400 Big Block Sonic Numbers

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plefe

plefe

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I have been following you folks for awhile now and have been learning what I can out here in the big open spaces of Montana. I've been around motors, machine shops, and race cars since the 60's but never learned enough to gain the knowledge you folks have because I was chasing cows and dreaming. I have been offered 3 400 blocks ranging from November 1971 to 1973. They are in various stages of completely stock form, having been pulled from their original cars. When it comes to sonic checks, what thickness should I be looking for, for the 500hp builds, the 600hp builds, up to my ultimate goal of a low - medium compression pump gas stump pullin torqued 750hp street/strip build? Since the motors are not local, however in the same state, I can't shell out the money without having them checked first for cylinder wall thickness and or any cracks (too far away to just drive over).
 
I started with a 400 block for my 499 build. It's a 1972 block. Some say its the strongest . Its also the first year for the 400. 750hp out of a stock 400 block will be living on the edge for sure. Having them checked for cracks is a good idea.
 

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The sad part is, you won't know until each block is tested which is the best of them. In terms of 750hp... If you are truely serious, I would not use a factory block at all. Reason being you will be spending within $1K of a new block just to make a factory block try to live. Order a Kieth Black B wedge and it's fully machined properly and well, and ready for assembly. 650's easy to reach, doesnt take tremendous rpms or compression, and a factory block will last a while. In terms of sonic test results... For the B wedge I would not use something that tests at under .200 after overbore on the major thrust. You are maxing out the block in terms of power. So the "if it's over .150" "deals isn't going to work for you. You will also need a much better head than the RPMs for any serious effort over about 580hp.
 
moper said:
The sad part is, you won't know until each block is tested which is the best of them. In terms of 750hp... If you are truely serious, I would not use a factory block at all. Reason being you will be spending within $1K of a new block just to make a factory block try to live. Order a Kieth Black B wedge and it's fully machined properly and well, and ready for assembly. 650's easy to reach, doesnt take tremendous rpms or compression, and a factory block will last a while. In terms of sonic test results... For the B wedge I would not use something that tests at under .200 after overbore on the major thrust. You are maxing out the block in terms of power. So the "if it's over .150" "deals isn't going to work for you. You will also need a much better head than the RPMs for any serious effort over about 580hp.
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I agree that I would be living on the edge at 750hp, but I'd sure like to bump it. And yes, I understand about dollars and a repop block for getting to the edge safely and economically. But you know it's not everyday a body has a chance to pick up 3 400 blocks for $200 a pop. I'd hate to do the overbore first to find out a block tests under.200, because the money is then being shelled out for machining. I would have all 3 blocks magna-fluxed at the very least. I was really thinking about spending the cash at Muscle Motors to collaborate on the blocks. Will see. Thanks for the numbers.
 
plefe said:
I agree that I would be living on the edge at 750hp, but I'd sure like to bump it. And yes, I understand about dollars and a repop block for getting to the edge safely and economically. But you know it's not everyday a body has a chance to pick up 3 400 blocks for $200 a pop. I'd hate to do the overbore first to find out a block tests under.200, because the money is then being shelled out for machining. I would have all 3 blocks magna-fluxed at the very least. I was really thinking about spending the cash at Muscle Motors to collaborate on the blocks. Will see. Thanks for the numbers.
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And by the way, that is my favorite Cuda body style and it's done up right.
 
No problem. Just and FYI...I wouldnt pay that much for them. I sell sonic tested, cleaned, magged, ready to machine ones for $400. A core 400 block that hasn't been magged or cleaned is a $50-100part tops.
 
It won't be livin on the edge if all you do is idle around town. lol
 
OKDart said:
That 1971 block may be a 230 block (sometimes called a cold weather block), it has thicker main webs. That would be the one I'd get.

More info:

http://www.dodgecharger.com/forum/index.php/topic,22484.0.html
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Thicker webs is nice but it doesn't mean much if the cylinder walls are thin and you need to sleeve multiple holes . The early 400's suffered with core shift. The later blocks , 75 up , would be a better choice .

Koleno is supposed to be releasing a low deck IRON wedge soon .

Dave that's not a bad price for a known good core 400 ready to machine .
 
Nope. But my inventory is not what it used to be on big blocks... I'm down to one each 383, 400, 440. And their the ugliest ones of each..lol. It's the small blocks that are "en vogue" now.
 
moper said:
Nope. But my inventory is not what it used to be on big blocks... I'm down to one each 383, 400, 440. And their the ugliest ones of each..lol. It's the small blocks that are "en vogue" now.
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\

I hear ya , I sold all my blocks except a for a 73 400 block , still got too many 383's though:munky2: , no smallblocks in my future .
 
