Engine out, now what. Advice Please

[jwrezz]

So the engine is out awaiting a rebuild. I need some advice. I'll try and keep it brief:

1) BBK headers are on now. Starter won't come out w/ out the drivers header removed--scratch that, header unbolted, Y-pipe needs to be removed. Luckily the engine came out entirely. Should I just put the old manifolds back on? It's not blown, but maybe they'll be good after the rebuild, see below.

2) New rings are a given. The block should be pretty solid, BUT is a .030 over bore an option? or even a .010? If so where do I go for parts? I quickly searched fastpartsnetwork.com but only came across stock replacements for pistons, rings, etc.

3) This is more of a question for Doug S. @ Bama Chips, but...I had an SCT xCal & 3 tunes. The xCal unit was stolen right from my garage! I still have one of Doug's tunes in the ECM. Can I get it back to stock? I know w/ all the upgrades, I'll need new tunes any way, but you get my question.

4) New injectors are a given, but how big should I go? Still, it's not blown, but maybe bored larger. What about the fuel press. regulator? And while I'm at it, that crazy fuel rail set up, what's w/ that? It does the job, but man it's not like any things else out there. Is there an after market for this stuff?

5) What size is the fan nut? I think I need an electric, esp w/ the body lift. Any recommendations?

If you need pics of the engine & removal, see:

http://www.flickr.com/photos/jwrezz/sets/72157600157573990/

Thanx all!

 

[aldive]

Have you considered a new crate motor rather than a rebuild?

 

[jwrezz]

Yeah, but I think the cost may not be worth it. I mean this motor has Doug's stage II heads, a crane cam w/ like 20k miles on it, the tune from Doug/SCT. Wouldn't I need a new computer? And a crate motor may not have the over all reliability if I get this work done by a good machinist, and I have one. But please Al, give me some reasons that the crate motor would serve me better. Keep in mind, this will not be a daily driver, but will be on the road, and trails quite a bit. It's lifted, and locked, w/ 33's and 4.10 gears, and prob'ly a transfer case change some time. One w/ a steeper low range. Thanx again,

 

[aldive]

When I suggested it, I didn't realize that you had all the goodies.

 

[jwrezz]

So any one else out there have some words of wisdom? I really need them! Gotta either get this motor out to the shop, or what ever really soon! I miss the trails!

 

[jwrezz]

Rebuild 4.0 OHV almost started.

So after reading http://www.explorerforum.com/forums/showthread.php?t=152071 I'm now diving into this. Found a good machinist. He's ready to research the 4.0 and get going. He said the more work I do for him, the better off I'll be. I've been ripping the engine apart. I busted the $h!t out of my knuckle ( no pics yet) getting those damned head bolts, but I'm moving along. The #2 cyl seems to be the prob. I think #2 is the middle one on the drivers side, right? Any way it's crudded up good. No cross hatching left, just up and down marks. All the others seem to have the cross hatching in-tact. I think the rockers were in fact wearing the tops of the valve guides like Doug had warned me about. We'll see when the springs come off. Here's one pic of the bad combustion chamber:

and the bad cyl:

More here:

http://www.flickr.com/photos/jwrezz/sets/72157600157573990/

 

[Xan]

i've never built a 4.0 before but i know you can get a kit from (.30 over or what ever with all the gaskets, ussaly oil pump) from summitracing.com you might have to call them though. going for .30 or .10 over would be a good idea always gives more power just don't go any bigger then .30 cause then you'll have too thin of walls and heat is a problem. i'd stick with the headers.. always more power with them. i think the fan has a special tool you need to rent to remove it. all the rest of the stuff no idea i've never built a 4.0 but look around on summit racing there site is incredably easy to navigate

 

[Ronin8002]

a .030 overbore is pretty much the max you are recommended to go on these blocks. I've heard of a couple of people taking it all the way out to a 4" bore so they could used a standard sized forged piston but you are risking making the cylinder walls very thin....so bottom line, I'd stay with a .030 overbore.

Speedpro makes pistons that will work for an overbored 4.0. You can get any variety of dish. 91-94 pistons with the heads you have will give you around 10:1 compression ratio. That will be good with pump gas as long as you get 93 octane all the time. SOHC pistons are completely flat top and I think you'd be seeing around 12:1 compression or higher with those...probably not the best idea on pump gas. If you could keep it from knocking that would be an awesome setup to use with the Compcams 49-422-8 camshaft though.

Headers: Always better than the stock manifolds. Some people think you "lose" torque on a 4.0 with headers but all you're doing is moving the torque band up a little higher in the RPM range. Really what they help mostly with is the higher RPMs....not a big concern if you are rock crawling but if you need to rev it up to get up a steep incline it will help.

As far as injectors go....the stock 19# injectors are fine. The only time you need to go up in size with those is with supercharger or heavy nitrous use. Along with that...there is no need to switch to a different fuel pressure regulator. You CAN....but it involves welding a fitting onto your fuel rail where the stock Fuel Pressure regulator goes. Again, really not necessary unless you are into heavy nitrous use or serious supercharger setup. I still run the stock FPR on my truck...though I have larger injectors. Yes, the fuel rail setup is weird, but there is no aftermarket support there either and as far as I know there is no need to go through the work of trying to make something work. there are 300+HP 4.0s out there that the stock fuel rail is more than adequate for.

