Stroker kit
- Thread starter BrianC
- Start date
dana44
NAXJA Forum User
- Location
- Trondheim, Norway
Hi BrianC!
I think this si a great site, but I'm not sure wether iit's the right one..
http://www.jeep4.0performance.4mg.com/index.html
Arnt H. Andresen
Trondheim, Norway
I think this si a great site, but I'm not sure wether iit's the right one..
http://www.jeep4.0performance.4mg.com/index.html
Arnt H. Andresen
Trondheim, Norway
you also have ACCURATE POWER
and i believe there is Clifford
and Hesco
but i think you'll find accurate power the cheaqpest and best results.
HTH
STROKER
and i believe there is Clifford
and Hesco
but i think you'll find accurate power the cheaqpest and best results.
HTH
STROKER
Renegade Jpr
NAXJA Forum User
- Location
- Corona, California
Why dont you just make your own? All you need is a 258 crank, and connecting rods...if you have a none HO motor I "hear" you could just drop in a HO cam, but it would be better if you go with Crane Cam's part #753901 cam.
- Location
- Desert Beach So Cal
Be carefull about what you "hear" (the HO cam may be the same as the non-HO cam, and neither works well for a stroker without major compression ratio matching).
Last edited:
simonsxj
NAXJA Forum User
- Location
- Daytona Beach, Florida
I have heard that quench is the thing to look out for. I believe that the only correct way of solving this is to use custom pistons. Is this correct or is there a way around it?
- Location
- Desert Beach So Cal
Do a 
search on the word "Stroker." I wrote a summary of the quench issues a week or so back.
You can also join and search the Strokers group for the answers on www.groups.yahoo.com (go to the main yahoogroups site and search for "strokers"). This is the web group that was formed by AMC six enthusiasts to eliminate the secrets behind the stroker package.
If you are trolling the typical web sites for information (, PBB, JU, Rockcrawler, off-road, etc.) the probability is high that the info for the articles and forum post experience came from a discussion on this web group (other than the HESCO and Clifford performance packages). Accurate Power was a participant in Strokers group discussions as well, and offer their forged piston kits to meet a group request for a long rod piston solution. Dino on JU's Speed Freaks forum is another regular participant who brings many questions and has assembled the most accurate summary of what has proven to work. You may find that if an AMC six performance question comes up on another forum, the question will eventually get posted to the Strokers group for advice (the participants range from AMC six drag racers to Jeep enthusiasts). Rather than ask the "expert" on any one general Jeep/AMC forum, you may find it better to ask the question on the forum where most of these "experts" come for advice (the Strokers group).
The other alternative is to sit down with your machine shop and talk to the engine builder about building an AMC six. Talk about quench and compression ratio with dished pistons (ask if they have built modern era 90's AMC six engines before). The principles are no different from building any quality performance engine, except there is limited off-the-shelf part combinations that work. The machine shop will need to be familiar with decking the block for quench and machining the piston dish to lower the compression ratio (or pay for custom pistons). If you get a bad feeling about the shop's capabilities find another machine shop (any shop who builds true performance engines, more than an assembly of catalog parts, will figure out what you are talking about).
Yes, to match quench height and compression ratio you need to machine stock replacement pistons (customize the pistons) or use custom piston forgings (or you can bolt in the stock replacement pistons and make the package non-quench compliant). If you are looking for a another way around the custom piston route, you will need to find someone else to offer encouragement (and if it works well, post the package because the results have been mixed).
It's your money and other than buying a package from one of the mentioned suppiers you will have to learn the tricks to know what you are building.
search on the word "Stroker." I wrote a summary of the quench issues a week or so back. You can also join and search the Strokers group for the answers on www.groups.yahoo.com (go to the main yahoogroups site and search for "strokers"). This is the web group that was formed by AMC six enthusiasts to eliminate the secrets behind the stroker package.
If you are trolling the typical web sites for information (
, PBB, JU, Rockcrawler, off-road, etc.) the probability is high that the info for the articles and forum post experience came from a discussion on this web group (other than the HESCO and Clifford performance packages). Accurate Power was a participant in Strokers group discussions as well, and offer their forged piston kits to meet a group request for a long rod piston solution. Dino on JU's Speed Freaks forum is another regular participant who brings many questions and has assembled the most accurate summary of what has proven to work. You may find that if an AMC six performance question comes up on another forum, the question will eventually get posted to the Strokers group for advice (the participants range from AMC six drag racers to Jeep enthusiasts). Rather than ask the "expert" on any one general Jeep/AMC forum, you may find it better to ask the question on the forum where most of these "experts" come for advice (the Strokers group).The other alternative is to sit down with your machine shop and talk to the engine builder about building an AMC six. Talk about quench and compression ratio with dished pistons (ask if they have built modern era 90's AMC six engines before). The principles are no different from building any quality performance engine, except there is limited off-the-shelf part combinations that work. The machine shop will need to be familiar with decking the block for quench and machining the piston dish to lower the compression ratio (or pay for custom pistons). If you get a bad feeling about the shop's capabilities find another machine shop (any shop who builds true performance engines, more than an assembly of catalog parts, will figure out what you are talking about).
