What did I do?

[goatbrother70]

OK cats,

I am in the USAF and did my first stroker motor about 7.5 years ago. I have a '90 Wrangler, love it, but I tow my boat with it and the Jeep didn't have the power I wanted. At the time of the stroker, I had endured the "craperator" for long enough. I wanted EFI, and a mild stroke....so this is what I did:

I took my 4.2, gutted it;
- Bored the cylinders .030 over, put hypuretic pistons in it
- Kept the 4.2 crank
- Kept the 4.2 rods
- Put a gone over 4.0 head on it (sealed off some water jackets because they didn't line up)
- Slapped a 4.0 Cherokee EFI setup on it
- Changed the EFI stuff I needed to (brackets and stuff like that)

Then I called it good and fired it up.
I'm in the USAF and was subsequently shipped overseas for 5 years. Put it into storage, up on blocks and when I went to fire it up, it took 3 cranks and vroom! It was back to life! Now that I'm back and with all the stroker talk.....I want to know....um,.....what did I do and what do I have? What liter is it? What is my compression ratio?

The power is OK, not what I thought it was going to be....not a CRAAZY amount better in towing my boat.
After I know what my Motor is at (in liters) I would like to get your advice.....I would like to get a little more power out of what I have. I "may" stroke it again, use a 4.0 block, my 4.2 crank, 4.0 head, etc....but for the short term I would like to get more power out of what I have.

1. I have a squeal in the throttle body....do I need a bigger one? Will that give me more power at the mid-high end? - I think I do but just asking for help and the technology behind it. I want to understand the "Why?" question
2. Do I need bigger injectors? The 24# perhaps? - I think so based on the increased cylinder volume.....
2. If I put in new injectors, do I need a new fuel pressure regulator and what should I set it at?

Thanks for your time - Ken

[IH 392]

It sounds like you have nothing more than a .030"' over 258 yielding 261CI.?, did you keep the 258 block or swap to the 4.0 block??, also you only state that the EFI is from a Cherokee?, what year!?, is it "RENIX", "OBDI" or OBDII", what camshaft did you use?, if you used the 258 cam that may very well be a large part of the no power issue?

[Cheromaniac]

Your engine still has the same 3.895" stroke but since you've overbored the cylinders +0.030", the bore is 3.780" and displacement is 262.2ci (4297cc or 4.3L).
The 4.0L cylinder head would have raised the CR by ~0.7:1 and, combined with the EFI, would have added a decent amount of power.
The stock Cherokee injectors and FPR are OK for the job with the engine as it stands, but I there are other things you could do to add some power e.g. header, exhaust, cold air intake, 62mm TB, better camshaft.
You could build a stroker from scratch by starting out with a 4.0L block (3.875" cylinder bore) and then adding your 258 crank/rods and other pieces to go from there. Alternatively, you could build a stroker based on your existing 4.2L block. The maximum cylinder overbore is 3.810" and with a 4.145" stroker crank, displacement is increased to 283.5ci (4646cc or 4.6L).

http://www.flatlanderracing.com/strokeramc-258.html
http://www.shop.505performance.com/cate ... egoryId=39

[BADASYJ]

I ran a 4.2 with the HO head for years. Not bad but not impressive either.
You have got to switch over to a 4.0 cam for the new brain you have. Also what are you using for a fuel pump?

[goatbrother70]

ALCON,
Thanks for the replies. I am going to re-do the motor and start with a 4.0 block from a junkyard and build from there. I am going to take one of the recipes from this fourum and use my 283 crank. I'm probably going to do it in some form of stages (take care of the intake TBI/injectors/etc) first and then get the block and head done. Once everything is here I can proceed with the engine removal, crank swap and install. I'm hoping for a short turn around on the crank and install, but I may end up taking a bit of time.

To answer some questions, I have a bosch fuel pump. It's an after the fact pump that is mounted near my gas tank. I used the stock camshaft because I didn't know any better,......my lack of research. I don't know the difference in the OBDI or OBDII computers so I can't really tell. The unit didn't make me hook up the check engine light so I didn't. I know it's probably engaged all the time, but since I don't see it, I;m not concerned.

The Jeep runs good, I just want it to run BETTER and stronger.

Thanks for the input.

Does anyone know the part numbers for24 Lb injectors? I just want to make sure I'm getting the right thing off of ebay.
Ken

[Cheromaniac]

Does anyone know the part numbers for24 Lb injectors? I just want to make sure I'm getting the right thing off of ebay.

http://www.summitracing.com/parts/sum-240024/overview/

The Ford Racing versions used to carry the part no. FMS-M-9593A302.

[gdl]

Does anyone know the part numbers for24 Lb injectors? I just want to make sure I'm getting the right thing off of ebay.

I bought a set of these from this guy on ebay four months ago.
http://www.ebay.com/itm/REBUILT-24LB-BO ... 27d6b9032a

Ran them in my 4.0 for three months and was very pleased with them, smoother idle, better throttle response. I should have my stroker up and running with these in a couple weeks.