Thread exclusively to discuss the best ways to build Jeep I6 Stroker motors

[Rescue Diver]

Let's try this again. In this thread, I would like to share what I'm doing, and get input from others specifically pertaining to ways to build 4.6 and 4.7 liter Inline 6 stroker motors.

I decided to pull the trigger on starting my stroker motor project. I'm picking up a good 1995 4.0 donor motor today or tomorrow, and over time I will pick up new Sealed Power dished pistons that should give me roughly 9.25 to 1 compression, getting the block bored either 30 or 60 over, and I'll be using the crank out of my 258 machined 10 under to clean it up.

My plan is to do a cheap but solid build using my 258 crank and rods, the 4.0 block and new pistons, and the stock 4.0 high output cam and lifters. I already have a killer 4.0 head that I'm currently using on my 258, but I also plan to continue using my HEI distributor and MC2100 carb instead of going the fuel injection rout that most do. Unless it shows signs of wear, I think I'll also be re-using the tru roller timing chan I already have in the 258. It only has 25k on it, so I expect to find it still in good shape. I guess I better check to make sure the 4.0 and the 258 take the same chain and gears?

What I've confirmed so far is that the bell housing bolt pattern is the same between the 258 and 4.0. The distributor will also fit. There is a little question on the motor mounts though. From what I gather, the later model 4.0's (TJ's maybe) require a little grinding on the block to get the CJ mounts to clear, but I don't know for sure what year in the 4.0 production that this change occurred. Any input on this would be welcome!

I also discovered that there's a slightly different part number for the oil pump. The 4.0 pump is the same number as the 258 pump but with an "A" on the end. Does anyone know if they're interchangeable? The motor I'm buying is complete, so I'll probably switch to the serpentine belt settup. I've read that I'll need to use some kind of spacer to mount the 4.0 serpentine's harmonic balancer to the 258 crank.

The last issue that I can think of to tackle is the fuel pump. Since the 4.0 was built for fuel injection, it won't take a mechanical pump, so I'll have to switch to electric. That goes against my "Keep it simple stupid" philosophy, but I have no other choice. I'm thinking of using a Mr. Gasket Micro electric 4-7 PSI pump with no regulator, and mounting on the inside of the right rear bump stop extention to keep it level with the bottom of the gas tank. Does anyone on here have any experience with these pumps? Should I carry a spare so I don't get stranded???

I think I covered all the bases. Did I miss anything????

Thanks for any input!
David

 

[CJ]

Thread exclusively to discuss the best ways to build Jeep I6 Stroker motors.

There ya go!

 

[Rescue Diver]

There ya go!

Thanks CJ! I still wish you'd delete the other thread so they don't get confused. I'd like a thread just for discussing the hows of building a stroker, not the whys because some other engine else is better in someone's opinion.

 

[Incommando]

Do you have an opinion on whether the early "heavy" crank is preferable for such a build or would the later "light" crank be better?

 

[Rescue Diver]

Do you have an opinion on whether the early "heavy" crank is preferable for such a build or would the later "light" crank be better?

I read that the early heavy ones like mine are strong, but I haven't read anything about the newer ones breaking, so I don't think it makes a lot of difference.

 

[Incommando]

Would the greater inertia of the heavy crank aid low end torque or at least make the engine harder to kill (as is often a reason cited for using a heavy flywheel) and make it preferrable in addition to the strength issue?

 

[Rescue Diver]

Just read this as of now ( it was further down the new posts list then some others I have already responded to such as folks hijacking the hijack thread with off topic stuff)

The most important thing for an inline electric pump IMHO ( O for opinion which is not necessarily a proven fact) is to run a good filter between the tank and the pump. Heat kills these pumps so don't mount them any closer to another heat source than necessary. A cheap rotary pump that has a max output that is hopefully what you need is not as good of an investment as say a Holley Blue pump with a regulator to give it the correct pressure. Mounting the pump close to the tank so the "pull" length is as short as possible is aso said to make them last longer.

Thanks. I plan to run a filter before the pump no matter which one I go with. I think even the cheap Mr. Gasket pump comes with a filter. I've given the Holley some thought. Whatever I end up using, I want it to be as reliable as possible. I've built this whole jeep from a frame with reliability and simplicity in mind. That's part of the reason I'm sticking with a carb, for now at least.

 

[Incommando]

It is your decision but as long as you avoid the Renault sourced Bendix FI (commonly called renix) used until 1990 you should be fine as reliabilty of the OBD I & OBD II system is pretty darn good. Many mistakenly place the filter between the pump and carb like with a mechanical pump but with the electric that doesn't protect the equally touchy pump. Might be good info for someone reading this later.

If you go with a cheapo McAutoparts place blister pack rotary pump by all means carry a spare. The additional cost of a pump like the Blue will recoup itself the first time the cheapo fails which will always be at the worst possible time for it to do so.

 

[rr41mag]

We get alot of returns on those cheap blister packs electric fuel pumps.

