M90 rebuild (rudy) | Page 8 | Ford Explorer Forums - Serious Explorations

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M90 rebuild (rudy)

well figured i would start a new thread.just a quick background.did the whole build on my explorer but built it using stock head gaskets and head bolts.did it really as a safety net and i just couldnt afford head studs at the time.well to say the least i blew the head gaskets off from it wile i was in the mountains on a forum trip about two years later.

i picked up a 1994 ranger,its got the 4.0 OHV and is a 5 speed 2wd.the plan is to pull the motor out of the explorer and rebuild it.

this thread will basically cover the rebuild and build up of the new ranger.it will basically end up as a street race truck.ive named it Rudy:D:D so let the fun begin.

new motor specs
BORE: 4" JE asymmetrical pistons (custom over bore)


RODS: 6.058 Manley (longer rod)

VALVES: IN-1.8 EX-1.5 Manley heavy duty (.150 over)




Transmission:T5 hybrid from a 2006 Mustang and 93 Fox
HEADS: 93TM HEAVILY ported with custom brass guides and copper gaskets/O-ringed with ARP studs
CAM: 422 Comp cams with 988 springs and Toms custom lifters,push rods and 1.7 roller rockers
Complete blueprint and balanced internals
GM M90 supercharged with one 1" intercooler plates with ASP 8 rib belt conversion. .
pushing 16 lbs of boost with small shot of NOS
Running on E50
Dyno tuned by Dyno Tune Performance outa Virginia using SCT

old thread and pic
3800 M90 Build
ported and polished gm 3800 gen 2 m90
Water to air intercooled
port matched 76mm inlet and intake tube
mustang 75mm race tb
90mm maf
36lb injectors
255 fuel pump
sct 5bank dyno tuned
2.7" pulley 10lbs of boost!!;)



and the new 1994 ranger 4.0 OHV 5 speed 2WD with 115,000 miles on it.o and i only paid $1,000 for it:shifty_ey


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well couple of us went to the dyno today to get some base pulls in.it was anual winter dyno day so there was kind of alot of people there.he did a pull in mine in 3 gear idk why but he did.he said the hp should be VERY close or if not a little lower but the tq numbers may be slightly higher.i did 169.4 HP and 230 TQ!! its alot higher than i was expecting that for sure;)

listen to that turbo spin!!haha



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That was 160 at the crank in 1994. You have got to be well over 200 at the crank now.

I can see why you could not make the last trip to the GWNF.

That was 160 at the crank in 1994. You have got to be well over 200 at the crank now.

I can see why you could not make the last trip to the GWNF.

This was with the stock ohv4.0 in it.just a baseline.all it has done is
300Lph pump and -6an lines
And no mufflers, it dumps right after the cats.had to cut it to fit the rear tank, sway bar
I also was running 108 octane

160 was at crank in 94 so should have put down around 130ish.so I did 39.4 more than stock (roughly):D

Well thought I had posted some updates but guess not.I ordered $1,200 in exhaust crap not including pipe. That was headers, two cut outs, two flowmaster 50 SUV mufflers and two tips.im going to muck it all up to find out the angles and offsets and order mandrel bent pieces.

But then I damaged the trans out racing and during slow roll burnouts.was hoping it would last but Sunday I jump in it and the trans COMPLETELY DESTROYS itself. I was going to replace the trans but cant find one ANYWHERE! !!

So I towed my explorer down to the shop and gonna start pulling the motor.need to pull all the parts out and make sure they are still good.then im pulling the motor out of the ranger and having it bored out for the old parts.everything from the SC motor is getting used.it then is going into the explorer.only thing left will be the 90tm block and SC parts, everything for that motor will be one off.im also buying new 93tm heads to drop the compression back down.this will still be probably two months away tho, till then I will be driving the explorer.;)
Fun is starting now, hopefully the motor for the ex will be done in two weeks.I only have weekends to use the indoor shop..




New doug's cutouts


Ok things have changed yet again.#xeek is going to trade me his 90tm block for my rangers 93 tm block.that means I can just pull all the SC stuff off the explorer motor, pull the heads and have them checked.unless I see a clear blowout in the head gasket, if I see that im not going to have the heads checked.this mean I dont have to pull the motor or have two blocks bored.

