yes, it's a decent deal. Cheaper mostly because of the less expensive pistons. Be aware that even with an SHP block this is not a throw together type deal. You'll probably need to make a couple trial builds with no rings or seals to get everything in the bottom end sorted. The block might have enough room at the pan rails to not need grinding there, but there's still the bottoms of the cylinders and the inevitable issues between the rod shoulders and cam lobes on cylinders 1, 2 and 5, 6. H-beam rods are better here because they're smaller around the shoulders and easier to clean up on a belt sander.

I'd think carefully about switching to a dish piston to lower the C.R. for trouble free operation on whatever pump gas is available and maximum tuneability for power and economy. Around 10:1 with quality aluminum heads is good. 10.7? not so much.

 

Wow, just went and looked at the ad on Speedways site. They're showing a pic of a flattop piston which would be over 10.7 with a 64cc head to begin with. In the text of the specs of the parts they get around to mentioning that the pistons have a .283 dome. this is 15-20cc, they don't give this critical information. in the reviews section they cop out to the real story, with those pistons and a 64cc head the CR is 14.1:1. Not close to something you're going to run on the street car unless you live at a race gas plant and never drive farther than 1/2 tank will take you. unless you don't care about getting back with the engine in one piece. This is why you have to regard those fine offers suspiciously. They should be publishing that info upfront and at the top but it would wipe out much of their potential market. So what happens if you buy it, have it balanced by them or somebody else, figure out what the real story is on the compression and want to send it back as completely unusable? Sorry Charlie, you've altered the parts and you own them now.

IMO it's irresponsible and dishonest of them to market that deal as being 10.7:1 on the page when they know it's not even close to that. Wonder if they did this type stuff when the old man was still alive?

 

with 4.155 bore, 3.875 stroke, 4.175 x .039 head gasket, zero deck, 64cc chamber and 12cc dome it's really 15.1:1. run right down and fill'er up with unleaded regular, hide and watch the explosion. This a 114 or 116 octane engine.

 

I don't like KB pistons. I have two different friends that experienced KB failures.

One cast one was forged.

Don

 

Keith Black is junk,,had one disintergrate on the dyno at 5000 rpm,there goes the block ,connecting rod,oil pan...

Not tobe confused with another company now sells piston with the KB signature..I believe it is Carillo industries...

 

I build quite a few of the 421's along with move moving rotators and machined blocks which seems very popular today.

Those rods are not a stroker rods which will not have much cam clearance or pan rail clearance which means you need a very small base circle which is tough on lifters, Pan rails will need a lot of machining and will most likely need a stroker pan which skips every other bolt hole which = leaks.

I have been using the Callies Compstar crank and rods along with a Mahle flat top pistons, I am a W/D for AFR and have been using the 75CC chamber heads which bring the compression to appox 10:8

I do use a solid roller cam .420 lobe and reduced the base circle to .990 in turn I go to a .904 lifter with a bigger .810 wheel = stronger body + bigger axel + bigger wheel = less revolutions around the lobe, and less lifter pressure angle.

Here is a link to a build I did. Some good info in this link and all shelf stock parts and can be duplicated very easy.

http://www.chevelles.com/forums/showthread.php?t=481081

 

Real world experience here with Scat forged crank, Scat forged I beam rods, and CP forged pistons in a Dart SHP 421.

Part numbers and cost:

Crank: Scat P/N Scat 4-350-3875-6000: $600
Rods: Scat P/N 2-ICR6000-7/16: $300
CP Pistons: BC1111-030-8: $670

So, for $170 more than the Speedway deal, you know exactly what you're getting. I have all this in my Dart SHP 421 built by Mike Lewis.

I can't even find those pistons listed on KB's website. Those rods area a crap-shoot in my opinion. And it doesn't actually list what crank it is...just that it's a Scat crank (which is fine, but I'd want a part number).

I won't disagree that 14:1 or more isn't gonna be street friendly but I do disagree that anything above 10:1 isn't street friendly. 11.23:1 here on 91 pump gas with my 421. Ran a 383 with a cast rotating assembly, hyper pistons, and Profiler aluminum heads at 10.7:1 for quite a while mostly on 91 but occasionally on 87. No problems.

