What BBC 427 block to start with? - Chevy Nova Forum
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Old 1st-March-2008, 05:44 PM   #1
justsomeguy

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Question What BBC 427 block to start with?

My son and I are working on a 72 Nova project and we have decided to build up a 427 BBC motor. I put an ad in the local paper for a block and am suppose to go Sunday and see a couple 427's and a 454. Which block would be best for a 500hp to 700hp build. How would I be able to tell the 427 block or 454 block I want from ones I don't.

Thanks for the help
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Old 1st-March-2008, 06:00 PM   #2
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the casting numbers... and get the 454 block... you can build a 496 with ease.. same cost as a 427 or 454.
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Old 1st-March-2008, 06:43 PM   #3
justsomeguy

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What casting numbers do I want for the 454 block and if that is not good . What casting numbers for 427 do I want? What is the actual differences am I lookig for. What questions should I be asking about the block? $bolt mains, year of block, what it came out of. What do I need to know>

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Old 1st-March-2008, 07:14 PM   #4
WILMASBOYL78

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Post BB engine...

There is a big difference between building a 500hp engine and a 700hp one....most common casting number for the 454/427 blocks is 512 (1969-1971) after that the 289 block (454) was used (72-75) these were 2 bolt versions...you can make a 427 from a 454 block with the correct crank and balancer. 2 bolt motors are usually fine up to 450-500hp...after that 4 bolt with studs is probably wise...earlier 427 blocks will also work...it really depends on your goals...for the high horsepower build a stroked 454 is probably the best bet. Those big cubes are hard to beat. Any used block should be magged and sonic checked before building...you need to know what you're starting with...others may have different thoughts...good luck.

wilma
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Old 2nd-March-2008, 12:49 PM   #5
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A 454 and a 427 block are teh same thing, and all are about the same strength. The only thing is that a 427 block is going to be alot more valueable to a restorer, so a 454 block should be cheaper to buy. A 512 block can be identified by the date code. If it's a late 68/early 69 date it's a 427 block. If it's dated after that it's a 454 block. If you happen to find a 427 block with the tapped and threaded plugs in the oil filter boss, I'll make a valueable engine, especially a 69 block. If you end up with a spare one of these, let me know and I'll take if off your hands
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Old 2nd-March-2008, 04:39 PM   #6
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Thank you very much for the info. My son and I went to see the engines today. The 454 in a79 chevy pick up and is the original motor. He said he drove it to where it is parked and it has sat there since, he says it needs rebuild, it been there awhile. One 427 is a goodwrench 427 about 7 years old with only about 3500 mi on it before the truck it was in was wrecked. It has sat outside for the 7 years with the front end removed and the top of engine, front pulleys, brakets and etc are very rusty. The third 427 is in a late 60's chevy C20 dump truck and is original to the truck. He says it ran good when he drove it to where it is parked. The place we went to is not much more than a private junk yard with vehicles and stuff sitting outside all over the place.
What would be a fair price to offer for these engines. I know it is hard to determine without seeing them but please give me an idea.

Thank you,
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Old 2nd-March-2008, 04:48 PM   #7
WILMASBOYL78

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BB engines...

Sounds like the 427 motors may be tall deck truck blocks....the 454 is a smog era engine...may have 4 bolt mains...should make a good base provided there is no serious wear or damage...heads may not be the best.....if you can get casting number off the back of the block and head numbers it would help.

Don't you know a reputable machine shop that has a core motor available for rebuild...might take some of the mystery out of this project.??

wilma
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Old 2nd-March-2008, 10:37 PM   #8
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I will check in my area for machine shops and see what is available.
Thank you for the idea and info
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Old 2nd-March-2008, 10:41 PM   #9
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Try This: http://mortec.com/

Lots of good info to use.
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Old 3rd-March-2008, 10:17 AM   #10
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If the C20 427 is in deed a tall deck... then that is the one I would go with... but thats me... the tall deck presents a few problems... the extra deck hight makes for header fitment a little different... Intake manifold is different and distributor is different.... but you can build a 535 ci with nice long rods... because of the deck hight....... It is purported that the 427 Tall decks suffer more than the passenger deck block from increased core shift......I can't speak to this...

I like the tall deck but it presents problems all its own... However; the 454 block can be made in to a 496 with little to no effort, and all the stanard goodies bolt on with no problems, and its cheaper to build... than the 535 tall deck
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