Tappet Clearances

Could someone please help me with a mechanical question regarding a Steve Mainey product. My go to Man is suggesting zero tappet clearance, which i find hard to imagine is correct but he is the guy who originally fitted all the components and is suggesting this is what was written in the notes, unfortunately he doesn't have the note anymore and I believe Steve Mainey has passed on his products to someone else. Any help would be really appreciated as I have no compression on the cylinder which has zero clearance.

regards

Danny

Hi,
It’s not up to me to say he’s wrong but it does sound rather strange.
I guess if done cold the coefficient of expansion of the aluminium head is greater than the valve but I don’t think I would like to rely on that for clearance.
I’ll be keen to hear a qualified answer from someone who actually knows something, unlike me
Alan

Senile old farts used to be able to set tappets ' by ear ' .

Was one who was deaf , who could ' feel the vibes ' .

The olde Screwdiver or plastic hose to the ear trick .

Avoid funny cigarettes while utilising this method ,
or the machine may end up dissassembled entirely .

Hagarr said:

Could someone please help me with a mechanical question regarding a Steve Mainey product. My go to Man is suggesting zero tappet clearance, which i find hard to imagine is correct but he is the guy who originally fitted all the components and is suggesting this is what was written in the notes, unfortunately he doesn't have the note anymore and I believe Steve Mainey has passed on his products to someone else. Any help would be really appreciated as I have no compression on the cylinder which has zero clearance.

regards

Danny

Click to expand...

You don't say what Maney product(s) you have.
If it's an ally barrel then maybe your man is correct. The aluminium pushrods should then expand about the same amount as the head & barrel assembly, meaning the should be no differential in expansion.
If you go down this path I would leave at least 1 or 2 thou, otherwise how do you tell the difference between zero and a valve hanging open?
Cheers

Tell us what Maney products you have in the motor, there are too many variables in your question otherwise to elicit any meaningful answer.

Stock Norton has a stock cam that needs a certain clearance. It also has an iron block and alloy pushrods that expand at different rates. So cold settings are calculated to take all of this into account and give the motor a desired hot setting.

A ‘full’ Maney motor has a Maney race cam which requires its own clearance. It will also have an alloy block and steel pushrods, giving a totally different cold setting / hot setting situation. IIRC it is THIS set up that requires nil clearence.

You could have any mix of the above cam / barrel / pushrod combo… so tell us what yer got…

Hagarr said:

Any help would be really appreciated as I have no compression on the cylinder which has zero clearance.

regards

Danny

Click to expand...

Could you not open up the clearance a few thou and recheck the compression?

Speaking of old farts, the maxim used to be, ‘a noisy tappet is a happy tappet.
nothing wrong with a nice chatter.
al

Alan L said:

Speaking of old farts, the maxim used to be, ‘a noisy tappet is a happy tappet.
nothing wrong with a nice chatter.
al

Click to expand...

Well no not really.

On an old cooking motor maybe.

But on a tuned bike, which I assume this to be given the high end components, a noisy tappet could mean a follower crashing straight into the maximum acceleration part of the camlift curve. Which is not good for any part of the valve train.

There are two choices here.

One an answer from Maney or another person familiar with these components- once we know exactly what the mix of parts are.

Or two a full measurement of the cam profile, identification of any quietening curve (there may not be one), an estimate of an appropriate cold clearance based on the cam dynamics for a starting point, and finally a check (not easy but possible) when the motor is as close to running temperature as feasible.

Or I guess there is also three. Run it with something sensible and inspect for wear.

I would really try to go with one and ask Maney or someone who has used his components.

I may be wrong, but I believe the reason behind zero lash has to do with the fact that the Maney cylinder is also aluminium, as opposed to the cast iron of the Norton cylinder assembly. With both the cylinder and the cylinder head being made of the same material [aluminium] as the push rods, these parts should all expand and contract at the same rate. Hense no need for valve lash settings.

My old 49 matchless g80 has zero clearance in the manual ,I was surprised , but will depend on cam grind you have .

