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10-14-2019, 01:14 PM | #1 |
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Join Date: Aug 2015
Location: Southern Alberta
Posts: 582
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adjustable tappets
looking for a set of adjustable tappets for a build with a modern set of valves and guides ive never used them before. single nut or double nut, which are best? how does the single nut hold your adjustment?
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10-14-2019, 02:27 PM | #2 |
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Join Date: Jul 2010
Location: Cow Hampshire
Posts: 4,188
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Re: adjustable tappets
My rebuilder recommended the single nut.
My first opinion was double nut - but never having any experience with either I asked him why for his preference. "The double nut version relies on the frictional 'jamb' between the two nuts which we take as locknut. However, the friction is entirely lost once the first nut is loose - and the second nut free to turn by vibration. It's an 'all or nothing' lock. Meanwhile, the single nut version relies on "prevailing torque," usually, but not always the the result of a plastic insert. That prevailing torque does not release suddenly like a single nut but requires a force larger than the torque necessary to set it to remove it." Plus he says "The single nut version are easier, are adjusted faster, two wrenches instead of three, and more consistent in setting - just the action of setting the second nut on the two nut version can be enough to change the gap requiring re-doing it again." I took him at his expertise - and have not had a regret. This included complete disassembly of the engine later for repainting - and a re-assembly using the marked & matched parts. Joe K
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10-14-2019, 02:38 PM | #3 |
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Re: adjustable tappets
During motor rebuild last winter, had the adjustable tappets added. I believe the single nuts/tappets have a slight mismatch in threads for an interference fit, additionally the rebuilder used some type of non permanent thread lock. He said the adjusters should not need the thread lock, however he uses it anyway to be safe.
He also relayed me the same info Joe posted. Said he has not experience the double nut issue because he does not use them, but has "heard" of rare cases of the issue of them loosening up. |
10-14-2019, 02:39 PM | #4 |
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Join Date: May 2010
Location: Wa.
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Re: adjustable tappets
The double nut will lock tighter but the face is 1 inch in diameter so make sure your cam is compatible with that. The single lock ones have a larger diameter face and are compatible with an ORIGINAL not reground cam.
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10-14-2019, 03:50 PM | #5 |
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Join Date: Apr 2011
Location: New Zealand
Posts: 444
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Re: adjustable tappets
From my experience it is desirable to get the block machined first to lower the castings in the valve chamber to facilitate adjustment of the tappet setting, otherwise it is a very tedious process.
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10-14-2019, 04:41 PM | #6 |
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Re: adjustable tappets
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10-14-2019, 04:42 PM | #7 |
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Location: Southern Alberta
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Re: adjustable tappets
well I asked that to, and couldn't get an answer. this is a stock B engine with stock cam. everything I read says tappets are wider for the B supplyer couldn't tell me
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10-14-2019, 05:05 PM | #8 |
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Join Date: May 2010
Location: So Cal
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Re: adjustable tappets
Vince says the 1" base tappets should never be used with the B cam.
http://www.fordgarage.com/pages/camshaftspecs.htm Bob |
10-14-2019, 06:19 PM | #9 | |
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Join Date: May 2010
Location: Wa.
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Re: adjustable tappets
Quote:
If you use the large face lifters, you will be safe with either cam but will have to worry about the setting changing randomly. This is just another one of those engine building things that if you do not get it right, you might have to do it over. |
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10-14-2019, 09:44 PM | #10 |
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Location: Southern Alberta
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Re: adjustable tappets
well good to know. I guess I need to find someone that sells the larger face tappets then as my cam is an original B untouched
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