4.0 rebuild question

shawn said:
It's been a while since I ran the numbers on any of that stuff, so I recalculated the compression ratios with the -24 pistons: 8.9:1 static. That's what Russ recommended when I said I wanted to be able to run 87 octane. I'm curious to know what suggestions he has for @84jimmy.
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I am at 9.6:1. I'll be running 89 octane. Also floated the pistons on this one. 7120 head at 55cc
 
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60 over
 
shawn said:
Did you deck the block, or did I fuck up my math?
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No, virgin deck. .043 crush gasket. I followed direction of Russ.
 
jeepinmatt said:
Dam, dem is "Custom Custom"! I dont even wanna know how much that mod cost. Probably to match up with the RV cam.
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custom grind cam too..
 
shawn said:
It's been a while since I ran the numbers on any of that stuff, so I recalculated the compression ratios with the -24 pistons: 8.9:1 static. That's what Russ recommended when I said I wanted to be able to run 87 octane. I'm curious to know what suggestions he has for @84jimmy.
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I am curious as well. He said he has been playing catch up but when he gets some time he will send me the info and we will talk via phone to figure out what I want/need
 
77GreenMachine said:
Highly recommend Kanapolis Engine repair, and I would also highly recommend an Enginetech gasket kit, which can be had from them.

If I were going to have an engine done that’s where I would go and it’s not as close to me as it probably is for you. They helped with my last 4.0, and they also done a complete rebuild on my buddy’s Jeep with a 1 year warranty.
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did you mean
Kannapolis Engine Service
1450 N Main St, China Grove, NC 28023?
 
84jimmy said:
Where can I find a place around here that will port a head for under $200? or were you more referring to be doing it myself?
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I was referring to you doing it. I don’t know anywhere that will do it for that cheap professionally.

$200 will get you a die grinder and assorted bits/abrasives

If you go that route make sure you study up on what to do and what not to do. You can scrap a head in a matter of seconds easily.

Do it right, and the cam/head porting will make the biggest gains per dollar.

There are several static dynamic compression calculators out there.
 
I would not say scrap a head in seconds. However I've got two junk heads if you want something to play with and see how far you can go. I ported a 0630 for the Jeep @336wheeler has now and it made a big difference seat of the pants. I can show you what I did when you come by. You'll have to disassemble and reassemble it but you can borrow the tool from xyz parts store. Easy peasy. May as well replace the stem seals & lap the valves. Remind me and I'll give you a tube of compound.
 
Just make sure you get carbides with 1/4" shank.. the 1/8" ones I got snapped easy in my air grinder and didn't remove near the material the bigger 1/4" bits would. Then polish it out.
 
So I have been looking and cannot seem to find the length of the connecting rods and what the crank stroke is. I am sure I am missing it and it is hear somewhere.

can anyone tell me if the 707 casting rods for the 258 are 6.123" in length?

And is the 477 casting crank for the 258 have a stroke of 7.895"?

Again I am sure it is somewhere on one of the forums and vaguely remember seeing something about it but cant seem to find it now that I need it
 
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