Whenever I get all my parts for my new motor made or whenever xeek needs the 93 tm block I'll pull it out of the ranger.I really wish I would have thought of this before because the explorer could have been running MONTHS ago!!!!explorer should be running by Monday or Tuesday, depending if I see a blow out or have to have the heads checked

How long have I been trying to tell you...

Fred has damn near everything we ever need... My ranger will be turbo 2.3 d44/8.8 with ideally 40's... We can wheel soon

I also have chosen to leave the 422 cam and the 95tm heads on the NA explorer block.I was planning on using the 95tm heads on the stroker motor but they have been milled and with first gen pistons it runs 10.67:1.thats to high for the stroker motor so was going to get the custom pistons made with more dish to lower it but after speaking to Manley they advised against that.because im running longer rods the compression deck of the pistions need to be smaller, which means thinner area from dish to pin.there is plenty of room but the thinner the weaker.so if I was to increase the dish to help lower compression because of the 95tm heads this area would get even thinner.so im now purchasing 93tm heads to lower my compression of the stroker motor back down to 9:1 so as much of material can be between the dish and pin on the pistons.

Explorer should be back together monday or Tuesday depending on the heads.it will be same motor as before the sc besides the ported lower intake manifold, that will be saved for the stroker motor.so basic .02 over,422 cam, slight ported/polished heads with SI valves, m328 HV pump and 10.67:1
Let the fun start!!! New motor parts for stroker motor should start showing up in next 4-5 weeks;)

Fred has damn near everything we ever need... My ranger will be turbo 2.3 d44/8.8 with ideally 40's... We can wheel soon

Haha. Between chris and I, we've got everything. I do need to stockpile more stuff soon tho.

It is nice having a network of explorer/ranger/truck people so close by and that doesnt include having EF.seems we can get most of everything we need off each other:D well besides a m5 trans!! Lol

Hey, Fishfood and I both have manuals. Just no spares.

So got started on the tear down today.tore it all down in a couple hours and found it is a blown head gasket.its pretty obvious, I also put some stop leak in it to try and get back from the trail to spikes house.you can see the build up from the stop leak and even left a flake/chunk hanging off the edge of the top cylinder lip where it blew.

I also have had a plug that would foul out every couple thousand miles or less, well I found out why.the valve seal is torn on the intake valve on that cylinder. ...its been like that sense I had the head built.im taking it back to the machine shop first thing in the morning and having him fix it!!

Things went pretty fast today so I think tomorrow should go good..o one other thing though. .I was pulling the pushrods out and one of the metal plunger pulled out with it and fell perfectly down into the motor.I sounded like it fell all the way to the bottom of the pan from the sound.I run the sohc oil pan so I can pull the bottom half and look for it.lets just hope it fell down and stuck to the bolt magnet and I wont have to pull the pan...

Any rate ..time for bed and pics!!;)






Well went to the machine shop this morning to have him fix the seals..what we found was not good at all...as soon as we pulled the springs off the valve was wobbling around in the guide. He says ""why didnt we put bronze guides in"" I said I dont know your the builder..for some reason we both thought we did put new guides in, I know we talked about it but obviously we didnt take it any farther. .he said the dual springs, high compression and cam was to blame for it but never seen them go bad that fast.he then asked me how many rpms and if I was spraying NOS on it and told him 6,200 and no.but told him I was SC which he didnt know and at the time I built this motor I was not..he then says well thats why, sc causes extra heat and would be why they went bad so fast..so long story short it needs new guides and seals.he gonna try and clean the guide material off the valves and try and re use them..

I then started cleaning the deck off on the heads and right where the gasket blew is a ton of pit marks.I dont know if they were there before it blew and caused it to blow or if it happened after it blew.the heads were milled to raise the compression so he swears the pitting had to happen after..so now the heads need to be milled also.hope its not much as it will raise my compression even more and im at 10.67:1 right now!!:(

So parts are at the machine shop and should be done some time this week.....
Pits are right where the gasket blew..rest of the head is smooth as glass..


just as additive as cocaine, twice as expensive.....

HELL YEA it is..sad part is im basically returning the upper end to stockish.just want a reliable off road truck with a little extra ummfff..my account is dry from the other stroker motor so any extra into this is effecting my real hot rod!!:banghead:

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Ouch. I hate to be selfish, but I wonder how the heads on my 4.0 ohv are holding up. I know I did not have the guides replaced.

I'm amazed on the pitting from where the head gasket went south also. Oh man. What do you do when you keep shaking your wallet upside down and not even pennies come out?