I have an abundance of std bore 396 engines and a strong desire to experiment with a twin-turbo setup.
By the time I'm done, certainly the cost of the block would be inconsequential anyway, but out of curiosity, I'm wondering if the thicker walls of a 396 would be stronger than a 427 by any noticeable margin?
I was thinking a 4340 crank and rods, splayed billet caps, and blok-cement the bottom couple of inches. Or after machining and parts would I be at the cost of a fully-forged crate block in 454/502 size anyway?
Nov 6th, 06, 07:23 PM
I guess it depends on which casting #'s 396 you're talking about, I've heard some are thicker than others, in fact, I've heard of them being bored out .125 to 427 cubes with no issues. My gut instinct would be to measure the cylinder wall thickness so you know for sure, decide if an overbore is needed, and then make your decision from there. If you've got an abundance of them, I say go for it!
Nov 6th, 06, 07:28 PM
Any way to check wall thickness without a sonic thingy?
Nov 6th, 06, 07:33 PM
Not a lot of difference between them. Both 2 bolts are close and so are the 4 bolts except the 65 396 4 bolt block is supposed to be thicker but I have never checked one. I would go with an aftermarket block.
Nov 6th, 06, 07:48 PM
Knock out the core plugs on one side of the engine. Check the distance between the cylinder barrels. If it's 1/2" or so, they're thinner walls, don't generally bore more than .060 over. if they're more like 1/4", so a pencil just fits between 'em, they have much thicker cylinder walls and can be bored to about the same dimension as a regular 427/454 block. I'd try to find a -289 block and use the bigger bore block - those are supposed to be some of the thickest cast.
Nov 6th, 06, 07:51 PM
The two blocks I have handy are 3969854 and 3955272. Where would the -289 you refer to appear?
Nov 7th, 06, 05:16 AM
289 would be the last 3 numbers in the sequence.
Nov 7th, 06, 05:30 AM
Bob is right, full casting number is 3999289. I've looked at a lot of 396's but never took the time to check casting numbers on the thicker blocks. That would be a good group of numbers to have handy, though!
Nov 7th, 06, 06:34 AM
Ed Saffel say's that he's found that a '66 396, -961 block would bore out .155" to 4.250" to create a 454 with no lower crank area grinding.
Nov 7th, 06, 05:28 PM
I have a 66 961 block that a pencil will go between the cylinders. I don't know what he has but I haven't come across one.