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Discussion Starter · #1 ·
Okay so my original motor that come out of my 79 Chevy pickup has the engine casting number 3970014 and now I have another engine block that's coming out of a box truck c30 with the engine cast number 3970010.which block would be better for rebuilding? Now I do know about mine, my block is good but I'm not so sure about the other block until I tear it down. they're both running the same exact valve heads or whatever the number is match up the 462628.
 

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Either of these are the sought after casting numbers from that period. The 010 is more common than the 014 but both are excellent platforms to build on.

The most desirable of either of these castings is the 4 bolt main version.

While we rodders look a lot at casting numbers in reality castings such as these that can be finished in 2 bolt or 4 bolt mains which would create different part numbers for the years of use. From a parts counter perspective the part number would be what you order whether that came on an 010 or 014 casting.

Same goes for heads a casting number can be used for 1.94 or 2.02 intake valves for example. At the parts counter that would be seen as different part numbers even though the casting used may be common. 628’s are low compression, open chamber SMOG heads which depending on what your doing is searching for more power and improved efficiency are not desirable. However, if this is a stock rebuild then they’ll get you buy as they have in the past.

Bogie
 

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Okay so my original motor that come out of my 79 Chevy pickup has the engine casting number 3970014 and now I have another engine block that's coming out of a box truck c30 with the engine cast number 3970010.which block would be better for rebuilding? Now I do know about mine, my block is good but I'm not so sure about the other block until I tear it down. they're both running the same exact valve heads or whatever the number is match up the 462628.
C30 should be a 4-bolt main. Probably the pickup is as well, but the C30 is in a heavy duty truck and as I understand it these were 4-bolt main engines.
 

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Also do yourself a favor and make the next item in your budget a modern set of heads. Even the best 60’s and 70’s heads will not flow as well as stock iron Vortecs, and there are several budget aluminum heads that work way better. Starting off with good heads and a set of matched pistons to give you the compression you want will make it all much easier with the rest of your build.

Bruce
 

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And depending on the year, it may also havfe a forged steel crank instead of the common cast crank.
The block in my S10 is originally from a 1972 C20. It was 4-bolt main engine and had a forged steel crank. The guy who sold it to me was all focused on the steel crank and I cut a deal to let him disassemble and keep it separately since I was going the 383 route. All I took away was the bare block and left him the rest. It was STD bore and really not worn much. It would have easily gone 0.020 overbore but I ordered 0.030 pistons before taking into the machine shop.

Also do yourself a favor and make the next item in your budget a modern set of heads. Even the best 60’s and 70’s heads will not flow as well as stock iron Vortecs, and there are several budget aluminum heads that work way better. Starting off with good heads and a set of matched pistons to give you the compression you want will make it all much easier with the rest of your build.
Amen. Your choice of cylinder heads and pistons determines the power potential for your engine. The beauty of good heads is that it's a big power increase without hurting driveability at all!! Much better to have a stock camshaft with good heads, than a good camshaft with stock heads. The best recipe is to put a good camshaft with good heads for your intended purpose and get the compression ratio where it should be. Beware that the better the heads, the more money they get for them. Your pocketbook can drive the choice. Figure $10 per horsepower minimum (total) when building a new small block Chevy engine.

For a mild hot rod engine, it's hard to beat a Chevrolet Performance L31 Vortec 350. Inexpensive, all new, moderately good iron heads - slap a performance cam, intake, and headers on it and you're set.
 

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I have had enough squarebodies to know that the engine power is not that big of a deal.

Any 350 will have enough torque to make a c30 do what it needs to as a truck especially if you have a 4 speed sm465 behind it.

A C30 is going to weigh between 5000 and 6000lbs depending on the length and equipment so it will never be a fast truck. From a braking and handling standpoint they are not meant to be driven fast.

250ft/lbs is all you really need to move the old girl. Even the smog motors can pull that once you loose the air pump.

If you want 350 to 400lbs really just go with a 5.3 LS. A Sm465 or a th400 will bolt right up and the final cost will be similar to a mild built 10 block with rv cam and vortec heads.

Leave the motor stock as stated it makes enough.

A 5.3 with around 160k still will have alot of life left in it. So just run it and when it goes grab another shortblock to throw your longblock stuff onto.

If your dead set on using a 10 block then let someone else spend the cash. A 350 with vortec heads is still a bit common. So you can probally find one carb to pan built and broken in with 20 to 30k from someone doing a LS swap. Just ask around and check the thing over. But for $1500 to around $2000 you will get you a nice quality complete engine saving you $1000 to $1500 if you were to build the same thing.
 

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Discussion Starter · #9 ·
so I got down and dirty and took my motor apart just the passenger side to check on the valves in the head to see where I'm at and this is what I came up with. My engine casting number is #3970014 it is a 2 bolt main, 350 with I heads casting number #462628. during inspection there's no cracks or splits or or fractures on my head that the gaskets were immaculate good condition last time I changed them was probably three years ago. So that's great however I can't explain what I did find which is not good, if I could post the pictures maybe y'all can tell me a little bit more of what I'm dealing with and what I need to do with it I can turn a wrench but I can't make all the decisions lol! Plastic Circle Loudspeaker
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Probably best to keep it on the same thread as before, instead of starting a new one.
You are doing good Bri. Toot your horn when you go by Service King in Frisco. I used to work there! LOL!
P.S. Im not drinking yet either, that starts in a few hours. Right before lunch!
 

