Casting # 3963512 is the one all the 70 Chevelle guys want as it's what the 450 hp LS6 used. It was also used on the 345 hp LS4 & 360/390 hp LS5's. I know the 1972-78 3999289 castings are more plentiful and somewhat cheaper.
427's and 454's share the 4.250" bore, but the 454 has a 4" stroke. As such, the 454 crank has larger counterweights and the 512 castings account for that. They started used 512 castings on late 1969 427's, were used throughout the 70 model year, and I think into the 1971 model year. What makes that casting valuable is the 69 Camaro COPO guys want early castings to make their cars #'s match (keep in mind they made 70 Camaro's until like January 1970 or something like that), and the 70 Chevelle guys want mid-year and later castings to make their LS6 Chevelles #'s matching. 70 Chevelle's didn't get the LS6 option until around February 1970, 70 Corvette's had the LS6 available to them all year.
I don't know if there's anything special about that block other than the casting #.
It was used in the late '69 427 and '70-'71 LS6 applications. Any 454 block is good whether it be a 4 bolt or 2 bolt main block. I know guys that are getting 500+ hp out of 2 bolt blocks. Don't get caught up in the 4 bolt myth. And 512 blocks are only special if you are one of the few who are restoring an LS6 car or a late '60's L72/L88 car. The LS5's had 2 bolt blocks, lower compression, oval port heads(good for bottom end torque), cast intake blah blah blah.... and are just as good. I had a "289" block in the 'Chief that made dyno'd 375 hp and 480 lbs/torque. It pulled like crazy. And I'm pretty sure a decent 454 can be punched .100. Mine was .060 over(468). And if you want to get creative, obtain a 427 tall deck(bus, big truck) and there is plenty of room for a real torque monster if you are inclined to stroke it. A 496 makes lots of power either way-torque/hp- and they are only 1/4 inch taller than a regular passenger block. They are like that as to accommodate an extra ring on the pistons. And if you can pick up a short block chances are it'll have a steel crank. Either 427 or a 366 which will have the same stroke as the 396 crank. It'll have the "6223" or "7115" casting on them. I've had a few of them over the years. If you don't mind me asking, what are you planning on building?
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"No matter how much you change, you still have to pay for the things you've done".
I started thinking about a 454 based budget 496 stroker to fill my power deficit after reading about them.
To start, stick with a lower compression, basic simple build, cast crank, good rods, Hyper pistons, milder flat tappet cam, good vacuum, smaller ports. A stump puller from 1500 and max not much higher than 5700 rpm. Built to somewhat under hood resemble a 67 427. The only indulgence might be budget aluminum heads, a good aluminum intake and WP (giving improved performance and lowering the weight) and a pair of good quality full length ceramic headers.
As much as I've been focused for some time on a SBC 383, the fact is, if careful, I've learned I might just be able to create a 496 for just a little bit more. And yes, no argument, a BB will produce gobs of unstressed torque. Reading all the articles on line have really swayed me. And having such an engine will leave room for much more, plus I'd get bragging rights just like Carl.
If I end up doing this, the plan would be to perhaps sell my nice running HO350 as a complete drop in turn key engine, everything included. This could help pay back the BB build.
I figure start with a good 2 or 4 bolt block, get it machined, bored and cleaned up. Then buy a decent pre-balanced rotating assembly and build up from there.
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65 Laurentian post, 67 Grande Parisienne 4 door HT.
I started thinking about a 454 based budget 496 stroker to fill my power deficit after reading about them.
To start, stick with a lower compression, basic simple build, cast crank, good rods, Hyper pistons, milder flat tappet cam, good vacuum, smaller ports. A stump puller from 1500 and max not much higher than 5700 rpm. Built to somewhat under hood resemble a 67 427. The only indulgence might be budget aluminum heads, a good aluminum intake and WP (giving improved performance and lowering the weight) and a pair of good quality full length ceramic headers.
As much as I've been focused for some time on a SBC 383, the fact is, if careful, I've learned I might just be able to create a 496 for just a little bit more. And yes, no argument, a BB will produce gobs of unstressed torque. Reading all the articles on line have really swayed me. And having such an engine will leave room for much more, plus I'd get bragging rights just like Carl.
If I end up doing this, the plan would be to perhaps sell my nice running HO350 as a complete drop in turn key engine, everything included. This could help pay back the BB build.
I figure start with a good 2 or 4 bolt block, get it machined, bored and cleaned up. Then buy a decent pre-balanced rotating assembly and build up from there.
I started thinking about a 454 based budget 496 stroker to fill my power deficit after reading about them.
To start, stick with a lower compression, basic simple build, cast crank, good rods, Hyper pistons, milder flat tappet cam, good vacuum, smaller ports. A stump puller from 1500 and max not much higher than 5700 rpm. Built to somewhat under hood resemble a 67 427. The only indulgence might be budget aluminum heads, a good aluminum intake and WP (giving improved performance and lowering the weight) and a pair of good quality full length ceramic headers.
As much as I've been focused for some time on a SBC 383, the fact is, if careful, I've learned I might just be able to create a 496 for just a little bit more. And yes, no argument, a BB will produce gobs of unstressed torque. Reading all the articles on line have really swayed me. And having such an engine will leave room for much more, plus I'd get bragging rights just like Carl.
If I end up doing this, the plan would be to perhaps sell my nice running HO350 as a complete drop in turn key engine, everything included. This could help pay back the BB build.
I figure start with a good 2 or 4 bolt block, get it machined, bored and cleaned up. Then buy a decent pre-balanced rotating assembly and build up from there.
You spend too much time reading and you have too much money.....
Just my two cents!
I approve of any and all big block conversions as long as they don't involve pirating big blocks from matching number Canadian Pontiacs. I could NEVER approve of that.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
I started thinking about a 454 based budget 496 stroker to fill my power deficit after reading about them.
To start, stick with a lower compression, basic simple build, cast crank, good rods, Hyper pistons, milder flat tappet cam, good vacuum, smaller ports. A stump puller from 1500 and max not much higher than 5700 rpm. Built to somewhat under hood resemble a 67 427. The only indulgence might be budget aluminum heads, a good aluminum intake and WP (giving improved performance and lowering the weight) and a pair of good quality full length ceramic headers.
As much as I've been focused for some time on a SBC 383, the fact is, if careful, I've learned I might just be able to create a 496 for just a little bit more. And yes, no argument, a BB will produce gobs of unstressed torque. Reading all the articles on line have really swayed me. And having such an engine will leave room for much more, plus I'd get bragging rights just like Carl.
If I end up doing this, the plan would be to perhaps sell my nice running HO350 as a complete drop in turn key engine, everything included. This could help pay back the BB build.
I figure start with a good 2 or 4 bolt block, get it machined, bored and cleaned up. Then buy a decent pre-balanced rotating assembly and build up from there.
My 454 .30 over BBC ( core from Carl S ) Gen IV high nickel , 2 bolt main, balanced steel crank, forged pistons, roller cam, 9.7 SCR, ported and blended cast oval heads and EFI easily made 575 lbs torque and 570 HP on only a few pulls on Dyno. Choice is yours, my car is scary fast and pulls like a freight train.
Les
-- Edited by Beau 69 on Monday 24th of November 2014 01:00:10 PM
