Best 350 Block for buildup.

[kilomanjaro]

I am getting ready to start a 350 buildup to replace the underpowered 350 in my 72 blazer. I am looking for a good block to start with. Does anyone know what the best year/number block would be to look for. I am wanting 300hp or so, nothing too outrageous. I have an original 350 out of another 72 blazer casing number 3970010. Is is a 4 bolt? Would it be a solid building block? Any help would be greatly appreciated.
Thanks
JOHN

[clay68c10]

The mortec site shows it could be 302/327/350 2 or 4 bolt.
http://www.mortec.com/castnum.htm
The only way to be sure is to pull the pan and look.
I've always heard the #'s behind the timing cover give the alloy composition of the block. The 010 020 sticks in my head as a desirable one. It was supposed to have a good amount of nickel in the iron which is good for wear...
Any 4-bolt is ok for 300hp. You could build a stroker for just a little bit more $. They're cheap these days.

[arkracing]

the '72 block will be fine for 300 hp

only way to see if a 3970010 motor is a 4 bolt is to pull the pan.

Doesn't really matter either way - 2 bolts can handle 500 horse if main studs are used and the motor is built right.

Clay is right about the 010/020 being the "high nickel" block - a little more desirable but for what you are looking for a regular 010 block is fine.

You have a realistic power goal and it won't be hard to acheive that with a 350.

you can get balanced rotating assemblies from www.enginekits.com for $500 -they seem like a good foundation.

[larry may]

There is a built 350 in the classifieds with 280 cam plus more. 300 DOLLARS. As for id of 4 bolt main engine I've noticed if the top center hole on back of the block is threaded have been 4 bolt . Also this hole being tapped was in a previous thread by another member .Do not remember how long ago been awhile. Good luck

[dougs69c10]

id rather start with a 2 bolt main, you get stronger bottom end when you splay the caps and turn the 2 bolt into a 4 bolt

[clay68c10]

I've also seen a lot of 4-bolt blocks with this 'extra' gallery plug. That was always a good thing to look for in the boneyard.

[Huck]

Hey~~~welcome back from Alaska!! The typical "010" block from a 72 is an excellent base 350 to build from. High nickle, 4 bolt, etc. Get the short block rebuilt then throw on some late model Vortec heads, a matching intake, good edelbrock carb, RV Cam for simplicity, and you are pushing well over 300HP with no strain or pain. BUT, for a meer $1400 or so, you can buy a NEW GM 350 that puts out about 265-75 HP with a 3 year, 50,000 mile factory warranty which is hard to beat and one I used for years with no problems at all. I am running a super rebuilt 350 with hi-po cam in my 72 blazer that never gives me more then 13mpg---too much cam for a low geared (373) 4x4. Make sure you think clearly as to what you want, why you want it and how you will be using it. My PO didn't do that too well~. Huck

[Bishops Trucks]

For a little more cash ($3400.00) you can get the 350 H.O. Deluxe with 330 H.P.. Comes complete from air cleaner to oil pan. I put one in my '71 2 wheel drive and ran it for about 3 years and then moved it to my '71 4X4 and it still runs as good as the day I bought it. It also comes with a warrenty and is a very reliable engine. Just my opinion.

[wibilly]

1970 oldsmobiel if you must have a lil 350

[jooooooe]

didn't know it til 'bout a year ago, but the pre '69 blocks have a taller distributor shaft housing and some other structural differences, plus it's very easy to see that the castings where much better on these blocks (less rough/sharp edges, smoother), seems like as the 70's went by the castings got sloppy.

[MikeB]

You might want to consider an 86-up block with 1-piece main seal. They're a lot easier to find unmolested.

I paid $175 for my truck's short block at a junkyard, and took the rods and crank to a machinist. He had to slightly hone the big ends of 2 or 3 rods, and then polished the STD/STD crank for a total of $45. The main bore was perfect, so didn't even have to hone it.

Had the block bored to +.030. but it cleaned up at less than .010". Also, I took the deck down to 9.010", but it cleaned up after taking off just a few thousandths. Older 010 blocks usually need much more removed to make the decks square to each other. Same for the bores.

I ended up using an inexpensive flat tappet cam, but the block is machined for an OE-type roller cam and lifters if I ever want to go that route. That's another advantage to the later model blocks, assuming it's not a 3/4 ton or larger truck block. Most of those had flat tappet cams, and some were NOT machined for cam and roller lifter retainers.

