Hey all,

Im driving a 85 ford bronco that has a 351M that is not the original engine. Originally the bronco had a I6 with a automatic. Now it has the t-18 in it which i would like to keep. The I6 seems like it is a great bullet proof tranny with some good numbers for torque. This vechile will be for some off roading every now and then and daily driver.

Here my question?

What would need to be done to go back to the I6.
Could I keep the bigger rad that it has in it right now.
Will the I6 bolt up to the t-18? or will i need an adapter.

What are your thoughts on a I6 t-18 combo?

thanks for your time

 

First off, you'll need to change your motor mount pedestals on the frame back to I6 mounts, and then you'll have to search for a smallblock bell for your T-18...and then it should bolt right to your tranny.

As for your radiator, i don't really know if it will fit or not, as i've never swapped out a 351M for the six.

As for my thoughts on the T-18/6 combo, it sounds great, and thats what i'm going for in my truck, i'm ditching my C4 automatic because its about at the end of its life span and i'm sick of automatics anyways. with a 6.32 1st gear, you aught to be able to latch onto whatever you want offroad and drag it with you... thats exactly what i'm going for too...stump pulling low end grunt.

It also makes for faster launches... though you won't attain much top speed in a first gear that low.

Good luck with it though, its good to have another six around!

 

I was under the impression that the bellhousing whould bolt straight up the I6 because the 351m is the same block as a 302, 351w. isnt it. Mine has the t-18 and the 240 I6 in it and I thought about putting in a 302 (decided against it) but it would bolt right up no problem.

 

351M's have the big block bellhousing, except in the rare occurance you got one of the early blocks that was drilled for both bellhousings. Usually with the M motor you have to swap tranny bells, to make the M transmission work behind anything other than a 351M/400.

 

I learn something new everyday.

 

351M the same as a 351W? I thought that the M was the same as the Cleveland, which would make it different from the 302/351W... maybe I'm wrong

 

M is the same as Cleaveland in the respect of heads. But the block is drilled for big block bolt pattern tranny's. Its different from the 302/351W in this respect, and a few others i'm sure that i'll think of later on.

 

My stock set up was/is I-6/T-18. All you should need is the old stock bellhousing - and stock motor mounts/pedastals, as mentioned.

The bigger rad shouldn't be a problem, unless it crowds your fan. Is it just wider?

I find the compound low (1st gear) to be useless most of the time, except when pulling VERY HEAVY loads. It would be more effective if you (or I) had highway gears. My 3.50's allow about 5mph (tops) in 1st.

Broncr

 

With my 2.47's i should be able to pull a little more than that in 1st...i might get lucky and get a whole 15 out of it.

 

The 351M has the large bellhousing the same as the 460,429,400 and will not fit the six you need a bellhousing from a 302,351w to fit and the rad has the inlet and outlet on the opposite sides from the six so to use it you would have to be creative with the hoses and I think the lower hose would be very difficult. The GM rads have the openings on the sides you need and you could get a 3/4 core rad from a wrecker and customize the fit, I used a rad from a cadillac in my 91 F150 , electric fans and no overheating worries no matter how hard it works.

 

you will also need the ball stud for the equalizer bar on your mechanical clutch linkage ... the 351M uses a bracket off the bell, the I6 has a stud the screws into a boss on the engine block. FYI the 351M clutch linkage will work but everything will be somewhat cockeyed (it's OK for daily driving but if you flex it in any way it'll bind up on you and you'll have to hop out, crawl under and smack it with a hammer).

If you have any Q's about the I6 swap feel free to e-mail me
rockfrog@island4x4.com ... I did the same swap three years ago now, and I managed to reroute the rad hoses to re-use the 351M rad .... until I get around to using a chevy rad.

 

Just curoius, what's the prob. w/ the 351M? You musta had to do quite a bit of adapting to get a 351M into a small-blocked bronco.

Redneck-Cowboy

 

In my case it was a dead M .... the only adapting required is the bellhousing, everything else is essentially the same all three of the available ford drivelines from 80-86 (SBF, I-6, M-block) are placed in the same relative position so all the crossmembers line up there is no difference in the size of the engine bay between them (besides the six is actually longer and taller than the M-block). It's actually a very simple swap .... wait .... I just reread the original post .... you'll have a hydro clutch linkage in that truck if that remained stock, the M-blocks went out of production in 82 (yes I realize it was swapped in) so there must of been some back and forth butchery going on. Not trying to insult but are you sure it's a 351M and not a 351W? if it's a W you'll just need new engine mounts, adapt the rad, and away you go.

BTW the I-6/T-18 is what is currently residing in my bronco until I swap the 435 in (the ratio's are better 1st, 2nd, and 3rd)

 

Hey rockfrog,

It is a 351 M, it has all the labelings on the valve cover etc. I bought this truck for cheap some im guessing that there is some shifty work in a few places, im not sure of what type of clutch setup was used? the radiator might even be the rad for a I6 how could I tell? I can just take the bell housing from a say 302 or any small block? Im kinda new to the game so do i need a bell housing from a standard transmission or will any old bell housing work? The truck was a stock automatic so im not sure if they actually would have spendt the extra cash on a hydraulic setup.

 

Yeah, any SBF belhousing will work (302,351W ...) you'll need to get the flywheel with the six you intend to use (they are a zero balance flywheel) you're current clutch components will work (on some six flywheels you may have to tap the holes for the 11" clutch as some came with a 10" clutch ... all the apprpriate holes are there though).
check the current bellhousing for what type of linkage was used .... if you see a slave cylinder then the job will be easier (I'm guessing they may have used some 84+ components here as it would've required a pedal assembly swap to convert to mech linkage)
when you grab the bell (mechanical, or hydro clutch) grab the clutch fork as well as the two types will differ.
Anything after 84 will be hydro linkage and anything prior will be mechanical (avoid anything post 86 as they started using internal slaves at this time)
the difference between the rads is easy .... V8 - upper hose is on the passenger side. I-6 upper hose is on the driver side (which is why a chevy V8 rad is an obvious choice for replacement) it's all standard 1 1/2" upper, and 1 3/4" lower rad hose (for all three rads mentioned above).
Let me know which type of linkage you find under there, the mechanical comes in three flavors (M-block, SBF, I-6) but the Hydro's are all the same.