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Fiat TC flywheel-crank dowel op

Posted: April 30th, 2007, 4:19 pm
by Guy Croft
If you are running a very high rpm motor it makes sense to double-dowel the flywheel to the crank. In the case of the 2 liter crank on ALL Fiat Lancia models the dowel holes are placed quite accurately symetrical to the 6 bolt holes. On other models they may not be. I say quite accurately, the reality is a little bit of polishing and fettling always seems to be needed.

Setting-off the holes in the fw by drawing or marking out is well-nigh a waste of time, I have tried it and never got the result I wanted.
In the case of these photos, a job for a Latvian client for a rally car with their own steel fw, you have to get it spot-on first time. It really is, sorry, one of those jobs for an expert. I have had firms try and do it and make a real hash of it. A loose dowel is no use to anyone, because then the torsional stress just gets taken on the bolts, which is what we're trying to avoid. A tight dowel is going to get stuck on crank or fw and there is no way of getting a tight dowel out! A misalignment can cause damage to the crank bolt threads and that really is catastrophic. The only way to do the job effectively, I have found, is to have a section of 2 liter crank as shown and use it as the jig for drilling and reaming. It take me about 2hrs to do this full op.