904 to727 tranny swap

[CeJohns]

Ive got a 75 fury that to make a long story short has a cracked block.i got a good deal on a 318A(poly) and found out when i tried to put starter in it wont fit with the 904.so going to swap it for a 727.i know theres a 4" difference on overall length but what other differences will i run into? Are the splines the same dia.and number on output shaft? And will the tranny mount be in the same location? Any advice will be appreciated.

 

[polara66hardtop]

318 poly engines are the base for small block 273/318 1964 and up LA engines i assume you are referring to the 1960-66 engines?
but you will have more Issues, like exhaust, linkage, etc.I have not ever considered putting that engine in a newer car. it also weighs as much as a 383 engine. the trans crossmember has to match a newer 727 as well.
And, it is hard to say that the old poly engine mounts are compatible ,,,,

 

[CeJohns]

318 poly engines are the base for small block 273/318 1964 and up LA engines i assume you are referring to the 1960-66 engines?
but you will have more Issues, like exhaust, linkage, etc.I have not ever considered putting that engine in a newer car. it also weighs as much as a 383 engine. the trans crossmember has to match a newer 727 as well.
And, it is hard to say that the old poly engine mounts are compatible ,,,,

Its a 66 model 318a.the motor mounts are the same.
Are you saying that the 904 trans crossmember is different than the 727?

 

[polara66hardtop]

Its a 66 model 318a.the motor mounts are the same.
Are you saying that the 904 trans crossmember is different than the 727?

yes, the 727 is roughly five Inches longer. all 727s have the crossmember compensating for the extra length. your drive shaft is also shorter.
it would be so much easier to go find another newer 318, and save yourself a whole bunch of grief by using the original 904.

 

[CeJohns]

Ok thanks

 

[polara66hardtop]

I would sell one, but I really like those little 318 engines, you can never have too many of those!Lol

 

[1970FuryConv]

Ive got a 75 fury that to make a long story short has a cracked block.i got a good deal on a 318A(poly) and found out when i tried to put starter in it wont fit with the 904.so going to swap it for a 727.i know theres a 4" difference on overall length but what other differences will i run into? Are the splines the same dia.and number on output shaft? And will the tranny mount be in the same location? Any advice will be appreciated.

What year is the car?
If 1975, It would be better to get a later 1989-1992 318LA. It has roller cam. Plus your accessories would set up in the right place and you could keep your good 904 trans and not have to shorten the driveshaft.

 

[traintech55]

What year is the car?
If 1975, It would be better to get a later 1989-1992 318LA. It has roller cam. Plus your accessories would set up in the right place and you could keep your good 904 trans and not have to shorten the driveshaft.

Roller lifters started in 1985 on the 318 engine.

 

[Big_John]

Ive got a 75 fury that to make a long story short has a cracked block.i got a good deal on a 318A(poly) and found out when i tried to put starter in it wont fit with the 904.so going to swap it for a 727.i know theres a 4" difference on overall length but what other differences will i run into? Are the splines the same dia.and number on output shaft? And will the tranny mount be in the same location? Any advice will be appreciated.

The Poly 318 is going to have the same bolt pattern as the 318 (or 360, you didn't say) that's bolted up to your 904 now. Sourcing a small block 727 is going to eat up any savings from buying that Poly 318.

IIRC, the hub diameter for the earlier cars was smaller(?) on the torque convertor so solving that issue on the 727 might be harder to do. Need the correct flex plate too. That's something you'll need to research BEFORE you do anything else as it may kill the whole project.

Then you have that small block motor mount change in the early 70's that might bite you, again, something to research. My memory is fuzzy on it, but I think a later engine in an earlier car is just a pile of washers, but an earlier engine in a later car is more of a headache.

This isn't even talking about everything else.... Exhaust manifolds may or may not clear the steering box and, of course, you'll need to have the head pipes custom built at minimum. Kick down linkage to the trans has to be right as does the throttle cable. I'm not sure if the power steering and alternator brackets will all work off your old engine either. This isn't a swap that has been done, so you are on your own.

So.... Here goes.... I usually get some **** for this, but I really don't care. It needs to be said. This is just a bad idea. The money saved will be lost in all the differences that need to be made up. I really like the Poly 318, but it's not the engine that you want for this car. Go find another engine. You will be money, time, and frustration ahead. THAT is my advice to you.

 

[polara66hardtop]

Now if you were working on a 56 Plymouth, things would work a lot better LoL

 

[Big_John]

This thread ( For Sale - 318 wideblock ) jogged my sharp as a bowling ball memory about the crank flange.

The 61 and earlier Poly motors used an extended flange like the early Hemi motors did. That might be why (I assume) someone has told you that a trans swap is in order. The trans that would bolt up would be the boat anchor cast iron torqueflight used in the '61 and earlier cars and that's just not in the realm of being practical to use. Just figuring out the cable shifter... Shudder... The best way with that would be to swap to a 318/340 crank and again, you aren't saving anything.