I'd spend the extra coin if I were building a motor with that block...it's not that great of a deal. Why skimp even $250 when building a motor like that...it has the potential with the right heads and cam to make 600HP. Build the bottom end right so later on if you change your mind, you won't be thinking "Gosh...I really wish I'd put a better rotating assembly in this engine."

 

Real world experience here with Scat forged crank, Scat forged I beam rods, and CP forged pistons in a Dart SHP 421.

Part numbers and cost:

Crank: Scat P/N Scat 4-350-3875-6000: $600
Rods: Scat P/N 2-ICR6000-7/16: $300
CP Pistons: BC1111-030-8: $670

So, for $170 more than the Speedway deal, you know exactly what you're getting. I have all this in my Dart SHP 421 built by Mike Lewis.

I can't even find those pistons listed on KB's website. Those rods area a crap-shoot in my opinion. And it doesn't actually list what crank it is...just that it's a Scat crank (which is fine, but I'd want a part number).

I won't disagree that 14:1 or more isn't gonna be street friendly but I do disagree that anything above 10:1 isn't street friendly. 11.23:1 here on 91 pump gas with my 421. Ran a 383 with a cast rotating assembly, hyper pistons, and Profiler aluminum heads at 10.7:1 for quite a while mostly on 91 but occasionally on 87. No problems.

I'd spend the extra coin if I were building a motor with that block...it's not that great of a deal. Why skimp even $250 when building a motor like that...it has the potential with the right heads and cam to make 600HP. Build the bottom end right so later on if you change your mind, you won't be thinking "Gosh...I really wish I'd put a better rotating assembly in this engine."

Sounds like a plan. I was just kicking around some ideas for a big inch, lower rpm SBC tire burner. No 6000 sustained runs ever or even track time..a street motor that lights the tires on demand. For something like that would a forged crank or pistons even matter? Probably not even available in cast I'd guess..

 

For a low RPM street motor I seriously doubt a forged crank or even pistons are needed. I ran my 383 SBC with a cast crank, PM rods, and hyper pistons to 6K all the time (no racing) and it was just fine...and that was on a 2 bolt main too. It wasn't a roller block, but I built it up to replicate the ZZ383 with a roller cam conversion and better heads...it was a really great little motor, but I wanted something much more powerful, hence the big Dart 421 I had built.

Here's the thing...if you want to build an SHP block up, you may as well put in a forged rotating assembly. The block alone will cost you close to $2K...just doesn't make sense not to put a forged rotating assembly in something built to handle so much power. I know CNC Motorsports sells them and you can spec them out with whatever parts you want. I know for a fact Dart was selling SHP short blocks with cast components in the rotating assembly...I can't remember which parts though. Might check that out...the SHP blocks are expensive though so it won't be a budget deal no matter what you put in it.

Nothing wrong with a GM 400 block if you can find a good one.

 

For a low RPM street motor I seriously doubt a forged crank or even pistons are needed. I ran my 383 SBC with a cast crank, PM rods, and hyper pistons to 6K all the time (no racing) and it was just fine...and that was on a 2 bolt main too. It wasn't a roller block, but I built it up to replicate the ZZ383 with a roller cam conversion and better heads...it was a really great little motor, but I wanted something much more powerful, hence the big Dart 421 I had built.

Here's the thing...if you want to build an SHP block up, you may as well put in a forged rotating assembly. The block alone will cost you close to $2K...just doesn't make sense not to put a forged rotating assembly in something built to handle so much power. I know CNC Motorsports sells them and you can spec them out with whatever parts you want. I know for a fact Dart was selling SHP short blocks with cast components in the rotating assembly...I can't remember which parts though. Might check that out...the SHP blocks are expensive though so it won't be a budget deal no matter what you put in it.

Nothing wrong with a GM 400 block if you can find a good one.

A good one would be the operative word there. I'll keep my eyes peeled for any big inch block