BBC Clam Shells

[Mr Clean]

I'm looking for a set of BBC clam shells. I put my BB in my Blazer today, got one motor mount bolt in, and the other one does not line up. I used SB clam shells and I'm pretty sure that's my problem. I looked at the Extracab that has a BB in it, and the clam shells look shorter. Let me know if you have a set.

 

[bucket]

I'm looking for a set of BBC clam shells. I put my BB in my Blazer today, got one motor mount bolt in, and the other one does not line up. I used SB clam shells and I'm pretty sure that's my problem. I looked at the Extracab that has a BB in it, and the clam shells look shorter. Let me know if you have a set.

If you are using small block rubber/urethane mounts, then the smalblock clamshells are correct. Depending on the brand and or condition of the mounts, it can take some finesse to get both bolted up. Even if you were installing a small block too.

 

[Mr Clean]

If you are using small block rubber/urethane mounts, then the smalblock clamshells are correct. Depending on the brand and or condition of the mounts, it can take some finesse to get both bolted up. Even if you were installing a small block too.

No... using Energy Suspension. The Clam Shell is about 1/2 inch off. The Small block clam shells look to long. The clam shells on the Extra cab look shorter. Im going to try and measure them in the morning.

 

[bucket]

No... using Energy Suspension. The Clam Shell is about 1/2 inch off. The Small block clam shells look to long. The clam shells on the Extra cab look shorter. Im going to try and measure them in the morning.

Yeah, sometimes the poly inserts don't fit in the mount halves perfectly and the bolt holes can be off a bit. Small block mounts work in conjunction with small block clamshells. If you use big block clamshells, you should need the big block mounts too that use different bolt holes in the frame.

 

[bucket]

Small block and big block engines share an identical mounting footprint. The mounts and clamshells are only different between the two (for some applications) for a slightly different mounting height within the engine compartment.

 

[Mr Clean]

Yeah, sometimes the poly inserts don't fit in the mount halves perfectly and the bolt holes can be off a bit. Small block mounts work in conjunction with small block clamshells. If you use big block clamshells, you should need the big block mounts too that use different bolt holes in the frame.

On a 4x4 there are no different bolt holes. The clam shells fit over the motor mounts, the the motor mount bolt doesn't line up. I can get one side in. The other side is off by about 1/2 inch. I'll get some pics.

 

[bucket]

On a 4x4 there are no different bolt holes. The clam shells fit over the motor mounts, the the motor mount bolt doesn't line up. I can get one side in. The other side is off by about 1/2 inch. I'll get some pics.

Yes, that's because your 4x4 frame was never offered with a big block.

If you are using the same clamshells that were in the truck with the small block (you are, right?), I can assure you that you are just dealing with an aftermarket mount issue. Been there, done that. It often involves a jack and/or a big prybar.

 

[vr1967]

Do you have the plates for the bell housing rods behind the mounts? They were about 1/4” thick each?

I’ll post a picture of some in a bit

 

[malibuman402]

My 84 came with a 305 and i used the same mounts and clamshells to install my 427 big block. make sure the tabs in the mounts are pointing in the correct direction. had to remove the eng to turn one around. LOL