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Unread 02-01-2013, 03:42 PM   #1
bigwhiteyj
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350 or stroker or 4.2

Okay guys I am wanting to upgrade my engine a little and I have a 350 but It needs rebuilt! My jeep has a 4.2 so I don't know wether to just do the 350 swap or build a stroker or just rebuild my 4.2 I am wanting something that doesn't cost more than about 1000$ and it is a 1988 jeep yj with a 3 inch lift and 33 tires I would like to put a bigger lift and heavier axles too? Any ideas? I am in high school and have a shop but it is my daily driver for a while longer

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Unread 02-01-2013, 03:45 PM   #2
lsukevinc
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no way you can do a 350 swap for under $1000. Plus if the motor needs a rebuild even more money. The adapter alone could cost $500 to mate the 350 to your tranny.
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Unread 02-01-2013, 03:50 PM   #3
bigwhiteyj
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I have seen a adapter for 250$ but I was just reading that my automatic transmission wouldn't take it so 350 is out!
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Unread 02-01-2013, 04:10 PM   #4
yjtyler
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yes u can rule the 350 out. i have about $3000 to $3500 in my swap doing basically all labor myself and i already had a chevy trans and tcase. i think the best option would be a stroker but with ur budget a standard rebuild may be better.
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Unread 02-01-2013, 08:59 PM   #5
kgb_m3
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Interesting, I'll be in the same boat at the end of this year. Either go nuts on the 4.2 and keep it or go with motor swap, most likely 350.

What's all involved with stroked 4.2? Will it pass smog after still? How much in parts? How much gains?
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Unread 02-02-2013, 02:33 AM   #6
Michaelgoesrawr
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Quote:
Originally Posted by kgb_m3
Interesting, I'll be in the same boat at the end of this year. Either go nuts on the 4.2 and keep it or go with motor swap, most likely 350.

What's all involved with stroked 4.2? Will it pass smog after still? How much in parts? How much gains?
You can't really build a stroker out of a 4.2 because it is already kinda stroked. Strokers basically takes the crank, rods and pistons and stick them in a bored out 4.0. They will pass smog like any other motor and no one will know what it is unless they dyno it.
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Unread 02-04-2013, 07:00 PM   #7
kgb_m3
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Quote:
Originally Posted by Michaelgoesrawr View Post
You can't really build a stroker out of a 4.2 because it is already kinda stroked. Strokers basically takes the crank, rods and pistons and stick them in a bored out 4.0. They will pass smog like any other motor and no one will know what it is unless they dyno it.
Got ya, I gotta do some more research when time comes.
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Unread 02-04-2013, 08:04 PM   #8
Michaelgoesrawr
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Quote:
Originally Posted by kgb_m3

Got ya, I gotta do some more research when time comes.
Sorry, it takes the internals I mentioned out of a 4.2.
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Unread 02-04-2013, 09:58 PM   #9
kgb_m3
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Originally Posted by Michaelgoesrawr View Post
Sorry, it takes the internals I mentioned out of a 4.2.
Sorry to thread jack, quick question. So if I was to take out the internals out of my 4.2 and install them into a 4.0 head on the 4.2 block. That would yeild more power? If so, approximately what numbers are we talking here?
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Unread 02-04-2013, 10:40 PM   #10
skyj
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Quote:
Originally Posted by kgb_m3 View Post

Sorry to thread jack, quick question. So if I was to take out the internals out of my 4.2 and install them into a 4.0 head on the 4.2 block. That would yeild more power? If so, approximately what numbers are we talking here?
No you got it backwards. You use a 4.0 block ,4.2 crank and rods, with 4.0 piston with a 4.0 head. That's kind of the recipe for a poor man's stroker in a nutshell. If you use 4.0 rods you will need custm forged pistons. Thats the simple version.
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Unread 02-04-2013, 10:53 PM   #11
Michaelgoesrawr
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Quote:
Originally Posted by skyj

No you got it backwards. You use a 4.0 block ,4.2 crank and rods, with 4.0 piston with a 4.0 head. That's kind of the recipe for a poor man's stroker in a nutshell. If you use 4.0 rods you will need custm forged pistons. Thats the simple version.
Ah my bad. I forgot the pistons were 4.0.

But you can put a 4.0 head on your 4.2. Probably get you 20-30 hp if I remember correctly. Not entirely sure though.
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Unread 02-05-2013, 07:05 AM   #12
skyj
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Originally Posted by Michaelgoesrawr View Post

Ah my bad. I forgot the pistons were 4.0.

But you can put a 4.0 head on your 4.2. Probably get you 20-30 hp if I remember correctly. Not entirely sure though.
Yep I run a 4.0 head on my 4.2. You will definaltely notice the power difference. There are some modification to the head and also the intake you have to do to make it work. Here is a link to my build. I have a link in my thread to a very good write-up on a 4.0 head swap its what I used to do mine. Been running it for 3years now http://www.jeepforum.com/forum/f12/s...build-1467426/
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2" BL, 4" stretch all on saggy waggy springs.
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Unread 02-05-2013, 09:04 AM   #13
MLJeeper
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If you do the head swap, have your machinist shave the head enough to give you a .5 to 1 point bump on compression. Give you a decent boost in torque for little investment.
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Unread 02-05-2013, 09:49 AM   #14
Beachcruiser
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For a Grand (with access to a shop) I would:

Do a leakdown test to see if your 4.2 has good ring seal.

If so, I'd install the following:

4.0 Head & exhaust header.
New performance intake manifold (offy, etc) and small 4 barrel carb.
Upgrade ignition/coil system.
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Unread 02-05-2013, 10:06 AM   #15
Drix
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Quote:
Originally Posted by Beachcruiser View Post
For a Grand (with access to a shop) I would:

Do a leakdown test to see if your 4.2 has good ring seal.

If so, I'd install the following:

4.0 Head & exhaust header.
New performance intake manifold (offy, etc) and small 4 barrel carb.
Upgrade ignition/coil system.
If your gonna do the head wouldn't you be able to move the manifold and bring the efi from a 4.0 over also.
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