[Billla]

Originally Posted by kilomanjaro

I am getting ready to start a 350 buildup to replace the underpowered 350 in my 72 blazer. I am looking for a good block to start with. Does anyone know what the best year/number block would be to look for. I am wanting 300hp or so, nothing too outrageous. I have an original 350 out of another 72 blazer casing number 3970010. Is is a 4 bolt? Would it be a solid building block? Any help would be greatly appreciated.
Thanks
JOHN

You could start with your block if you don't mind it being down - virtually any block is a good starting point for the level of HP (<1 HP/CID) that you're looking for.

A couple of notes:

• A 2-bolt main block is fine, although it's worth the extra $ for studs vs. bolts
• the '010' block could be either 2 or 4-bolt, but it's usually a "high nickle, high tin" block and if it's been treated right may show virtually zero bore wear. You can tell if it has an 010 and 020 casting mark under the front cover.

Any SBC block is a good start; my oft-repeated advice is start with your budget - that number will guide every decision you make and otherwise you end up with something 1/2 finished.

Let us know how it goes!!

[Billla]

Originally Posted by dougs69c10

id rather start with a 2 bolt main, you get stronger bottom end when you splay the caps and turn the 2 bolt into a 4 bolt

For 300 HP??? Adding splayed caps is ~$700 and not needed until 450+ HP IMHO...

[roj2323]

Originally Posted by MikeB

You might want to consider an 86-up block with 1-piece main seal. They're a lot easier to find unmolested.

I paid $175 for my truck's short block at a junkyard, and took the rods and crank to a machinist. He had to slightly hone the big ends of 2 or 3 rods, and then polished the STD/STD crank for a total of $45. The main bore was perfect, so didn't even have to hone it.

Had the block bored to +.030. but it cleaned up at less than .010". Also, I took the deck down to 9.010", but it cleaned up after taking off just a few thousandths. Older 010 blocks usually need much more removed to make the decks square to each other. Same for the bores.

I ended up using an inexpensive flat tappet cam, but the block is machined for an OE-type roller cam and lifters if I ever want to go that route. That's another advantage to the later model blocks, assuming it's not a 3/4 ton or larger truck block. Most of those had flat tappet cams, and some were NOT machined for cam and roller lifter retainers.

i really have to agree with this as the one peice rear seal is the big seller for me. whether the bock is made to have roller lifters however really isin't an issue though as there are literaly tons of manufactures that make roller lifters for just that type of application.

in my situation i got my 350 one peice rear seal 4 bolt main with roller cam provisions from a 3/4 ton van. gotta love free stuff!

[clay68c10]

Yes, one piece rear main is the way to go. I've never seen a 2-piece that didn't at least seep a bit. And the benefit of a roller cam is a plus.

[MikeB]

Originally Posted by roj2323

i really have to agree with this as the one peice rear seal is the big seller for me. whether the bock is made to have roller lifters however really isin't an issue though as there are literaly tons of manufactures that make roller lifters for just that type of application.

Yes, but the OE lifters are less expensive, and the cam retainer plate means you don't need a thrust bearing. Also, the lifter bosses/bores are taller to compensate for the taller roller lifters. A lot of good reasons there to use a late model block, IMO.

[arkracing]

Originally Posted by jooooooe

didn't know it til 'bout a year ago, but the pre '69 blocks have a taller distributor shaft housing and some other structural differences, plus it's very easy to see that the castings where much better on these blocks (less rough/sharp edges, smoother), seems like as the 70's went by the castings got sloppy.

"Distributor shaft housing" is the same on ALL Small Block and Big Block Cevrolets - except for Tall Deck BigBlocks and 348/409 "W" motors.

Structural differances??? - the early motors '69-'75 or so had more "meat" than the later model 80's and early 90's blocks - if you bore a later model motor over .040 and plan to make alot of horsepower - you are wasting your time - as the bores actually flex more than the early motors. BUT for 300-350HP any block is fine.

Watch the '87+ (1-piece rear main seal) motors, as some of them did not have provisions for a "mechanical fuel pump" - there is no hole for the fuel pump push rod.

2-bolt mains are good to 500 horse with Main Studs - if you install main studs you MUST have the block AlignHoned

[Billla]

[QUOTE=arkracing;1829169if you install main studs you MUST have the block AlignHoned[/QUOTE]

with everything, but this is new to me - does this really change the shape of the crank bore that much?

[arkracing]

Originally Posted by Billla

with everything, but this is new to me - does this really change the shape of the crank bore that much?

Yeh you really should have it done - because they will changed the clamping load on the bearing caps - you'll just shorten the life of you bearings and crank if you don't