C3 Frame conversion from big block to small
09-23-2017, 07:18 PM
#1
C3 Frame conversion from big block to small
I have located a rust free replacement frame for my 71 small block car w 4 speed trans. Would there be a lot involved in making the big block C3 frame work??
09-23-2017, 07:46 PM
#3
Race Director
Member Since: Mar 2003
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Depends on the frame year 68 to 72 swap easy o, bb or sb, 68 has a few little things different nothing epic,
My factory 69 sb car auto has the frame from a 68 4 speed car, we did add the rear frame kick up reinforcement that early 68 lack,
A bb frame itself isnt different to sb
My factory 69 sb car auto has the frame from a 68 4 speed car, we did add the rear frame kick up reinforcement that early 68 lack,
A bb frame itself isnt different to sb
09-23-2017, 07:54 PM
#4
Melting Slicks
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so the replacement frame is from a similar year corvette , namely 68,69,70,71,72,?
the BB and the SB use exactly the same mounting points and bell housings ,so any early vette frame will accept a BB or SB.
If its a 73 or 74 the frame starts to get different as in regards to mounting the "new " bumper type
the only thing I would be concerned with is the measurements of the replacement frame , if its from those 5 first years , no one pulls apart these cars for no reason ,so its more than likely it was involved in an accident so it could be bent .
the BB and the SB use exactly the same mounting points and bell housings ,so any early vette frame will accept a BB or SB.
If its a 73 or 74 the frame starts to get different as in regards to mounting the "new " bumper type
the only thing I would be concerned with is the measurements of the replacement frame , if its from those 5 first years , no one pulls apart these cars for no reason ,so its more than likely it was involved in an accident so it could be bent .
Last edited by bazza77; 09-23-2017 at 07:59 PM.
09-23-2017, 08:00 PM
#6
so the replacement frame is from a similar year corvette , namely 68,69,70,71,72,?
the BB and the SB use exactly the same mounting points and bell housings ,so any early vette frame will accept a BB or SB.
If its a 73 or 74 the frame starts to get different as in regards to mounting the "new " bumper type
the only thing I would be concerned with is the measurements of the replacement frame , no one pulls apart these cars for no reason ,so its more than likely it was involved in an accident so it could be bent .
the BB and the SB use exactly the same mounting points and bell housings ,so any early vette frame will accept a BB or SB.
If its a 73 or 74 the frame starts to get different as in regards to mounting the "new " bumper type
the only thing I would be concerned with is the measurements of the replacement frame , no one pulls apart these cars for no reason ,so its more than likely it was involved in an accident so it could be bent .
09-23-2017, 08:11 PM
#7
Melting Slicks
Member Since: Jul 2010
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Just a thought , if your frame is rusted too badly ,how's the birdcage ?
09-23-2017, 08:21 PM
#8
I have read , from someone on this board who knows more about the history around these cars than I ever will , that GM sold the 74 frame as a service replacement for the early C3 , Also I have had a 74 frame here (parts car) and the bare rear is not to far from the early frame , I think there's a tab that needs to be cut off. More than likely holes drilled but definitely do-able !
Just a thought , if your frame is rusted too badly ,how's the birdcage ?
Just a thought , if your frame is rusted too badly ,how's the birdcage ?
09-24-2017, 11:49 AM
#9
Drifting
A 74 frame is a modified 69-73 frame. And it can be easily un-modified. The four mounting holes for the front bumper will have to be re-drilled along with changing the two welded nuts on each side. The frame horns themselves are exactly the same as the 71. Check for cracks around the front spring pockets and lower a-arm mounts.
Mike
Mike
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