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1990 YJ with 4.7 Stroker

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RustyTruck
Posts: 8
Joined: December 19th, 2017, 12:04 pm
Stroker Displacement: 4.7
Vehicle Year: 1990
Vehicle Make: Jeep
Vehicle Model: Wrangler

1990 YJ with 4.7 Stroker

Postby RustyTruck » December 19th, 2017, 12:28 pm

I am working on a stroker project and have now experience. Wish me luck. :mrgreen: Here is an introduction to my financial pit.

I have a 1990 YJ with a 4.2L running a MC2150 and MSD 6AL ignition. That will be replaced with a 4.7L built from a 2003 TJ motor using a Holley ECU with the factory coil rail.

This motor started life as another gentleman's 2005 TJ project. He had problems, gave up, and then sold the jeep in frustration. The next owner of the TJ with stroker was also not happy with its performance. That gentleman took the jeep, with a stock 4.0, to an off road shop and had them put the boring motor in it. After multiple conversations with the first gentleman and his machinist, I bought the 4.7 stroker from the shop owner.

Here are the details as I know them for my new 4.7L stroker project.
- 2003 4.0 block
- 1982 4.2 crank
- 4.0 rods
- KB944-060 pistons
- Tuppy cylinder head with larger valves, beehive springs, bronze guides, a 3 angle valve job, roller rockers, and some port work
- The block (0.027) and cylinder heads (0.10) were milled to raise the compression ratio. Numbers were best memory from the machinist.
- 10:1 compression ratio
- ARP bolts or studs for everything
- All new bearings for everything
- Custom mains girdle.
- Custom solid lifter bullet cam. <- I will add the details when I find the picture of the cam card.
- 70mm throttle body
- 27 lb/hr injectors
- Banks header
- 93 octane

The huge throttle body & bigger injectors stayed in the TJ. I banks header stayed as well, but I had one of those already.

Why did the original gentleman give up on it?
- Error codes all the time. He PCM was never touched by Ryan, so I am gambling that the error codes was caused by the engine being too modified for a stock tune.
- A ticking noise. Both the machinist and original gentleman believe this is coming from the lack of correctly setting valve lash with a solid lifter.

RustyTruck
Posts: 8
Joined: December 19th, 2017, 12:04 pm
Stroker Displacement: 4.7
Vehicle Year: 1990
Vehicle Make: Jeep
Vehicle Model: Wrangler

Re: 1990 YJ with 4.7 Stroker

Postby RustyTruck » December 19th, 2017, 12:55 pm

I need to figure many things out on this motor before I can drop it in the jeep. That is okay because the jeep is currently driven everyday to high school by my daughter. I cannot rip it apart until she move to college in the fall. There is still much to do right now though.

Item #1 to work out
I do not have the front accessories for this motor. I need to add an alternator, AC compressor, and power steering pump to it. I have a donor 4.0 from a ~97 TJ in my shed with everything still on the front of it. Can I move everything from a pre 2000 motor to a post 2000 motor. I is my understanding that more than the intake manifold changed.

Item #2 to work out
I need to order new injectors. I only have stock ones right now. I found many different lists of usable injectors on the internet, so I am not clear what are the preferred options. I also can use either connector option since I have two donor wiring harnesses with different connectors. I am not sure if the Holley ECU opens more options compared to the factory PCM.

User avatar
SkylinesSuck
Donator
Donator
Posts: 295
Joined: February 14th, 2009, 11:11 pm
Stroker Displacement: 4.6L
Vehicle Year: 1998
Vehicle Make: Jeep
Vehicle Model: Wrangler
Location: Northern VA

Re: 1990 YJ with 4.7 Stroker

Postby SkylinesSuck » December 19th, 2017, 1:59 pm

That's some pretty decent compression! I'd take care of the valve lash issue sooner rather than later as it could bigger something up in the long term. Does it have adjustable rockers? How do you set the lash? I have a set of injectors for sale in the for sale section that should work for you. Make sure your daughter isn't giving it the beans until you get proper fueling taken care of though!! If you Google the newer style intake manifold swap, it should show you what you need to make your accessories work. Shouldn't be too bad.

RustyTruck
Posts: 8
Joined: December 19th, 2017, 12:04 pm
Stroker Displacement: 4.7
Vehicle Year: 1990
Vehicle Make: Jeep
Vehicle Model: Wrangler

Re: 1990 YJ with 4.7 Stroker

Postby RustyTruck » December 19th, 2017, 3:49 pm

That's some pretty decent compression!

It is higher than what I want. My plan was to build a 4.6 from scratch, using a 4.0 donor that I have in the shed, with a more moderate compression ratio. This 4.7 came along and was a good deal. Oh well. Now I will never use less than 92.
I'd take care of the valve lash issue sooner rather than later as it could bigger something up in the long term.

