Size/qty of bolts for bellhousing to motor

[RockinRobin]

Need all of the bolts to attach a 727 torqueflite to a 5.7.
How many of what size bolts do I need?
Do they need to be the factory bolts?
Thanks!

 

[Joe Dokes]

The bell housing uses 3/8" 16 threads per inch bolt. The bell housing is the same pattern as an LA or Magnum SB Mopar MINUS a single bolt at the top. If using a 904, 727, or 833 bell housing simply leave this bolt out.

I would simply re-use the transmission bolts from your existing transmission and simply omit the top bolt.

Keep in mind that there is a .060" difference between old school transmissions and modern transmissions, so putting a 727 or 904 behind a Gen III Hemi may require a .060" spacer.

Regards,

Joe Dokes

 

[66plyValiant]

yes the factory bolts will work just fine

 

[RockinRobin]

The bell housing uses 3/8" 16 threads per inch bolt. The bell housing is the same pattern as an LA or Magnum SB Mopar MINUS a single bolt at the top. If using a 904, 727, or 833 bell housing simply leave this bolt out.

I would simply re-use the transmission bolts from your existing transmission and simply omit the top bolt.

Keep in mind that there is a .060" difference between old school transmissions and modern transmissions, so putting a 727 or 904 behind a Gen III Hemi may require a .060" spacer.

Regards,

Joe Dokes

Thanks Joe! Unfortunately I have a crate motor that came with no trans bolts, that's why I was asking. It also means I have no idea what length they should be and if some are longer than others. Interesting that they are 3/8" I would have thought they would be metric. ATI makes a flex plate that needs no spacer to take care of the .060 difference and I have one on the way.....

 

[Joe Dokes]

Glad to hear about the flex plate.

It is odd that they are 3/8" When I bought my motor I stopped at the hardware store and bought a bunch of metric hardware so I could mount the motor to engine stand. Much to my chagrin, I was back at the hardware store buying some 3/8" bolts. GRRR.

There are 4 3/8" tapped holes they are tapped over an inch deep so you should be able to safely use 1 1/2" bolts, remember for a bolt to achieve full strength you need the diameter of the bolt + 1 thread for full strength so you need to engage 7/16" minimum into the block.

Also there are 2 untapped through holes at the bottom of the bell housing, these use 7/16" bolts with nuts. Again 1 1/2" in length should be fine.

Regards,

Joe Dokes

 

[66plyValiant]

Thanks Joe! Unfortunately I have a crate motor that came with no trans bolts, that's why I was asking. It also means I have no idea what length they should be and if some are longer than others. Interesting that they are 3/8" I would have thought they would be metric. ATI makes a flex plate that needs no spacer to take care of the .060 difference and I have one on the way.....

there are 4- 3/8" bellhousing bolts, but you'll also need the 2 bolts that go from the engine block into the transmission; one goes above the starter and the other goes behind the oil filter I believe those are 7/16" bolts not sure the thread count

 

[RockinRobin]

there are 4- 3/8" bellhousing bolts, but you'll also need the 2 bolts that go from the engine block into the transmission; one goes above the starter and the other goes behind the oil filter I believe those are 7/16" bolts not sure the thread count

Are we talking 5.7 hemi here? Pretty sure oil filter is in front of motor.

 

[66plyValiant]

Are we talking 5.7 hemi here? Pretty sure oil filter is in front of motor.

I'm talking about relative location to where they go into the transmission, not sure where everything is located on a hemi

I'll put it this way, you'll need 2 7/16" bolts that go above the dowl pins on the older transmission or else it will not stay in the car without breaking