In the bowtie blocks, What is the difference between the "one piece rear main seal" and "two piece rear main seal"? I noticed the two piece is more pricey.
Bowtie block question
BigBrad
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MkIV is two piece up to 92. Because of the number of blocks out there in the field the 2 piece seal is going strong in the aftermarket. I understand the Gen 5 is in its own drama class but that the gen 6 is useable with it's 1 piece seal crank. The gen 6 will even accomodate MkIV heads with the correct gaskets.
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The Gen 5 Bowties use a block that's made for and uses the rear cap for the 1-piece rear main seal. They are factory fitted with an aluminum adapter that allows use of the traditional 2-piece rear main seal and crank. You'd have to remove both halves of the adapter (1 on the block, one on the cap) to be able to run the 1-piece cranks.
So....if you buy a new Bowtie block, it's fitted for early cranks.
And I agree, 1-piece RMS forged cranks for 454/502's are tough to find.
And GM hasn't released a Gen 6 Bowtie block, they're still Gen 5's.
You might check at Scoggin-Dickey here in Lubbock, they tend to run good sales on blocks from time to time.
So....if you buy a new Bowtie block, it's fitted for early cranks.
And I agree, 1-piece RMS forged cranks for 454/502's are tough to find.
And GM hasn't released a Gen 6 Bowtie block, they're still Gen 5's.
You might check at Scoggin-Dickey here in Lubbock, they tend to run good sales on blocks from time to time.
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Buy a Dart block.
Is it better than the GM Bowtie blocks?
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It doesn't require a two piece seal adapter. Honestly I can't say it's "better" than a bowtie but Dart is accessible after the fact.
Well for the price difference if they aren't that much different other than the two piece seal adapter, i'll stay with the Bowtie block as I can get it cheaper than I can get the Dart block of the 502...
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It's either a bowtie or a 502. Bowtie has one on the side, 502 will have 8.1L. Bowtie is a better block.
They come in two varieties, just like the Dart. One with ductile iron caps and one with billet caps (CNC version).
They'll both take more than most of us can afford to throw at 'em.
They come in two varieties, just like the Dart. One with ductile iron caps and one with billet caps (CNC version).
They'll both take more than most of us can afford to throw at 'em.
Thank you, for the helpful info.
What is the main differences, between the Bowtie and Dart block, I am just wondering?
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I like the look of the Bowtie better - looks very much like a production block. The Dart has had metal removed all along each side in the interest of making it lighter. It'll also have the name on it in a few spots and a few other things.
I went with a Bowtie on mine because I wanted it to look somewhat stock. You have to look to find the markings when it's assembled and most observers won't pick up on it. It's easy to see that a Dart isn't "stock appearing", definitely looks aftermarket.
As for construction, I think they're close enough to make 'em a wash.
Oh, and the GM block has provisions for running their dogbone/hold down lifter system. Might be good if somebody comes up with a good quality lifter that'll fit that setup.
I went with a Bowtie on mine because I wanted it to look somewhat stock. You have to look to find the markings when it's assembled and most observers won't pick up on it. It's easy to see that a Dart isn't "stock appearing", definitely looks aftermarket.
As for construction, I think they're close enough to make 'em a wash.
Oh, and the GM block has provisions for running their dogbone/hold down lifter system. Might be good if somebody comes up with a good quality lifter that'll fit that setup.
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I was looking at buying a bowtie block.
If you want to use a carb, be sure the block has provision for a mechanical fuel pump.
If you want to use a carb, be sure the block has provision for a mechanical fuel pump.
What if I wanted to use an electric fuel pump with a carb on the bowtie block ? The one i'm looking at does have a pad for a mechanical fuel pump. Would local Chevy dealerships carry the bowtie blocks I could just pick up ? I don't wanna have to pay the freight shipping if I don't have to....
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You may want to check with your local dealer as some of the BBC Bowtie blocks have been discontinued.
Dart, World or Blue print blocks maybe your choice.
Really ? Why did they discontinue them ?
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Like I said check into what P/N you need ! When GM was in financial trouble they did away with a lot of P/N
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