regorih383

iTrader: (21)

ok here is my story, about a 5weeks ago i bought a LT1 383. The guy i bought the motor from told me that it was balanced and blue printed, it has a eagle 4340 forged crank, je forged pistons, and forged eagle H beam rods...here is the problem: when i went to put my stock flywheel on the back of the motor it did not fit , the diameter of the (were the flywheel mounts on to) did not fit at all ... i called around and found out that i need a flywheel with a bigger center diameter.. i also need to find out if the motor is a 1 or 2 rear main seal . and i also need to find out if the motor was balanced internally or externally?????? i tryed calling the guy i bought the motor from but he has moved to Louisiana... i called center force and told them my story , the man i talked to told me that the motor sounds to be a 2 piece rear main seal, and told me that they offer a neutral balanced flywheel and a counter balanced flywheel... i also called jegs and the guy i talked to told me that if it is an lt1 motor that it is a 1 pieace rear main seal and the stock flywheel should fit and i told him no it dosent fit and he told me well the motor is not an lt1 and i told him yes it is, i checked the block numbers and it is an lt1 motor and he said well its not a 383 and i told him yes it is i checke the numbers on the crank and it say 30600375 i think which means 30 over 6.o rod and 3.75 strok (a machine shop told me)

so here it is i need help big time , can anyone tell me how to determine if the motor is 1 or 2 piece rear main seal and advice me to what flywheel i can get thanks\

Desparte in Texas ,
Roger

you can e-mail me at regorih@yahoo.com

FASTONE

Does the motor have the front lt1 waterpump and ingnition system?The rearmain seal for a 1 pc seal will have a large seal about 4inches,the 2 pc seal crank has a seal behind(looking from the back of motor) the crank flange also the 1 pc seal will have a perfectly round flange where as the 2 pc will have cut outs in the flange,not perfectly round.Also the 2 pc crank has a bigger flange,if its a 1 pc seal your flywheel should work.As for the internal balance part its hard to say,look at yourharmonic balancer does it have a section cut out of one side say to balance it?Maybe you can get a part # off the balancer and call the manufacturer,can you find out who built the motor?CAN YOU GET A PART # OFF THE CRANK?

rich

Another thing could be is that you have a lt1 block with a 1 piece rear main. you can tell because you can remove the seal without removing the pan. Now to confuse you even more they sell a 2 piece rear main adapter that you can use on a 1 piece block. If you have a part # on the crank the manufacture will be able to tell you what the crank is for and you can then determine which style clutch you need. then you need to know if it is internal or externally balanced. You need to find that out from the builder or old owner you bought it from. Good luck Rich

CRASH 02

iTrader: (3)

If it is an LT1 then it should be a 1 piece. Chevy went to 1 piece rear mains in the late 80's. It is real easy to see what rear main you have. The rear main seal will either be 1 or 2 pieces. Just look at the back of the crank to see.

bad2000ss

iTrader: (6)

What he said. I believe it was 1986 when chevrolet switched to the 1 piece rear seal and moved the oil dip stick to the passenger side of the motor.

Beast96Z

iTrader: (21)

That they did, BUT, some people are cheap and don't want to pay for a LT-1 crank, so they buy the old school SBC crank and get the adapter to convert the seals. This is what it sounds like to me anyway. Looks like someone sold you a LT-1 383 with an old school crank in it. You'll just have to find what parts you need and go from there.

FASTONE

They changed to the 1 pc seal in 1987,I don"t think the lt1 crank is any different then the other 1 pc seal motors.Also 1 pc cranks don"t cost that much more then the 2 pc ones, but it does sound like he has a 2 pc seal crankshaft.I would be more concerned about the internal or external balance part!!!

Scoggin Dickey

iTrader: (34)

If its a 2-piece seal with 3.75" stroke they are normally external balance, but if it has 6" rods it can also be balanced internally. Prob need to find out who did the machine work. On a brighter note, if its externally balanced and you use a neutral flywheel you will definatly feel the imbalance... it almost shakes you to death.

I do know there is a flywheel available, I seen one before on a customers car, LT1 383 2-piece crank w/M6. Its not the right way to build a LT1 stroker though.


-Joseph- on Matt's name