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Discussion Starter · #1 ·
I have searched through old threads only to be more confused. I have a 1980 El Camino I will be swapping out the small block for a big block in. I did not know there was a difference between sbc and bbc frame mounts. When I did my Cutlass with the bbc after taking out the sbc I never changed them but the engine did sit kinda high. It would be great if the engine could sit lower since space is at a premium but it says it moves the engine to the passenger side. I have super comp headers and in my '84 Cutlass I had to cut the end of one of the A-arm bolts flush with the nut for them to fit. If moved over to the passenger side more they probably won't fit. My big thing is getting the engine to sit as low as possible in my Elky. I really need to hear from the G-body guys who have made this swap and what worked best for them. My car is really nice so I want to try and keep it all under the hood. (Is it possible?) I feel I didn't get the most accurate information reading some of the old threads. Can I please get some clarification on this from the experts?
 

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The offset motor frame mount for BBC applications thing is not for your chassis...it is just a 1st Gen Camaro/F-body and 3rd Gen Nova/X-body thing (since they share a front subframe).

Your 1980 A/G-body never came with a factory Big Block option and even if it did there would have been no need for an offset motor mount, the engine bay and frame gives enough clearance for centered mounts.
The common BBC into G-body swap uses the same mounts as the small block does.

An fact, every generation of A or G body, from 1964-up all use centered mounts.

With that said , there is a difference in the height of the engine mount cup on the style of mount your car uses....car mount and truck mount.....the truck cups are taller from block face to thru-bolt hole and would put the engine higher.

Your header fit and having to trim the bolt is typical Hooker crappy fit.
 

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Discussion Starter · #3 ·
The offset motor frame mount for BBC applications thing is not for your chassis...it is just a 1st Gen Camaro/F-body and 3rd Gen Nova/X-body thing (since they share a front subframe).

Your 1980 A/G-body never came with a factory Big Block option and even if it did there would have been no need for an offset motor mount, the engine bay and frame gives enough clearance for centered mounts.
The common BBC into G-body swap uses the same mounts as the small block does.

An fact, every generation of A or G body, from 1964-up all use centered mounts.

With that said , there is a difference in the height of the engine mount cup on the style of mount your car uses....car mount and truck mount.....the truck cups are taller from block face to thru-bolt hole and would put the engine higher.

Your header fit and having to trim the bolt is typical Hooker crappy fit.
Interesting.. I was on Summit's site and by typing in a 1973 Chevelle they show two different clam shell frame mounts- one for a small block and one for a big block. Not sure what the difference is but they look like the same frame mounts as are in my Cutlass. Part numbers are: DEA products A2395 for BBC and DEA products A2292 for SBC. If there is indeed a difference between the two mounts just listed, then would they also require different engine mounts?
Still confused....
 

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That '73-up style mount, the pieces with the rubber isolators in them bolts to the frame, and the engine has a metal cup.....the trucks and vans had taller cups than cars.
Typically if the isolator mounts are bolted into their correct holes on the 1978-1980 A-body/1981-1987 G-body crossmember you won't get the wrong cups to fit, as the cup being taller pushes the thru-bolt hole farther away from the block, meaning the mount pads would have to be further apart.

Where it can go bad is if a guy tries to use truck cups and just places the mount pads on the frame where the truck cups fit to them when they do a swap....which will be higher on the crossmember's "V" shape and raising the engine.

Early '73 and previous years use a totally different system, the rubber isolator pad is on the block and the frame portion is just metal. Opposite of what you have.

The difference in the two 1973 applications you listed may be nothing more than the amount of rubber in the mount, or the durometer(stiffness) of the rubber being different. BBB weighs more, and may have differenct vibration characteristics.
 

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Discussion Starter · #7 ·
That '73-up style mount, the pieces with the rubber isolators in them bolts to the frame, and the engine has a metal cup.....the trucks and vans had taller cups than cars.
Typically if the isolator mounts are bolted into their correct holes on the 1978-1980 A-body/1981-1987 G-body crossmember you won't get the wrong cups to fit, as the cup being taller pushes the thru-bolt hole farther away from the block, meaning the mount pads would have to be further apart.

Where it can go bad is if a guy tries to use truck cups and just places the mount pads on the frame where the truck cups fit to them when they do a swap....which will be higher on the crossmember's "V" shape and raising the engine.

Early '73 and previous years use a totally different system, the rubber isolator pad is on the block and the frame portion is just metal. Opposite of what you have.

The difference in the two 1973 applications you listed may be nothing more than the amount of rubber in the mount, or the durometer(stiffness) of the rubber being different. BBB weighs more, and may have differenct vibration characteristics.
I typed in 1974 Chevy Monte Carlo at Rock Auto and checked the difference in motor mounts. It appears that the only difference I could find is that the BBC ones have three bolt holes to mount them compared to the SBC ones having 4 mounting holes. I would guess that depending on how they mount they would have their own dedicated engine mounted cups too.
Perhaps I'm just over thinking this. I'm pretty desperate for hood clearance as my El Camino is really nice and I don't want to butcher the hood to make my 489 fit.
 

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I typed in 1974 Chevy Monte Carlo at Rock Auto and checked the difference in motor mounts. It appears that the only difference I could find is that the BBC ones have three bolt holes to mount them compared to the SBC ones having 4 mounting holes. I would guess that depending on how they mount they would have their own dedicated engine mounted cups too.
Perhaps I'm just over thinking this. I'm pretty desperate for hood clearance as my El Camino is really nice and I don't want to butcher the hood to make my 489 fit.
You're between a rock and a hard place and overthinking it....you've got a chassis that never had a factory BBC installation offered by Chevy.
The 73-77 A-body chassis is far different from the downsized 78-87 "Metric" A/G-body.

There is no different mount height or cup height in that style mount, just car or truck/van cups, and the truck cups move in the opposite direction you want to go.

If you want the engine to sit lower than it sits on the standard car SBC mounts and cups, you are either going to have to fabricate your own, switch to front and rear motor plates, ....or design a whole new front crossmember, gut the old one, and weld in your fab'd one.

If your not going to re-configure the mounting system, then you've got two choices....compromise the power of the engine using a short intake manifold, or add a hood scoop/change the hood.
 

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Discussion Starter · #9 ·
You're between a rock and a hard place and overthinking it....you've got a chassis that never had a factory BBC installation offered by Chevy.
The 73-77 A-body chassis is far different from the downsized 78-87 "Metric" A/G-body.

There is no different mount height or cup height in that style mount, just car or truck/van cups, and the truck cups move in the opposite direction you want to go.

If you want the engine to sit lower than it sits on the standard car SBC mounts and cups, you are either going to have to fabricate your own, switch to front and rear motor plates, ....or design a whole new front crossmember, gut the old one, and weld in your fab'd one.

If your not going to re-configure the mounting system, then you've got two choices....compromise the power of the engine using a short intake manifold, or add a hood scoop/change the hood.
I hear ya. I was looking for an advantage that just wasn't there. On the plus side today I learned that the big block thing is really common in g-bodies. But after literally searching through threads ALL day on gbodyforum I found no real solid information on what intake people used to keep their BBC under the hood. I started another thread on this very thing but so far no joy.
I kinda feel stupid as I literally have a car right now with a big block in it. I know everything it takes to put one in, just not how to keep it under the hood. When I built mine I threw an air gap on it with a tall air cleaner and cut a hole in the hood. Not good if it rains.
I certainly didn't mean to waist your time as I very much value your knowledge. Sometimes I find bits of info on something and won't let it go until I have learned what I needed to about it.
 
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