Re: Is it true that .....
 

high nickle blocks have a little more nickle in the iron than a normal block, and they don't wear nearly as fast. I took apart a caddy big block (they were all high nickle) that had a tad over 100K on the clock, and there was not only no ridge at the top of the cylinder, but you could actually see a little bit of the cross hatch from 100,000 miles ago.
that 300,000 mile (never rebuilt) 350 did have some ridge, but the pistons still came out the top by hand with no ridge reamer needed.
On chevy engines, high nickle blocks can be ID'd by seeing 10 and 20 under the timing chain IIRC. In my opinion, high nickle is WAY more important than 4 bolt mains.

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Longhorn, could you confirm this method? Do regular blocks have nothing and the high nickel has the 10 or 20 under the timing gear.

Also, how do you tell a forged crank?
Thanks,
s/t

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Yep, only the high nickel, high tin blocks have the 010 (10% tin) and 020 (20% nickel) casting marks under the front cover - here's what those marks look like. I tore this block down and it had virtually no measurable bore wear after 160K+ miles!

Cast cranks can be distinguished from forged cranks by the parting line on the nose of the crank - a wide parting line means forged, thin means cast. I can upload a picture if that's not clear.

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IIRC, on this subject, all 307's are also low-nickel...FWIW. :hm:

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I definitely seen some numbers under my timing gear, but not positive on what they were. Do regular blocks have nothing? I can pull the time sprocket back off if need be.

Bill, if you don’t mind posting the picture that would be great.
And what is the silver plug for? I seem to remember a hole in mine.
s/t

Re: Is it true that .....
 

they all have markings, but the 10 20 is the magic number.

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This turned out to be a good thread with lots of interesting info.

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It was eat’n me up about this 10 20 stuff so I removed the timing sprocket and look what I found…..:metal:
s/t

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:agree:

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Now I want to know what the end caps are and how to tell what I have. I read (somewhere recently) about a good end cap that came with some motors. How do you check this? Is the end cap what holds the crank in (4 bolt or 2 bolt)?
I also want to check my crank for a forged crank, but not sure how to do this.

I decided to pull the motor & clean everything up replace gaskets. (Look for a new thread on this subject).
s/t

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I don't know of any upgraded or HD rear caps - anyone?

I've attached a picture of my Chevy forged 350 crank which I hope helps illustrate the differences. Look at the nose of the crank on the back of the first rod throw...see the very wide mark there? On a cast crank, this will be very thin line of casting flash. I wish I had a cast crank to show the differences, but this is all I have on hand at the moment - it's for my 'Vette LT-1.

And before anyone says anything, yes - it's being stored flat. I have teenage kids that also use my garage. I'd rather straighten it later than get it beat to crap now :)

Ummm..that whole "gee, I'm just going to do this one thing" usually leads to an overhaul "while I'm in there" :)

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It's a front oil gallery plug - there are 3 of them and they should definitely have plugs in them. Many rebuilders tap these for 1/4" NPT...but for street engines I just put in the stock-style plugs.

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for the record, I've found the 10 20 motors to be almost common in these trucks.

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Yep, me too. The most common applications seem to be police/taxi/truck engines - basically commercial or heavy-duty use. I also can't think of a single '010 block that I pulled that wasn't one of these. I scam about every one of these blocks I can get :)

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well i got one better GM has over 15,000 of the 010 4 bolt main from Mr goodwrech and the price verys from your low Horse power of 220 hp and the 255 hp the 220 hp eng Long block all brand new from GM is 1400.00 if you build a engine for around the same HP your getting ripped off to days eng market cost you rully 1300.00 to build a 30 over or even 40 over 350 eng with a re gounded cam and crank in the new engine every thing is brand new so why waste the money the one for 300hp is like 1900.00 you will have over 1800 to 2300.00 after all said and done from GM you get the oil pan valve covers no intake and these are the 3970010 blocks 4 bolt mains

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The original truck motors are almost all 010 or 020 castings. Of the dozens I've pulled over the years, they were all 4 bolt main with high nickle. THis is why knowledgeable builders pay big bucks for them--$400. is great money --ty to get that for a late 70's to mid 80's!!! If you really want a nice hi-po small block, I would have a 010 small block rebuilt hooked up with some Vortec heads and a high torque--low rpm performance cam to match up with your application---race, cruse, haul-tow, etc. Then you can maximize the potential of carb, intake, headers. Just throwing performance crap on a stock block is like putting premium fuel into a 6 banger!! My .02---Huck

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oil galley plug holes plugged for a member :)