Classic Engine Tech 1967 - 1981 Engine Related

Well the 302 is cracked

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Old 04-11-2008, 08:51 PM
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Well the 302 is cracked

After praying it wasn't true either the heads or the block on the 302 is cracked. Rented a pressure tester after finnaly finding a store that would rent it out and antifreeze was pouring out of the oil pan.

I am assuming it would be the block because the car is not burning antifreeze it was all ending up in the oil pan.

Anyone have a suggestion for a replacement block, it was the original 4 bolt 350 short block with just 8,100 miles on it.. I see GM performance makes one but it says for mildly modified motors. I really do not want to go with a junk yard block. Another other suggestions? If it is going to be more than $1,000 I would rather find a wrecked LS1. Thanks

(and yes I know there are many boards that specialize in older cars, but I like this one alot more.. less grumpy folks )

http://store.summitracing.com/partde...4&autoview=sku
The GM Block
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Old 04-11-2008, 08:57 PM
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get a junkyard block. Nothing wrong with it.
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Old 04-11-2008, 09:02 PM
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The problem I see with that is, I will have to fork over more $ to have it checked (however they do that). I'd like to have 4-bolt mains on it as well. I just think it would be easier (and at this point don't care if it costs more) to throw everything into a brand new block. Let alone finding one around here... I've looked.

Do I have to have the rotating assembly rebalanced once put together?

This is my dads motor originally and aside from having headwork done 20+ years ago it had never been apart so we've never done internal motor work so that's my excuse for ignorance.
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Old 04-12-2008, 10:26 PM
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call a machine shop, i'd be they have a 69 or 70 4 bolt block in house. that way at least you'd have an era correct block. look for an 010 i believe. shouldn't run more than $500 for one thats ready to go w/ plugs and cam bearings.
If the rotating assembly is screwed up we've got a Lunati 302 crank, make you a good deal on as well as a set of diamond pistons to go w/ it.
The only reason you'd need to rebalance the rotating assm is if you change any of those parts. it would be best to have the rod bolts done and of course new bearings. if you upgrade the pistons you'll need to have it balanced.

and the $50k question...how'd it break?
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Old 04-13-2008, 05:06 PM
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No idea how it broke. The motor was stored for 15 years. We replaced all the gasket's, cleaned the block and heads out a good 3-4x's before reassembly. Started it up a few times, bought a new edelbrock manifold, got the car driving for 2 years, and then one day noticed there was antifreeze in the oil. Motor was running fine (much better than the car looks).

My dad did a pressure test the other night and antifreeze was coming out of the oil pan.

The block is 010, if I cant find a used block for a decent price I'll just get a new one, keeping it period correct is not the most important just wanted to keep the high reving 302 in the car. We had just sent the headers out to get coated by jet hot too so they get to stay in the box for a while. Going to finish the body work then focus on the motor again I guess.
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Old 04-14-2008, 01:45 PM
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Originally Posted by FiefSS
No idea how it broke. The motor was stored for 15 years. We replaced all the gasket's, cleaned the block and heads out a good 3-4x's before reassembly. Started it up a few times, bought a new edelbrock manifold, got the car driving for 2 years, and then one day noticed there was antifreeze in the oil. Motor was running fine (much better than the car looks).

My dad did a pressure test the other night and antifreeze was coming out of the oil pan.

The block is 010, if I cant find a used block for a decent price I'll just get a new one, keeping it period correct is not the most important just wanted to keep the high reving 302 in the car. We had just sent the headers out to get coated by jet hot too so they get to stay in the box for a while. Going to finish the body work then focus on the motor again I guess.
FYI block castings 3970010 were used for the 327's in 68 and for 350's from 69-79 in cars, trucks, and vettes

i got a core from a 76 chevy pickup for 200 bucks when i opened it up despite the 3 rounded off cam lobes it was still factory bore with hone marks still visible
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Old 05-09-2008, 10:44 PM
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Pull and disassemble it before you panic. In fact, check the intake gasket first. Even if it's cracked, it might be repairable.
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Old 05-17-2008, 08:35 AM
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Originally Posted by go2fast
Pull and disassemble it before you panic. In fact, check the intake gasket first. Even if it's cracked, it might be repairable.
I second that. Don't get too excited before tearing it apart to see what is actually going on.
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