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Is that a chunk of piston in the second picture?
Knowing where to go from here depends on where you wanna be when your finished.
Daily driver? Drag? race only? Some or both? you gotta decide what you wanna be first.
 

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Somebody’s been in there before you as those are not production pistons unless this is an old pre SMOG LT-1.

Going with the expectation that this has already been rebuilt you should expect the cylinders walls have been bored to some oversize, the problem now is how much. To get to a good wall is going to require more boring but this has limits. Most 010 and 014 blocks will tolerate a maximum of .060 inch over the factory 4 inch bore. Beyond that the wall thickness becomes structurally unreliable.

Rust in the cooing jackets is bad news, shows inadequate amount of anti-freeze coolant to suppress rust formation. Rust is an insulator which reduces heat transfer so even trying to improve that function over the thermal characteristics of ‘coolant’ with pure water quickly becomes a lost cause. In addition, the rust gunk can and does plug small passages which ends any cooling in those places. The Chevy engine, especially the heads, are given to cracking so reducing or eliminating heat transfer and surface wetting is an invitation to cracking problems. With saying that; any rebuilding effort needs to be preceded by cleaning and crack inspection. The latter with magnetic or UV dye inspection unless the cracks are so large you can see them with the unaided eye. There is no sense in spending money for machine operations and expensive parts to find the block or heads have cracks.

I’ll leap ahead to heads for a moment in that the material the heads are made of strikes back at machine operations on the block. The issue is getting at the ideal squish/quench clearance between the piston crown and the step of the combustion chamber to be between .035 to .045 inch give or take a few thou to either side. The head material affects the gasket construction which affects its thickness. Since the squish/quench clearance is the sum of the piston crown to deck clearance plus the gasket thickness these dimensions are vitally important. Cast iron is a hard material that used in a head along with the block share the same thermal expansion/contraction rate which if the mating surfaces are good will tolerate shim type head gaskets in the range of .015 to .019 inch, so the factory block castings don’t need to be milled unless surface quality dictates. However, with an aluminum head it’s rate of thermal expansion/contraction is greater than cast iron and it is a softer material, so to reduce to prevent surface abrasion with the head gasket over extended time periods beyond only used for races kind of engine a thicker composition type gasket is used. This allows the differential movement to be absorbed within the gasket. The thinnest composition gaskets being about .026 maybe .028 inch when combined with the factory piston crown to deck clearance of .025 inch is moving too far on the upper limit of squish/quench clearance. So using aluminum heads requires the block be decked to remove this factory piston to deck clearance or the selected pistons need to have a taller pin center line to crown distance which is called the “compression height“ of the piston. These are usually .020 inch above the factory 1.560 inch compression height of the 350 piston.

Now as if this diatribe isn’t long enough the subject of pistons needs a caution, there are pistons named “rebuilder pistons” these are short compression height pistons that are used mostly by the mass-production shops building reman stock spec engines where every block is zero decked to get a warrantee proof head gasket seal with the original factory compression ratio. So rebuilder pistons reduce the factory compression height of 1.560 inch to 1.535 to 1.540 inch. Seems small but taken across the area of the piston crown, if these are used in a stock deck height block the compression ratio is greatly reduced. I’m pointing this out because it is an all too common pitfall that hobby engine builders trip into. This forum sees this several if not many times in a year.

So you need to be armed with a lot of info going in to this. I think it advisable to paper build the engine as you see what you’ve got going on with the pieces. It’s a lot less expensive than learning by mistakes.

Hope my typing, spelling and grammar workout as I’m not going to edit this before or after posting.

Bogie
 

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Somebody’s been in there before you as those are not production pistons unless this is an old pre SMOG LT-1.

Going with the expectation that this has already been rebuilt you should expect the cylinders walls have been bored to some oversize, the problem now is how much. To get to a good wall is going to require more boring but this has limits. Most 010 and 014 blocks will tolerate a maximum of .060 inch over the factory 4 inch bore. Beyond that the wall thickness becomes structurally unreliable.

Rust in the cooing jackets is bad news, shows inadequate amount of anti-freeze coolant to suppress rust formation. Rust is an insulator which reduces heat transfer so even trying to improve that function over the thermal characteristics of ‘coolant’ with pure water quickly becomes a lost cause. In addition, the rust gunk can and does plug small passages which ends any cooling in those places. The Chevy engine, especially the heads, are given to cracking so reducing or eliminating heat transfer and surface wetting is an invitation to cracking problems. With saying that; any rebuilding effort needs to be preceded by cleaning and crack inspection. The latter with magnetic or UV dye inspection unless the cracks are so large you can see them with the unaided eye. There is no sense in spending money for machine operations and expensive parts to find the block or heads have cracks.

