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Discussion Starter #1
I have a 1975 nova 350 and would like to know if any came with a 4 bolt main. I looked up the casting numbers and they said 2 or 4 bolt main:confused: Any one have a clue on what is under the oil pan:D Thanks ( it had a factory 2 barrel carb)
 

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Most were a 2 bolt! But the only way to be sure is to drop the pan!!
 

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No factory 4 bolt main 75 novas. All 4th gen's were two bolt main. If you find one it was swapped in. Check the block numbers to see if they even match the model year. If they do it's 2 bolt.
 

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It means the main caps that keep the crankshaft into the engine block are held down by four bolts each ( a 4-bolt) or two bolts each ( a two bolt). Four bolts are better usually, unless you want to get a two bolt and make it four bolt with aftermarket main caps. Hope that makes sense.

-Aaron
 

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Here's a picture of the different types of center main bearing caps.
(from right to left)
2 bolt
4 bolt
4 bolt splayed (outer bolts are at an angle)

Material varies from cast iron to billet steel.

Main caps are machined in place and can't be interchanged. If you convert a block to 4 bolt or have to replace a cap the cap has to be fitted to the block.
 

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Another point is small block chevys only have 4 bolts in the center 3 main caps. Big block chevys have 4 bolts in each main cap on 4 bolt blocks. Some other style engines have cross bolted mains where the bolts come in through the block pan rails and bolt into the side of the caps. Some Ford FE series engines used those. There are lots of different configurations used.
 

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Discussion Starter #9
Oh well there gose my big money dreams of selling a 4 bolt main motor :rolleyes: Hey do any of you need a low mile 2 bolt main:D
 

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Paul Wright said:
Here's a picture of the different types of center main bearing caps.
(from right to left)
2 bolt
4 bolt
4 bolt splayed (outer bolts are at an angle)

Material varies from cast iron to billet steel.

Main caps are machined in place and can't be interchanged. If you convert a block to 4 bolt or have to replace a cap the cap has to be fitted to the block.

Um........Paul, wouldn't it be better if your block had matching main caps??:D
 

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Switching to main studs

The oil pan package I'm looking at includes a windage tray. The windage tray looks like it mounts on main studs. Do I need to have the mains honed to switch to studs from bolts?
 

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i believe ARP, Milodon etc recommend align boring or honing on all applications of main studs... whether it's actually needed... that i dunno. every job i saw come in for stud install... the mains were honed or bored. never saw one NOT have it done.
 

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If the mains checked out good and there's new bearings and a new crankshaft, would it still need to be honed or align honed then?
 

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Dave, some (or most) of these guys are smarter than i am... but according to the manufacturer... it's needed. check with yer guy who's doing the work. i'd wager he'll insist on it.
 

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JohnnyRotten said:
Dave, some (or most) of these guys are smarter than i am... but according to the manufacturer... it's needed. check with yer guy who's doing the work. i'd wager he'll insist on it.
I'll check with the shop and ARP.
 

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Why do you think installing a stud rather than using a bolt would require honing the mains? I have installed many main studs in many motors and never alighn honed any of them because of adding studs. Also not one ARP stud kit ever suggested that be done. Maybe I'm just a lucky guy?????? LOL
 

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Quit monkeying around and get that ride back together Dave. The showdown is on.:eek: :D
 

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Real McCoy said:
Why do you think installing a stud rather than using a bolt would require honing the mains? I have installed many main studs in many motors and never alighn honed any of them because of adding studs. Also not one ARP stud kit ever suggested that be done. Maybe I'm just a lucky guy?????? LOL


RM, you may be right... i have no real proof it's needed other than from what i was told years ago... i know my APR studs came with a sheet that said it was required... maybe it's BS, i dunno... Milodon recommends it too...


maybe it's to ensure main bores are straight so there's no legality issues from a blown block (guys blaming the studs fer an outta whack block)... know what i mean ???


i'm relearning and learning every day...
 
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