Is the flywheel alignment hole to crankshaft hole critical? I may have botched that up causing the vibration that I am experiencing.

you may have. always , ALWAYS put flywheel back in the same place it came off.

But if the crank is zero balanced and the flywheel is zero balanced, should it matter?

one wouldn't think so. but if suddenly you have a vibration, always double check the last thing you did.

To close the loop on this question, I spoke with technical support at RAM. They said that because the crankshaft is zero balance and the flywheel is zero balanced, the flywheel can be bolted to the crankshaft in any of the six radial positions and it won't matter. Positioning only matters on externally balanced engines (i.e. 400).

I don't remember that it mattered how the flywheel bolted to the crank on my zero balanced motor, but I will say that when I bolted my pressure plate to the flywheel and omitted some guide dowels I got a significant vibration. Did your PP come with any additional holes for dowels?

Your clutch components need to be centered on the flywheel so that everything is balanced well. If you just 'bolt it on', you will most likely have noticeable vibration.

Great question and this was answered as well by RAM. Pre-metric sized flywheel/pressure plate combinations used shoulder bolts that centered the pressure plate to the flywheel. Later (metric) use three dowel pins to center the pressure plate and non-shouldered bolts. That written...it IS possible I used the wrong bolts. I don't think so as there is zero issues with clutch engagement and operation. But, going to go back and look at what I ordered just to be sure.

if your car is the one shown in your avatar (68-9) than the shoulder bolts for the PP are what should be used
they are special bolts for that purpose

Respectfully disagree. If this were true why then when you get a crankshaft assembly back from the balance shop is the flywheel marked to the crank and pp marked to flywheel??? Also not using correct bolts for PP can be a vibration problem.

If you have them all balanced together, then yes you have to put it back together in the same place.
​​​​​​Zero balance engine, zero balance flywheel, and zero balance clutch ***'y can be mated together in any location.
That being said, if you take it back apart, it would be a good idea to mark the clutch and flywheel.
If you have a super duper high performance engine, then maybe you should have them all balanced together, but by the same token, if you have to replace the pressure plate or flywheel, you will, due to your sdhp engine, have to get everything re-balanced. That would entail tearing the motor back down and starting the balance over again.....

And definitely as recommended above, make sure you have the correct pp bolts

Good luck.
Jeff

I was referring to the position of the flywheel only relative to the crank...specifically whether the alignment dowel was relevant to the flywheel position in the crank.

i used the correct bolts for the application.

If you left that dowel out, and assembled the flywheel to the crank, or shoved it into the crank hole with the backside the flywheel, you may very well have thrown the balance off. Especially if it is externally balanced, and the dowel was the locator.. it may be externally balanced.
Is it a 383 ?
Without specific information about the engine, it's all just speculation.

Good luck.
Jeff

You have two threads going on this.....tough to keep continuation.
Fact is that ALL neutral balance cranks that come from the aftermarket are spun up without a balancer and flywheel. ALL flywheels and pressure plate/disc are spun up neutral......by the aftermarket. BUT how good it is balanced is strictly up to the person doing the job and the companies quality control. That said.....you can have a crappy flywheel, a crappy clutch or a crappy crank OR all three. You state in the other thread that it didn't vibrate when you got the car but now it does. Now I threw out a few ideas but they were just that, ideas.....you have changed the flywheel and clutch and now it vibrates.....you also state that you may have the dowel hole in the wrong spot. This may or may not effect your situation solely contingent on how well your components were manufactured.
But to answer your original question....no, it will not have any effect assuming it is all neutral balanced properly.

Jebby