95-01 Heads - 95TM vs 98TM vs Alabama New Castings

[r37ribution]

I recently recieved a set of heads from Alabama Cylinder Heads. I got my motor pull out and noticed that the exhaust ports on my stock 1996 4.0 heads are much larger than those which are on the new Alabama stock replacement heads. The heads that BBK and JBA sell for a 95-98 4.0 have 1 5/8" primaries and their newer heads as well as Pacesetter and Hedman for 98+ are 1 1/2" primaries. So I'm guessing that Alabama ships a generic head for the 96-01 Xs with the smaller exhaust ports similar to that of the 98TM.
I have heard that there smaller ports in the 98TM heads causing the gases to leave the heads faster and thus heat up the cats more quickly making them more efficient. I thought they were referring to the exhaust valve size not the exhaust port for the headers.

So my question is, ignoring the cats which I don't have, which head performs better? I would assume the larger exhaust port, it looks much bigger. I have a set of BBKs with the 1 5/8" primaries and want what would work best with them.

95TM vs Alabama:

95TM:

Alabama:

 

[r37ribution]

Reply from Doug904

Here is a reply I got in an email from Doug:

Hey guy,

Well that's a weird one. In stock form the larger exhaust ports are the best but if you plan on doing port work then the smaller ports of the 98 TM heads offer more ability to grind and shape. So basically it comes down to this, if you want the best out of the box then get the larger 95-97 ports, if you want the best for port work get the 98TM's.

Yes, I still do dynotuning and just got back from tuning a OHV in Arizona for a class 7 desert racing team.

Thanks,

Douglas Studdard
www.BamaChips.com

Just figured I would take your opinions as well and also show the Alabama heads on here for reference.

 

[r37ribution]

Some additional info

Some additional info on the heads:

The 95 and up heads have the smaller chambers which [with the early piston design gives the 10:1, all of the OHVs are 9:1 with the matching year piston/head]. The 98 and up heads have the small chamber/ small port for higher velocity the headers and manifolds all bolt to the different years.

I dont think the lean burn heads have anything to do with the computer- the computer is adaptable enough- even less important if you have a chip that changes the timing curve. I think in the context of the article Doug Anderson was trying to save some unknowing rebuilder from accidentally raising the compression on a customers rebuild when they expect it to replace a stock engine. The increased compression will require the use of a higher octane fuel or you will have detonation, and may cause a "melt down" of the engine, or specifically a piston. If your willing to run the premium, or you're adding some duration to the cam I doubt the extra compression would do anything but help- particularly in the lower rpm range.


The rebuilder article is aimed at stock rebuilders who are not interested in anything outside stock parameters. It is an excellent guide for the 3 periods of the 4.0 ohv, lots of great information and worth the read if you are going inside the 4.0.

The 95 and up engines use deeper dish pistons which keeps the CR at around 9:1.

If the 95TM+ heads are used with the 90-94 pistons it will give a CR of around 10:1.

I'm using the 98TM heads on my 92 and I think overall with the rise in CR and fresh heads I probably gained around 10-15HP. In stock form with no bolt on mods and 3.08 gears it was easily quicker off the line and on the highway than my stock 93 with 3.73s. With intake, exhaust and chip isn't what I would call fast but I can feel a nice firm push on hard acceleration.

The down side is that it does ping on high octane fuel. The owners manual tells us that on the first generation "some" pinging is normal with low octane fuel, I'm down to "some" pinging on high octane. Since I don't drive the vehicle everyday it really doesn't bother me.

This is not a good mod for those who find themselves in low speed high load (4x4ing) situations. The higher CR seems to produce more heat and when combined with lack of cooling in a crawling situation under high load will give a lot of really bad detonation.

The cam bearings are pretty cheap, fresh bearings for a fresh cam =)

90TM/93TM + 91-94 style pistons = 9:3:1

90TM/93TM + SOHC pistons = 10:1

95TM/98TM + 91-94 pistons = 10:1

95TM/98TM + SOHC pistons = 11:1

90TM/93TM heads + 95-98 pistons = 8:9:1 compression (need to check on that) this is your best bet if you plan on turbos or a supercharger.

All those numbers I confirmed with BIRD on RPS (Doug904's stage3 head builder)

The 410/422 cam love the 10:1 compression, although it would require 93 octane to be 'streetable,' and you couldnt run any forced induction... although nitrous loves the higher compression also

Not all head castings are the same! I recommend these guys for heads http://www.alabamacylinderhead.com/fordproduct.htm

The stock ford castings are weak around the valve seats and are more prone to cracking. The MAHLE castings are much more resistant to cracking, they are also what alabama cylinder head sells.

The MAHLE castings were what BIRD (again, doug904 ported head builder) used when he built and sold stage three heads.

if you plan on using the newer style heads, use the 98TM heads, they have a better flowing exhaust runners. Both the 95TM and 98TM have the smaller fast burn heart shaped chambers

BTW, watch the classified section on www.rangerpowersports.com for ported head and intake deals. Otherwise you will need to find a local hotrod shop to do the port work for you. If you plan on using the 422 cam, you will need dual valve springs and retainers, you will also need your heads machined to fit the dual valve springs. The 410 cam doesnt require it, although it might be a good investment in the long run.

