, would it be a good idea to take them back and have the three angle valve job done on them? Thanks.....

bushwackertn

Also the rod that I had talked about was just for checking the deck height only, he wasn't talking about doing all of them that way, and installing bushings in them. It was just for quick assembly and disassembly. Is it a good idea to have the rods w/bushings in them? What would the purpose of that be? Thanks....

bushwackertn

I have done some more research and found that the 343's had the flat-top pistons and the small cc heads and they only had like 10:1 to 10.2:1 compression. Why would the 360 have more compression than the 343? I don't mean to sound stupid here or anything, I have always heard the only stupid question is the one that wasn't ask. And that is why I don't hesitate to ask questions.

bushwackertn

jeepsr4ever wrote
You want solid midrange is what I am hearing. 343 pistons will yeild 12-1 compression in a 360 with 52cc heads (IIRC) This is pretty high and I wouldnt run them with those heads.

What is the (IIRC)? in your message. What does that mean?

pyagid

bushwackertn wrote
jeepsr4ever wrote
You want solid midrange is what I am hearing. 343 pistons will yeild 12-1 compression in a 360 with 52cc heads (IIRC) This is pretty high and I wouldnt run them with those heads.

What is the (IIRC)? in your message. What does that mean?

If I Remember Correctly

bushwackertn

Oh, O.K. I'll have to remember that one (IIRC) 111!!! Thanks....