Have a lead on 68 big block - Team Camaro Tech
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post #1 of 5 (permalink) Old Apr 20th, 17, 05:08 PM Thread Starter
Terry
 
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Have a lead on 68 big block

I have a lead on a 68 big block 4 speed car. Its been in storage for over 10 years and was told it was a 396. Owner later corrected that its a 427 - ok real excited now. Then owner says its a 427 with a 396 crank as he was trying to remember all the details. I now think it may be a 454 with 396 crank to equal a 427. I've never seen one and wonder what I should be looking for. Will also be looking for details to see if it is a factory big block car. Would actually be happy with any big block car...Hope to see it soon as it is a ways away. Any experience with this engine combo??
Thanks in advance,
Terry
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post #2 of 5 (permalink) Old Apr 20th, 17, 05:24 PM
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Greg
 
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I've got a 427 from a 69 Impala in my 69 Camaro. It's originally a 390HP motor that had some minor tweaking as well as a cam upgrade. The engine builder estimated about 450HP which is fine for me in the lightweight Camaro body with a stick.

It's a blast to drive and revs like a small block. While I've heard before that a 454 block with a 396 crank yields a 427, I have no experience with an engine built that way.

I'd be interested to hear feedback on this combo.
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post #3 of 5 (permalink) Old Apr 20th, 17, 06:37 PM
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Dave
 
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Re: Have a lead on 68 big block

A 454 with a 396 crankshaft displaces 427 cubes; but the crankshaft has the wrong counter weights for the bob-weight of the larger diameter bore 427 piston.

The 396 crankshaft is the same as the 427 crankshaft in stroke and journal size, but the counterweight design differs. The third counterweight on a 396 crankshaft is 3/4" wide, and with a 427 it is 7/8" wide. If you use a 396 with standard weight pistons you will need some Malory metal to balance the rotating assembly.

You could use longer rods to lighten the pistons by changing the compression height, and have them lightened even further in the machine shop, but it will cost more in labor; plus you are now buying eight rods as well as eight pistons. Better to buy a 496 rotating assembly from Scat and just run 350 horse 396 decals.

Big Dave
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post #4 of 5 (permalink) Old Apr 21st, 17, 07:38 AM
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Bill
 
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Re: Have a lead on 68 big block

Assuming it's actually a 427, check to make sure that it's a low-deck (passenger car) motor and not a tall-deck truck motor.
To make sure it's a 427 and not some other big block, check the block casting numbers against mortec.com
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post #5 of 5 (permalink) Old Apr 21st, 17, 12:15 PM
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Bryan
 
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Re: Have a lead on 68 big block

Quote:
Originally Posted by Larger Dave View Post
A 454 with a 396 crankshaft displaces 427 cubes; but the crankshaft has the wrong counter weights for the bob-weight of the larger diameter bore 427 piston.

The 396 crankshaft is the same as the 427 crankshaft in stroke and journal size, but the counterweight design differs. The third counterweight on a 396 crankshaft is 3/4" wide, and with a 427 it is 7/8" wide. If you use a 396 with standard weight pistons you will need some Malory metal to balance the rotating assembly.

You could use longer rods to lighten the pistons by changing the compression height, and have them lightened even further in the machine shop, but it will cost more in labor; plus you are now buying eight rods as well as eight pistons. Better to buy a 496 rotating assembly from Scat and just run 350 horse 396 decals.

Big Dave
I did just about like Dave is describing with my 447 BBC. Used a 3.76 stroke Callies crank with 496 pistons and 6.635 inch rods. Came to within 0.005" of the stock deck height that way. The balance guy did have to lighten the crank a little to get it to balance, drilled a pretty healthy hole in both front and rear counterweights. The engine runs real well with the large bore and short stroke, revs almost like a small block.

Bryan
1967 Camaro 427 BBC, Viper T-56 6-Spd, Z28, Red w/ White Stripes
No, it's not stock.
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