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Swap the mercruiser 240 5.7L 350 for the DZ302?

  • Swap it.

  • Don't swap it.

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2000 S10
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No there are all kinds of urban myths about the 010 block. Some folks swear it's 10% nickel. Not true. The one true thing about it is there were probably more of that casting number built than any other because it was around a long time and was used for all kinds of engines. 302, 307, 327, 350, 2 and 4 bolt. Not sure if it was used for the 262 or 305 V8's like the ones in the Monza's.
Agree, All kinds of myths and misinformation. I will say that you will not find a 397010 block as a 307, since a 307 does not have a 4” bore. Also, I could not make out the TBM as someone noted, but the “T” means it was in a truck, however it is not a 1970 307, if it is a 397010 block, it will be the 1979 truck 350, which is also correct for the square pad with the stamps.
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I just got my hands on a genuine DZ302 and man am I excited to build and slap that bad boy in my truck. I'll pull the mercruiser 240 out and put that sucker in and bam high rpm monster. What do yall think?
The 3" forged/nitrided crank alone is near gold. Only available as a custom build now.
Great street engine in <2500# vehicle with glide or 5spd.
352cid destroked 400 is similar combo for heavier stuff . With good heads they can push 2 tons into high 12's.
 

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The 3" forged/nitrided crank alone is near gold. Only available as a custom build now.
Great street engine in <2500# vehicle with glide or 5spd.
352cid destroked 400 is similar combo for heavier stuff . With good heads they can push 2 tons into high 12's.
The engine's pedigree is in it's large journal specific forging 3" stroke crankshaft and specific forged Pistons .

Small journal 283 engines were oft bored 1/8th inch to create high rpm larger 302 displacement
before GM had 4" bore blocks.
 

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until you put the engine on a stand, and completely take it apart to verify what it is, I wouldn't get too excited.
If it turns out to be a REAL DZ engine, with all the correct parts, it's worth close to $15k to the right person.
And, in todays world, a junkyard 4.8 Ls swap will run circles around that 50 year old technology.
 

· Boozebag
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Geezer technology.... Ha;)

Bragging rights for a DZ... BUT... not the best choice for performance unless you have a weekend original Z28 cruiser.
All of the guys piping up are pretty much accurate.

You have a possible rare turkey. If so, take advantage of the rarity

A completely rebuilt/detailed DZ gem would look smashing on a stand in your living room... :LOL:
 

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I've heard about the 010/020 marks under the timing cover supposedly meaning 1% higher tin and 2% higher nickel.
I also know a guy that's run a hone for 30 years in addition to other shop equipment. Like a lot of folks that worked at GM, he said the 010/020 is myth. Over time, you learn the machine and it's sounds and learn to interpret what they're saying. They're saying BS.
And I agree with others comments, that's not factory stamping.
At any rate, that's a very good block assuming it passes sonic testing and magnafluxing. If it's a large journal short stroke crank, you can sell it for more than a stroker crank will cost, you still have a WIN.
 

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I ran a Buick 455 and a Cadillac 500, and got familiar with them. It was a fact that those had the nickel (5% or something like that) to reduce cylinder wear, and maybe it stabilized against cumulative changes due to heat cycling. I was in a conversation where Denny Manners, the Buick engine head engineer from the '50-80's said it gave the cast iron some elasticity. I never heard if Olds or Pontiac did anything with that. I was involved with accurate resto of '62-63 and '70-71 Chevys and never heard or saw anything that confirmed use of nickel in any of their blocks.
 

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Bowtie and Dart blocks are hard as *, something similar to nodular iron. Even an unexperienced ear can hear the differences when they're being machined. It took a long time to convince racers to push it all the way to 4..600 on the first bore. They just don't wear, most need nothing more than a few passes through each bore and new rings when freshened. Unless a cylinder gets damaged, most will last for many years, even when having the * beat out of them. I have a suspicion that LS iron blocks are cast out of something similar, maybe not the whole cast recipe but definitely something that makes 'em harder than the old soft smallblocks.
 

· Boozebag
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Many of these older engines have gone through many stages of rebuilds/modifications.
I have a 1969 327 with the early "double hump" heads that have screw in studs and double valve springs.
Also has small dome pistons...
And I didn't do any of it


Point of this - you usually don't know what has been changed until you disassemble the engine in question.
I have also seen blocks that were decked and lost the factory serial number....
Anyone say "counterfeit"?
 

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Many of these older engines have gone through many stages of rebuilds/modifications.
I have a 1969 327 with the early "double hump" heads that have screw in studs and double valve springs.
Also has small dome pistons...
And I didn't do any of it


Point of this - you usually don't know what has been changed until you disassemble the engine in question.
I have also seen blocks that were decked and lost the factory serial number....
Anyone say "counterfeit"?
Quite possibly fake. However if block in question contains a 3" large journal stroke reciprocating assembly, that's about as genuine as a DZ gets .
 
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