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Unread 11-15-2012, 06:14 PM   #1
dsk
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4.2 parts on 4.0 ho engine

Piston rings broke in my 1977 258 already .60 over. I want to swap to 4.0 ho. Can I use my 1977 258 intake and carb, my dui distributor, and hedder on a 4.0 ho engine. Not sure if it will all work. Has Anyone ever done this? Would it work?

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Unread 11-15-2012, 07:21 PM   #2
jeepwhore
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I know an aluminum 2 bbl intake can be slightly modified to fit the 4L head.....but a 4.2L exhaust manifold or header won't fit. The distributor......not sure.
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Unread 11-15-2012, 07:39 PM   #3
tombstne
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consider a stroker motor, your crank and rods in the 4.0

http://www.jeepstrokers.com/forum/in...321b593a72acd4
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Unread 11-15-2012, 08:06 PM   #4
danm3275
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I'm going through this now, 4.0 head, 4.0 exhaust manifold ( you may have to heat and massage the pipes to clear the intake) the 4.2 intake sits on top of the guide dowels on the 4.0 head so you'll need spacers to make sure and secure the intake and exhaust manifold together. Plus grind some of the corners on the intake manifold so it plays nice with the exhaust manifold.
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Unread 11-15-2012, 08:07 PM   #5
danm3275
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Oh and it's pre 79 so you might need new rockers too. ( 79 and up they are all the same)
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Unread 11-15-2012, 09:58 PM   #6
dsk
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Thanks for the info. Tryin to keep it simple can be a pain. Maybe I should just get another 4.2 block. That way to I can reuse my crane cam , hv oil pump, headman hedder, dui distributor, webber carb. I like that 4Lho though. Mmmmm...
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Unread 11-15-2012, 10:59 PM   #7
danm3275
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I dont have an hei in it ( next plans after the head swap ) but the 4.0 head conversion IMO is a good start for future plans.
And once you get all the info, it's pretty easy to coordinate all the parts together.
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Unread 11-16-2012, 03:47 AM   #8
RWise
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I used the intake, dizzy, harmonic balancer, water pump (everything from front of engine), fly wheel, from my 81 4.2 on an 89 4.0. To use the intake I had to pull the locating dowels out of the head so it could drop down enuf to cover the (oddly shaped) intake ports. I also had to message a place or 2 on the exhaust header (from the 89) with a hammer. Dizzy dropped right in, drivers side moter mount had to modded, hole drilled out for 1/2 13 bolt, and same hole tapped 1/2 13 on the block (anti knock censer)
NOTE the water pump on the 4.0 turn in reverse to the 4.2, if you keep the belt set-up on the 4.0, keep the water pump also (not sayin to use the old one, but the correct one)
Edit I also made a few mounts for stuff like the alternator that was never on a jeep, power steering pump,,,,,
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Unread 11-16-2012, 11:20 AM   #9
bleoh
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The distributors are the same from the block down on the 4.2 and the 4.0 ho. Here is a comparison picture.

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Unread 11-16-2012, 11:34 AM   #10
jeepwhore
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So can a 4.2L distributor be used in a fuel injected 4L or 4.2L? I think I read something about it being compatible if the vacuum advance is locked down?.....
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'84 CJ-7: Yota axles (spartan locked front, e-locked rear) 4" BDS, 1" Daystar & 3/8" shackle lifts, 35" X-Terrains on steelies, YJ Tub & family roll bar, heater blower upgrade, 4.2L w/MC2100 & Team Rush, Warn 8274. Rebuilt 4.2/4.0 hybrid, AX15 and twin sticks/clocking ring waiting to go in.

The advertised position for a topless, dirty jeep girl has been filled......by my wife. Thanks to all that applied.
<------------and yes, that is her.
:-D
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Unread 11-16-2012, 12:56 PM   #11
dsk
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Sweet nice pics. Thanks a lot . Trying to use 4.2 distributor and my webber carb on 4L ho. No fuel injection for me. jeep goes too deep to have electronics. Wonder if the cams are the same? Thanks again you guys are awesome
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Unread 11-16-2012, 02:35 PM   #12
jeepwhore
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Quote:
Originally Posted by dsk View Post
Sweet nice pics. Thanks a lot . Trying to use 4.2 distributor and my webber carb on 4L ho. No fuel injection for me. jeep goes too deep to have electronics. Wonder if the cams are the same? Thanks again you guys are awesome
I can't say if the 4.2L cam will physically work in the 4L block but I do know that depending on the grind of your cam (if it does fit), stock 4L valve springs may not work.
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'84 CJ-7: Yota axles (spartan locked front, e-locked rear) 4" BDS, 1" Daystar & 3/8" shackle lifts, 35" X-Terrains on steelies, YJ Tub & family roll bar, heater blower upgrade, 4.2L w/MC2100 & Team Rush, Warn 8274. Rebuilt 4.2/4.0 hybrid, AX15 and twin sticks/clocking ring waiting to go in.

The advertised position for a topless, dirty jeep girl has been filled......by my wife. Thanks to all that applied.
<------------and yes, that is her.
:-D
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Unread 11-16-2012, 06:14 PM   #13
danm3275
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Another quick lesson from my journey of a 4.0 head conversion, the rocker arm bolts are different pre 79 also. And they are a pain to find in a short time. Most places dont even carry them and oddly a decent amount of machine shops dont either. Dealership wanted 6 a piece, online they are about 1.50 each.
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