4.0 OHV 90TM/93TM Head port match, tips?

[Creager]

I searched around for some 'tips' on port and polishing the heads on my 4.0. I remember a thread while back where Doug904 was talking about being careful with the exhaust runners. "If you do port the heads on the pre-98's don't remove the exhaust bumps in the ports, you'll find holes underneatht them." -

For those of you that have done it, do you have any tips for me? Match the gaskets and have at it? hehe

I plan on running the 422 comp cam, but i might end up with the 410 cam due to money and time restraints. Any Input will be appreciated.

 

[Ronin8002]

Check with BIRD on rangerpowersports. He used to port the heads as a business and could give you a lot of good info.

 

[87xjmike]

Bump.... I'm struggling to find info on this. Anything new? Good or bad to do for a stock cam truck ?

 

[jd4242]

Bump.... I'm struggling to find info on this. Anything new? Good or bad to do for a stock cam truck ?

What are you trying to find out??

 

[87xjmike]

What are you trying to find out??

Is it worth porting the heads for a motor that's running a stock cam and headers? If so tips? Should the exhaust ports have that hump stay in tact?

 

[jd4242]

Is it worth porting the heads for a motor that's running a stock cam and headers? If so tips? Should the exhaust ports have that hump stay in tact?

Sure if you doing the work yourself but dont expect to feel any real gains.porting the lower manifold helps some too,a ton can be removed..problem with this motor is the small valves..a cam really helps and makes the port work way more noticeable ..

Personally id swap to 95tm to raise compression to 10:1 if you can afford better than 87 gas..id be VERY nervous porting stock heads,especially pre 95tm..or swap to aftermarket 93tm if wanna keep compression stock

 

[jd4242]

Here my heads.quote from my thread..the pockets and valve pedestal has been milled and redone by the machinist, he still has them so havent taken a picture yet

So got one of the heads all the way done ported and polished. .you dont even wanna know how long it took me if your notice in the pictures the stock ports was pretty bad.it had chunks of cast and also had a hump in each port.the hump was for the valve cover bolts, only two actually are drilled/tapped for bolts.the third there isnt a bolt.I totally removed the hump and put studs M8 with red high temp locktight. They went in very tight as the threads didnt go all the way through, just drilled.then took and grounded them flush and polished them.you can see it in one picture. .also did the same for the three bolts holes ontop of the exhaust. I used two M10-3/4 and one M10-1.5-40 stud.the back bolt on one side holes the coil bracket and the front one on the other side holds my dip stick and a tb bracket.

I also straightened the ports out some, re-ramped it and did little pocket work..I wasn't going to touch the ramp or pocket and let the machinist mess with it when he does the larger valves but figured it couldn't hurt, sure he's going to do little more also but hey its a start for him.

Studs for the two holes that came through

Stud for coil bracket one side and tb other.other two holes aren't used

Gives you an idea of how much needs to be removed just to gasket match them to the headers

I polish the CC also

 

[jd4242]

Here is my lower..be careful going into the actual ports though, they are thin..you can come through the sides to make them more straight but you need to make new walls or fill the holes..i used stuff called "lab metal"..

Stock

 

[jd4242]

I use cheap wheels from harbor freight that are like sponge type material for final porting and polishing..they are like $5 for a 6 pack..cant touch that in dremel world..they also sell the tool to use which is PRICELESS. .fyi i took a 4"-1/4x20 bolt and make a extension to reach up in the port

 

[87xjmike]

Wow that looks really good thanks for sharing! If you're saying it won't be noticeable then I won't bother. I'm trying to get this rebuild done asap so....

 

[jd4242]

Wow that looks really good thanks for sharing! If you're saying it won't be noticeable then I won't bother. I'm trying to get this rebuild done asap so....

On a stock motor it wont make a huge noticeable difference. These motors dont make much power so it takes really a combination of things.if you was doing a cam or other mods then its worth it,otherwise the HOURS it takes to do really isnt worth it..but again depends on how you value you time..but same time i wouldnt touch a stock head,those things crack for no reason.ive head of them cracking just from removing and installing them..

Id do a 410 cam if you want "cheapish" power your feel and hear