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Nigel Abrahams (UK)

Joined: 03-17-2005
Location: Taunton, United Kingdom
Posts: 1
My engine rebuild strategy is to use JE Flat top Pistons (+0.030" oversize) and get the cylinder liners re-bored and honed to suit. What is the standard practice for this machining operation ? Should the liners be kept clamped in the block for the re-bore or removed and done indvidually ?

My guess is that they should be kept in the block to avoid liner/nip problems etc..

Also, I have tried to remove the bearing studs in the bottom of the block but I have only managed to remove only one of the ten studs (using the double nut method and a 3ft breaker bar). I have a stud extractor tool I can use, but this will damage the studs and I don't want to go to the expense of buying new ones. 

Any advice on how to remove these studs, and should they be removed if the liners are re-bored in the block to give access to the bottom face of the block to serve as a datum for machining purposes?

Judson Manning

Joined: 03-14-2005
Location: Atlanta, Georgia USA
Posts: 406

Your initial strategy is correct, however, many have found it necessary to hone all .030" rather than bore ~0.025" and hone the last 0.005".  The liners tend to warp and wiggle under the stress of a boring bar.  Delta stocks  0.005" o/s pistons as well as the 0.030".

The overwhelming consensus is to leave the liners in the block as any jig or clamp would oblong the liner during machining.  A number of people have machined a torque plate to hold eveything in place, and I know of a few people who have even heated the block with a 180^F water bath while completing the honing process.

We found that with a few pieces of scrap aluminum we were able to hold the liners in place during the ridiculously long honing process.  As for the 180^ water-bath...how perfect is practical?

With 30 years of corosion, I can understand how difficult it can be to remove the studs.  The double-nut method works fine for me, however, my machinist was able to work around the studs and I only remove the studs when the block needs to be decked.


Jensen Healey
Super Moderator

Joined: 03-11-2005
Location: San Anselmo, California USA
Posts: 983
Barry Spencer pulled my liners and clamped them into a custom made jig for boring. He said the jig cost him lots of $ to have manufactured. Sadly, he has closed his shop but your local Lotus shop may have a similar setup. 




Joined: 11-14-2011
Location: West Linn, Oregon USA
Posts: 3
I have recently acquired a liner retainer jig that is made from a sacrificed 907 head. The head has been machined so that its possible to bore or hone the liners while in place in the block.My intention is to donate this jig to the club to used as loaner if there is interest. Regards Greg West (Lake Oswego, OR.) gwest@jhkelly.com


Joined: 04-01-2008
Location: Sandefjord, Norway
Posts: 583
With fresh liners being around 60£ each, why bore to oversize?


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