That guy on ebay always comes back with more lifters... i see him with a new set like once a month.

 

[r37ribution]

This makes me wonder:

We have a guy on the board who bought the 98TM heads from Vanir. He hates them and wants to go back to stock and he's running premium and it still knocks.

Todays fuels SUCK, especially if you live somewhere that used reformulated fuel with ether or alcohol blended.

I'm seeing a lot of mixed feelings about the 98TM heads. In the last post where I quoted Creager, he was talking about how much he liked them but then again I believe he ported them which is what Doug said they would be good for.

I wonder if the guy Rick was talking about above got his ported...

 

[CDW6212R]

Altering the mechanical compression ratio is fine if the camshaft is matched to the new compression. The best result from any change like that would be to install a custom designed cam for the new combination.

Higher compression can gain a lot of power and efficiency, but a proper camshaft is critical. The PCM programming also needs to be tuned for the new combination. Just bolting miss matched parts, and with a stock PCM is not going to achieve the best result. Stay near stock compression and cam, or plan to do the whole cam/tuning as part of the project. Regards,

 

[r37ribution]

So maybe my reason for posting other than general info about the 95TM vs Alabama may have been masked by the other info I included here about the heads which possibly was a little counter productive.

I would like to see some opinions about which head, 95TM or 98TM, is a better performer. Keeping in mind that the 98TM/Alabama heads have smaller exhaust ports as you can see in the pics. I have posted a few members thoughts in the mess above.

I will be leaving my stock pistons in the engine, so my compression ratio should stay 9:1 as I don't believe there were any compression/piston changes during 95-01 correct? If anything I would prefer to lower the compression ratio because I would eventually like to put a blower on top; however, avoiding bottom end work and still keeping a 9:1 ratio will be fine for now.

 

[CDW6212R]

Yes, select your compression for boost. The trans will be the weak link though, look into that soon also.

 

[jd4242]

So maybe my reason for posting other than general info about the 95TM vs Alabama may have been masked by the other info I included here about the heads which possibly was a little counter productive.

I would like to see some opinions about which head, 95TM or 98TM, is a better performer. Keeping in mind that the 98TM/Alabama heads have smaller exhaust ports as you can see in the pics. I have posted a few members thoughts in the mess above.

I will be leaving my stock pistons in the engine, so my compression ratio should stay 9:1 as I don't believe there were any compression/piston changes during 95-01 correct? If anything I would prefer to lower the compression ratio because I would eventually like to put a blower on top; however, avoiding bottom end work and still keeping a 9:1 ratio will be fine for now.

what did you end up going with? im ordering the same heads (95tm97tm98tm)from Alabama and wonder if it safe too just bolt them on my 92 with out machining the ports out?do the sell the newer heads with the bigger ports?

 

[r37ribution]

what did you end up going with? im ordering the same heads (95tm97tm98tm)from Alabama and wonder if it safe too just bolt them on my 92 with out machining the ports out?do the sell the newer heads with the bigger ports?

Alabama only sells the 98TMs which are better for porting. I'm having mine ported by a guy who has been doing this for over 30 years but has never ported the 4.0L OHV engine heads. I picked up another 98TM from the scrap yard for him to fine tune his program for the CNC to so he wouldn't have to worry about messing up my new heads. The more I tore into my engine the more my project changed. I'm doing the entire bottom end and installing forged rod/pistions and possibly the Tom Morana stroker kit. I have mixed feelings about it though after hearing comments from different people including Doug904 and talking to Tom. The guy porting my heads says that my 98TM ports will be a good size after gasket matching them to the BBK header gaskets. The problem is the sharp bend on the exhaust runner right above the valve. That is one of the worst parts about our heads. The intake side has a nice smooth gradual bent to the valve. He said if I can find larger valves he would be able to make a considerable improvement in the angle.

 

[jd4242]

I just called them because i want the bigger ports that the 95tm and 97tm have and they said that the heads that are listed as 95tm/97tm/98tm have the bigger ports is he full of it or what because you said you have them and the are def the 98tm size of 1.40 not the 95tm size of 1.70

 

[r37ribution]

I just called them because i want the bigger ports that the 95tm and 97tm have and they said that the heads that are listed as 95tm/97tm/98tm have the bigger ports is he full of it or what because you said you have them and the are def the 98tm size of 1.40 not the 95tm size of 1.70

They are a "universal" head based on the 98TM casting, that's why they are "95tm/97tm/98tm" compatible. I found this out after I received mine and later decided to port them.

 

[jd4242]

i asked this in my 95tm thread but do you know where i can get a true set of new 95tm heads?
if you want to answer there instead
http://www.explorerforum.com/forums/showthread.php?t=235660