thunderbird muscle

I'm looking for a set of performance heads for the 95 ford thunderbird with the 4.6 at any price the best that can be found I hope, I am willing to wait and save up. I've looked and none of the heads I've seen seem to work for the standard 4.6. And also any other bolt on parts for the 95 4.6 that add decent horsepower. Thanks

THUNDERIN'bird

How about the 'Stang Cobra DOHC heads? Does anyone know if those are an easy bolt on?

That would be sweet...

RavenProjecT

The Cobra DOHC heads will not fit if you're running SOHC. It would require an entire engine swap.

I think the GT-40 heads will fit, but require serious modifications or you risk cracking the block. The 4.6 is just a 289 core, so it is possible that heads/intake can be adapted with other SBF parts, but I have yet to see it done.

I'd look at a Summit catalog and see what's available, and you can also call their 800 number for product support/questions.

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RavenProjecT

OK, update: I was told by a friend that using SBF 289 parts will not work on a 4.6 (damn shame too, lol). Although i do believe that the 99-up GT 4.6 mustang heads are a direct swap.

HOWEVER, I was told that it is possible to adapt the heads of a 5.4L triton motor with some new gaskets/runners and that's it. don't know if it'll really be that easy, but its worth a look if your looking for extra HP. i think someone on cardomain.com might already have a similar set up.

Just a thought.

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thunderbird muscle

Thanks for the help, I will try and see if I can find a good set. Would jegs have a set of heads that would offer some power.

ModMech

Ok, let's set the record straight as there is more urban myth in this thread than facts.

1) The 4.6L was introduced in 1991 in the Lincoln TC. It is NOT in ANY WAY a derivitive of a prior Ford engine, not the SBF, BBF, FE etc, NONE. NO parts from a pushrod enigne can be used on these "modular" OHC eninges.

2) You cannot just bolt on 4V heads.

3) There is NO difference between 4.6L and 5.4L heads of the same design... they are completely interchangeable.

4) There are two basic 2V heads. The newer "Performance Improved" (PI) heads with rectangular intake ports and slightly larger exhaust valves, and the Non-"PI" or NPI heads.

5) There are EXACTLY TWO 2V cam profiles. One for the "NPI" heads ('91-'98 all, some thru '00), and another for the "PI" heads. If you have a '96 or newer modular engine, you CAN use the "PI" cams in it w/o modification, but you CANNOT use them on '95 and older engines... NO WAY.

6) The combustion chamber on the "PI" head are SMALLER than on the "NPI" head. Therefore, if you replace a NPI head with a PI head you will increase your Compression ratio from about 9.4:1 to nearly 10.3:1.. which is a good thing if you want more power and better economy. The catch is you will NEED to run premium fuels.

7) If you are mechanically inclined, you can install the newer "PI" cams, and replace your intake with one for an engine with "PI" heads, and those two things alone will gain you close to 20 RWHP. Add some full length headers and better exhaust and you could be nearing 200 RWHP (about 165 RWHP is stock).

RavenProjecT

ModMech: I have a 94 4.6, and am wondering about a new cam/internals upgrades. Is there an aftermarket cam made for the pre-96 4.6 or similar swap? Summit has a cam kit for 221-302 SBF, would that fit/work with my engine or are we basically S.O.L.?

I know a new cam will change my valvetrain geometry and possibly require new pushrods, seats, etc, so what are our options? The last thing I want to do is throw a rod through my hood as one older thread indicated.

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ModMech

Raven,

The 4.6L is a MODULAR engine, they are ALL Overhead Cam. There are no push-tubes, or lifters. One cam in each head.

There are also 4.6L DOHC and 5.4L DOHC engines, but none in a factory 'Bird (Mustang Cobra, Naviagator, Lightning, Ford GT, Maruader).

With a '94, you NEED different heads to install a different cams, or you could pull your heads and have them re-machined.

About the only way you toss a rod with a 4.6/5.4/6.8 is to either: Run really thick oil and spin the bearings, knock HARD, or over-rev it (6200 RPM). Then they'll break for sure. The stock 2V rods are only "good" for about 6200 RPM, after that they begin to streatch, and at about 6350 they no longer snap back, they just snap.

thunderbird muscle

ModMech is this the same for a 95?? Thanks for the help.

ModMech

"the same", as in not being able to get better cams? Unfortuneately, yes. Ford changed the valve train in '96, well actually very late in '95 but I do not know what the part number chenged from/to.

I do not know of anyone who has been able to install "PI" (or any other cams) in '95 or earlier heads. The problem is the amount that you can compress the valve before the spring coils bind. As far as I know, there are not even aftermarket springs that will solve this for the '95 and earlier heads, it's that short.

RavenProjecT

thunderbird muscle: the 94+95 4.6L block is the same and still applies (for tbirds, cougars, and mark VIIs). The 96-2004 4.6L are all the same as well (mustangs, tbirds, cougars, explorers,), but differ from the 94/5 "production prototype" years. Ours are not as refined/debugged as the newer ones.

ModM: thanks for the info, though i've had this car a while, i'm not familiar with the modular engine internal specifics; i got my feet wet on a 390 FE and other 289s. I ask cause i've already located a pair of 5.4 heads in perfect condition from a local auto dismantler and was curious about the possibilities, what cam options are there for a 4.6 with a 5.4 head swap?

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ModMech

Raven, what are the intake port shapes of your "5.4L" heads? If they are tear-drop, then you have NPI heads... basically the same as all other '92-'98 4.6L heads. If they are squareish, then your in luck..you have the newer "PI" heads.

In any event, since the 5.4Ls are ALL '97 up, you can install "PI" cams without any problems at all. If you have PI heads, the cams should have come with them. If not, they will set you back about $250/pr.

Many different cams have been tried, so far, I've not seen anything better overall then the factory PI cams for a normally aspirated engine. If you have a turbo or blower, then definately, there are better cams for that.

thunderbird muscle

I'm really just looking for a set of heads that are made just for the 4.6 less risk.

RavenProjecT

ModMech: so what is the net difference in performance between PI and NPI 5.4L heads installed on a 4.6 (HP, TRQ, etc.) besides dispalacement?

Also, while I'm at it should I also try and snag the 5.4 intake manifold as well or reuse stock one (is there a PI 5.4)? Would the 4.6 PI intake in a 99+ GT be interchangeable with the 5.4 heads or no dice? I'm looking for the best combo.

Will my 4.6 headers bolt up easily with the new 5.4 heads as well? Thanks in advance.

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thunderbird muscle

will any year 4.6 heads and from any make (except for the DOHC and supercharged ones) work with a 95 4.6 If not what years and what makes will Thanks for all the help!!!!!