312 Crankshaft and grinding the Rear Seal Journal for a 292 block

Author	Message
Daniel Jessup	Posted 11 Years Ago
Supercharged Group: Forum Members Last Active: Yesterday Posts: 2.0K, Visits: 130.1K	Got a call from the crank grinder today. They have my 312 crank all ready on the main journals and rod journals but they are concerned about the rear seal area. They are telling me that their crank grinding machine will "grab" the rear seal journal if they use the machine to turn that journal down. They want to use their lathe to turn down the rear main seal journal and then polish the journal to match the 292 crank I left in the shop for them to compare. I have not heard of doing this, but they have been in business for over 50 years and have an excellent reputation and have done top notch work for me in the past. They believe by turning the rear main seal area down this way they will be able to keep the rear slinger also. Any of you guys have any words of wisdom on this one? 312 cranks are drying up and I don't want to lose this one Daniel Jessup Lancaster, California aka "The Hot Rod Reverend" check out the 1955 Ford Fairlane build at www.hotrodreverend.com
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NoShortcuts	Posted 11 Years Ago
Supercharged Group: Forum Members Last Active: 2 Years Ago Posts: 1.4K, Visits: 179.6K	In machining work you TRY to do everything with a single set-up of the workpiece in a machine, Dan. In working on a crank, the concentricity of the main bearing surfaces to the rear seal diameter are important. It is realistic to move the the crank from the crank grinder to an engine lathe and using a a four jaw independent chuck and a dial indicator, accurately set-up the crank to permit turning the rear seal area so that it is concentric with the previously ground main bearing surfaces. By my calculation, 0.130 inch needs to be removed (in total) to accomplish the needed modification to the existing 312 seal diameter. The reduction of the slinger diameter by 0.200 inch will likely be done at the same time of the set-up to cut the rear seal diameter. While the '55 cranks did not have a rear slinger, I like this lathe turning alternative to grinding away the rear slinger which some shops do because of not having the appropriate width crank grinder stones. NoShortcuts a.k.a. Charlie Brown near Syracuse, New York
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pegleg	Posted 11 Years Ago
Supercharged Group: Forum Members Last Active: 3 Years Ago Posts: 3.0K, Visits: 8.7K	You might talk to Mummert here. He has run into the same issue. His shop wanted to eliminate the slinger, but he wouldn't allow that. I think he found a shop that would make stone to grind it, but I've forgotten the details. Frank/Rebop Bristol, In ( by Elkhart)
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aussiebill	Posted 11 Years Ago
Supercharged Group: Forum Members Last Active: 5 Years Ago Posts: 1.8K, Visits: 11.4K	pegleg (7/29/2014) You might talk to Mummert here. He has run into the same issue. His shop wanted to eliminate the slinger, but he wouldn't allow that. I think he found a shop that would make stone to grind it, but I've forgotten the details. Frank you,r right, its just a matter of the machine shop having narrow wheel to do that part! another important matter is the actual slinger dimension, it too needs minor turning to orig 272/292 dimension to fit in block. AussieBill YYYY Forever Y Block YYYY Down Under, Australia
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312 Crankshaft and grinding the Rear Seal Journal for a 292 block

312 Crankshaft and grinding the Rear Seal Journal for a 292 block

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