the bellhousing, flywheel, starter and block spacer will not match up. Personally, I would not do the swap. I would save up for a 302 swap first since the 255 is a lump no matter what you do to it

I like having the 255 because there aren't many around but I agree that it is a lump. Would a cam and lifters help liven it up?

Cam and lifters would definatly help. If you take a look at 1980 255ci on Summit thats about all there is for upgrades...

A cam is not going to do all that much since there is NO aftermarket intake for a 255. The 255 has round intake ports on the heads that are unique You can try porting it, but I really think that you will be wasting time and money, especially when 1 out of 1000 would not know that a 302 was not the orrigional engine

kellar86 said:

I like having the 255 because there aren't many around but I agree that it is a lump. Would a cam and lifters help liven it up?

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I work at CarQuest so I was on the computer at work trying to get some prices on a flywheel, clutch and starter but there were no listings available for a manual transmission. However all the other engines had parts available. Was there a manual 255 produced?

yes, all V8 Mustangs built in 1980 and 81 had a 255

The 255 will use the same flywheel as '82 and up 5.0's. Most were Autotragics, so they may not list the part, but the newer stuff will work. As a side note, the 255 was used in '82 as well for all V8 'stags ordered with an Auto.

Some 255s are 50 ounce unbalance, like the '82 and up HOs, but others use the old 28 ounce spec. I think you can stick some good heads and an intake and all the rest of the stuff on it, but you will be down nearly fifty cubic inches to a 302.

Would those mods make much horsepower? I'd like to atleast double the stock rating of 119. Has anybody swapped a 351M into a Mustang?

I doubt it, and why put a 351M in? they are WIDER than a 351C, HEAVIER than a 351C, and their bellhousing pattern is the same as the 385 family, plus there is only one decent aftermarket intake, and since it is wider, you will have to have your ENTIRE exhaust system custom made

kellar86 said:

Would those mods make much horsepower? I'd like to atleast double the stock rating of 119. Has anybody swapped a 351M into a Mustang?

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There is a 351M for $350 so I thought it might be a easier way of getting some extra power but I scrapped that idea.

its time to change my cam in my 81 4.2 and was wondering what cams would fit i know crane cam shows that a few 302 cam will fit but does anyone know exactly what cams from which years will fit the stupid thing im having alot of trouble finding one

I've been looking at cams too and Crane cams are the only ones I have seen for a 255. Do you have any mods done to your motor?

goaticimo said:

its time to change my cam in my 81 4.2 and was wondering what cams would fit i know crane cam shows that a few 302 cam will fit but does anyone know exactly what cams from which years will fit the stupid thing im having alot of trouble finding one

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well i threw on a holly 450 i had kicken around and it gave me a little more juice but wouldnt really recomend that, but what i also did is when my 88 4 banger blew i took the fuel pump and drilled it in my 81 and just put a toggle switch on it to turn it on so it wasnt running the whole time. if i do leave it on it wants to stall and floods all the time but when i flick it at around 5grand i was surprized it actually worked getting a little more fuel into my carb better than the mechanical pump i was thinking about blocking the mechanical pump of and trowing in a nice electric pump in there but its defintetly not worth the money not on that motor anyway

kellar86 said:

I've been looking at cams too and Crane cams are the only ones I have seen for a 255. Do you have any mods done to your motor?

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When I bought my car the fender and door were buckled where something hit it so I bought a 83 Mustang v6 for parts. The 83 is in better shape than my car so I was wondering which is the better of the engines...255 or 232?