Propane injected 4.7L Stroker build for my MJ

[hot_rod_hooligans]

I guess I could have chosen a few different parts to make this a little easier on myself when it comes time to installing the engine in my Jeep, and being able to figure out how I'm going to run all of my accessories once it's all in, but I guess that's what makes it custom.

Here is the run down:
99 or 00 WJ 4.0 block
04 TJ TUPY revised 0331 head
4.0 connecting rods
AMC 258/CJ7 4.2L crank
Keith Black forged pistions- IC945-060- .060 over with 10.80cc dish
COMP Cams 68-239-4 Cam and Lifter Kit
COMP Cams High Energy Timing Chain Set - 3219
Victor Reinz/Full Gasket Set - 95-3568VR
GotPropane.com conversion kit
And possibly a Clifford carburated 4.0L intake manifold if I can spare the funds

I decided to go with the 99+ Wj/00+ TJ block originally because I had intended on building this for a 00+ TJ, but plans changed. I decided to stick with it for several reasons, ease of installation was not one of them.
For starters, it was free. It had been swapped because the previous owner had failed to change the oil for quite some time, causing sludge build up, so bad that eventually it spun the #1 rod bearing due to lack of oil.
It had enough miles on it that the block is close to whats called a seasoned block. After several years/miles of being heated up and cooled off, an engine will shift and distort as molecules realign themselves through a slow heat treat process, causing parts to not quite line up as perfectly as the day everything was machined. Lots of engine builders prefer old, high mileage engine blocks over a brand new one, for this very reason, believing after you go through and bore it out, deck it, and line hone it, you are not going to have any more movement since they are starting with a block that has already been heat treated, and everything has settled.
The 99+ WJ and 00+TJ blocks are a little different than the earlier style, and has a lot thicker castings around the cam shaft to fix a problem with the cams shaking themselves apart at high RPMs(higher than most factory 4.0s will ever see, but none the less), and have thicker cylinder walls, able to support up to .080 over, safely. Both may not be needed, but better to have it and not need it, than need it and not have it.

I wanted the head because, despite how everyone says the older heads flow better, I like the late model exhaust headers better, and since I'm doing all the port work myself, I'm confident I can open the exhaust ports up enough to make them flow similar numbers to the older heads. That and the head only has 13,000 miles on it. Yes I know that goes against the logic of using a seasoned block, but this way I don't have to have a bunch of machine work done, and if it gives me any problems, I'll just upgrade to a Hesco aluminum head.

Why Propane?
Originally I wanted to build this motor to put in a 00+ TJ with the coil ignition, and run it on E85, but I decided to build a Comanche instead. Well the Comanche has the old RENIX FI system, and I'm not a fan of it, too many quirks, and I still don't like that it has an EGR valve. I could do a HO swap and update everything to OBD 1 or 2, but then I would have to cut and splice wiring(I hate wiring!), and I would still have to fight a computer tuning the engine.
With Propane, I pull out all of the computer controlled stuff and bring it all back to a carbureted style setup, using a propane injector in place of a carb. Clean, plain, simple, easy to work on, easy to tune, and for as little as this will be driven over long distances, it will work for me.

Now for the pics:

The donor block



#1 rod journal

Sluge build up in the timing cover

The oil filter




4.2L Crank

I was really trying to get a crank from a carburated YJ, since they have the short snout, but due to a mix up at the shop I bought it from, didn't have one to sell me, so they threw in the spacer for free.




Keith Black forged goodness

[hot_rod_hooligans]

Block and head just got back from being thermo blasted today, stripped the entire thing down to the bare cast iron.





This should make working on it a lot more enjoyable, especially with how sludged up the block was.


Spent part of class going through and tapping all of the bolt holes out, this will make it a lot easier to assemble, and ensure I don't get any false torque readings from boogered up threads.

[hot_rod_hooligans]

Spent a little time working on the head tonight. I've been putzing around with this head on and off for maybe a year and a half, I have about 60% of the intake and exhaust ports gasket matched and roughed in, as well as several of the combustion chambers roughed in. I finally got the #1-2 cylinder intake ports about 90% finished tonight, down to the final polishing.

Stock intake port


Ported and polished


I'm not sure I'm satisfied with the roof of the bowl, there is a pretty hard turn at the back of the port at the turn down into the combustion chamber. With all of the material I removed from the valve guide, it makes the turn a lot more noticeable. Air doesn't like to make hard turns like that, really slows down air flow. A common way to take care of something like this is to use an epoxy putty to build the area up, and then grind into a more flow friendly shape. Not sure if I really want to bother with it though.

Originally I had plans of using the COMP Cams 68-232-4 cam and stock intake and exhaust valves, but in light of my larger port job it was decided to make the most of it. COMP Cams 68-239-4 and LS1 Intake and Exhaust valves were decided on, as well as LS6 valve springs.

[hot_rod_hooligans]

I'd been emailing M.O.R.E. and Brown Dog about block brackets. Both of them say that they have what I need. For the complete bracket and motor mount, BD is about $75 cheeper, has free shipping, and a 10% discount through JF, but MOREs brackets hit more bolt bosses(7/8 vs BDs 6/7), and don't come in that ugly yellow. Here is what I've been able to work out, MORE is willing to sell me their block bracket just tacked together for a discounted price, making them a good bit cheeper than the BD ones. This also allows me to cut tacks and easily modify the bracket if need be. Although getting the motor mounts from MORE would wash any savings made by welding the brackets myself, so I will be going to BD for the motor mounts, I'll just have to sand blast the yellow off and repaint them before they go on the Jeep. In all, it will save me about $40 from buying everything from BD, and $115 from MORE.

M.O.R.E Bombproof engine brackets





Block has been at the Machine shop for about a month now, his mother has been really sick with heart problems the last few weeks, so he hasn't been getting a lot done around the shop, not a big deal since I still have plenty to keep me busy with the head. He is doing the work for free, so I wouldn't complain even if I wanted to.

Still porting on the head, intake ports are all roughed in, and most just need polished, I'll wait till after it gets back from getting all the machine work done, and can blend the bowl in to polish. Going to hit the exhaust and combustion chambers next.
Last side by side comparison.

[gregorio87]

I have propane comversion from BRC on my stock 4.0L YJ. I've done 160.000 miles without any problem, but I go for 3.5km with one liter of propane; and with this, I feel the loose HPs, I think about 20-25 HPs from run with 98 octane gasoline.
I wish you that your stroker will be run well with propane. I have to think about use my conversion kit on my stroker when I will finish it. But Ithink of no, because I want to make a turbo stroker, and propane cant gives needed power for this engine.

[Desertjr]

What ever happened. O this build? I'm very very curious about it. Looks like it could be a very potent motor.

[sly-jeeper]

yea me two im very interested in building a propane stroker