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914World.com _ 914World Garage _ Bearing dowel pins

Posted by: brer Apr 22 2007, 01:26 AM

The FSM has a note to watch for tight or "perfect" fit in the bearing dowel pins.

I'm wondering how loosy or tighty these little buggers are best at?

Mine move a little in the three large mains and kinda loosy in the case at the nose bearing. So are we needing a specific fit here or what?

fit in the bearing halves (mahle) is not snug at all.

I bolted the halves together today without the cam gear and the crank seems nice and smooth. The rod for #3 was plastiguaged and came up at .0015 or so, but its bloody impossible to keep the bloomin' rod still while torqueing it. So I'm not sure its totally accurate. After installing the rod on the crank it would fall on its own weight but kind of quick, not smooth and slow. After I check the deck height I'm thinking maybe i'll take that guy off and fiddle.

Cam is snug, I think the axial play is to little.... >.001

Adams Ave. Roots and Blues is happenning down the street, so I had some swinging bluegrass to listen to all day.

Posted by: McMark Apr 22 2007, 11:36 AM

Sounds about right...

Posted by: brer Apr 22 2007, 03:11 PM

I haven't worried about these before, just stuck them in.
The note in the FSM to watch for perfect fit made me wonder.

Whats the deal with that?
Should they just be kind of loose in there or what.

Posted by: craig downs Apr 22 2007, 04:29 PM

The dowel pins should slip down in the holes of the case without any side movement

Posted by: brer Apr 23 2007, 12:25 AM

Ended the day with rod bolt interference with the cylinder. drats. Looking like about a 1/16" too long.

and since i'm measuring deck height on domed pistons I took it at either side of the dome and found .025 on the flywheel side and .035 on the other (cylinder 3), with a base gasket installed.

anyone care to comment on what the difference could mean? bent rod? or perhaps its the case?

Posted by: Jake Raby Apr 23 2007, 06:57 AM

Another point of interest concerning main dowel pins.... They should not exceed 8.0mm in length.

Sounds like your case has a drooped cylinder register, its becoming common after 30 years and is more prominent with 2.0 cases, especially of the GA series. The only way to remedy it is to tear it back down and deck the spigots evenly.

If you do not do this head leakage and uneven cylinder wear are to be expected.

Posted by: brer Apr 23 2007, 12:27 PM

I hates leakage.