As far as electric fans go, I use a black magic electric fan I got from summit. PArt number at summit is FLX-150 I think. It seems like it wouldn't work so well because the shroud on it doesn't cover your whole radiator but in actuality it works very very well.

 

[jwrezz]

Max Violence, you are the man! You had lots of helpful hints on Craeger's thread that I learned lots from. Thanx for encouraging me on this build-up! Man it really sucks to type w/ this busted up knuckle! thanx again,

 

[Ronin8002]

No worries, dude. By no means am I an expert at this though....if you run into issues during the rebuild you ought to consult the guys on the RPS 4.0 V-6 Tech board...a number of them have built and taken apart the 4.0 many times and can help you with performance as well as the basics of building your motor.

 

[jwrezz]

So, is there a problem or what?!?

I can't believe I didn't see this originally! Bad angle, but today I rotated the engine, and saw this beautiful stuff:

So I burnt it up? The cyl. wall looks messy, but not bad. How many times I started and moved the truck between the first instance, and before the disassembly! I must've had buck-shot coming out the tail pipe!

So is it fixable? Man oh man! Oh yeah, here's what happens when you use the wrong tool for the job. I used a cheap harbor freight torque wrench as a breaker bar:

 

[schmidlkofer]

ouch.

 

[Cali' Explorer]

Whether its rebuildable really depends on the block. Since you will be replacing the pistons anyways, its just a mater of finding out whether they dug in enough that .030" overbore will not clean them up enough.

My concern at this point would be finding out whether or not any additional damage was done to the motor (metal filings in the oil, etc). You might be best off finding a clean, seasoned, rebuildable motor at a junk yard and then swapping in all your upgrade goodies.

Also, as some mentioned, getting .030 overbore should not be a big deal. Most piston manufacturers make pistons in all shapes and sizes. Plus, rebuilds with overbores (to clean up cylinders) are really common. You can probably find a whole out of the box kit with everything you need to do it from PAW or someone similar.

 

[jwrezz]

Well the rebuild is going well, if not slowly. I was guided towards getting new heads because the ones that I got for the last "top end" rebuild 2 years ago were not ported correctly for what I needed. He said the heads were great if I wanted to run 4-6k rpm, but that I'd loose a lot of mid range power. So I have a nearly new set of heads w/ a brand new 3 angle valve job for any one out there building a high revving 4.0 ohv! My new heads are from the same place, Alabama Cylinder Head so I know they're cast well and will last. I'll get pics of my heads for sale up here asap.Thanks for all the help, and I'll get pics of the rebuild up here too.

 

[jwrezz]

Some pics of the block

I'll get the head pics up next.

 

[jwrezz]

Some more work...

Here's the pics of the block (bored, not honed yet) crank, and the heads that got the valve job, but that I have to sell because they will not be going on my engine. Again they were opened up too much for my application, but will work well on a higher RPM 4.0 OHV. Here's a web site w/ all of them too...

http://web.mac.com/jwrezz/JWREZZ/Explorer_Crank,_Block,_Heads.html

 

[Xan]

looks good, now get it back together! I've been waiting to see the finished product

 

[jwrezz]

Yeah, I know. I'm prob'ly gonna have to wait a few weeks. I'm a teacher, and school's starting next week. I also gotta prep the engine bay a bit. Pressure wash, and paint the frame. Get new water pump, and replace stock fan w/ an electric unit (any suggestions?). I'll keep y'all posted.

 

[jwrezz]

Engine is DONE!

It's not in the truck yet. Heck, it's so pretty, I don't wanna even put it in there! So here's some new info before I get to the pics. Bob, my machinist, had found some little details that may have led to the motor's demise.

1) That cam from Crane, well when I bought it, it said stock springs were ok ( I changed them any way) but now crane says that they must be upgraded. They still do not say anything about their lift being too much for the stock valve guides. Well, every one of my valve seals had some kind of damage. He machined each guide down .070" and now I have plenty of room.

2) Bob asked me if the engine had ever been disassembled before. I told him just the top 1/2 for the heads. He said he thought so, but that my engine may have been mis-assembled at the factory. He went over it a few times w/ other people and they all came to the conclusion that the drivers side connecting rods were in "backwards". By that I mean, apparently there is an oil passage that runs thru them, but it only works with the rod facing a certain direction. Mine weren't on the one side. Again he went over it a few times w/ other people during installation to make sure they were in facing the right way.

So it's .030" over, port matched, 3 angle valve job, new injectors, all clean, blah, blah, blah. Here's some pics...

Yes, I'll replace the oil filter before I first fire it up!!

I still have those heads if any one is interested. I'll post them on the FS forum...

 

[Jamieh560]

Looks good man! I just rebuilt a 4.0 sohc... how much power you looking at?

here my post: http://www.explorerforum.com/forums/showthread.php?t=195277

Jamie