Michael J. Barnes Posted October 27, 2021 Share Posted October 27, 2021 (edited) On the block of my 1924 Cadillac there is a priming cup for each cylinder. Three or four of them have the cup upright when they tighten, but others go around nearly another half turn before they tighten. Seems to me it looks better when the cups always face up. Is Loctite a solution to this? Put it on the threads, turn till the cups are up, and tighten no more? Will the Loctite do the rest of the work? I would like to hear what product is recommended for this. Thanks. Edited October 27, 2021 by Michael J. Barnes (see edit history) Link to comment Share on other sites More sharing options...
Mark Shaw Posted October 27, 2021 Share Posted October 27, 2021 I suggest gas tank sealant would prevent leaks if not completely tightened. Link to comment Share on other sites More sharing options...
prewarnut Posted October 31, 2021 Share Posted October 31, 2021 Another solution is a small thin washer filed to size so not seen when seated. Why the condition exists in the first place is a question unless this happens...Or, the base of the priming cup could be machined (if it can be chucked on a lathe's independant jaw face). Link to comment Share on other sites More sharing options...
ejboyd5 Posted October 31, 2021 Share Posted October 31, 2021 I would pursue the washer idea, much like indexing spark plugs. Link to comment Share on other sites More sharing options...
Mark Gregush Posted November 2, 2021 Share Posted November 2, 2021 Priming cups generally have pipe thread, so don't think washer will help. You might try recutting the thread in either the head or on the priming cup just a little more with the proper size NPT cutter. Or you could wrap Teflon tape around them. People used it on spark plugs all the time. Link to comment Share on other sites More sharing options...
Michael J. Barnes Posted November 24, 2021 Author Share Posted November 24, 2021 Thanks, all, for suggestions. Link to comment Share on other sites More sharing options...
LI_BENTLEY Posted November 27, 2021 Share Posted November 27, 2021 Swap them between cylinders until you get top facing with a good tighten up. Link to comment Share on other sites More sharing options...
26-25Buick Posted December 5, 2021 Share Posted December 5, 2021 The priming cups also need to minimise leakage during the compression stroke. Would the Loctite be able to do this task? Link to comment Share on other sites More sharing options...
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