adjustable tappets

[Beater]

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?

[Joe K]

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

[30 Closed Cab PU]

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.

[Pete]

Originally Posted by Beater

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.

[wensum]

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.

[Beater]

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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]

Originally Posted by Pete

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

[Bob C]

Vince says the 1" base tappets should never be used with the B cam.
http://www.fordgarage.com/pages/camshaftspecs.htm


Bob

[Pete]

Originally Posted by Bob C

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.

[Beater]

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