Yes, to match quench height and compression ratio you need to machine stock replacement pistons (customize the pistons) or use custom piston forgings (or you can bolt in the stock replacement pistons and make the package non-quench compliant). If you are looking for a another way around the custom piston route, you will need to find someone else to offer encouragement (and if it works well, post the package because the results have been mixed).
It's your money and other than buying a package from one of the mentioned suppiers you will have to learn the tricks to know what you are building.
simonsxj
NAXJA Forum User
- Location
- Daytona Beach, Florida
I have decided to stick with the 4.0 if it doesn't have enough power I will lower my gearing.
Renegade Jpr
NAXJA Forum User
- Location
- Corona, California
I highly sugest that you do a stroker if your going to have your motor pulled anyways. Here is a very good write up on it, he also used a 258 crank, connecting rods, and the crane cam's part #753901 cam.
http://rockcrawler.com/techreports/stroker40/index.asp
http://rockcrawler.com/techreports/stroker40/index.asp
- Location
- Terra Firma
As Ed wrote, beware of what you "hear" -- or read. Using the 258 rods in a stroker results in excessively high compression, requiring premium grade gasoline, unless you take specific steps to mitigate the problem. Ed alluded to both -- running a cam with enough overlap to bleed off some cylinder pressure, and machining a deeper dish in the pistons to lower the compression.
Building a stroker engine sounds great but it isn't something to dive into assuming you can slap it together and have it run like stock. ALL of the early stroker engines had problems with ping. The discussions on the Strokers group to which Ed referred have found ways to resolve the problems, but it does require a bit or effort and research.
I second Ed's recommendation that anyone contemplating a stroker spend some time reading the archives and monitoring the discussions on the Strokers group. However, kindly be polite. This is not a simple formula, and it gets very irritating when a new-comer logs on and essentially says "I just heard about you guys, I wanna build a stroker and I don't have time to do the reasearch so what should I do?"
It has taken the strokers group something like three or four years to get to having some idea of what works, but even now every new engine is an experiment. DO NOT expect that anyone on the group can give you all the answers in 25 words or less.
Building a stroker engine sounds great but it isn't something to dive into assuming you can slap it together and have it run like stock. ALL of the early stroker engines had problems with ping. The discussions on the Strokers group to which Ed referred have found ways to resolve the problems, but it does require a bit or effort and research.
I second Ed's recommendation that anyone contemplating a stroker spend some time reading the archives and monitoring the discussions on the Strokers group. However, kindly be polite. This is not a simple formula, and it gets very irritating when a new-comer logs on and essentially says "I just heard about you guys, I wanna build a stroker and I don't have time to do the reasearch so what should I do?"
It has taken the strokers group something like three or four years to get to having some idea of what works, but even now every new engine is an experiment. DO NOT expect that anyone on the group can give you all the answers in 25 words or less.
Renegade Jpr
NAXJA Forum User
- Location
- Corona, California
In that artical I posted, it shows that the stock compression ratio of a HO 4.0L is 8.8:1 . His stroker motor is running a 9.4:1 compression ratio. Strokers can be built to run pump gas, but again like stated above...its hard to do and it is all not yet figured out. I however am in the middle of peiceing together a stroker so that I can build it for my YJ. Im doing the same thing as the write up I posted. Should come out great.
- Location
- Terra Firma
The stock 4.0L has a compression ratio of 8.8:1, but because of minor discrepancies in deck heights and piston pin heights, using the 258 crank and rods in a 4.0L block and using off-the-shelf 4.0L replacement pistons results in compression ratios more in the 10:1 range. To get down to 9.4:1 (which is still likely to require at least 89 octane fuel) requires doing more than bolting together off-the-shelf parts. That's the only point I'm trying to make. I like the idea of the stroker motor, I have a friend who built one that is now beginning to run well, but he has been through several changes and adjustments since putting it on the road to get it to run without ping and without a lean-run hesitation.
Do the research before buying parts, and leave a few extra $$$ in the project budget because more than likely you'll have to change something after you fire it up. In Bob's case, I believe he is now on the third set of injectors, and he had to make some other mods as well.
Do the research before buying parts, and leave a few extra $$$ in the project budget because more than likely you'll have to change something after you fire it up. In Bob's case, I believe he is now on the third set of injectors, and he had to make some other mods as well.