I’ll leap ahead to heads for a moment in that the material the heads are made of strikes back at machine operations on the block. The issue is getting at the ideal squish/quench clearance between the piston crown and the step of the combustion chamber to be between .035 to .045 inch give or take a few thou to either side. The head material affects the gasket construction which affects its thickness. Since the squish/quench clearance is the sum of the piston crown to deck clearance plus the gasket thickness these dimensions are vitally important. Cast iron is a hard material that used in a head along with the block share the same thermal expansion/contraction rate which if the mating surfaces are good will tolerate shim type head gaskets in the range of .015 to .019 inch, so the factory block castings don’t need to be milled unless surface quality dictates. However, with an aluminum head it’s rate of thermal expansion/contraction is greater than cast iron and it is a softer material, so to reduce to prevent surface abrasion with the head gasket over extended time periods beyond only used for races kind of engine a thicker composition type gasket is used. This allows the differential movement to be absorbed within the gasket. The thinnest composition gaskets being about .026 maybe .028 inch when combined with the factory piston crown to deck clearance of .025 inch is moving too far on the upper limit of squish/quench clearance. So using aluminum heads requires the block be decked to remove this factory piston to deck clearance or the selected pistons need to have a taller pin center line to crown distance which is called the “compression height“ of the piston. These are usually .020 inch above the factory 1.560 inch compression height of the 350 piston.

Now as if this diatribe isn’t long enough the subject of pistons needs a caution, there are pistons named “rebuilder pistons” these are short compression height pistons that are used mostly by the mass-production shops building reman stock spec engines where every block is zero decked to get a warrantee proof head gasket seal with the original factory compression ratio. So rebuilder pistons reduce the factory compression height of 1.560 inch to 1.535 to 1.540 inch. Seems small but taken across the area of the piston crown, if these are used in a stock deck height block the compression ratio is greatly reduced. I’m pointing this out because it is an all too common pitfall that hobby engine builders trip into. This forum sees this several if not many times in a year.

So you need to be armed with a lot of info going in to this. I think it advisable to paper build the engine as you see what you’ve got going on with the pieces. It’s a lot less expensive than learning by mistakes.

Hope my typing, spelling and grammar workout as I’m not going to edit this before or after posting.

Bogie
 

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79' Chevy Big 10
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Discussion Starter · #18 ·
Okay so my original motor that come out of my 79 Chevy pickup has the engine casting number 3970014 and now I have another engine block that's coming out of a box truck c30 with the engine cast number 3970010.which block would be better for rebuilding? Now I do know about mine, my block is good but I'm not so sure about the other block until I tear it down. they're both running the same exact valve heads or whatever the number is match up the 462628.

UPDATE:
moment ago
I took the oil pan off the 350 that is located in the c30 truck, & it's a 4-bolt main. However, there are two cylinders that have been broken inside. Would this be worth fixing up with new pistons? The engine I currently have in my C10 pickup is a 2-bolt main. It does need need new Pistons as well. You are a couple pictures I hope you can make it out and let me know if it's worth my time and trouble cuz I will do it. I will fix it up, help me Ol' wise & great knowledgeable guys!
Automotive engine part Machine Space Engine Automotive engine timing part
Automotive engine part Machine Nut Engine Automotive engine timing part
 

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Discussion Starter · #19 ·
Okay so my original motor that come out of my 79 Chevy pickup has the engine casting number 3970014 and now I have another engine block that's coming out of a box truck c30 with the engine cast number 3970010.which block would be better for rebuilding? Now I do know about mine, my block is good but I'm not so sure about the other block until I tear it down. they're both running the same exact valve heads or whatever the number is match up the 462628.
Okay so my original motor that come out of my 79 Chevy pickup has the engine casting number 3970014 and now I have another engine block that's coming out of a box truck c30 with the engine cast number 3970010.which block would be better for rebuilding? Now I do know about mine, my block is good but I'm not so sure about the other block until I tear it down. they're both running the same exact valve heads or whatever the number is match up the 462628.
moment ago
I said I took the opening off the 350 that is located in the c30 bolt main period there are two cylinders that have been broken inside. Would this be worth fixing up with new pistons? The engine I currently have in my C10 pickup is a 2-bolt main.

Automotive engine part Machine Nut Engine Automotive engine timing part


Automotive engine part Machine Space Engine Automotive engine timing part
 

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You'll have to be more clear about what you mean by "two cylindrs broken inside"...I can't spot what you are talking about in the pics you just posted.
Since it doesn't appear so bad that major things are loose and flying around in there, and all you mean are bottoms of the piston skirt "tabs" are broken off, just reboring the cyloinder and new pistons will typically fix it.
Same if you are talking about small areas of the top outer edges of the piston broken out.

If the block isn't hurt beyond repair then it is a better candidate for rebuild than your 2-bolt block.

Piston skirt tabs and ring lands are commonly broken off on stock cast pistons that have been run too hard...as long as the block doesn't get cracked it can be easily fixed.
 
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