trouble getting stroker project off the ground

Well I've mentioned that I'm trying to get a stroker project together, but the thing is, right now the only place that has what I need, happens to want WAY too much for it. they refuse to come down to less than $1000 for a burnt 01 WJ 4.0 which has sat for a year, and they want $500 for an old 258, which I only want the crank from, they refuse to sell the crank separate. I'm getting fed up with them, an I was just wondering if this would work. I have a pretty good block out of a 1990 Renix XJ, and I can get a crank from an older 258 that would need the spacer installed. The question is, is the old Renix block up to the job, and will it accept the newer 7120 head. The reason that this might work out is that I'm planning to keep the Renix electronics, for simplicity sake. any input would be appreciated. The aim of this project, for me, is to be around 4.5 liters (I don't want to bore it if I don't have to) I'm looking for around 250-265 hp and maybe just shy of 300 lbs/ft. of torque, with an 87 AW4&NP231 behind it. I know they have the weaker 21 spline shaft, but I'm not going all out, so I don't really want to replace the whole drive line. The question is though, is the old Renix block a good foundation, or just not up to scratch, and can the 7120 head work on it without issues?

Thats a bummer on the prices. Around here I can get a crank and rods for $100. A rebuildable core runs around $300-$400

There are quite a few stroker guys around here to help. What year vehicle is it going into? I run the Renix Stroker. Stateside we actually have a lot of us who perfer the Renix due to its ping sensor.

I am not persoannaly familiar with that head but I know many people have moved heads between the early and later 4.0L's. The 4.2L head can even be used with some mods to the water jacket.

You can also go to groups.yahoo.com and go to their stroker forum. It is dedicated to the 4.0L stroker.

The 7120 head is the early H.O head, 91-94 I think, best flowing 4.0 head, the later 94-?99? head is the same except for minor changes, and I hear that the newer heads have less flow for emissions reasons and are prone to cracking. I plan on installing the stroker into an 87 4.0 Renix Cherokee w/ AW4+NP231, and a Dana 44 (stock one it came with) to turn the rear wheels. My motor is starting to get a little tired and has a tap from a bad valve lifter, and I just figured that, if I'm going to replace the engine, then I should do somthing unique (around here any ways, I don't think there are any stroker jeeps in Atlantic canada, none that I've heard of any way) I also looked at getting a short block from an auto parts dealer, but that would come to around $1600+core, which is too high for now. I know the fair price around here for that motor is about $650 and the crank and rods should be around $200. If they would sell at a fair price I'd buy, but not before. The reason I want the crank from them is that its a 87-90 YJ 258 that uses serpentine, no need for a crank spacer (the earlier ones use V belts and need a custom spacer to work with 4.0 serpentine). Today I'm off to see another yard that has 2 older 258s, to see if they are any more reasonable. I was just wondering though if the older Renix block I have would stand up, because I hear strokers are mostly built form post 96 NVH blocks that are reinforced and supposedly a good bit stronger.

Do a web search for engines....can just about guarantee you'll find one over the border in Maine.

I'll check into that, but then shipping becomes an issue. Getting a 300 pound engine block delivered all the way up here probaby won't be cheap.

Check his sig. Next door to him is New Zeland.

As for the space, it is a real simple thing to make. Heck, I could probably turn you one on the lathe for $20USD. You might be able to find them premade cheaper. I use the long snout crank with the spacer and it works fine. Some people turn down (chop off) the snout, but I wanted to make sure there were plenty of threads. The dimensions on the spacer are not in any way critical.

Check the yahoo site. They will know if anybody makes the spacer. By the way, I didn't buy a kit. I rolled my own and love it. If you want specifics, PM me or hit me back here and I can tell you what I did.

actually I'm up here in the frozen North. That's Sydney, Nova Scotia, on Cape Breton island, right before Newfoundland. Its a sleepy little place, no machine shops and only a few small junkyards.

Well, yesterday I didn't have time to get out to the junkyard, but I have my day off tomorow, I'll head out and check it then. I can't find the stroker website, all the info I'm runing off is from Dr Dyno's "from junker to stroker project". The crank is from an 80s vintage CJ so as I mentioned I'll have to look for a spacer. There are enough of the 7120 heads around here that I don't need to worry about looking too hard. I can get one for $100, which is a fair price. just a question though. If I plan on keeping Renix, and using this new head, will I have to swtich intakes, TBs and fuel rails/injectors? Also, if so, how do you guys adapt the Renix TPS to work with the H.O TB?

the_bandit87 said:

actually I'm up here in the frozen North. That's Sydney, Nova Scotia, on Cape Breton island, right before Newfoundland. Its a sleepy little place, no machine shops and only a few small junkyards.

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Don't be so modest. You are the home of some of the best Celtic music anywhere. Rock on!!

