BB casting thickness differences
Thread Starter
Le Mans Master
Joined: Jan 2005
Posts: 8,226
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From: Lake Wylie SC
BB casting thickness differences
I am trying to determine which 4 bolt 454 9.8 BBC blocks have the thicker castings. I have heard that after 1975 the castings were thinner on some but not on others.
Any help is appreciated
Doug
Any help is appreciated
Doug
Drifting
Joined: Aug 2004
Posts: 1,883
Likes: 124
From: Lubbock TX
Easiest quick way to tell is to knock the center core plug out and check the distance between the cylinder barrels. If you can barely shove a #2 pencil between 'em, it should be a fairly thick casting.
What is the casting number of your block? the -289 block is supposed to be the thickest, but I haven't seen any scientific proof or sonic check comparisons. The thinnest I've checked have been the '445 castings which is one of the most common.
What is the casting number of your block? the -289 block is supposed to be the thickest, but I haven't seen any scientific proof or sonic check comparisons. The thinnest I've checked have been the '445 castings which is one of the most common.
Thread Starter
Le Mans Master
Joined: Jan 2005
Posts: 8,226
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From: Lake Wylie SC
Thanks for the tip on the center plug
I will post the casting numbers of the two blocks I have tomorrow. I know the one is a marine block and that is the one that I have high hopes for. It is an original bore but has some rust damage that going 30 over may not remove....... kinda hard to tell until I bore the worst cylinder.
I know I need a sonic tester but I do not have one....... maybe on monday I can find someone local who has one.
Doug
I will post the casting numbers of the two blocks I have tomorrow. I know the one is a marine block and that is the one that I have high hopes for. It is an original bore but has some rust damage that going 30 over may not remove....... kinda hard to tell until I bore the worst cylinder.
I know I need a sonic tester but I do not have one....... maybe on monday I can find someone local who has one.
Doug
Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
I'm with L88Plus- I've got a -512 casting block that's .060 over and there's lots of meat left visually. I hope it is, since it's going to be a 496 when I'm done.
Thread Starter
Le Mans Master
Joined: Jan 2005
Posts: 8,226
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From: Lake Wylie SC
What I have been told is that as a rule of thumb if the block casting number shows that it entered production after 75 then the casting is thinner than those cast prior to 76
That reasoning is given evidence with the 289 block being one of the better ones with the 445 block being a not so good one. Also blocks that were designated for rectangular ports came with valve reliefs to enhance air flow....... this might be an indication of one of the better blocks and I will get back on what can be confirmed about that.
I built a 496 out of a 959 block that did not give me any issues but now that it needs to go to 70 over I am not so keen on the idea. You can do the old drag racer trick and put filler in them but IMO anyone who would put concrete in a vette other than a pure drag car has some serious malfunctions going on upstairs.
Doug
That reasoning is given evidence with the 289 block being one of the better ones with the 445 block being a not so good one. Also blocks that were designated for rectangular ports came with valve reliefs to enhance air flow....... this might be an indication of one of the better blocks and I will get back on what can be confirmed about that.
I built a 496 out of a 959 block that did not give me any issues but now that it needs to go to 70 over I am not so keen on the idea. You can do the old drag racer trick and put filler in them but IMO anyone who would put concrete in a vette other than a pure drag car has some serious malfunctions going on upstairs.
Doug
Last edited by Shurshot; Apr 5, 2009 at 08:03 AM.
Thread Starter
Le Mans Master
Joined: Jan 2005
Posts: 8,226
Likes: 2
From: Lake Wylie SC
The best I have found is a 445 4 bolt marine block with a standard bore...... so I bored it for a 30 over piston and it is fine even before being honed. According to the above post it is a thin casting but at 30 over I would imagine that I will have more meat than my old 959 block at 70 over.
I have a 351 block that is 60 over that would just need a quick fine hone if I was to use it. But it is part of very fresh good running motor (1000 miles) that I prefer not to tear apart just to use the block.
Doug
I have a 351 block that is 60 over that would just need a quick fine hone if I was to use it. But it is part of very fresh good running motor (1000 miles) that I prefer not to tear apart just to use the block.
Doug
