I swapped an LT1 into my monte..
It ran fine for a while..now its making a scratching a grinding noise...at idle in park..after I start the car (not starter or flywheel) after it turns over...it is hard to start tho..
Carbed LT1
Headers
Th350 trans
HEI distributor
Non computer controlled


Could it be low trans fluid?

It sounds like a wrench is stuck in the flywheel...
Starter and flywheel are fine tho..
Possibly loose bolts on torque converter?

Any ideas appreciated. Thanks.

 

Anything?

 

It could be the starter isn't moving far enough from the flywheel...

I'm guessing its a bolt backing out of the flywheel... does the sound speed up with the motors RPMS?

It probably hard starting due to improper timing when its hot.

You really cant tell if the flywheels broken with it in the car .. most times..cause its usually cracked where its not easily visible thru the inspection cover. Is the inspection cover metal? Maybe its banging on the flywheel?

Heres just a few things to check out.

Maybe someone else will chime in with some other ideas.

 

Double check your converter bolts.Dids you use lock tight on the flywheel/converter bolts?there supposed to have it.If the flex plate is cracked it will make that noise too an can be hard to see some times

 

I put lock tight on converter bolts, flywheel was already on when i bought the motor..but they may be backing out..I have no inspection cover over flywheel

Timing was fine when the motor was running good.
I don't run it long enough to really listen..
Wouldn't want to rev it either..

I'm guess starter...it is hard to start..
The wires were loose and touching which caused a spark firework show, but I did tighten them now they are fine but still weak crank..

I'm going to drop the starter and replace with an extra one I have..hopefully its okay after that.

Appreciate the ideas.

 

This is where my line of thought first went also. A flexplate can crack (around the mounting holes then spider) if the bolts weren't properly torqued, the wrong bolts were used (sae vs metric), or the wrong flywheel (improper balance) is used. But with additional info you provided it sounds more like the starter bolts vibrated loose creating excess clearance between the ring gear and starter gear. While swapping the starter though I think I'd take a bright light and look at the flexplate around the mounting holes to insure no cracks have formed.

 

I know flexplates crack..I hear LT1 ones are common with cracking..I do have an additional SFI flywheel..how would I identify if its interanly balanced or external?

Its possible my starter bolts loosened, but I've done starters a thousand times I would hope I tightened it correctly lol

I've had a grinding flywheel/starter problems before in previous motors.. Thats not the sound I'm getting now..

I'm leaning more towards loose bolts from either flywheel or torque converter.

Thank you for your replies.

 

Loose flywheel bolts is a problem.. Hopefully that will stop the noise!!

Cross my fingers

 

Cant wait till spring to start her up!

currently saving up for a new starter.

 

Finally got some nice weather.

Started her up today, sounded great!!
The problem was the loose torque converter bolts.


Thanks again for the help!