La360 and 727

-
74@scamp

74@scamp

Member
Joined
Oct 10, 2024
Messages
15
Reaction score
11
Location
Milwaukie oregon
Ok I am new here and have done a couple google searches and a couple searches on here to try and find the answers needed. Hopefully somebody can help. I have a 74 plymouth scamp that came with a 1979 360 motor. I am trying to find a 727 transmission to go with it. Do all small block 727 and 727 torque flight transmissions share the same bolt pattern and have the same spline count? I would love to find a torqueflight but haven't found one yet
 
Big block, small block, and slant 6 all use different bellhousing bolt patterns. You need a smallblock 727.
Input splines were different between standard 727s and ones with a lockup convertor (late 70s-early 80s?). Output splines are all the same, as is the overall length.
Stay away from '65 and earlier transmissions- output used a flange for a ball and trunnion, had cable shift, and a different speedo drive.
Also some HD truck and motorhome trannies had a stubby tailshaft, and/or a flanged output or parking brake drum- but those are readily obvious.
More importantly, most smallblock 727s will have a neutral balanced convertor- your 360 requires an externally balanced (LA 360 only) convertor, or an aftermarket externally balanced flexplate.
 
As Prof. Fate stated smallblock A727's as well as V8/V6 904's all share the same bolt pattern
If you're lucky and can find one, an A998 or A999 out of a 1980's M-body or 2WD Dakota is a great transmission as well. They're basically beefed up 904's with wide ratio gears.
 
Professor Fate said:
Big block, small block, and slant 6 all use different bellhousing bolt patterns. You need a smallblock 727.
Input splines were different between standard 727s and ones with a lockup convertor (late 70s-early 80s?). Output splines are all the same, as is the overall length.
Stay away from '65 and earlier transmissions- output used a flange for a ball and trunnion, had cable shift, and a different speedo drive.
Also some HD truck and motorhome trannies had a stubby tailshaft, and/or a flanged output or parking brake drum- but those are readily obvious.
More importantly, most smallblock 727s will have a neutral balanced convertor- your 360 requires an externally balanced (LA 360 only) convertor, or an aftermarket externally balanced flexplate.
Click to expand...
Thank you so much for all the info, I appreciate it. My plan was to use an updated external balanced flex plate. The la360 I have is a 79, would be nice to find a 727 around that same year.
 
Cuprum-74 said:
As Prof. Fate stated smallblock A727's as well as V8/V6 904's all share the same bolt pattern
If you're lucky and can find one, an A998 or A999 out of a 1980's M-body or 2WD Dakota is a great transmission as well. They're basically beefed up 904's with wide ratio gears.
Click to expand...
Got ya, thank you, I will do some looking
 
So I finally got around to pulling my automatic transmission today. Turns out it is a 1972 904 transmission. Curious what flex plate and torque convertor I need to mount it to my 1979 la360?

Or would I be better to sell the 904 and find a 727
 
i'm a little confused... you have a 72 904 that goes with or was attached to the 360?

if you have that, what's wrong with it? why do you want a 727?
 
No matter, they (727) are a better trans. Don't blame the guy for going that way
 
junkyardhero said:
i'm a little confused... you have a 72 904 that goes with or was attached to the 360?

if you have that, what's wrong with it? why do you want a 727?
Click to expand...
Sorry, that was confusing, I have a 72 904 that came from the factory behind a 318, the car I bought came with a la360 on an engine hoist
 
the low-buck move would be to build the 904 out, and get a proper converter that's already weighted.

the other option would be to sell or trade the 904 (+ cash) for a 727 and then sort out the converter and flex plate. but then you're still in the boat of [likely] needing to build a trans and buy a converter.

so it's kind of a 6 of one situmanation with the added expense if you want a 727

and yes, a 904 will live just fine behind a 360 as long as it's not some super rowdy build.
 
Yes, rebuild that 904.
Sure a 727 is stronger but not necessarily the better option. As stated before, you'll have to sort out a torque converter, and on top of that you'll need to shorten your driveshaft.
A 904 with a good HP rebuild kit can handle a mild 360 easy.
Heck the guy who helped me rebuild my A999 is very confident that my trans can handle a 408 stroker. And he's been rebuilding these transmissions, as well as building ones for racing for over 30 years, I'm glad I got to pick his brain.
 
Cuprum-74 said:
Yes, rebuild that 904.
Sure a 727 is stronger but not necessarily the better option. As stated before, you'll have to sort out a torque converter, and on top of that you'll need to shorten your driveshaft.
A 904 with a good HP rebuild kit can handle a mild 360 easy.
Heck the guy who helped me rebuild my A999 is very confident that my trans can handle a 408 stroker. And he's been rebuilding these transmissions, as well as building ones for racing for over 30 years, I'm glad I got to pick his brain.
Click to expand...
Thank you for the great info. I figured I would have to change the driveshaft, might upgrade the axle at the same time to something a bit stronger. Next question is who would I contact to find the correct torque convertor and flexplate? Is that something summit racing could help me get my hands on or would I need to contact a transmission shop to find the correct torque convertor that will bolt up to the flex plate?
 
You must log in or register to reply here.
-

Back
Top