4 or 2 bolt main? - Camaro Forums - Chevy Camaro Enthusiast Forum

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Old 12-02-2008, 07:06 PM
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Default 4 or 2 bolt main?

theres a camaro i want to buy, but im only interested if its a 350 4 bolt main, and this guy doesn't know whether its a 2 or 4 bolt main and refuses to remove the oil pan to find out. and i dont want to drive over there and buy it just to figure out its a 2bolt when i want a 4 bolt.
the guy said its the original engine tho, its a 1976 camaro 350 4bbl. so i was wondering if anyone can find the exact details about that car and tell me whether it came with a 2 or 4 bolt main when it was produced, thank you.

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Old 12-02-2008, 07:17 PM
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Default RE: 4 or 2 bolt main?

Im sure they can, and i would suspect its hidden in the VIN. im gunna move this thread to the 2nd gen section for you, because we have some VIN reader type folk over there.
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Old 12-02-2008, 07:54 PM
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Default RE: 4 or 2 bolt main?

There really is no bullet-proof method to be certain if the car has a 4 bolt or not. It is best to get the casting number from the block, you can check it here: http://www.mortec.com/castnum.htm
Be aware that the casting numbers are not 100% correct either, they are probably about 90% accurate. I have also heard that if the top bolt in the trans mounting bolt pattern is threaded it is a good indicator of a four bolt, but I have not tried that for accuracy.

Question: Why do you specifically want a four bolt block? I used to use only four bolt blocks until I tried using billet main caps and converting two bolt blocks. In checking the oil clearances and tearing them down later to rebuild again, I think the torque & wear patterns on a converted block are better. Also, the splayed position of the bolts is stronger. I have used two bolt blocks in my son's race car with absolutely no issues.
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Old 12-02-2008, 08:19 PM
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Default RE: 4 or 2 bolt main?

why would you refuse to buy it if it was a 2 bolt main? i understand that you want the 4 bolt main. but if the car is nice you shouldnt pass it up for that sole reason. you can always do a 4 bolt conversion and have it line bored with the new main caps. also depending on your application you probably would not need a 4 bolt main. its nice to have that insurance but if its just a daily driver 2 is just fine. if its a drag car you want you want a 4 bolt. my big block pushes about 500 horse and its a 2 bolt 396.

i am also building a 383 stroker, and i was going to convert it to a 4 bolt. but alot of people (machinist) and they all said unless your super charging it. dont bother. "its more than strong enough"

so like i said. dont pass up a nice car for the sole reason of the main bearings.
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Old 12-02-2008, 08:29 PM
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Default RE: 4 or 2 bolt main?

Old school 4 bolt main blocks are not hard to come by anymore, Everyone wants 93+ LT1's or better yet a LS motor. If I remember right the only 350 4 bolts in 1976 where in the 1 ton trucks. These truck where not subjected to emissions till 1979.

Some quick research shows there was only one 350 was offered in 1976. It was the LM-1. It was a 2 bolt main block with 150 HP. You might want to do some more research there many race teams that like the 2 bolt blockbetter because they can add two angled bolts and not have to worry about crossing the existing holes they would not use. With that mod the two bolt block can hold more HP then the 4 bolt.
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Old 12-02-2008, 09:10 PM
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Default RE: 4 or 2 bolt main?

My thoughts have been pretty much covered in the previous responses. Unless you plan on building a killer engine, there'sreally not going to be any benefit for you tohave a 4 bolt. And that 350 in the 76 is a very tame engine. If you ever wanted to build it up, it can be machinedto a 4 bolt. Don't let that keep you from getting the car, if that's your only reason for not wanting it.
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Old 12-03-2008, 12:04 PM
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Default RE: 4 or 2 bolt main?

OK, let's see... If I'm not mistaken, I believe in that era 4 bolts were only found in trucks. My '75 RS 350 is a 2 bolt, for reference. But, as mentioned above, it's better to start with a 2 bolt and splay it anyway. And you'd need to be making at least 350 horses before you would have to worry anyway, even if it was just a 2 bolt. If the car is in good shape, go for it; two bolt or four bolt.
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Old 12-03-2008, 05:41 PM
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Default RE: 4 or 2 bolt main?

I dont think it is worth it to have the splayed caps installed, its around $800 for a set of caps line boring/ honing plus then the cost of other necessary machining. You could be real close to a dart block especially if you get a bad factory block and have to start over.You might be able to find it cheaper http://www.dartheads.com/products/shp-blocks.html
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Old 12-04-2008, 07:51 PM
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Default RE: 4 or 2 bolt main?

No offense intended Griff, but you gotta find a different machine shop. My Milodon caps cost $220 and my guy does all my machining (bore/hone cyl, bore/hone crank & deck block) and cooks the block for $350. I have had the same guy prep my blocks for going on 20 years, so maybe he just likes me or it could be just backwoods Minnesota pricing too, where you at?
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Old 12-06-2008, 11:34 PM
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Default RE: 4 or 2 bolt main?

I am in western Pa the machine shop is one of the better ones around here so they could be a bit higher is cost then some. I cant remember the cost specifics exactly but they included the caps, setting the register in the block, machining the pan rail, drilling and tapping, line boring and finish hone of the caps, I believe there was something to do with a strap on the rear main also.
I guess my point is by the time I would have a block done with the splayed cap installation and the cleaning, crack testing, sonic testing, boring, torque plate hone, squaring the deck/decking, deck plugs, oil main plugs, and the purchase of a hopefully good factory blockI wouldstill end up with a block that is inferior to the Dart block for close to the same cost, I just cant get all the formentioned machine work done for $350 I wish I could though.
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1976, 1996, 350, 361959, 76, bolt, building, camaro, chevy, converting, engine, horsepower, main, mains, worth

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