 

[Rescue Diver]

It is your decision but as long as you avoid the Renault sourced Bendix FI (commonly called renix) used until 1990 you should be fine as reliabilty of the OBD I & OBD II system is pretty darn good.

If I ever decide to go FI, it'll most likely be the factory setup from a mid to late 90's XJ. I hear the later 90's horse shoe shaped intakes flow better.

 

[Rescue Diver]

We get alot of returns on those cheap blister packs electric fuel pumps.

By "blister pack" I take it you mean the Mr. Gasket? That's the input I'm looking for on these. I wonder how many of your returns are due to them not being mounted in the right location or people running them dry to many times? I'm leaning towards going with a Holley or Carter.

Thanks

 

[gert]

By "blister pack" I take it you mean the Mr. Gasket? That's the input I'm looking for on these. I wonder how many of your returns are due to them not being mounted in the right location or people running them dry to many times? I'm leaning towards going with a Holley or Carter.

Thanks

I have heard many good things about the Holley pump. Me personally I have the Carter pump. I like it and have had several of them and will be installing it on my CJ

 

[Rescue Diver]

Picked up the 4.0 today.

 

[rr41mag]

The mister gasket, actually now that I think about it, it seems it's mostly the one people get for deasel

 

[IOPort51]

On the subject of fuel pumps.

When and if I decide to go with EFI I have a plan to modify the original tank to accommodate the XJ in tank pump and sending unit. The plan includes putting the sending unit centered in the access hole in the bed. This will, more than likely require an after market fuel gauge.

 

[coldair]

How many miles does I have on it?

 

[Cheepjeep85]

That looks new, what did it set you back. details man details

Sent from my DROID3 using Tapatalk 2

 

[CJ007]

Let's try this again. In this thread, I would like to share what I'm doing, and get input from others specifically pertaining to ways to build 4.6 and 4.7 liter Inline 6 stroker motors.

I decided to pull the trigger on starting my stroker motor project. I'm picking up a good 1995 4.0 donor motor today or tomorrow, and over time I will pick up new Sealed Power dished pistons that should give me roughly 9.25 to 1 compression, getting the block bored either 30 or 60 over, and I'll be using the crank out of my 258 machined 10 under to clean it up.

My plan is to do a cheap but solid build using my 258 crank and rods, the 4.0 block and new pistons, and the stock 4.0 high output cam and lifters. I already have a killer 4.0 head that I'm currently using on my 258, but I also plan to continue using my HEI distributor and MC2100 carb instead of going the fuel injection rout that most do. Unless it shows signs of wear, I think I'll also be re-using the tru roller timing chan I already have in the 258. It only has 25k on it, so I expect to find it still in good shape. I guess I better check to make sure the 4.0 and the 258 take the same chain and gears?

What I've confirmed so far is that the bell housing bolt pattern is the same between the 258 and 4.0. The distributor will also fit. There is a little question on the motor mounts though. From what I gather, the later model 4.0's (TJ's maybe) require a little grinding on the block to get the CJ mounts to clear, but I don't know for sure what year in the 4.0 production that this change occurred. Any input on this would be welcome!

I also discovered that there's a slightly different part number for the oil pump. The 4.0 pump is the same number as the 258 pump but with an "A" on the end. Does anyone know if they're interchangeable? The motor I'm buying is complete, so I'll probably switch to the serpentine belt settup. I've read that I'll need to use some kind of spacer to mount the 4.0 serpentine's harmonic balancer to the 258 crank.

The last issue that I can think of to tackle is the fuel pump. Since the 4.0 was built for fuel injection, it won't take a mechanical pump, so I'll have to switch to electric. That goes against my "Keep it simple stupid" philosophy, but I have no other choice. I'm thinking of using a Mr. Gasket Micro electric 4-7 PSI pump with no regulator, and mounting on the inside of the right rear bump stop extention to keep it level with the bottom of the gas tank. Does anyone on here have any experience with these pumps? Should I carry a spare so I don't get stranded???

I think I covered all the bases. Did I miss anything????

Thanks for any input!
David

I say go as low as you can when boring, in case you need to go higher later or keep the engine long term and need to do again.

I am not sure about the oil pump with the "A" but I do know the 258 actually had a couple oil pumps that were different because the screen faced a different direction, basically the drop in the oil pan was either at the center or to the rear. Not sure how that works on the 4.0 but just thought I should mention.

 

[Incommando]

Around '99 they made some internal engine changes that dropped the output. The new intake brought it back to the previous levels. Swapping the late intake on an earlier 4.0 gives you from 12 to almost 20 horespower at the flywheel depending on who you believe. Depending on the year of the donor you have to swap some accessory brackets as well. To really see the jump you need both the correct regulator for the fuel rail and higher flow injectors. The donor intake can come from an Grand as well.

 

[Rescue Diver]

Here's one answer to the question of performance gains you get with the stroker.

Stroker