Has Anyone Sorted Out the "LA" Cylinder Block Motor Mount Tab Variations?

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dibbons

dibbons

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Is there an online reference to explain all the ins and outs of Mopar LA block motor mounting tabs? I have three motors with three different arrangements! There must be a bunch of different factory brackets out there, too.

The 318 block I am looking at (casting date 12/04/79) has:
On driver side 2 tabs in front and 2 tabs behind for a total of 4 tabs.
On passenger side 2 tabs in front and 1 tab behind (upper location) for a total of 3 tabs.

The 340 block I am looking at (casting date 09/28/71) has
On driver side 2 tabs in front and 1 tab behind (upper location) for a total of 3 tabs.
On passenger side 2 tabs in front and 1 tab behind (upper location) for a total of 3 tabs.

The 273 block I am looking at (installed in a '65 Signet convertible) has:
On driver side 2 tabs in front and 1 tab behind (upper location) for a total of 3 tabs.
On passenger side 1 tab in front (upper location) and 2 tabs behind for a total of 3 tabs.

I can't see the 273 driver side bracket very well, I am fairly sure it only has 3 tabs total.
 
Isn't the 360 different as well? When I pulled my 318 I had to fab up one of the brackets to fit my 360 block.
 
The passenger side motor mounts are interchangeable between all 273-318-340-360 blocks...

The driver side motor mounts are about 1/2" different on the 273-318 than on the 340-360.... 273-318 are one spread, the 340-360 are another....
 
The hole arrangement is what I am referring to.

My 273 and 318 on the passenger sides are exactly opposite one another (tabs meaning a spot with a hole to slide a bolt through):

my 273 had only one tab in front on passenger side while the 318 has two tabs in front (front meaning toward the fan).

the 273 has two tabs in rear on passenger side while the 318 has one tab rear (rear meaning toward bellhousing).
 
krazykuda said:
The passenger side motor mounts are interchangeable between all 273-318-340-360 blocks...

The driver side motor mounts are about 1/2" different on the 273-318 than on the 340-360.... 273-318 are one spread, the 340-360 are another....
Click to expand...

I knew someone would know all the differences. Now I have a question... why? I mean damn everything will bolt on why not the stupid mounts?
 
Search Crackedback. He had some photos modifying the older 273 / etc brackets for 340........

EDIT cannot find the post anymore.................
 
dibbons said:
The hole arrangement is what I am referring to.

My 273 and 318 on the passenger sides are exactly opposite one another (tabs meaning a spot with a hole to slide a bolt through):

my 273 had only one tab in front on passenger side while the 318 has two tabs in front (front meaning toward the fan).

the 273 has two tabs in rear on passenger side while the 318 has one tab rear (rear meaning toward bellhousing).
Click to expand...

Without having the whole array of blocks to look at, I can't tell you all the differences on which ones have how many holes... I think as long as you can get at least three good solid bolts on each ear to the motor mount, you will be ok...
 
Hellrats said:
I knew someone would know all the differences. Now I have a question... why? I mean damn everything will bolt on why not the stupid mounts?
Click to expand...

For some reason Chrysler had to change them for the larger bore blocks... I don't know...
 
The brackets bolts to the block it was made for. No mystery there. Not really familiar with the other brands but it seems like we got it pretty good. 72 brackets bolt up to a 96 block :)
 
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