SB to BB swap on my 74 3/4.....same motor mounts?

[chev406]

My truck was originally a 454 but I had a small block in it for the last 4 years or so. I'm ready to intall the 454 again, but don't remember if I had to change motor mounts or not?

My neighbors are pricks even though my yard is well maintained, so I'll have to make this swap quick! A delay would be bad news, and leave me vulnerable to attacks from the county! I have to be stealth.

motor mounts, engine bracket, are the same on 74.............right!

Thanks!

[superchevy]

They aren't the same...at least the ones in my '77 C20 aren't.
I pulled the original 454 to swap in the 468...went down to the local parts house to get new mounts...parts guy says "Chevy used same mounts for small and big blocks after '73" so he gives me the mounts...I take them home and compare to originals...they are not the same...go to different parts house and show them originals and ones I just bought...after a little research in the parts book - yes, an actual book, not computer...we find the right mounts for the big block.
Just my 2 cents
SC

[Gray Ghost]

My 73 3/4 ton truck used the same mounts when the PO swapped in the 350 I just swapped out for a new one. As far as I know it will use the same ones.

[bigblock73]

I have always believed them to be the same as well. I replaced the 350 in Yeller with a 454...used the same mounts and everything bolted up fine. I also even used the same engine stands...even tho people have told me the big block and small block stands are the same. I alse went as far as to buy "BBC" stands from another board member, but they do not line up without having to drill holes..so I never used them. Perhaps the difference is the frames (1/2, 3/4, and 1 ton)?

Superchevy, do you happen to have a pic of yours, or a part number. I am curious and would like to find out the real story about the "sbc and bbc mounts the same?" questions that keep popping up here (for my own good as well).

[BIGCHEVYMAN]

when i pulled the 350 from my truck i swapped the block mounts from the 350 to the 454 and used the original frame mounts with no problems at all.

[superchevy]

Yes, I will take a pic tomorrow. They are not the same...they are very similar, but not the same.
SC

[1FaastC10]

are we talking about the clamshell engine mounts that bolt to the frame?

[1971ChevyTruck]

Big block motor mounts= Small Block motor mounts

[chev406]

Dudes you rock I gotta get it done fast before the neighbors have a chance to

[bigblock73]

Originally Posted by 1FaastC10

are we talking about the clamshell engine mounts that bolt to the frame?

Technically the clam shells do not bolt to the frame, they bolt to towers/stands/plates (what ever you want to call them)...and they bolt to the frame.

[1FaastC10]

ok smartass, are those what we are discussing here?

[bigblock73]

As far as I know, we are talking about the mounts...not the stands/towers.

[MSL]

On my 78 chevy 1/2 ton i swapped to a 454 from my small block and nothing changed other than repostioning how you mount the motor mount to the front cross member. also the block mounts where the same too.

[bigblock73]

Originally Posted by MSL

On my 78 chevy 1/2 ton i swapped to a 454 from my small block and nothing changed other than repostioning how you mount the motor mount to the front cross member. also the block mounts where the same too.

What do you mean? Did you mount the engine mounts in a different position on the engine stands, or did you mount the engine stands in a different position on the frame? I know the engine stands have two different sets of holes, one labeled "6" (for inline sixes), the other labeled "8" (for v8's). I am curious to know how you all have done your swaps. Mine went fine, but I don't have much clearance between my trans and floor (but I am using a 700r4 too). Swervins trans clearance is the same as mine..but it just seems too close. I have been wondering if I have things set up incorrect.

[MSL]

Here you go this is what i used out of my truck manual i hope this helps and ifg anyone wants a larger pic email me at ml2418@yahoo.com maybe someone can put it on there webpage or make it a sticky. I mounted my stuff as showed and it all worked out fine.

[bigblock73]

MSL, thanks for the diagram! I mounted mine the same way the pics show, except my motor mounts are the 350 variety...so I wasn't able to mount them the way "view A" shows. By looking at this diagram, it appears the clam shell motor mounts are different only in how they bolt to the towers...but not really in size. I still wish I knew the truth about the towers, and if there really is a BB and SB version...and what the differences are.

[MSL]

Well i took my motor out of a 74 chevy 3/4 ton and the towers where the same as mine and the 74 truck was factory with the 454 so i myself would assume no difference in SB or BB.

[Captkaos]

I still stand by my original statement that there is not difference in BBC vs. SBC engine stands.

[BIGCHEVYMAN]

i agree with the captain.

[corn]

On mine, I unbolted the 305 & bolted the 402 right in. Only issue I had was one header tube didnt want to clear the cup style mount(DR side) on the engine but it clears now...corn

[longhorn71]

Originally Posted by BIGCHEVYMAN

i agree with the captain.

me too.changed to a big block in my 85 and it dropped into the small block mounts.

[superchevy]

The mounts are not the same...they might work, but they're not the same. The pics below show the differences. The mount on the right is for a '77 C20 with a smallblock (these are the mounts given to me by the parts guy because "they're all the same")...the mount on the left is the original GM mount out of my '77 C20 454/T400 truck.
Do they look the same to ya'll?
The 454 mount is longer, taller, has a different mount thru-bolt location, and has a different mount-to-tower bolt pattern.
That's why I took the smallblock mounts back and went to a different parts store to get the right mounts...the 2395's...they were exactly like the originals...I kept the box so I would know which ones to get again in the future.
So in my opinion, 3/4 ton mounts for small blocks and big blocks are different, but the book shows that a 1/2 ton trucks do use the same "small block" mount...the 2292's shown in the pics...interesting, huh?
SC

[Gray Ghost]

He's talking about a 74...they are the same for that year as well as the 73 on the 3/4 ton trucks. Not sure why the 77's are different.

[bigblock73]

SC, here are some pics of my stock SB mounts (on the right), and the BB mounts I purchased from a board member. By looking at your pics, and comparing them to mine...it is in fact clear there are different mounts...but when things changed is still up in the air.

[superchevy]

All 73 - 77 3/4 ton big blocks show the same part number, 2395, for the mount. All 73 - 77 3/4 ton small blocks show the same part number, 2292, for the mount. The mounts are different...they might work for the 350 to 454 swap, but the question was "are they the same", and the answer is, no.
SC