Another 4.0L OHV Build Thread (with 95TM heads)

[TennTechMan]

Another 4.0L OHV Build Thread (with 95TM heads) Now with a Video!!!

A couple months ago I picked up a '94 Sport 2-wheel drive for a very reasonable price with some motor problems (previous owner is a ExplorerForum member). My original intention was to swap a V8 drivetrain from a mid-90's model Mustang GT. After considering the total cost vs. benefit of the V8 along with reading through Craeger's thread, I had decided to build up the 4.0L unless the whole motor was trash. I've now got the motor pulled and tore down. The bottom end looks fantastic. One head has an exhaust valve with some damage, but it's destruction has done nothing to the rest of the engine.

I've thoroughly read about 75% of Creager's OHV build thread and skim read the whole thing twice. I had intentions of doing a very similar build until I had the heads pressure checked for cracks. Both of which were cracked at the bridge between the intake and exhaust valve on the middle cylinder. Since I'm buying new heads anyways, I figure I'll buy the 95TM ones to get to the ~10:1 compression ratio. I also want to use the 422 CompCams cam. I'm a little worried about valve clearance. Does anyone have this exact setup to confirm everything clears? Is there any reason why I should choose to use 94 model heads and SOHC pistons over 95TM heads and 94 OHV pistons? Does anyone know what pushrod length I would need with the 95TM heads? Where's a good place to get the upgraded valve springs that I will need with the 422 cam?

Here's a rough parts list so far:

-Rebuilt 94 OHV bottom end (stock bore, hot-bathed and honed, new oil pump, new bearings, new rings, possibly new pistons)
-New (not reman'ed) 95TM heads
-422 cam and custom length pushrods
-Stock rockers and lifters
-Upgraded valve springs (recommendations?)
-Headers and Y-pipe (JBA?)
-New timing set
-New water pump, etc.


Any input is greatly appreciated (both possitive and negative).

Thanks,
Aaron

 

[91exploreron37]

I know this has nothing to do with what your asking but what are 95tm heads and where can i get some from

 

[TennTechMan]

95TM heads are 4.0L OHV cylinder heads that were used in the 95-97 model 4.0L motors (except in the Aerostar van). Supposedly, they can be installed on a 91-94 model motor to increase compression to 10:1. You can buy the heads used from junk yards or eBay. I currently intend to buy some new heads from Tri State Cylinder Heads.

 

[Ronin8002]

As far as the 422 cam goes you will not have any valvetrain clearance issues with any style piston or head. The only way you would run into issues is if you shave too much off the block surface or the head, but since you're buying new heads and just getting the block cleaned up it won't be an issue.

Source for some good 4.0 heads: AlabamaCylinderHead.com They have the good aftermarket castings that are less prone to cracking

Pushrod length: with either the 410 OR 422 cam it's going to be the same. If you use a set of "bone stock" rockers then go with 5.550" pushrods. If you go for a set of the DeltaCam rockers with the hardened tips and pushrod cups (highly recommended for good longevity) then you need 5.525" pushrods.

For valve springs with the 422 cam you're going to need Compcams 988 dual coil springs. You will also need a set of valve locks from Crane Cams....I'll have to research what the part numbers are for both springs and locks and post later. What you will need also is to have the spring perches on the heads machined down so the dual coil springs will sit properly.

I am not an expert tuner but there may be a difference in using early style heads with flat pistons VS using 95 tm heads and dished pistons. As long as you stay naturally aspirated it should not make a difference though. I believe the 95tm heads have a different burn rate since the chamber design is different than the earlier style. If you're not adding nitrous or a blower or anything like that then the stock computer shouldn't have any problem keeping up with the changes as long as you use good premium gas.

Only negative I see with your proposed setup is...why use old pistons if you're going this far? Get some new ones in there!

 

[TennTechMan]

I found this site last night.

Dead Link Removed

It warns that using the fast burn heads (95TM style) with the 91-94 style pistons would result in the motor burning up. I was really hoping to not be the guinea pig for this configuration, but it's starting to look that way.

Should I abandon the 95TM heads and stock style pistons, and just go with what's already been proven?

 

[bikeboarder]

go with the sohc pistons. you already know that they work and the pistons are lighter so you can get more power out of of them.

 

[Ronin8002]

I understand your concerns. However, you're not being a guinea pig if you try swapping heads or pistons. It's been done many many times and successfully. That article you're referring to is a good resource but it isn't the end all be all.

For example, I've run my truck for 2+ years with the mods below....9psi boost and no issues with melted pistons or detonation. On a stock computer. I switched out computers to allow me to tune it but it certainly wasn't having any durability issues with the stock one. If the 4.0 can handle that, it can certainly handle what is basically a .7 compression increase from stock

Take a look at the below thread. The guys there are a wealth of knowledge on these motors and have gone way beyond stock.

http://www.rangerpowersports.com/forum/showthread.php?t=189491&highlight=compression

At the bottom notice the post that talks about the fast burn chambers actually being LESS prone to detonation. 95TM/98TM heads are the same in the combustion chamber area, the main difference between them being that the 98TM exhaust ports are smaller. That being the case, unless you port those 98TMs....95TM heads are much mo' bettah.