Thanks man, actually they just had the celtic music festival here, celtic colors. I haven't been to that in years, but I think I'm going to try to take the next one in.

well I made it out to the other junkyard today (the one with the long nosed 258 crank) and unfortunatly, because it about 4:30 on a friday afternoon, I couldn't go up to see the 258 because the hounds had been released. I was able to speak with someone who was working there, and I'm going to speak with them again next week. These guys seem a bit more level headed than the other junkyard. So I'll be able to find out next week if I'll be able to get the crank or not. In the mean time I need to get some of the micrometer specs that I need to check on the crank. I assume that it is the journals that need to be micrometered. I'm going to try to get a micrometer by the time I get the crank pulled. Another thing,what are the exact numbers that will tell me weather the crank is too worn and needs to be turned down?

Well I just read the article on Jeep strokers by Robert Bryce. According to what he says, any 4.0 block can be used as a stroker. This gets me back to the question, should I switch over to the higherflowing H.O head with its bigger TB, different intake, and better exhaust? According to the same article I'd need to change the fuel rail around, and probably the injectors, which I guess I'm up for, but I wonder if it would work with just a boared Renix TB, and new injectors on the old Renix head?

If I were you I wouldn't even screw with swapping the engine to HO. It really isn't worth that much trouble, lots of little changes will end up frustrating you, but if you're out to get that extra ounce of horsepower, go for it. As far as the crank and rods go, I would get a crank with the rods that go with it, I personally wouldn't mix and match (even though some people do, I am against it) Just port your head and maybe think about boring the Renix throttle body, its a little more complicated than the HO one. Just follow Dr Dynos guide and you should be fine.

I hear you about the H.O swap. I should have been a bit more clear, I don't want to switch over to the H.O computer system, I'm keeping my Renix for simplicity sake, I was just thinking of switching the head over to H.O, but I understand that I'd have to do a few things, like get the TPS to work, and change fuel rails, to make that happen. I don't even have an intake or exhaust for this motor, so I figured that if I need an intake and stuff any way, I'd just get the H.O head. I know where your coming from though, the KISS principle (Keep It Simple, Stupid). I'm still going to have to see where I stand wutg tge crank.

While the stroker isn't very common around here you defineately won't be the only one in the maritimes. I know of three and they all came from the same shop; Carman Christies Garage in Barrington NS. It's all the way at the opposite end of the province but it's probably the closest you'll find. They race 2 strokers and Carman Jr. has one in his DD MJ. If I run into problems with my eventual stroker build-up it'll be the first place I call.They may be able to help you out with parts as well. I've posted pics of all three of they're stroker powered jeeps in the picture showcase here if you do a search on off-road racing in NS. You should try to see them in action next season, the power is impressive. Unfortuneately I think the closest we come to you is Rawdon. Good luck with your project.

the_bandit87 said:

I can't find the stroker website, all the info I'm running off is from Dr Dyno's "from junker to stroker project".

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Wise man.
I suggest you do the following for simplicity sake and for reliability:

1. Renix block. Overbore cylinders 0.030" to ensure they're round and not tapered. You'll need matching +0.030" pistons. Ask machine shop to remove old cam bearings and press new ones in.
2. AMC 258 crankshaft. Any from '72 onwards will do. If it has a longer snout, no problem. Just get an old crank pulley and have the rear 10mm sliced off on a lathe. That'll be the keyed spacer that goes in front of the new crank pulley. You'll need to have the main/rod journals reground and use matching undersize bearings.
3. Renix head. Do a home port job on it and don't bother with the 7120 head (don't even think about using the very poor-flowing 258 head). Otherwise you'll also need the HO intake/exhaust manifolds, injector rail, TB, and fuel lines, adding to the cost (unless you think it's worth it).
4. Renix TB. Buy a bored 58mm Renix TB or have your local machine shop do the boring and make your own custom 58mm butterfly.
5. Oversize injectors. You'll need Ford 24lb'ers and you can keep your Renix fuel rail.
__________________________________
Dino's "Mean Green Machine"
1992 XJ Laredo 4-dr - 191k miles - 16k miles on 4.6L HO Stroker
AX15, NP231, D35c, D30

265hp@4900/325lbft@3500, 1/4 mile = [email protected], 0-60 = 5.5secs
Websites - Jeep 4.0 Performance, 4.6L Stroker Build-Up, Dino's Jeep Tricks

Forever in the s#!t. It's only the depth that varies!

Hey, thanks for all the info. I'm going to have to take a shot down to that place in Barrington, I'll need to know who they use as a machine shop. Up here its going to be hard enough to find some one with a lathe to make that spacer. The main reason I wanted to go with the 7120 was for the better flow characteristics, and the fact that the head the I have for the other renix is filled with a oil/rust/sludge combination inside the ports. I'll try to clean it up and see how that works out. The other reson was that, I don't have any other Renix parts for the head (Intake, TB, exhaust, fuel rail, ext.) unless I take them off of the engine that's in my Jeep now, and the other reason is that the H.O engine is more common to find in yards now than the Renix is. This summer I could have gotten a 7120 for $100, so I figure for $150-200 I can get everything I need. Now the only thing that stands in my way is findind a machine shop to bore the engine .030 over. thanks for all the help, I'll let you guys know how the pices start falling together. By the way, would a .030 over bore make mine a 4.6 or 4.7?