StrokerScamp said:
It won't be livin on the edge if all you do is idle around town. lol
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Not likely, as we have three drag strips within 3 hours drive and 1 within 2 hrs and a local guy to run with. I'm not into just driving around, but the urge will be there just the same. I want to have some fun again, and a stump puller pump gas friendly bustin a move 400 stroker could be that ticket.
 
glad to see im not the only montana person on here. besides that im looking to build a 400 stroker motor for my 68 d100 that i want to use for a street/strip truck, so where im going with this is any info you or anybody has about making a 451 stroker that makes over 500hp/500trq on some what of a budget but i dont want to go to cheap, would be greatly appreciated. thank you
 
moparmorrell said:
glad to see im not the only montana person on here. besides that im looking to build a 400 stroker motor for my 68 d100 that i want to use for a street/strip truck, so where im going with this is any info you or anybody has about making a 451 stroker that makes over 500hp/500trq on some what of a budget but i dont want to go to cheap, would be greatly appreciated. thank you
Click to expand...

Hello! So where are you located? I'm in Great Falls. If you haven't checked out the Mopar Magazine and thir articles for low budget low deck motors, you are missing out. In fact, if you go to http://www.moparmusclemagazine.com you can sign up and search the articles.
 
JohnRR said:
Thicker webs is nice but it doesn't mean much if the cylinder walls are thin and you need to sleeve multiple holes . The early 400's suffered with core shift. The later blocks , 75 up , would be a better choice .

Koleno is supposed to be releasing a low deck IRON wedge soon .

Dave that's not a bad price for a known good core 400 ready to machine .
Click to expand...
Ive always been under the impression 76+ 400s (and 440s) were ALL thin walled and risky to use or at least bore more than .030???? When did that change? And if you have an early 72 ish 400 by all means fill it too the bottom of the freeze plug holes with hard blok and they have been proven good to 900hp in a B1 head with good main caps configuration. Pretty sure time hasnt changed those facts.
 
plefe said:
Hello! So where are you located? I'm in Great Falls. If you haven't checked out the Mopar Magazine and thir articles for low budget low deck motors, you are missing out. In fact, if you go to http://www.moparmusclemagazine.com you can sign up and search the articles.
Click to expand...

Hello, im located in missoula so not to far. thanks for the tip ill be signing up tonight on there and check out there articles
 
Hey, one of my sites is in Missoula! This is the second place I've ever heard of the town...lol.
 
72BBSwinger said:
Ive always been under the impression 76+ 400s (and 440s) were ALL thin walled and risky to use or at least bore more than .030???? When did that change? And if you have an early 72 ish 400 by all means fill it too the bottom of the freeze plug holes with hard blok and they have been proven good to 900hp in a B1 head with good main caps configuration. Pretty sure time hasnt changed those facts.
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The problem is there's "facts", and theres "fact". The engineers say that and it's published with all the other "facts". And, on paper, the facts are usually pretty close to true. However, singular "fact" is the chunk of iron sitting on the stand as the foudation of your engine. The foundry execution of the casting process wasn't really good. With the core shift issues that affect pretty much all Mopar engine blocks (including many MP versions), any block could be gold, or only good enough for mild builds only. Regardless of year, block casting number, directives for thicker or thinner, directives on higher or lower nickel content, or anything else. Reality of the block in one's hands is different from historical record. "Facts" ain't "fact".
 
72BBSwinger said:
Ive always been under the impression 76+ 400s (and 440s) were ALL thin walled and risky to use or at least bore more than .030???? When did that change? And if you have an early 72 ish 400 by all means fill it too the bottom of the freeze plug holes with hard blok and they have been proven good to 900hp in a B1 head with good main caps configuration. Pretty sure time hasnt changed those facts.
Click to expand...

It's a myth given to us by larry shepard, Andy F pretty much debunked that one a few years ago. He found that the later blocks were actually thicker and the core shift was not as bad, what he did find out was that the metallurgy was different , the later blocks are a little softer and depending on who you talk to that is not a bad thing.

No matter what year you use have it checked out FIRST and plan your build accordingly, or just buy the Koleno block when it becomes available.
 
Small World !

Howdy to you Montana Guys, I'm 10 minutes north of Eureka on the B.C. side.

750 is alot for a stock 400 Block to be sure ?
It can be done, even on just a 451 inch to maintain the better Geometry,
but IMO,
aftermarket Main Caps would be req'd at the very least, for any reliability at all ?

Nonetheless, you have a Neighbor who's already done it,
see here;
http://www.dodgecharger.com/forum/index.php/topic,78039.0.html
 
moparmorrell said:
glad to see im not the only montana person on here. besides that im looking to build a 400 stroker motor for my 68 d100 that i want to use for a street/strip truck, so where im going with this is any info you or anybody has about making a 451 stroker that makes over 500hp/500trq on some what of a budget but i dont want to go to cheap, would be greatly appreciated. thank you
Click to expand...

Thats pretty easily done ?
send me a pm I'll send you a coupla Combos with Dyno Sheets.

Bob
 
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