Like I said, use good premium gas to reduce possibility of detonation. Also, remember that using a longer duration cam like the 422 is going to bleed off a bit of that extra compression so it's not like you're going way into the danger zone for pump gas. The only thing I would not recommend NOT doing is using flat top pistons and 95TM heads. You're looking at 11.7-12:1 compression with that combo and that would probably give you some issues on pump gas. It would have some serious torque though

 

[91exploreron37]

Does "422" refer to the cams lift? If so what about a 500 cam do you think thats too much

 

[Ronin8002]

people call it the "422" because the Compcams cam grind number for it is 49-422-8. It's a .500 lift on intake and exhaust. It doesn't have any clearance issues but it does require dual coil valve springs and longer pushrods. The stock type won't hold up.

There is a milder Compcams grind that some people have also used...the 49-410-8, off the top of my head I think it's something like .460 intake lift and .500 exhaust lift, with less duration than the 422. You can PROBABLY get away with NEW stock springs on this one. The pushrod length is the same as with the 422. It also idles better.

Main differences between the two are the idle, the difference in valve springs, and the powerband. If you're keeping stock compression I'd say go with the 410 cam. The 422 is more for higher compression, nitrous, or superchargers.

What you will notice with both of them, though, is you know how your motor starts to run out of steam after 3500rpms or so? Both cams will let your motor keep pulling hard way past that.

 

[91exploreron37]

Could you get away with just the double valve springs and keep the stock pushrods and how much do the pushrods cost

 

[Ronin8002]

Yes. you need new pushrods. You should not use your old ones for 2 reasons:

1. they're going to be worn out
2. if you use the stock length pushrods....they are too short. At a best, this will result in you getting no extra valve lift from the cam. At worst it will let your valvetrain hammer itself to pieces.

Go to SmithBros.com....call them at their listed contact number....tell them what motor you've got and they can quote you a price....I think it was about 70 bucks for a set but it's been a while so it might be more or less

If you're going to do all the work to swap the cam and work on the heads....expect to replace at least the parts I've listed, and be prepared to replace other worn out stuff too. With the time and effort it takes to get your motor apart to do this, you might as well make sure you won't have to go in there again in a few months and fix something else.....just a suggestion.

 

[TennTechMan]

Thanks for all the responses. I've decided to go with the 95TM heads, the stock style pistons, and the 422 cam (along with all the other standard motor rebuild parts). Has anyone on the board done a write-up on how to measure for the correct pushrod length? Where do you measure the length of the pushrod; overall height, or from the centers of the spheres at each end of the pushrod?

I should start ordering parts for the motor soon. The machine work for the block should be complete sometime this week. I'm hoping to have the whole thing back together and in the truck in about 3 or 4 weeks.

 

[Ronin8002]

Here is a thread that might help with measuring them:

http://www.explorerforum.com/forums/showthread.php?t=59809&highlight=adjustable+pushrod

Or, you could follow this as a guide:

Pushrod length: with either the 410 OR 422 cam it's going to be the same. If you use a set of "bone stock" rockers then go with 5.550" pushrods. If you go for a set of the DeltaCam rockers with the hardened tips and pushrod cups (highly recommended for good longevity) then you need 5.525" pushrods.

You could also find out how much they are machining off your heads/block (if any) and subtract that number from the lengths listed above.

Found some part numbers for you for the valve springs, retainers, and pushrods:

Valve Springs: Comp Cams #988-12
Valve retainers: Crane Cams #99947-12
Pushrods: Smith Brothers #54A-A 5.550" or 54A-A 5.525" (if you don't get the block or heads milled)

 

[TennTechMan]

The block is not being resurfaced, so that's no concern. The heads will be new from either Alabama Cylinder Head or Tri State Cylinder Head. I plan on using stock rockers. Assuming the heads will be cast with the same dimension between the head deck and the surface that the rocker arms bolt to, I should use the 5.550" pushrod, right?

 

[Ronin8002]

correct

 

[TennTechMan]

I've been so busy with work the past couple weeks that I haven't had much time to do anything to the Explorer. I got the block, internals, bearings, and gasket set back from the machine shop today. I started to order some of the parts today. Summit didn't have the cam in stock. They expect to ship it 6/28, so it looks like it will still be a few weeks before I am able to get the motor back in the truck. I'll probably order the 95TM heads tomorrow.

I'm still trying to decide between the Borla and JBA headers. I've seen pretty similar prices on them. I've got a set of JBA's on my 2.9L Ranger. They seem to be good quality and I've been generally happy with them. Any opinions either way? Anyone else got any other recommendations on any other brand of headers? I know that I definitely want a set that come with a Y-pipe. Other than that, I'm open to suggestions.

 

[Ronin8002]

I've seen borlas and JBAs up close and installed and they seem equal in quality and the way they fit. I wouldn't go with any other brand. Only difference is last I heard JBAs had a ceramic thermal coating option to help keep the heat in. They both came with a y pipe from what I saw.

 

[TennTechMan]

Just wanted to give an update and ask a question.

I've gotten all my parts on order and some are starting to come in. I've began building the motor, and I need some info. Do we not have a list of motor torque specs anywhere on this site? I've searched around this site and the internet in general with no luck. Should I just go buy a repair manual?

 

[Ronin8002]

a chilton or haynes manual would help you with that. You might also try sending a PM to Creager on here...I think he may have a list of torque specs seeing as he built his motor not too long ago.

 

[TennTechMan]

Has anyone tried removing their EGR valve? I've heard elsewhere that you can see a power gain from removing it and using a block plate and plugging the hole in the exhaust. Is it much of a power gain? How does it affect fuel economy?

Any opinions?