Head and Bottom ends.... whats the story

[santoitaliano]

someone please explain to me what the story is with heads and bottom ends (3.9 and 4l) i know about mpfi etc...

im just tossing up which way to head towards.. i dont want to have to modify anything ecu or clutch related etc.. just basically in and out swap... whats the way to go? ea head ok? ea botom end ok?

someone sort the rubbish for me please..

[5speedeb]

if u can find one a late el head 96da on a ef-el bottom end should do the trick

[papaghia]

got an EF head if your interested.. PM me for more details

[Gunns]

Ok 3.9 had deeper dish on the pistions and smaller chambers on the heads
4.0 had less dish on the pistion and larger chambers on the heads.
3.9 head + 4.0 bottom end = incressed compression
4.0 head + 3.9 bottom end = Decressed compression

The blocks are the same the 3.9 had a slight over bore to make it a 4.0

[InitialD]

Originally Posted by Gunns

4.0 head + 3.9 bottom end = Decressed compression

Shave a little off the head and "apparently" it will be roughly the same as stock 4.0 santo. therefor you would be keeping the same engine number meaning matching numbers. For a APV That might be worth keeping?

"caarrrn the 3.9"

[santoitaliano]

hrmmm... apv didnt have any engine mods as such (def not bottom end)

i think i can get away with just doing a sump gasket without removing engine for now.. hrmm

[FordFan86]

I remember talking with a guy who raced an EA saloon car.
Apparently the EA heads had about 8 different castings, the 'better' ones (for cooling I think it was) where found on late '88 or late 89'models...

[Gunns]

Originally Posted by FordFan86

I remember talking with a guy who raced an EA saloon car.
Apparently the EA heads had about 8 different castings, the 'better' ones (for cooling I think it was) where found on late '88 or late 89'models...

Yep the ones with a 4 or 6 cast into the head next to the 3.9 are the better ones.

[EA2BA]

Originally Posted by Gunns

Yep the ones with a 4 or 6 cast into the head next to the 3.9 are the better ones.

mine has a 6 on it :

[EA2BA]

3.9 head + 4.0 bottom end = incressed compression

i have this, plus a slight deck on the head and bloc plus an AU head gasket

yet to start the car, but getting closer every day

[EFFalcon]

are you sure the EA heads have smaller chambers?
i was told despite the little seperator in the chamber, the rest of the chamber was actually bigger.
we need someone to go and CC all the heads :P

[Gunns]

Originally Posted by EFFalcon

are you sure the EA heads have smaller chambers?
i was told despite the little seperator in the chamber, the rest of the chamber was actually bigger.
we need someone to go and CC all the heads :P

Thats right, but because of the seperator in the chamber the CC size is smaller.

[santoitaliano]

mine is a late '89... so if i wanted to keep my head, what would be a good block to screw it to? much difference at all or just do seals and ИИИИ on mine?

i don't understand the theory behind compression except that for a forced ind. motor lower compression is better.. so do i want inc. comp or dec. comp?

and what exactly goes harder?? a 4 or a 3.9? the ea 5spd was fastest wasnt it, or was that purely due to weight?

my mods: wade 977b, crow valve springs, extractors... pretty plain and simple stuff...

i just did cam and stem seals and springs, so id like to keep my head...

thought i had a bottom end rattle.. turned out to be new thrust bearing already making noise... how would i know if my current bottom end is a bit iffy?

would i just be better off changing sump gasket seal and putting a chip on it?

p.s. i also have a complete 3.9 cfi sitting around...

thanks all!

[mcflux]

EF-onwards bottom ends have better counterweights or something like that for better balance and rpm.

I think.

Can someone confirm this?

[santoitaliano]

so do i want a 3.9 head on a 4l block? is higher comp what i want?