Help Chevy Flexplate question
#1
Member
CRAFTSMAN
Thread Starter
Join Date: Apr 2003
Posts: 56
Help Chevy Flexplate question
Just pulled an engine out, it was shaken (not stirred, LOL) The car had a bad vibration. After getting out the engine, noticed the block was a BBC 427 with a internal balance dampner, but the flexplate looked like it was for an external balanced engine. The flexplate had a counter weight, is this correct? or is there another way to tell? I guess my question is will an internal balanced engine flexplate be smooth (no counter weight welded to the flexplate)??
#2
Senior Member
RACING JUNKIE
Join Date: Sep 2007
Posts: 4,137
You have a 454 flexplate.An internal balance will NOT have a weight. Are you certain it isn't a 454? The block is the same. The old 512 casting block was used on both 454's and 427's...just a different crank and pistons.
#5
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CRAFTSMAN
Thread Starter
Join Date: Apr 2003
Posts: 56
Tod74, how can I tell which it is 454 or 427 the cast # 3963512 by the location of the crank? I did not install the old flexplate, but I will get the right one and a new ATI dampner (to be safe) then take both the flexplate, dampner, along with the rest (the lightest rod, bearing, piston, rings, crank)
#6
Senior Member
RACING JUNKIE
Join Date: Sep 2007
Posts: 4,137
You Can't.....You can find out what it was from the facvtory by the suffix on the front pad, but you have no way of knowing(without pulling a head or pan) what crank someone has put in it since,other than the balancer and flexplate.... If that is a 512 block I WOULD NOT have it in a hotrod. Depending on the casting date they can bring big bucks. If it has a late 1969 cast date then it is a ls5 or ls6...chevelle and vette guys will pay big bucks for it if the dates are right ...I have 2 of them.One IS A Dec 68 cast 427 4 bolt main and one is a December 69 LS5 2 bolt main...It came in a chevelle with a manual trans.....It is damaged from a lifter failure because I didn't know it was worth anything and had it in my race car...
http://www.chevelles.com/forums/showthread.php?t=289174
I think they used the 512 block for several years after 70 so it may be just another 454 but I would look at the dates on the block and see.
http://www.chevelles.com/forums/showthread.php?t=289174
I think they used the 512 block for several years after 70 so it may be just another 454 but I would look at the dates on the block and see.
#8
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RACING JUNKIE
Join Date: Sep 2007
Posts: 4,137
Originally Posted by jjam
Well just my luck the stamp numbers are gone, block must have been decked... the heads are 3873858. Are there any other numbers I can find on the block, now I have the heads off and droped the pan