80's chevy 350 weak in the mains vs 70's - Hot Rod Forum : Hotrodders Bulletin Board
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Old 11-03-2011, 08:03 PM
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80's chevy 350 weak in the mains vs 70's

My machine shop says my 80's 350 block is junk??I was going to use a a SCAT steel crank, decent rods, forged dish pistons and retain the 2 bolt main block and mess around with either a small Turbo or 144 blower. Keep boost to a minimum 6psi to 8psi. Forged pistons because Their will be a learning curve as i try to tune. I now what happens with detonation hence forged pistons
The machine shop has me in a Merlin block with all forged components and expensive!!!
I dont want to spend that much. If you guy's agree the 80's 350 is junk(GM cut back on the metal in the mains area in the 80's) and the 2 bolt mains won't withstand 6psi to 8psi of boost then I will just build a hot little 350 and call it a motor!!!
A daily driver not a dragster no strip time. Its a 54 truck

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Old 11-03-2011, 08:58 PM
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News to me. I'd run it. Keep the rpm down to 5500 with the blower and you will be ok.

If this is your only machine shop I'd specify exactly what I wanted each step of the way. Check each item carefull before you accept it.

I just suspect all work that isn't mine.
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Old 11-03-2011, 09:01 PM
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Ask them about splayed caps to make it a four bolt main. You should easily handle 500hp with a stock block if you are not mounting slicks to it. I made 450hp with a stock 2bolt 400sbc w/stock crank and rods. Been running for six years with no problems. Use knowledge to make power not $$$.
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Old 11-03-2011, 09:43 PM
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In 1979 chevy did take some of the meat out of the blocks. I used to have over 10 scrap blocks and one of those was a 1979 block. It was lighter than the rest of them. However, I recently sold a 1985 4 bolt main 350 to my machinist. He circle track races and on the last race he blew his engine and ruined everything internally. I told him I had a standard bore 350 that was a `85 model and he jumped on it with both feet. Last I heard he`s prepping it and doing the machine work to run it again. He`s likely running around 475 to 500 horses and he wasn`t in the least worried that `85 block wouldn`t hold up to the job. The block will be bored .030 and he doesn`t have a sonic machine either.
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Old 11-04-2011, 05:58 AM
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Thanks for the replies
I am going to go for it. Be a nice entry level forced induction project. Lot to learn

If i blow it up it won't be the end of the world-Thats Hot Rodding
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Old 11-04-2011, 08:11 PM
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3970010 block casting number. its a 70's. Guy told me it was an 85 i bought it from
Ready to break some eggs.
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Old 11-04-2011, 09:04 PM
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This block started production in April/May of '69. It was a completely new design for sbc engine cases. Both 2 and 4 bolt main configurations used in all chevy models including trucks, at least through the end of '75. HP ratings from 145 ('75) to 370 ('70 Corvette).

You should be very successful building a blown engine with your block, provided it's in servicable condition.

Do you have date codes, stamped codes (on engine pad)?
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Old 11-04-2011, 10:55 PM
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The 3970010 and it`s twin brother the 3970014 are the most common 4 inch bore blocks out there. They`re also the most popular and there casting numbers were the longest in production. The 010 started production in 1969 and went all the way to 1980. The 014 started production in 1968 and ran until 1979.
Both those casting numbers are sought after by drag racers and especially by roundy round racers. We drag and mud raced with both casting numbers.
High rpms, caked with mud, shot them with 350 horses of nitrous and they all held up well. They`re plenty stout blocks. Cool thing is millions of them were cast so alot of`em are still out there for the pickings.
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Old 11-05-2011, 07:11 AM
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If its a decent block would it be worth the investment to have them drill it four bolt main caps? Would it make it THAT much stronger?
I am going to run the 177 supercharger for sure. A guy that was cutting my tree down yesterday had a polished 177 with carb off his boat for sale. $1400 for the whole thing. He blew the 350 and pieced the boat SMALL WORLD SOMETIMES and SOMETIMES THE WIND BLOWS THE RIGHT WAY!!!
(GOD WANTS ME TO HAVE A BLOWER) I guess.
He has some iron Dart heads too for a SBC ????
I am mainly a MOPAR guy but I will check and see what the DART heads are??

My machine shop would only add 4 bolt caps to a 70's block.
Refused on a post 80's and said it wouldn't be much stronger

Last edited by bigalow; 11-05-2011 at 07:20 AM.
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Old 11-05-2011, 07:37 AM
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I have re-read and thought about everything that you guy's are telling me and I have learned ALOT about CHEVY
In summation:
I got lucky and got a 70's block wich can handle plenty of HP and Torque with a 2 bolt main. A little stronger
There is some merit to less material on the mains in the post 80's blocks
Disregard my last post the 2 bolt main it is.

FOOD FOR THOUGHT FOR THE FUTURE:
You can buy ready to go from SUMMIT a machined 4 bolt main SBC Block for $650.00---WOW it almost doesn't pay to buy an old block and have it machined?
Plus I read a machine shop needs to really know what there doing to add splayed caps---
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Old 11-05-2011, 08:18 AM
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Most all of my experience building engines is for oval or road racing. Personally I would not use a two bolt block past 450hp or a stock four bolt past 550hp.
If you're building a street rod to blast around on the highway I would still get at least a stock four bolt block due to the low speed torque increases that a blower can produce.

I guess I'm just cautious after seeing people put many thousands in a stock block engine only to have it bust out a cylinder, or pull the main web completely out of the case, and then oil down the tires and wreck their car.

Around here there are many four bolt blocks available for $200 or less.
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Old 11-05-2011, 01:33 PM
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$200 for a 4 bolt not around my area-snapped up

Thanks, I got a good 70's 2 bolt and a good 177 blower in my hands. I am gettin off the bench and into the game with my set-up!!!
I know one thing its exciting!!! Sure beats a craftshow!!
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Old 11-05-2011, 08:38 PM
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bigalow if you are interested I have an 010 block in good shape in madison wi for 150, its not that far from chicago, about 4 hours. If you are going to do it you might as well do it right.
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Old 11-06-2011, 06:39 AM
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Quote:
Originally Posted by charliemiller4
bigalow if you are interested I have an 010 block in good shape in madison wi for 150, its not that far from chicago, about 4 hours. If you are going to do it you might as well do it right.
/


Of Course I am ? could you wait till next weekend?
Its a 4 bolt block?
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Old 11-06-2011, 07:13 AM
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Bigalow, this is an excellent site for SBC Info >> http://www.chevytech.info/
click on any of the 3 links then click on the Part or the # for tons of Info, very easy to use.

Todd
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