M90 rebuild (rudy)

Dono said:

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?

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I wonder to.I know any built motor should really have them but just didnt consider this to be a ""built"" motor and especially at the low rpms these motors turn.I could have sworn we did put them in anyways but obviously we didnt.its the added pressure and heat from the sc that causes them to wear so fast.sure SS valve on cast steel guide is also not a good idea.no way to tell also unless you pull them to check or a valve gets stuck open..

I also ran this motor pretty damn hot up in the mountains when I was trying to get back to camp..think I drove it 40ish miles with it over heating every 5minutes. I would have to stop fill it with water and go again.2 hours into the rest of the group found me after the trail and gave me a bottle of stop leak.worked for about 5 miles till it built boost and it blew again...so there was alot of heat involved for awile, that could have messed the valves up even worse and im sure there was alot of pressure and steam going through where the gasket blew, causing the pitting ..

Just hate throwing more money at this motor but certainly dont want it breaking down again in the mountains or having to pull it apart againalso sucks because it looked like I wouldn't have to mess with the heads, just fix seal and gasket.that all went south FAST the next day!!

well just a little updat.got the heads back Tuesday and got it all back together that night.for some reason a normal non-ac belt wouldnt fit,only thing different is it has a overdrive pulley on the alt which should still work with a stock belt if not a .5'' smaller.i ended up having to get a 78.5'' belt where stock was 80''(i think, off top of my head).i then had a water leak which looked like it was coming from the head behind the alt so i tore the whole front of the motor off to only find it was my heater hose leaking...started right up and after a check of the fluids i ran it up to rpms for a couple mins.it took 4 mins for it to shut up and run smooth but runs quiter than ever

had a long talk with my machinist about alot of stuff.for starters he had to machine a one off set of guides for it as they dont make guides in that size.he also had to mill the head down to get ride of the pits where the gasket blew.he said it took out about 1.5cc so im very close to 11:1 now ...he also had to do a valve job,new guide seals and test to make sure they were sealing.

then talked to him about larger valves for the stroker motor and he said the sizes i got picked out would work just fine and make a huge difference.so exhaust will now be .150 larger and intake will be .050 larger.he said i probably have room to go a little larger but wouldnt push it or know for sure till he starts cutting them.talked about the block and if he feels i have room to go to 4'' pistons and length of rod i plan on running and again he said it shouldnt be a problem.so next week or so im going to get the 90tm block from xeek and take it down there and have him start boring it out.the cank and rods should be here in two weeks.the crank has been turned and balanced and it a 8 bolt so it will work with my T5 trans.pistons and valves are going to have to wait till next month or when tax money comes in.so its starting but is going to be a slow going but looks to be a finish date of around april..money is going to be the biggest issue and Manley has a 5 week wait on custom parts soo..

ill post some pics of the block,rods and crank soon:

vid of restart

Can you rebuild the m5od or did the case blow apart? I have one but it is in use just like your other buddies.

Found some used trannies near you, but for that price you could buy a reman trans. Here is the link: http://car-part.com/cgi-bin/search.cgi

Here is a link for a reman trans and it's the best price I've seen. http://www.smartpartsauto.com/manual_transmission_m5r1_mazda.html

mr cribb said:

Can you rebuild the m5od or did the case blow apart? I have one but it is in use just like your other buddies.

Found some used trannies near you, but for that price you could buy a reman trans. Here is the link: http://car-part.com/cgi-bin/search.cgi

Here is a link for a reman trans and it's the best price I've seen. http://www.smartpartsauto.com/manual_transmission_m5r1_mazda.html

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I dont know what happened to it and dont really care now.I decided to get the explorer runing so I didnt have to deal with the M5.I have a T5 built for the new motor, it requires a 8bolt crank and new motor has that.the stock 94ohv has a 6bolt so it wont work.its just gonna sit for a couple months till I finish my new motor, im starting on it next week

That is depending on how my work situation goes..its wasnt a good year last year except three months and this years looking to be the same.we cant afford another year like last...military spending cuts is killing us...... .

jd4242 said:

I dont know what happened to it and dont really care now.I decided to get the explorer runing so I didnt have to deal with the M5.I have a T5 built for the new motor, it requires a 8bolt crank and new motor has that.the stock 94ohv has a 6bolt so it wont work.its just gonna sit for a couple months till I finish my new motor, im starting on it next week

That is depending on how my work situation goes..its wasnt a good year last year except three months and this years looking to be the same.we cant afford another year like last...military spending cuts is killing us...... .

