427 exhaust manifold bolt locks.
07-25-2014, 01:50 AM
#1
Burning Brakes
Thread Starter
427 exhaust manifold bolt locks.
Did the 427 engines come from the factory with the sheet metal "bend the tab over" style locks installed for the exhaust manifold to head bolts? Cant find any info on it in the AIM(maybe Im not looking hard enough) and I cant recall ever seeing them in the past. I'm guessing if they did most of them are long gone but was wondering if they were on there when delivered. Thanks.
07-25-2014, 02:09 AM
#2
Melting Slicks
Did the 427 engines come from the factory with the sheet metal "bend the tab over" style locks installed for the exhaust manifold to head bolts? Cant find any info on it in the AIM(maybe Im not looking hard enough) and I cant recall ever seeing them in the past. I'm guessing if they did most of them are long gone but was wondering if they were on there when delivered. Thanks.
No French locks on the big blocks, just the small blocks. You wouldn't find it in the AIM also because the exhaust manifolds were installed at Tonawanda.
07-25-2014, 07:54 AM
#4
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Hi,
From what I read at the DB about bb exhaust mounting it seems that the french locks were no longer used starting during the 69 model year. (Maybe before?)
I believe this was possible because of a change in the design of the bolts.
Regards,
Alan
From what I read at the DB about bb exhaust mounting it seems that the french locks were no longer used starting during the 69 model year. (Maybe before?)
I believe this was possible because of a change in the design of the bolts.
Regards,
Alan
07-25-2014, 08:30 AM
#5
Melting Slicks
That is what I have read, that the bolt head changed to a flanged head.
All the photos of top flight '69 BB cars I have do not have French locks. They could be all wrong and I may be proliferating the mistake.
Maybe someone with definite knowledge will chime in.
All the photos of top flight '69 BB cars I have do not have French locks. They could be all wrong and I may be proliferating the mistake.
Maybe someone with definite knowledge will chime in.
07-25-2014, 09:53 AM
#6
Melting Slicks
This has been my experience as well. It appears that most '69 big blocks don't have the French locks. I've tried to think of an original 1970-72 big block I've seen that had them, but can't. Anything in that date range should probably have the shouldered bolts... Generally at the front an rear manifold branches with non-shouldered bolts at the center positions.
Regards,
Stan Falenski
07-25-2014, 05:42 PM
#8
Race Director
The Corvette Parts Book only lists them for use on 1965-67 big blocks, not the 68-74's.
If you have access to a parts book, they're found in group 3.604. You will need an earlier book though, as they were discontinued in the late 70's, and aren't listed in books published after around 78.
If you have access to a parts book, they're found in group 3.604. You will need an earlier book though, as they were discontinued in the late 70's, and aren't listed in books published after around 78.
07-25-2014, 06:59 PM
#9
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Hi d74,
In an older thread (2010) at the DB there is a post stating that the use of the french locks ended with the 67 bb engines when the different 'locking' bolt was introduced.
I don't know if that is still considered to be when the change occurred.
Maybe?
Regards,
Alan
In an older thread (2010) at the DB there is a post stating that the use of the french locks ended with the 67 bb engines when the different 'locking' bolt was introduced.
I don't know if that is still considered to be when the change occurred.
Maybe?
Regards,
Alan