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Topic: 4 Bolt or 2 Bolt Main

in Forum: C3 Engines

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4 Bolt or 2 Bolt Main (1/12)
4/5/08 5:02pm

Metal Man
Former Member
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Canada

Vette(s):
1980 L48 Automatic

Joined: 7/15/2007
Posts: 49

Is there any way to tell if it's a 4 or 2 bolt with the pad numbers. I got these #'s off the block front passanger side, V0515ZAK. Next set below 1AS431943, these #'s match the VIN on the drivers side windshield piller. Smile

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4 Bolt or 2 Bolt Main (2/12)
4/5/08 5:56pm

lukesvette

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HOWELL, NJ - USA

Vette(s):
1979, Targa Blue (72 Color), Pace Car rear spoiler, L88 hood, Dark blue factory interior, 525HP 406, HD 700R4, 370 gears,Steeroids, composite rear spring, TT IIs wrapped in T/A Radials.

Joined: 5/18/2004
Posts: 6812

I think you want the block casting # - usually 7 digits on the rear drivers side of the block - just below the head.

eg 3970010

Check this site:

http://www.chevy-camaro.com/chevy-camaro-chevy-engine-block-codes.asp?group=6

LukesVette2008-04-05 18:05:39

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4 Bolt or 2 Bolt Main (3/12)
4/5/08 7:19pm

Adams' Apple

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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

Joined: 11/8/2003
Posts: 20207

ZAK = L48 engine...not likely to be a 4bolt main...
Problem is, without actually pulling the pan and looking, there's really no way to know. Casting #s are not 100% accurate in telling if it is 4 or 2 bolt mains. Normally, the only engines using 4 bolts were the higher output engines, ie: LT1, L82, ect.

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4 Bolt or 2 Bolt Main (4/12)
4/5/08 9:52pm

Metal Man
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Canada

Vette(s):
1980 L48 Automatic

Joined: 7/15/2007
Posts: 49

14010207 is the # that was on the back of the block. From the searches that I've done it could be a 4 or 2 bolt. Like you say no way of knowing unless I pull the pan. That looks like a really fun job. Is the gasket a one piece deal?

4 Bolt or 2 Bolt Main (5/12)
4/5/08 9:57pm

lukesvette

My79 was an L48. When I pulled the pan off the motor, it turned out to be a 4 bolt. All depends in whats on the assembly line when they run short....

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4 Bolt or 2 Bolt Main (6/12)
4/5/08 9:58pm

Adams' Apple

[QUOTE=Metal Man]Is the gasket a one piece deal? [/QUOTE]

Sure it is...one piece on the right side, one piece on the left side, one piece at the front, and one piece at the rear!

Sorry...a little mechanic humor there...

Is it really important enough to pull the pan just to find out?
As I said, an L48 ain't likely to be a 4 bolt, unless someone has built it that way, in which case it wouldn't be the original engine for the car.
The only exception I could see for that would be if the factory ran out of 2 bolt blocks for a period of time, and they just used the 4 bolt blocks..it has happened, but it's just not a likely scenario...

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4 Bolt or 2 Bolt Main (7/12)
4/7/08 8:09am

VetteSpecialties
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Mounds View, MN - USA

Vette(s):
70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe

Joined: 5/24/2007
Posts: 1031

Like Joel said... Is there some reason you need to know, or just curious? If you need to know, it is not too hard to drop the pan in the car. Just unbolt the idler arm and pull the tie rod assembly down a bit. The pan is then clear. I know someone who occasionally forgets to drain the oil first, then I have (I mean, he has) a mess to clean up.

The new one piece replacement pan gaskets are nice. Be sure to put a dab of sealer in the corners where the main caps touch the block.

Larry

4 Bolt or 2 Bolt Main (8/12)
4/7/08 8:23am

MikeMc71
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Tucson, AZ - USA

Vette(s):
1970 White L-46 Air Roadster, 1971 White LT1 Coupe, 1971 Red Auto Air Coupe, 383 stroker, 430 HP, 2002 Millennium Yellow Auto Coupe

Joined: 10/7/2007
Posts: 341

OR....you could rent or borrow a nice bore scope to check it out....now who was the guy here that just got one of those?......hmmmmmmmmm........I think his name started with a J.............

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4 Bolt or 2 Bolt Main (9/12)
4/7/08 10:06am

Adams' Apple

[QUOTE=MikeMc71] OR....you could rent or borrow a nice bore scope to check it out....now who was the guy here that just got one of those?......hmmmmmmmmm........I think his name started with a J.............[/QUOTE]

Hmmm...now there's another useful idear...

You'd still need to drain the erl tho...

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4 Bolt or 2 Bolt Main (10/12)
4/7/08 10:07am

6880Mike
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Horse Cave, KY - USA

Vette(s):
1968 convertible; 1980 L-82

Joined: 10/22/2007
Posts: 488

[QUOTE=Metal Man]...V0515ZAK...1AS431943, these #'s match the VIN on the drivers side windshield piller. Smile

[/QUOTE]

It's original; it's an L-48; and it's almost certainly a two bolt main.

4 Bolt or 2 Bolt Main (11/12)
4/7/08 5:28pm

Lynne73
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Easton, PA - USA

Vette(s):
1973 Coupe 350 Auto.T-Tops L48,65450 miles.

Joined: 11/6/2003
Posts: 232

I've always been told by the old time Chevy guys that raced at local tracks, that any Small Block Chevy ending in a 0010 was a 4 bolt block. Every motor I ever rebuilt with the 0010# was 4 bolt. My 73 L48 Vette, it's block ends in 0010. I may just pull the pan to find out!

Dave- Lynne 73

4 Bolt or 2 Bolt Main (12/12)
4/7/08 7:40pm

Adams' Apple

My '74 has the 010 block, and I know it is a 2 bolt. Ya just never can tell without actually looking.
I had the pan off of mine when I was detailing all of that stuff years ago...I put a windage tray on it while I was in there. Don't know why I did tho...I just had one laying around, so I went ahead and stuck it in there!

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