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I know all about military cuts. It has to suck on the civilian side but imagine being the soldier dealing with the cuts. I was in a unit in NC that never had money and our vehicles needed serious repair. We were forced to use them as is.

Hopefully it all gets better. The current political staff is the guilty party for the cuts.

mr cribb said:

I know all about military cuts. It has to suck on the civilian side but imagine being the soldier dealing with the cuts. I was in a unit in NC that never had money and our vehicles needed serious repair. We were forced to use them as is.

Hopefully it all gets better. The current political staff is the guilty party for the cuts.

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I agree.its a sad situation and cant really just blame one side either..just hope things turn around for EVERYONE! !!

jd4242 said:

I agree.its a sad situation and cant really just blame one side either..just hope things turn around for EVERYONE! !!

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Not trying to get political because I really care less, but the D's usually cut the funds while the R's usually give the funds. Just my observation over the years. In all seriousness I hope you get more business flowing so you can get more modding done.

I know what it is like during slow times, I deliver concrete now and winter and rainy weather cuts business down.

mr cribb said:

Not trying to get political because I really care less, but the D's usually cut the funds while the R's usually give the funds. Just my observation over the years. In all seriousness I hope you get more business flowing so you can get more modding done.

I know what it is like during slow times, I deliver concrete now and winter and rainy weather cuts business down.

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Oooo im with you my friend. .im definitely a republican but seems lately neither side can get it together, I do like to blame one side more obviously got a slight slim bit of hope today though so hopefully things pick up.there is a race car shop right down the road I've been hanging out at alot and probably could get a job there in worse case.they do all tube race cars, im not that advance but sure I can find work there.I've been practicing my tig and learning cad lately, owner really has been showing me alot.

Hopefully the weather shines bright for you also and things pick up.tough times only makes us stronger

stroking your 4.0L ohv

jd4242 said:

. . . if your a member over on rps I'm sure you have seen some of my secrets, dont wanna release them here yet.ill start a new thread for ""how to stroke and forged a ohv"" as soon as all the parts are done.they have a 5 week lead time, plus going to be another 2weeks before I can afford the last parts.BUT I WILL be breaking the 400 mark motor will be good till 700hp so don't have to worry about it.got a feeling ill be going through a lot of m5 till I can afford the racing t5

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I spend very little time on RPS and I overlooked this part of your post until Dono mentioned it on one of my threads: 4.3l sohc v6? I'm curious about what you're planning. I found the later post about the Manley XR6 Turbo rods. What about piston details? Are you getting your OEM crank reground locally? What will the new stroke be? Will you have to machine the block or cradle for clearance?

2000StreetRod said:

I spend very little time on RPS and I overlooked this part of your post until Dono mentioned it on one of my threads: 4.3l sohc v6? I'm curious about what you're planning. I found the later post about the Manley XR6 Turbo rods. What about piston details? Are you getting your OEM crank reground locally? What will the new stroke be? Will you have to machine the block or cradle for clearance?

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Yea im running the xr6 rods, they will be here next week.I dont have all my paper work here.but belive they are 6.058 im running a 8bolt crank from rock auto.no mods as of now is planned for the crank and plan to run ohv bearings.the rods will be machined on both sides of the big hole to match ohv piston rods, it is VERY close right now.if you look at the new rods your see its flared or slight lip where the bearings go, manley said it could be safely milled..may change once rods and crank is in my machinist hands..

the piston is a 4.0" from Manley that is being modified (not complete custom) im copying my stock piston specs except the compression height, is slightly shorter for the longer rods.im sending them a stock rod and piston for them to take specs off from.they are also doing my valves.so rods, pistons and valves will all be from Manley.

Sure alot will come up as parts really come in tho.

Just to clear things up if anyone is on this thread and not the other..I will not be changing the stroke of the new engine. .what I meant to say is ""overbore and forged"" the stroke is staying the same, only way to stroke an ohv is to offset grind it which makes it very weak.I will be making this as strong as possible, which means stock crank, forged rods and pistons.the bore will be increased to 4" tho and the rods are longer but neither will change the stroke or weaken the crank

deck height?

jd4242 said:

No the rods are 6.058 for a ford falkon 4.0 turbo and the pistons are 4" with a compression height of 1.132. . .

