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4.2 stroker is it really worth it? Need help!

SpencerKemp

NAXJA Forum User
Location
Snohomish, WA
Has anyone done the Trucks 4.2 stroker build?
Is it really worth it?
How is the performance...
MPG?
Power?
General performance on and off road?
And small cost break down?

Info and input would really help me out need to rebuild my engine in my '99.
Thanks :yelclap:
 
Search on here. There's lots of info on strokers. Are you planning on just doing a 4.2, or using a 4.2 crank and an overbore to hit 4.6 or larger.
 
Has anyone done the Trucks 4.2 stroker build?
Is it really worth it?
How is the performance...
MPG?
Power?
General performance on and off road?
And small cost break down?

Info and input would really help me out need to rebuild my engine in my '99.
Thanks :yelclap:

If you are referring to the the build done on the Trucks show that comes on Spike TV then they built a 4.6L motor using their 4.0L block and the old 4.2L motor's cranks shaft which is what nearly every combination of stroker builds use. They used some other parts to build their stroker but I can't recall what combo of parts they used. There are many different ways to go about building a stroker motor out of the 4.0L.

To answer your question, yes it would absolutely be worth it especially if your motor is old and worn out anyways. Many people report back some improved mileage since the motor now has more power and doesn't have to work as hard to push that heavy Jeep down the highway. Don't expect it to be drastic and don't expect very much if you have stock gearing with some very oversize tires. But who wouldn't want more power!!! If you have the time and money then absolutely go for it!!!
 
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From my understanding and correct me if I'm wrong they used stock pistons, 4.2 crank and connectors then honed and ported... or do i not remember correctly
 
Stock pistons would put you at 4.5. While you've got it apart it wouldn't be a bad idea to have it bored to make your cylinder walls perfect.

Or you could just pull the head and have a look at them. If you don't mind the walls, then it doesn't matter.

Just know that with stock pistons, and depending on the length of the rods you get, your compression is going to be a little higher. There's a cutoff where you have to run premium to prevent detonation (fuel detonating before spark due to heat+compression...same concept as a diesel engine).

You need to consider every aspect of every part and how it works with everything else.

You can't just slap parts you think you like in there and it work. I mean you could if you're a good guesser, but guessing isn't the way to go about building an engine.
 
Unless you really know what you're doing with rebuilding an engine, or have someone who is, I would hold off.

If I could do it all over again I would leave the engine alone and spend the money on a supercharger.

This engine has been rebuilt twice (after the initial build) in the last year. I knew what had to be done to stroke it, but some things that should have been done (that would have been done by someone who's actually rebuilt engines before/mechanically smart) weren't thought about on my part.

Knowing nothing about breaking a cam in I let someone else do it for me that worked mostly on older chevy small and big blocks. He only did it for about 15 minutes and didn't hold it a 2000 the whole time. I'm flakey on exactly how that part went, but in the end the cam was wiped out. That was a rebuild.

I didn't replace the radiator which was developed a small leak that turned into a waterfall a few months later, and on a long trip I overheated a few times. That was a rebuild.

In the end I have spent enough on this stroker that I could have bought almost 2 supercharger kits. And installing a supercharger is much easier and faster. When you obey the laws of boost and don't overdo the boost for a stock engine. Gas mileage would have been about normal, possibly increased. I haven't broken 12 MPG (usual is 9-10) since I've built it. That alone has been about another 400 bucks or more in the last year with gas prices.

Yes a stroker CAN be built for cheaper than the supercharger... if you know what you're doing.
 
Well I am just trying to preplan because Im looking at getting another and want to just rebuild the motor if i get it. but can you explain how it makes it a 4.5... I'm a little confused
 
Unless you really know what you're doing with rebuilding an engine, or have someone who is, I would hold off.

If I could do it all over again I would leave the engine alone and spend the money on a supercharger.

This engine has been rebuilt twice (after the initial build) in the last year. I knew what had to be done to stroke it, but some things that should have been done (that would have been done by someone who's actually rebuilt engines before/mechanically smart) weren't thought about on my part.

Knowing nothing about breaking a cam in I let someone else do it for me that worked mostly on older chevy small and big blocks. He only did it for about 15 minutes and didn't hold it a 2000 the whole time. I'm flakey on exactly how that part went, but in the end the cam was wiped out. That was a rebuild.

I didn't replace the radiator which was developed a small leak that turned into a waterfall a few months later, and on a long trip I overheated a few times. That was a rebuild.

In the end I have spent enough on this stroker that I could have bought almost 2 supercharger kits. And installing a supercharger is much easier and faster. When you obey the laws of boost and don't overdo the boost for a stock engine. Gas mileage would have been about normal, possibly increased. I haven't broken 12 MPG (usual is 9-10) since I've built it. That alone has been about another 400 bucks or more in the last year with gas prices.

Yes a stroker CAN be built for cheaper than the supercharger... if you know what you're doing.
Sounds more like a scenario where you should've done your homework ahead of time rather than something that was bad about the stroker. If you do it yourself, make sure you research everything. If you pay someone else, make sure you research them thoroughly as well as knowing what should be happening so they don't try to screw you or screw up your engine.A bad radiator would've killed the engine without or without the stroke.
As far as mpgs, a lot of guys on here are getting close to what they got pre stroker if not better. Cal for instance gets better mileage out of his stroked XJ on 37s than I'm getting with a stock engine on 33s. Both are geared for the tires.
 
Well I am just trying to preplan because Im looking at getting another and want to just rebuild the motor if i get it. but can you explain how it makes it a 4.5... I'm a little confused

The AMC 4.2L and Chrysler 4.0L are virtually the same motor only differences in the internals was the 4.2L's pistons were a little smaller but the stroke of the crank shaft and the piston rods were larger giving it an overall larger displacement than the 4.0L. So when you combine the 4.2L's crank shaft and piston rods with the 4.0L's pistons the displacement comes out to 4.5L.
 
The AMC 4.2L and Chrysler 4.0L are virtually the same motor only differences in the internals was the 4.2L's pistons were a little smaller but the stroke of the crank shaft and the piston rods were larger giving it an overall larger displacement than the 4.0L. So when you combine the 4.2L's crank shaft and piston rods with the 4.0L's pistons the displacement comes out to 4.5L.
Punch it out a bit and you have 4.7L!
 
My 4.6 was basically about $200 more for the stroker build than a regular build.. Got a CL deal on a guy swapping his 4.2 for a V8 and wanted it gone. $50.... Dished pistons cost me a bit more than regular but got a deal on them as well. Other tid bits and deck machining. Followed instructions and built it myself.. Second motor ever.. Got ~35k on the DD and still running strong..
 
If you do the research, and plan ahead, it turns out really well. The one I built for my daughter's tj runs like a champ and gets about the same milage around town, better than stock on the highway.

Only two regrets, forgot to do valve seals, and STUPID Crane performamce lifters. The lifters work fine, but NOISY.
 
If you do the research, and plan ahead, it turns out really well. The one I built for my daughter's tj runs like a champ and gets about the same milage around town, better than stock on the highway.

Only two regrets, forgot to do valve seals, and STUPID Crane performamce lifters. The lifters work fine, but NOISY.

You can still do valve seals with the engine in the Jeep. Not too bad of a job.
 
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