Im just wondering Because I got mine used and it appears to have had some machine work done to it bye the previous owner.

 

I don't believe that any of the stock IROC motors had 4 bolt mains. They were all 2.
bsa

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"If they do not run, Then they will die." - Stonewall Jackson
#3
'87 IROC, 355 TPI, Converted to SD, 700R4, B&M Megashifter, 3.42, Trick Flow Twisted Wedge Heads, Edelbrock Intake, Accel Runners, Comp Cam, Crane Gold rockers, Lucas 24# injectors, Edelbrock headers, Flowmaster 3'' exhaust, Mallory Ignition, Transgo Performance Shift Kit, Corvette Servo, 2,000 Stall Torque Converter

 

Right idea, wrong way around... none of them came with 4 bolt mains.

 

Only the Corvette L98 did.

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89 Transam GTA, 350TPI, auto, 3.27 rear, dual cats, gray.
Magnaflow cat-back,
K&N open element,
Best E.T. 14.63@95mph

 

Do you know what the ID number might be for that Block? For all i know it might be a vette L98. Was there any way to tell besides the ID numbers?

 

Even the ID #s won't tell you for sure. I have a 350 block in my garage that I'm building. Using the casting #s that it has I looked it up on www.mortec.com and a few other places. In the description it say 2 or 4 bolt mains. Mine is a 4 bolt, but I only know that because there ain't no oilpan on it.

Well I take that back. There are a select few that were strictly 4 bolt. Look it up after you find the cast #. It should be on the block on either side above the motor mounts. It'll be the last 3 digits, but that's really all you need. GM never used the last three # twice.

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92 RS w/t-tops 305 TBI Auto.
170K miles and don't burn a drop o'oil
-K&N Truck filter #1500 w, open ele.
air cleaner
-Dynomax 2 1/2" cat-back
-B&M TransPak
-Jet Stage2 Chip
-180* T-Stat w/ 185* Fan Switch
-JVC CD--Alpine speakers & 4ch. amp
Rockford 2ch. to 2 MTX 12" subs

 

My 87 L-98 came from the factory with 4 bolt mains...original block even has the VIN stamped on the block...I am positive this is the original block and have been called a liar by so many people....but yes mine came 4-bolt.

-Brian

 

I assume you had the pan off?

 

Have I had the pan off? Yes I have...I took the motor out, had it bored .030 over...forger crank..6.0 manley aluminum rods and forged dome pistons and afr aluminum heads and a shatload of porting up top....now the car is more to my liking...12.96@107mph with only motorwork and a full manual competition shift kit...woohooo!

-Brian