Technical Chevy 327 crankshaft question can not find a flywheel that fits! HELP!!!!

I'm with greybeard360 on this.
If lined up with the dowel, the notches in the flange line up.

 

Still waiting for @Bryan Andrews to give us the bolt pattern diameter of the crank flange and "new" flywheel that does not work to see if they match and conclude that "new" flywheel is of correct years to work with early SBC's.

 

Good to see you back, holding on for solution.

 

Until @Bryan Andrews gets a set of dial calipers and reports back with some accurate numbers nothing else here is meaningful.
He should see a bolt circle diameter on both the crank flange and flywheel of 3.580. If six holes on that B.C. are spaced equally (as they are on a Chevy crank flange and flywheel) those holes will measure 1.790 center to center.
Forget the guesswork and eliminate the bull shit, the only way to check accurately is to measure. If no calipers are available you can come really close with a good machinists scale.
The worst part of a thread like this is not getting accurate, and enough, solid information.

 

This may sound crazy, but is he trying to put it on backwards?

 

He said he was putting it on the correct way in post #57.

 

Two things come to mind ... is there a burr on the crank (or flywheel) that is preventing the flywheel from sitting flush against the crank or is there some ancient crud in the bolt holes on the flywheel that are making the holes slightly smaller than they should be, preventing you from lining up the holes. I'd run a drill bit through the flywheel holes, a bit that won't open the holes any larger than stock but large enough that it will clean up any crud. I am assuming the new flywheel is faulty and the old flywheel has slightly smaller holes than originally drilled due to crud accumulation over the years.

Another thought just crossed my mind ... are you getting one or two bolts in then torqueing them on before all the bolts have been started? Make sure you don't tighten ANY until they have all been started, this will allow some slight wiggle room. Oh, yeah ... I would focus only on lining up the dowel holes as that is how it is designed to work.

 

Some searching of the part number 3197021 shows that it is indeed the correct flywheel for that crank as the witness marks show.
143470180322 Ebay listing showing one for sale.

I've seen guys fight with a flex plate on an engine because they had it on backwards but never a flywheel for a stick.

I'd say it is a real bad case of the op not lining up the dowel pin holes or lining up the witness mark with the crank. I've fought that battle while laying under a rig when I was upside down and backwards a time or two but I've learned a few tricks since those days.

 

I'm not understanding the need to line up the dowel pin holes when there are six holes spaced 60° apart on a 3.580 bolt circle.

 

Do you feel like a productive contributor to this community when you make posts like this?

Asking for a friend.

 

Here’s one I ran into before. Someone drilled and tapped for larger bolts the crank flange. Crank came with correct looking bolts. Trying to put on a new flex plate a few of the bolts would not go in. Took a little while to figure it out. I had to open up the bolt holes on the flex plate to the next size to get it to fit. It was an aftermarket remanufactured crank. Thank God there were no weird vibrations! Might want to check that.

 

That is a good point. I wonder what the diameter and pitch of the bolts he's using are.

 

My feeling is the dowel pin hole was put in the crank and the flywheel for a reason so why wouldn't you line them up? With the dowel pin holes lined up, there should be no worry that the crank and flywheel are clocked incorrectly. If the dowel pins line up, the bolt holes should fall into place. In this particular case, the apparent fact that the bolt holes aren't lining up even when the dowel holes are, suggests something is being overlooked or something is definitely wrong/has been altered from factory.

 

Nawwwww....should'na done it! Sometimes my brain 'jumps-outta-gear!
Sorry guyz
6sally6

 

Means you have never put a flywheel or flex plate on a Chevy crank as they will only go on one way period. The holes aren't perfectly spaced.

 

Every single machining operation takes time and costs money. If there was no need for a dowel pin to establish pattern alignment, it would not be there.

 

The bolts should be 7/16-20 (0.4375"), with a shoulder. If your bolts are not that diameter and pitch, this has been modified. If they have the correct diameter and pitch, but no shoulders, then they are the wrong bolts.

The holes in the flywheel should be 15/32" (0.46875"). The shoulders on the bolts should be just shy of that.

GM did not throw away a crank if it had an issue. If the pattern was off, this would have been sent for rework. So it is possible that you had a matched-set crank and flywheel (or flexplate, if that is what it started life with). Product Lifecycle Management rules, even then, would have dictated that this was a fix that likely would not have caused an issue within the design lifetime of the vehicle (which you are WAY past).

If this is the case, your options are limited. Chuck the crank, or rework the flywheel.

A good machinist with a set of transfer screws can mark the current pattern on the undrilled portions of the flywheel, and then drill new holes. The dowel hole will get worked into a new hole.

 

Nope holes not same same.
It only goes on when clocking is correct

 

Just my two cents but have you measured the o.d of the crankshaft flange and the i.d of flywheel to see if either one is out of round.good luck hope you find the problem

 

All this talk about needing a dowel pin. Good thing timing chain sprockets don't need a dowel pin to line up. Hole to hole like dot to dot?

 

I don't think others are saying you NEED to have a dowel it just makes it easier for someone not experienced in fitting flywheels.

 

All the timing gears I have worked on either have a key way,,,,or a dowel pin to align up .
The gear to the crank,,,,,the gear to the cam .
LoL,,,,,,did I miss something ?

Tommy

 

I don't know if my eye's are playing tricks on me or what, but from the pic's the OP posted in post 45, it looks like the register's for the converter pilot and the pilot bushing are way off center and wollered out like hell. Could this be where the problem stems from?

 

Hard to tell, I would just match up the ghost pattern on the flywheel with the crank pattern and see what happens. Get another flywheel, borrow one even... just for a sanity check.

 

In 50+ years of working on SBC and BBC engines I don't recall ever seeing a dowel pin in a crankshaft? And don't recall ever having to turn the flywheel or flexplate to make the holes line up with a dowel pin hole? Maybe I'm getting too old, and don't recall crap? Guess I need to go try one again to refresh my memory!

 

The part about sprocket alignment.

 

If they have a weight on them like the SBC 400, they only go on one way.
The dowel pin usually gets left out and I don't ever recall seeing one one a flexplate.

 

I wonder if they turned the crank inside out for the wash cycle but forgot to return it for the rinse ... that would explain almost everything

Depending on the water temp used, there could be the oft forgotten "shrinkage factor" too

I have seen the actual dowel once before (SBC).

 

Talk about beating a dead horse or in this case dowel pin, you don't need one on a sbc period. I think that I remember back when 265 and 283 were new that they had a pin in the crank but cost cutting removed the unneeded pin but the holes remained. There is no reasonable explanation why that flywheel won't go on if you line up the dowel holes use a drift pin, the bolts should line up. Collectively we have all done this hundreds of times.

Pat