Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 10-14-2019, 01:14 PM   #1
Beater
Senior Member
 
Beater's Avatar
 
Join Date: Aug 2015
Location: Southern Alberta
Posts: 499
Default 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?
Beater is offline   Reply With Quote
Old 10-14-2019, 02:27 PM   #2
Joe K
Senior Member
 
Joe K's Avatar
 
Join Date: Jul 2010
Location: Cow Hampshire
Posts: 3,384
Default 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
__________________
Shudda kept the horse.
Joe K is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 10-14-2019, 02:38 PM   #3
30 Closed Cab PU
Senior Member
 
Join Date: Aug 2018
Location: Wisconsin
Posts: 1,515
Default 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.
30 Closed Cab PU is offline   Reply With Quote
Old 10-14-2019, 02:39 PM   #4
Pete
Senior Member
 
Pete's Avatar
 
Join Date: May 2010
Location: Wa.
Posts: 3,505
Default Re: adjustable tappets

Quote:
Originally Posted by Beater View Post
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?
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.
Pete is offline   Reply With Quote
Old 10-14-2019, 03:50 PM   #5
wensum
Senior Member
 
wensum's Avatar
 
Join Date: Apr 2011
Location: New Zealand
Posts: 419
Default 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.
wensum is offline   Reply With Quote
Old 10-14-2019, 04:41 PM   #6
Beater
Senior Member
 
Beater's Avatar
 
Join Date: Aug 2015
Location: Southern Alberta
Posts: 499
Default Re: adjustable tappets

I asked at the sellers point in the technical help department and they told me the single nut is a cross thread , and once gone to far will not stay tight if you have to back them out again. so opted for the double nut system. it will be slower to set up but more permanante once done it looks like to me
Beater is offline   Reply With Quote
Old 10-14-2019, 04:42 PM   #7
Beater
Senior Member
 
Beater's Avatar
 
Join Date: Aug 2015
Location: Southern Alberta
Posts: 499
Default Re: adjustable tappets

Quote:
Originally Posted by Pete View Post
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.
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
Beater is offline   Reply With Quote
Old 10-14-2019, 05:05 PM   #8
Bob C
Senior Member
 
Join Date: May 2010
Location: So Cal
Posts: 6,457
Default 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
Bob C is offline   Reply With Quote
Old 10-14-2019, 06:19 PM   #9
Pete
Senior Member
 
Pete's Avatar
 
Join Date: May 2010
Location: Wa.
Posts: 3,505
Default Re: adjustable tappets

Quote:
Originally Posted by Bob C View Post
Vince says the 1" base tappets should never be used with the B cam.
http://www.fordgarage.com/pages/camshaftspecs.htm


Bob
That is correct, if the cam has an ORIGINAL type grind on it. The original grind had NO clearance ramps. It was of the 3 arc design. Most modern REGRINDS have clearance ramps and can be used with 1 inch diameter lifters.

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.
Pete is offline   Reply With Quote
Old 10-14-2019, 09:44 PM   #10
Beater
Senior Member
 
Beater's Avatar
 
Join Date: Aug 2015
Location: Southern Alberta
Posts: 499
Default 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
Beater is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 07:03 AM.