HELP! new heads dont match up

[red.EDDIE.4x4]

ok so i ordered some brand new heads for the 4.0 ohv ford v6. the seller (ebay) even had me give him the cast number on my old heads. the only difference between them is the exhaust ports, the new ones are more round and smaller then the factory ones, and the other difference is in the combustion chamber. other then that, the valves are the same size, all bolt holes line up, all coolant holes line up, everything.
pictures tell all.

exhaust ports

overall

my options are, return them and get my money back, OR port the exhaust areas and also "port" or modify the size of the combustion chamber/valve area.
or if i leave the heads as is, what would happen? performance loss?

any help or comments are appreciated.

 

[Anime]

What you have there are later 95TM or 98TM heads, found on the later '95-up 4.0's.

91-94's used either 90TM or 93TM heads.

The differences are as you note, in the smaller exhaust ports and smaller combustion chamber area.

They will work, but you will probably want to use newer exhaust manifolds/headers.

"Porting" is not really an option and not cost effective, especially on steel heads.


If you use 95/98TM heads with the 91-94 block/pistons you get a compression increase due to the reduction in volume. This can be "good" for performance, but can require the use of 93+ octane and possibly other performance tweaks. There are plenty of threads by those who have done this, search and read up and see if you want to go this route.

If you gave him the wrong thing as the cast number, it might be your fault and you wound up with the wrong heads by your mistake. If not, it's the seller's goof that they sent you 95/98TM heads for a 91-94 Explorer that clearly would only have 90/93TM heads. You could probably have them exchanged at their expense if you're polite but insistent.

 

[ranger7ltr]

These will raise your compression a bit...

Because the combustion chamber volume is smaller... And the exhaust port size promotes velocity by restricting the flow out of them...Frankly i think the heads you have are probably 98TM heads...

I replaced mine with 95TM heads when I built my new engine last year... The exhaust ports were larger in diameter[1.7" vs 1.4"] and they would support the dual exhaust configuration I am running...

I don't know if you could port the exhaust ports without hitting water or something else... I would probably return them...

 

[red.EDDIE.4x4]

Anime- I will be running the comp cam mild lift 410 cam, and keith black aluminum .050 over pistons, that being said...would I still have to use 93+ fuel? What would happen if I were to throw 87 in there?

I will prob return them but would like to get more input from others. I'll contact the seller in a day or two. Thank you both.

 

[Anime]

The cam and .050 over pistons won't change much in terms of compression and having to use 93 octane. You might want to check out the possibility of using double valve springs and longer pushrods with the 410 cam as well. If you use 87 octane with high compression, you'll usually get detonation, knocking, pre-ignition, and other bad stuff.

Unless you're prepared to spend the additional $$$, I'd say you're best off returning them and getting 93TM heads, which will be a bolt-on replacement and allow you to use everything as-is. You might still consider the double-valve spring/longer pushrod arrangement for the 410 cam though.

While you're at it, be sure to replace the rockers or rocker assemblies. The stock rockers wear down at the valve/pushrod contact points quite severely. Replacement with new rockers while doing any sort of head work is a no-brainer.

 

[red.EDDIE.4x4]

Unless you're prepared to spend the additional $$$, I'd say you're best off returning them and getting 93TM heads, which will be a bolt-on replacement and allow you to use everything as-is. You might still consider the double-valve spring/longer pushrod arrangement for the 410 cam though.

While you're at it, be sure to replace the rockers or rocker assemblies. The stock rockers wear down at the valve/pushrod contact points quite severely. Replacement with new rockers while doing any sort of head work is a no-brainer.

just emailed them about returns.
i was already planning on doing the rockers and the push rods. any idea on what size pushrods? i was going to order from smith bros. from what ive seen, i would only need for double spring valves if i go to the 422 cam.

 

[red.EDDIE.4x4]

seller is sending some new 90/93 tm heads. problem solved