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Old 06-29-2013, 07:00 PM   #1
Join Date: Jun 2013
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Stroking a California 4.0L, can it be done?

Hi all, just curious if anyone has attempted and achieved building a 4.0 liter using a stroking kit in california that is smog legal...
I looked into this somewhat, even called a cali referee and the ref said that since there would be nothing that would be visually different, as well as no timing modifications, then a smog shop wouldn't even know let alone be able to fail you for such a modification. (given the fact that you don't tell a smog mechanic that you have made such a mod, even though modifying stroke wouldn't affect emmisions.)
Anyways, I have also read that you would need larger injectors, which would in my mind, raise a red flag in the smog department. But I am still curious...
The reason I go into this for a california 4.0 liter is that I live in california, but I also am trying to keep this old jeep in the family as the original 2.5 liter has ran out its life at about 350K!
I have also asked the ref about swapping in the stock 4.0L, and as long as the 1991 YJ I have originally came with a 4.0L injection, then the engine swap wouldn't have to be reffed.
I still would like to swap the 4.0L in, even if I can't legally stroke it. But I am curious as I have seen a few jeeps on the road that have 4.7L STROKER tags on the body, or is that a later OEM engine?
Thanks for your time!
Once again, I want a jeep for on and off highway, not a trailer queen.

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Old 06-29-2013, 10:07 PM   #2
Cali Smog Nazi.

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I would not be able to tell a 4.0L is stroked, and as far as injectory, the difference between ford, Bosch, Jeep injectors is small, and usually not looked at (other then they are present).

As far as stickers on the body? meh, I personally never pay attention. kinda like the Type R stickers they put on the 88 Preludes, they mean nothing...


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Old 06-30-2013, 09:16 AM   #3
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My measly $0.02 says that so long as the emissions output meets the criteria then have at it.

I personally don't see much issue with running aftermarket parts, so long as the emissions output is fine. But the California hippies always have issue with everything.

2.5L Genius of some sort.
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Old 06-30-2013, 11:07 AM   #4
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Never had any issues even with stock injectors on my 4.6 stroker passing emissions here in Colorado. They never ask, I never tell...
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Old 07-01-2013, 05:10 PM   #5
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So you don't have to replace the injectors on your stroked engine, I wouldn't think so, but I figured I'd throw that out there just to make sure.
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Old 07-01-2013, 06:12 PM   #6
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Seems to run OK. I guess the fuel injection compensates. I plan to add a better exhaust and other things later and they might neccesitate bigger injectors. I might not be getting the full benefit of stroking the engine yet without those upgrades either, but it needed rebuilding anyway.
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Old 07-15-2013, 04:18 PM   #7
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Jeep 4.0 Stroker Kits - Stroker Kits

To get the full effect of the stroker it is recommended to replace injectors and TB.
one of my wheeling buddies has a 4.9, 285hp stroker, he replaced the injectors with the 24lb and a 62 mm Hesco TB verses the 58mm stock TB.
There is another wheeling buddy that has the 4.7 stroker, he hasn't done that to his yet. Both have had no problems with smog.
Check the links out for more information on stroker kits.

It's not about getting out of the Storm, but learning to dance in the rain.
When I die I am going to be buried with my Jeep, cause I haven't yet found a hole it can't get out of!!!!!
06 TJ Rubi 4.0 and alot of other crap
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4.0l , fuel injectors , larger crankshaft , smog legal , stroker

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