double check me!

[eastin82]

great forum! really appriciate all the good info. ive been gathering info and parts for a while now so that i can drop in an in a 4.0 into my 81 cj5. well after doin some research and finding out that i have alot of the parts i need to stroke to a 4.6 (couple of cracked 4.2 in the corner of the barn) my low dollar swap has turned into an all out stroker build. the only knowledge of this process i have is from the internet(but is very good) so im open to any suggestions. part i have now are
91 complete 4.0 completely dissasimbled (ready to go to machine shop when i figure some of my quest. out)
crank out of 83 258 ( ready for magn and regrinding )
rods with 707 casting number (ready to be cleaned and magn)
t176 tranny and d300 transfer goin to rebuild both but thats not a concern at the present time
planning on getting the silvolite pistons and dishing to 24cc or so(1.581 pin height)
what is the most that i can deck the block?
i was hoping to get my quench to .0475
if the deck height is 9.453 stock and i had a .051 gasket thickness this means i need to deck it to 9.407 and have a .044 gasket thickness correct. my figures say this gives me .0475 quench.0035 deck clearance and scr of 9.37
should i dish less for higher cr
what does plaining the head do to your quench?
not sure on cam maybe comp cams complete kit 68-232-4 but i read somewhere there springs are to strong?suggestions
what will i do to my head to make up for the decking of the block?
would like to port and polish head but dont think i can afford it about 1800 to spend an rebuild
these are just the questions i have at the moment. i would have liked to researched and figured it all out for myself but between work and kids. i can use all the help i can get. thanks in advance

[eastin82]

is there a better piston that can be dished that would allow me to deck less maybe speed pro 802?

[Exos]

what does plaining the head do to your quench?

not sure on cam maybe comp cams complete kit 68-232-4 but i read somewhere there springs are to strong?suggestions

what will i do to my head to make up for the decking of the block?

Welcome to the forum. Lots of questions here, I think I can answer a few.

-Milling the head will change nothing for quench.
-I was asking the same question about springs a while back, and most seem to agree that Mopar perf. springs are a better choice. (P5249464)
-You don't have to do nothing to your head if you deck your block. Of course, you will want to test it for cracks, check it for straightness and have a valve seats job done.

[eastin82]

thanks alot for the reply been waitn all day, i did find a good thread on hear that awnsers most of questions on rocker ratio and how it is affected. hadnt thought about valve seat job need to get a price on that. i guess i will buy a cam and parts seperate no where near got that figured out. suggestions i cant find many for fuel injection does a piggy back increase my options?

[SilverXJ]

great forum! really appriciate all the good info. ive been gathering info and parts for a while now so that i can drop in an in a 4.0 into my 81 cj5. well after doin some research and finding out that i have alot of the parts i need to stroke to a 4.6 (couple of cracked 4.2 in the corner of the barn) my low dollar swap has turned into an all out stroker build. the only knowledge of this process i have is from the internet(but is very good) so im open to any suggestions. part i have now are
91 complete 4.0 completely dissasimbled (ready to go to machine shop when i figure some of my quest. out)
crank out of 83 258 ( ready for magn and regrinding )
rods with 707 casting number (ready to be cleaned and magn)
t176 tranny and d300 transfer goin to rebuild both but thats not a concern at the present time
planning on getting the silvolite pistons and dishing to 24cc or so(1.581 pin height)
what is the most that i can deck the block?
i was hoping to get my quench to .0475
if the deck height is 9.453 stock and i had a .051 gasket thickness this means i need to deck it to 9.407 and have a .044 gasket thickness correct. my figures say this gives me .0475 quench.0035 deck clearance and scr of 9.37
should i dish less for higher cr
what does plaining the head do to your quench?

