Originally Posted by b\o
All of the following questions are about the 3.8 engine.
1) Will heads from the early ('84-'87) fit later '03 block?
2) What are the differences between the '84-'87 heads and the following years through '03? Did the exhaust port pattern remain the same?
3) Is '98 an odd ball year because of the counter rotating balance shaft? or?
4) How did the compression ratio's change from '84 through '03?
5) Is the imbalance on the V6 50oz?
6) What type of rockers did the '84-'87 heads have? Will those from an '03 head work with a '84 head? Push rods?
7) The book I have on Fords claims that the heads on V6 Mustangs were cast iron. I have not found any other reference to a cast iron head for any ford V6. Were any ever made?
8) Will the front cover from a '84-'87 fit on a '03 block so that a distributor can be fitted? Or other options/suggestions for distributor ignition?
My best educated guesses: *noted with *** for guesses, otherwise
it is info I have checked...
1. *** Yes, as far as I have seen, and I did a set for RPM before I started
teaching him porting, that used later heads on an early block. So early heads
will fit a later block, they just might have issues with accessories and such.
2. Exhaust port pattern was same as far as header/manifold and same as
*** far as port shape as much as I could tell. Best factory header was by
far the 94-98 Mustang units, get those for any swaps.
3. They had header changes, slight but they were different. *** I think it
was an air injection tubing change, but guys use the headers from the earlier
years on the odd-ball 98's with minor tweaks.
4. They generally went UP. For the old carbed and CFI stuff, I have no figures
but It was close to or at 9:1 and the current stuff (03 at least) is 9.36:1 ...
5. *** I believe it is, I've always heard that it's the same as the later 5.0's
and it is externally balanced until a split year at (late '00 or late '01) can't
remember which year they did the mid year change. The later ones, including
you '03 are internally balanced, same as neutral balance. That part I know for
6. *** Rockers are interchangeable (AFAIK) and PR's should be the same.
Just measure the pushrods. If you do go thru with this, keep your '03 PR's
just in case. I believe there might have been a change between roller and
flat tappet years in pushrod length. The roller tappets (lifters) are taller in
most engines that went roller, using a shorter pushrod.
7. No, the earliest carbed and CFI heads I have seen on a 90* 3.8 V6 were
all aluminum. Your book is probably referring to the 60* V6 which is the 2.8,
2.9. 3.0, 4.0 family. Things like Taurus, Ranger, etc. Entirely different engine.
8. *** It probably will, but definitely a step backwards. (that part is a FACT!)
Sounds like you have an '03 and wanting to use it in an older V6 application.
It would be almost as easy (IMO) to get a computer in there and keep all
the extra HP the '03 has from the EFI and SPI heads. The only advantage
you would get is the new block and roller cam, and that roller is mighty weak.
You should rebuild your 83 or whatever year it is. Much easier. I even have
a performance cam for the early V6, it's bigger than the '03 roller by far,
even if you block is toast (busted cylinders or some such thing) you can get
a cheap block from the JY and rebuild that easier than swapping in a new
block that takes all these changes. The only benefit you will get is the roller
cam block and the fact that it is new. Tell us what you are doing and we can
at least give you more specific info, if you decide to go about it this way.
What year exactly are your heads and stuff? Carbed and single port (EFI)
stuff has been mixed successfully, but those look the same except for the
EFI bungholes in the heads for the later years (88-98) Ports are bigger
in the EFI heads too.
That's all I got for now, if we can get Mikael in here, he is the one that put
my ported EFI heads on an '83 and that is kinda the reverse of what you
are doing, it will help to know partly what he did. Make sense?