Motor is currently on a stand. I am going to swap in a hydraulic cam before it goes into the jeep.
Does it have adjustable rockers? How do you set the lash?

Adjustable roller rockers that are purple!
I have a set of injectors for sale in the for sale section that should work for you.

Would 24lb ones be enough? The previous owner ran 27. I am leaning towards 30 per advice from the machinist that did all the work.
Make sure your daughter isn't giving it the beans until you get proper fueling taken care of though!!

Daughter is driving the jeep now with the craptacular 4.2. It is a dog.
If you Google the newer style intake manifold swap, it should show you what you need to make your accessories work. Shouldn't be too bad.

Now I know what to search for. Excellent. Thank you.

User avatar
SkylinesSuck
Donator
Donator
Posts: 295
Joined: February 14th, 2009, 11:11 pm
Stroker Displacement: 4.6L
Vehicle Year: 1998
Vehicle Make: Jeep
Vehicle Model: Wrangler
Location: Northern VA

Re: 1990 YJ with 4.7 Stroker

Postby SkylinesSuck » December 19th, 2017, 6:33 pm

Ah, I missed the part about the motor not being in it now. I'm not really familiar with the Holley ECU but I'm assuming it's similar to my EFI throttled body conversion on my Cutlass and is self tuning, but uses the factory fuel system? If so, 24# would be fine, but so would larger as I'm sure you'll just punch in the values for your injectors and let it tune itself (or tune it yourself). Most people on here are very particular about injector sizing because most use untuned ECU's and size the injectors to try and nail good AFR's at WOT with the factory tune and moderately larger injectors. Not ideal for sure but it works surprisingly well. I'm running 24#'ers with a ported head and decent cam if that tells you anything. Your machinest is recommending massive overkill, but as long as you tune for them and don't mind spending the coin, have at it. 27#'ers on a stock ECU would probably throw a check engine light for being too big/rich I'm guessing. Maybe that was his issue? BTW, have you done a compression test on the motor?

About the accessory swap, the block mounting bosses/holes are all the same as far as I know. The earlier head doesn't have any way to mount the coil rail, but that sounds like it won't be an issue for you. Can't think of other stuff that would be an issue other than the power steering pump mounting with the new intake. What a/c compressor will you use? I don't know how they mount on a YJ/4.2.

jsawduste
Strong Poster
Strong Poster
Posts: 944
Joined: February 28th, 2008, 3:13 am
Stroker Displacement: 4.9
Location: Michigan

Re: 1990 YJ with 4.7 Stroker

Postby jsawduste » December 20th, 2017, 8:00 am

Before going to far answering questions..........

You are aware that the TJ block has different engine mount locations than the YJ ?

Meaning the TJ block will not bolt into the YJ. Plus the accessories and how they mount are different also.

RustyTruck
Posts: 8
Joined: December 19th, 2017, 12:04 pm
Stroker Displacement: 4.7
Vehicle Year: 1990
Vehicle Make: Jeep
Vehicle Model: Wrangler

Re: 1990 YJ with 4.7 Stroker

Postby RustyTruck » December 20th, 2017, 8:46 am

You are aware that the TJ block has different engine mount locations than the YJ ?

Correct. I am using motor mounts from Brown Dog Offroad to solve that difference.

I need to figure out the accessories now.

RustyTruck
Posts: 8
Joined: December 19th, 2017, 12:04 pm
Stroker Displacement: 4.7
Vehicle Year: 1990
Vehicle Make: Jeep
Vehicle Model: Wrangler

Re: 1990 YJ with 4.7 Stroker

Postby RustyTruck » December 20th, 2017, 10:56 am

BTW, have you done a compression test on the motor?

The offroad shop did before he pulled it out of the previous jeep. He said everything was fine. I have not been able to redo it since I picked up the engine about 10 days ago. I can not seem to find my compression test kit right now. I will just order a new one.

RustyTruck
Posts: 8
Joined: December 19th, 2017, 12:04 pm
Stroker Displacement: 4.7
Vehicle Year: 1990
Vehicle Make: Jeep
Vehicle Model: Wrangler

Re: 1990 YJ with 4.7 Stroker

Postby RustyTruck » January 4th, 2018, 9:17 pm

I have a compression tester like this one. URL Generic cheap kit. It will not work. It will not fit in the spark plug hole. :( What do I need so it works?

I have my front accessories sorted out. The 2003 TJ motor (4.7) came with an alternator, the belt tension doodad, and the power steering pump bracket. My 98 TJ motor (original 4.0 donor that I am nolonger going to use) in the shed donated its power steering pump. I just need to buy a new belt and I am all set. Hopefully I find the AC stuff at some point. AC would be pretty sweet. My jeep has never had it though, so I am not worried much about it.

Motor mounts are sorted out. Brown Dog Offoad mounts are pretty slick. And bright yellow.


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