4L Block, 3.9L Head MPFI - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

SiX_iN_a_RoW · 12-20-2002, 13:50

Hey guys, was just thinking that if and when my 3.9 CFI becomes tired would it be possible to fit a 4L Block but use a 3.9L head with all the multipoint gear ( Computer & Fuel Pump included ) to get around the Smart-lock problems with using the 4.0 Computer?
what would be the pro's and con's of this setup if any?

Thanks for your time

gm dstroya · 12-20-2002, 18:32

look at getting a complete ed motor instead
but only run it with the ea mpfi ecu because the ed is the last model with the distributor on it also cos the ed head will be far more efficient than the 3.9 ea one (148kw ed VS 139kw ea)
also ed was far more refined and will be a better basis to start a build up of the motor if you have performance mods in mind.
alternatively you can get a 4lt botom end of the eb/ed then bolt on either an ef/el/au head with the dual runner manifold design. hook up the dual runner butterfly switch to an shiftlight. either way you'll have to get the ea ecu remapped to suit what ever engine you buy cos all the 4lt have better breathing quality and to gain maximum power and tourqe benifits your best of getting it re-mapped

NZ · 12-20-2002, 19:04

If you wanted to rebiuld the engine another option is to use a set of 4.0 pistons and have the block machined to suit the pistons. Im not sure what the cost of the pistons is vs a set of O/S 3.9's though.The EA Head is the same as the EF in terms of fitment and design.
The EF head has the same size valves, and the same port design and flows the same as the EA. With having the 3 speed using a 4.0 computer isnt desirable. BTW early EB's didnt have smartlock so they can be used on EA's. I am running a non smartlock 4.0 computer.

The statment that the ED was the last with a dizzy is wrong as the EL went back to dizzy and also went back to the 60 pin ecu connector. EF had coilpacks with 112 pins I think.

A lot of the refinment of the EB - ED was they had a better crank with 8 counter weight vs 6. EF onwards has a 12 counterweight.

I am in the process of rebuilding an engine at the moment. What Ill be doing is using the pistons from an EF engine I got for $180, using a 3.9 block, the 3.9 crank will be balanced as they are better for 'hotrodding' motors since they are lighter than an EF and dont draw HP to turn them and the EF head will be used as the EF has an open chamber where 3.9 has the swirl port.
I will also be converting to serpentine belt drive and using an EF alternator to run twin thermos. At the end of it all I hope to see 170kw at the flywheel.

Hope this helps

MightyEFGhia · 12-20-2002, 20:19

Out of interest, the general concensus is that you shouldnt use a standard 3.9MPFI computer on a 4.0lt engine? Because that is what I am doing currently, and the only component i needed to change was the fuel pump. Hmm

SiX_iN_a_RoW · 12-20-2002, 21:02

Very intersting guys, thanks for the replies
so basically I can run a 4.0 engine and the only thing I would have to change/look out for is the fuel pump, make sure I get a 4.0 non smart lock computer and the rest pretty much bolts in. Obviously I will need the MPFI wiring harness etc etc
they way I see it, its basically a MPFI conversion but changing the block from the 3.9 to 4.0 first.

vbman187 · 12-21-2002, 01:46

what kind of advantages and power etc, will you gain by getting the 4l block and using the 3.9 head on mpfi?

galapogos01 · 12-21-2002, 05:35

i thought the only EBs without smartlock were series one - which were 3.9s?

SiX_iN_a_RoW · 12-21-2002, 22:57

vbman187
I had been told previously that the 4.0 head and intake assembly differed to that of the 3.9 but would physically bolt sirectly onto the block. ( which I found out is incorrect as the heads are pretty much the same )

So to get around the smartlock problem I thought if I used the 3.9 head and intake assembly on a 4L block then I could use the 3.9 non smart lock computer.

Anyway now that I know theyre the same it wont make any difference which head I use.

MightyNA...havent had any dramas using the 3.9L ECU on the 4.0 engine? are you running the 4.0 head etc?

MightyEFGhia · 12-22-2002, 01:04

Nope, mines even the MPFI ECU for the 3 speed auto, no smart lock or anything and its meant for the 3.9. To my knowledge the EBII and the ED both used EEC IV which is the same as 3.9 MPFI ECU. So there shouldnt be any real difference. Obviously set the base idles n crap and it should work, after all the intake manafold is the same.

I got the whole engine changed, its EBII 4.0 head, block and intake manafold with injectors. and I only had a drama at the start where it would stutter under full throttle, this was fixed by changing the fuel pump to the one that was in the EBII which I assume is just a normal fuel pump for that car, it solved that problem, and it also solved by fuel leakage problem (the fuel pump seal was rooted on the old fuel pump)

Bass Crazy · 12-23-2002, 00:22

How big was the improvement dude?