The Stovebolt Site Forums The Shop Area Engine Shop drilling out a flywheel

i don't have a clutch for my 292 i am using for a project. it a 292 out of a big truck. it has the wider spacing for a pressure plate on the flywheel. i have a good used 10" clutch. the only flywheel i have for this spacing is the older style with the 7/16" holes for mounting to the crank flange. i was thinking about just drilling out the holes on the flywheel but i noticed the crank flange on the 292 has 3 alignment pins instead of 1! can 2 of these be removed easily with the crank in engine? or... should i try to drill 2 more holes in the crank plus drill out the mounting bolt holes. or ..... should i stop being such a cheap $%^&* and buy a bigger clutch (this option sound the worst to me) . anybody else run into this? thanks, sorry about the 3rd post in one day. hr

i forgot to mention this is going in front of a 3 speed and i heard the bigger clutches are a little harder on the synchros, plus, dang it, i don't want to buy a new clutch.

hoggy,

Things sometimes get funky when you start pulling dowel pins and drilling holes in rotating assemblies. Hole position is critical and has to be exact. Sticking with stock, matching components is really the best way to go, especially when you are talking about flywheels, clutches and pressure plates...IMHO!

Stuart

I had a flywheel drilled at a machine shop from 7/16" to 1/2", cost was minimal and they did a precision job.

you are right stuart, and i always have my best luck sticking with stock matching stuff too- really no matter what. with all my work this weekend on it i'm going pretty wild today wanting to chop driveshafts and drill flywheels. thaks chevman32 i always over look the simple answer. i might call the machine shop and see what they would charge. i might even take the larger flywheel in and get the dowel holes too. hr

Ive drilled out the holes in flywheels many times for 292's. The center hole is the alignment hole. The dowels keep it from turning & wallering out the holes. All this said I would still use the 292 flywheel as long as you have it. It is heavier for the big stroke engine. When you put it on make sure you dont force the dowels back. If you push them back you are in trouble because there is no easy way to get behind them. You might be able to pull them out with big dikes or line pliers. Then put the flywheel on with the bolts not tightened down & drive in the dowels. The flywheel will take 11" or 12" clutch. The 11 will work OK with the 3 speed.

wow, i did it. i set it up on my mill and drilled it out also drilled out the holes for the other dowels. i found out something interesting- the single dowel hole on the old 7/16" mounting flywheel was 15/32". i didn't know there was 2 sizes!!! the 3 dowel holes on the newer 1/2" mounting flywheel was 7/16". i got to thinking rather than remove the 2 dowels and leave the flywheel alone, i should drill it out to make it more balanced. how can be assured the weight of the dowel removed will equil the weight of flywheel not drilled out. sounds confusing. i thought the dowels all equil out so if i drill the holes to accept them i will have the best chance of keeping it balanced. the holes in the newer 1/2" flywheel were actually 17/32" so when i drilled the old one i kept them to 1/2" plus a little. now i see why none of the machine shops i called wanted to do this. now i'm going to throw this on a tire balancer and balance it. just kidding, don't want to stop anyones heart. they can do this at the machine shop. anyone know about the 2 dowel sizes? hr

i forgot to mention wrenchbender, this flywheel is same size and thickness as the one that was on it. it just has closer mounting holes for the 10" clutch.

Yes there is 2 different sizes of dowels. The new engines came with a smaller hole. You get it bolted on & then drill it out to 7/16 going through the flywheel first. Then they were lined up. The weight is so close to center it won't effect the balance. I've run them with 1 dowel. Just make shure its snug enough so the dowel doesn't get in to far. If you are drilling the crank don't go all the way through so there will be a ledge to stop it.