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912 vs 907 cam towers  Rating:  Rating
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 Posted: 11-29-2008 06:41 pm
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subwoofer
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I'll look for the process description, but I fear she'll need a full teardown. I have only changed the oil on her once (just after I got her), and a done head gasket is not unlikely as she overheated a few times while debugging the cooling system. A rebuilt radiator fixed the problem, but there may be more dogs buried in the back yard.


As far as the line bore goes, I believe I can get it done for roughly $3-400 at the local hot rod builder. If line boring, what would you rather do: resurface & bore with original bearings, resurface & bore for Chrysler bearings, or just bore for Chrysler bearings? Mike said he would recommend staying with original bearings, he could supply a full kit for £250, which sounds a bit more expensive than the club store.

--
Joachim

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 Posted: 11-30-2008 11:38 pm
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Judson Manning
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A typical 'watch builder' would re-surface both the block and main-panel about .005-.010", machine for all ten dowels, add the tabs for Esprit bearings, cross-drill the crank, then line-hone so everything is 'perfect'.  The extra .030" in "line bore" cost for Chrysler bearings washes when compared to the higher cost of the Esprit bearings.

I doubt there is any significant performance difference between the Chrysler and Esprit bearings, but thinking long-term I'd want the option of multiple (low cost) suppliers the next time I did a rebuild.

If we assume a sub-200hp engine doesn't need doweling AND we assume our block isn't warped, then we could drop-in a set of Turbo Esprit bearings by machining the tabs and cross-drill the crank.  A very cost-effective solution requiring a certain amount of faith derived from looking at the old bearings. 

If we assume a sub-200hp engine doesn't need doweling, but our block is warped and our mains out of round, it would add significant cost to remove the studs, surface each side and line hone to fit those same Esprit bearings.  This envokes the dreaded While You Are At It and it makes sense to add some dowels. 

Alternatively, a line-bore for Chrysler bearings takes out a lot more material and is a short-cut around the need to remove the studs and surface each side.  It could cost a little less or may not cost any different depending upon your Machinist.

BTW:  Do be sure you are asking Mike to price the post 1986 crossed-drilled 910 version of the Esprit bearings and not the 907 version.

Last edited on 11-30-2008 11:43 pm by Judson Manning

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 Posted: 06-16-2012 03:19 pm
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Dakota123
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(started new topic rather than append here.)

Last edited on 06-16-2012 05:00 pm by Dakota123

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