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6.058" + 1.132" = 7.190" which is the same total as stock (5.748" + 1.442"). The stock deck height is 8.858". 1/2 the stroke (3.320") = 1.660" + 7.190" = 8.850". So if you have the stock deck height the top of the piston will be .008" below the deck at TDC. That represents an additional 1.6 cc to the size of the combustion chamber. The thickness of the head gasket also increases the volume of the combustion chamber.

Edit: That's for the stock bore of 3.950". The chamber volume will be slightly greater with the 4.0" bore (1.64 cc instead of 1.60 cc).

2000StreetRod said:

6.058" + 1.132" = 7.190" which is the same total as stock (5.748" + 1.442"). The stock deck height is 8.858". 1/2 the stroke (3.320") = 1.660" + 7.190" = 8.850". So if you have the stock deck height the top of the piston will be .008" below the deck at TDC. That represents an additional 1.6 cc to the size of the combustion chamber. The thickness of the head gasket also increases the volume of the combustion chamber.

Edit: That's for the stock bore of 3.950". The chamber volume will be slightly greater with the 4.0" bore (1.64 cc instead of 1.60 cc).

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Correct. Im matching the stock specs, besides the bore,just with forged rods and piston

Well some parts are rolling in.I got the new 93tm heads,8 bolt crank and my forged rods in.cam,988 springs and head studs should be in next week.hopefully next week or after ill tow my truck down to the shop so I can start mocking up the new radiator, supercharger firewall clearances and exhaust.then the block and heads need to go to the shop so he can take final measurement for pistons and valves.they should be done by next month. Getting excited now!!!!

Rods are soo sexy!!! Cant wait!!!






Ill post some better pictures and comparison ones tomorrow

Now after comparing the two side by side, im glad im stepping up.stock is just so weak and flimsy looking.these new H-beams are a beast and there honestly isnt much difference in length. They are ruffly 57 grams heavier but doesnt make as much difference compared to how much lighter the pistons will be.I also dont have a way to break down the small end or big end difference on the stock rods but from looks it would be lighter.
More pictures; )

Very nice!

Those are definitely what I would call stout. They should be able to take quite a beating and survive. I hope in the not too distant future to modify some of my engine internals.

Well just a slight update. I have all my parts but valves and pistons.my company looks to be going outa business pending if this order comes in or not, either way it probably will after that order if it comes in.so things are about to SLOOOWWWW way down and it sucks because the pistons and valves are the most expensive parts...I still plan to order them tho!! Lol

If been doing some port and polish work on the heads right now just trying to save up cash.I've got the combustion chambers pretty much done.starting on the exhaust, there is alot of work there.the intake im not going to do much, just a slight smooth out..the machine shop is going to CC the combustion chambers, do the pockets and re-ramp both intake and exhaust ports when I bring him the heads to fit the new larger valves.

Im going to tow the truck down to my shop (we still will have the building even if we go outa business) and start doing some mock up soon.I need to fit the sc and mark out where I need to make some firewall clearance. Going to cut and box it after I pull the motor.then I need to make new mounts for the radiator so I can tuck it into the header panel. I ordered a 3 core radiator and its wayyy thicker than my 1 core. Next I need to make a set of solid motor mounts that raise the motor up a 1/2" for oil pan clearance. Last I need to fit my headers on so I can take some angle measurements for my dual exhaust so I can order mandrel bent pieces. Not running a Ypipe or Hpipe or anything just true duals.so plenty of work to do and plenty time while im saving some cash


Pics....









And a before....

looks smooth as butter.
Sorry about the job though, it sounds like you really enjoyed it.

Dono said:

looks smooth as butter.
Sorry about the job though, it sounds like you really enjoyed it.

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Hope to get the exhaust the same took awile to get it like that tho.

Yea I love my job.just sucks, military spending cuts have hurt us bad.we all knew it was coming tho.im going to take a couple months off and just work on my truck so its not all bad.I needed some good one on one time with it anyways! !! Lol ill probably end up working for my engineer. He is part owner of a race shop called Fantom Motor Works.its one of the biggest on east coast. Its also on tv on the velocity channel if you all get it up there

k, i gotta know how much time there is on doing that (i cant remember if i asked that or not), and what did you use.
on the exhaust part, i would put at min a H pipe on it, or even a X pipe