Planing the head does noting for quench. It just decreases the combustion chamber size and ups the compression. I have never heard any one mention the max amount you can deck the block, so I don't know. As for dishing less, that is up to you and what you are trying to achieve with your build

not sure on cam maybe comp cams complete kit 68-232-4 but i read somewhere there springs are to strong?suggestions

Yes, their springs in the kit are ridiculously strong. I and others like the Mopar performance springs and their associated retainers and locks. But you aren't limited to that. I've heard that the Crane 99833 springs are good but you will have to source the retainers, locks and the correct install height for them. You can do research on other springs. As for the 68-232-4 being the only computer safe cam made by comp cams that is wrong. I have the 68-231-4 in my stroker and computer doesn't bat an eye, there may be others as well. The not for EFI statement is just to cover their asses as the LCA goes below 113 that is usually the minimum that computers can tolerate.. As for is a piggy back would make a cam more computer friendly that is a no.

what will i do to my head to make up for the decking of the block?

Nothing other than having it machined for flatness

would like to port and polish head but dont think i can afford it about 1800 to spend an rebuild

Get the standard abrasive's P&P kit and do a clean up yourself.

[eastin82]

more great info ive already read alot of your posts all good stuff. pretty stoked about the cam info back to the internet where do you get your mopar perf products

[SilverXJ]

I think advanced auto or autozone has them for $7 each.

[eastin82]

cool i cant get a discount at autozone thanks to a budy any other ideas

[dwg86]

The Jeep valve is an 8mm with a round groove lock. The jeep lock is 8 degree. This is what limits the spring/retainer selection. You will need to either 1)change valves 2) find a spring that will fit the stock jeep retainer or the mopar performance retainer 3) Use a Chevy LS1 retainer and spring or find a spring that will work with the ls1 retainer. The ls1 retainer is made for an 8mm valve with an 8 degree lock.

The Comp Cam spring kits and the Crane spring kits are made for the 258. The 258 used a 11/32 valve with a 7 degree retainer. So even if you wanted to use those springs...you can't.

I just got my 7120 head back from the macine shop. I had them put 1.94/1.50 stainless chevy valves in the head. My valves and guides were worn. The SBC stainless, undercut, swirl polished valves were half the price of new stock Jeep valves. The machine shop opened the guides up to 11/32, so I didn't half to pay for new guides. I had already bought the mopar performance springs before I got the head, so i used them. The springs have more pressure than Mopar advertises. My the shop said my springs are 130-135 on the seat and around 290 open @ .500 lift. My springs bind @ .600. I'll be posting some pics and more information of my head in a few days(when I get some time). BTW the machine work cost $580.00 That included new hardened valve seats.

[eastin82]

so do you think ill be ok just with the performance springs and shim up the rockers till i can afford to go all out with port and polish and larger valves. i think ill have a valve job done or should i wait? i know theres a guy in town hear thats pretty good with heads but havent talked to him yet. really apreciate all the help. think ive decided on comp cams 68-231-4.

[Exos]

.....That included new hardened valve seats.

Does this mean that the valve seats on the 4.0L head are replaceable? I'm asking in case I make a mistake while porting... wich I may already have.

[Mgardiner1]

Yes, valve seats are generally replaceable.

Don't worry if you run the tool across the valve seat by accident, unless you are actually GRINDING the seat down on purpose, it will usually clean up with a valve grind.

[Exos]

Is the important part the 45 degree cut, or is the valve seat going deeper in the bowl? I did not hit the 45 degree cut, but I grinded close to it.

Let me reformulate : Is it safe to grind just below the 45 degree cut ?

[SilverXJ]

You should see where the valve sealed against the seat, that is the important part. If you are grinding the combustion chamber drop two old valves in to protect the seats.

Yes, valve seats are generally replaceable.

They aren't replaceable stock, but they can be cut out and a new seat installed. However, one person tried to replace them with diesel seats and cut into the water jacket, making his head scrap.

[Exos]

I am moving this to my porting thread : http://www.jeepstrokers.com/forum/viewt ... ?f=5&t=892