Motor Mounts 101

[gazooba]

I need some education on motor mounts! I have no experience with small block (or any GM engine for that matter) mounts.

This is what I discovered when I pulled the engine from the 79 C1500. Seeing only 3 bolt holes on the clam shells filled definitely threw me off. Is this the way it's supposed to be?

Do the frame brackets look right / is there supposed to be that extra hole at the bottom edge?

Thanks for the insight!

 

[RangRayy]

Looks similar to my '87 three bolts holding the mounts to the brace and four holding the brace to crossmember and frame.

 

[74 Shortbed]

My 74 is the same way..

 

[highdesertrange]

yes that is how it's supposed to be. highdesertranger

 

[87scotty]

Since this question.is here do I need to do anything with mounts going from TBI 350 to 454? 1987 3/4 ton 4wd turbo400

 

[highdesertrange]

I used the mounts from the 350 in my 78 1 ton when I install a 454. I did use the buckets for the 454. highdesertranger

 

[87scotty]

I used the mounts from the 350 in my 78 1 ton when I install a 454. I did use the buckets for the 454. highdesertranger

Bucket or brackets? Lol and what brackets day you mean?

 

[bucket]

I used my smallblock mount setup on my 454. Bolted right in. I never trust the engine brackets that are from other body styles or cars, even though they might look the same, the holes might not line up when you drop the motor in.

 

[gazooba]

Thanks for the insight guys!
I think I read somewhere that big block and small block mounts are a little different, but they are still more or less interchangeable, as was said above - can anybody clear up what the differences actually are?

 

[87scotty]

I used my smallblock mount setup on my 454. Bolted right in. I never trust the engine brackets that are from other body styles or cars, even though they might look the same, the holes might not line up when you drop the motor in.

So your saying when I pull the 350 take the mounts off the block and use those rather than the ones that came off the 454! Should I worry about strength this truck should be around 5-600 ft lbs and hp

 

[highdesertrange]

I used the buckets off the 454. the buckets mount to the block. then I used the 350 motor mounts because they mount to the frame. the 454 motor mounts use the other hole that the op was inquiring and the frame is not drilled for that bolt. so unless your truck came with a 454 or you drill the frame, use the 350 mounts. highdesertranger

 

[MikeB]

I used my smallblock mount setup on my 454. Bolted right in. I never trust the engine brackets that are from other body styles or cars, even though they might look the same, the holes might not line up when you drop the motor in.

Or the holes may all line up, but the engine will sit too high or too low. I was lucky and only needed to buy two pairs of clam shells before I got the right ones for my 250-six to 350 conversion. I spent hours and hours at GMPartsWiki.com to find the correct P/N, and actually bought a pair from my Chevy dealer. Not easy going through the parts lists, though.

If it helps your search, GM terms for the parts are:

clam shell = "bracket, engine mount" or "bracket, engine mt"
brackets that bolt to the frame = "bracket, engine mt frame"
rubber motor mount cushions = "mounting, engine" These are available at your local parts store.

This is the dimension that varies among clam shells:

You must be registered for see images

 

[gazooba]

Or the holes may all line up, but the engine will sit too high or too low. I was lucky and only needed to buy two pairs of clam shells before I got the right ones for my 250-six to 350 conversion. I spent hours and hours at GMPartsWiki.com to find the correct P/N, and actually bought a pair from my Chevy dealer. Not easy going through the parts lists, though.

If it helps your search, GM terms for the parts are:

clam shell = "bracket, engine mount" or "bracket, engine mt"
brackets that bolt to the frame = "bracket, engine mt frame"
rubber motor mount cushions = "mounting, engine" These are available at your local parts store.

This is the dimension that varies among clam shells:

You must be registered for see images

Very helpful!! Cheers!