When In raced my short stroke Triumph engine I used clearances of 2 and 4 thou of an inch. I use the same on my 850 Norton engine. One complete turn on the tappet adjuster is one 26rh of an inch - effectively 40 thou or 1 millimeter. Half a flat on a square headed adjuster on the inlet valve and one flat on the exhaust valve is usually enough clearance. Often the tip of the valve can be dimpled and if you use feeler gauges, you can end up with too much clearance. When I do valve timing, I use zero clearance and share the error in the timings at the opening and closing points.
If you open your tappet clearances to 10 thou then wind the cam by hand until it tightens, compared with zero clearances, you usually get a lot of travel. Some cams have quietening ramps on them. My 1958 Triumph Thunderbird had them, it was as quick as a normal 650 fitted with E3134 race cams

chaztuna said:

I may be wrong, but I believe the reason behind zero lash has to do with the fact that the Maney cylinder is also aluminium, as opposed to the cast iron of the Norton cylinder assembly. With both the cylinder and the cylinder head being made of the same material [aluminium] as the push rods, these parts should all expand and contract at the same rate. Hense no need for valve lash settings.

Click to expand...

I agree that makes sense.

But if the cam has a quietening curve then normal practice is to try and take up the clearance on the low acceleration part of the quietening ramp.

So you really need to know more about the various components and the cam grind.

chaztuna said:

I may be wrong, but I believe the reason behind zero lash has to do with the fact that the Maney cylinder is also aluminium, as opposed to the cast iron of the Norton cylinder assembly. With both the cylinder and the cylinder head being made of the same material [aluminium] as the push rods, these parts should all expand and contract at the same rate. Hense no need for valve lash settings.

Click to expand...

A ‘full’ Maney motor has alloy barrels and STEEL pushrods.
Hence the head and barrel grow MORE than the pushrods with heat.
Resulting in the tappet clearance GROWING.

Fast Eddie said:

A ‘full’ Maney motor has alloy barrels and STEEL pushrods.
Hence the head and barrel grow MORE than the pushrods with heat.
Resulting in the tappet clearance GROWING.

Click to expand...

If those are the components being used then that is correct. Clearance will grow as it gets hot.

johnm said:

If those are the components being used then that is correct. Clearance will grow as it gets hot.

Click to expand...

And that’s why we need to know what components are being used before any meaningful advice can be given.

Setting zero clearance seems dicey to me because, just as in using a feeler gauge, some folks use a tight "X -thousandths" and some use a loose "X-thousandths." When there is actual clearance - say .008", that doesn't really matter. But with NO clearance, it could.

IF - as has been suggested - the particular combination of components actually increases tappet clearance as the engine warms up, then it seems logical to figure it's OK. But if the clearance decreases, like every other solid-lifter engine I've ever heard of/worked on, it would be a problem.

As suggested, I'd really want clarification directly from the manufacturer re this before setting to zero clearance. It will be interesting to see (a pic of) the actual instruction sheet or an email message from the manufacturer for the Maney setup.

Ok fantastic, thanks to everyone i may not respond to each reply individually.

I won't name the gentleman who the vehicle belongs to as I don't feel at this stage necessary but information comes in dribs and drabs.
Not so much his fault, more mine because he has had extensive work done so I need to go over what he's told me a couple of times sometimes.

Ok I now understand the products i'm referred to are "Maney"

Yes he has Maney push rods and barrels with a megacycle grind camshaft, cylinder head is a "Fullauto" brand new cylinder head with Black Diamond valves, springs not confirmed (can't remember) but obviously upgraded.
Tri-spark ignition, belt drive, CNW starter and a myriad of other upgrades, so I believe it's sorted well or well sorted.

I am from a mechanical background, Fitter and Machinist and have spent considerable years in the Automotive machining industry so consider myself fairly well experienced across most mechanical aspects, especially when it comes to clearances and fits, Bore to piston, crank to bearing clearances or even the tappets section mentioned in this post.

Now someone did make the comment i'm about to make, apologies don't recall the name but you will know who you are, the problem i have is with "zero" lash, sure when you have a hydraulic lifter like a Harley where the clearance is formed due to the nature of the valve train components this is acceptable but not with a solid tappet cam and lifters.

The cylinder i have low compression on (35 psi) is consistent with that cylinder having zero clearance (determined by compression and leak down tests), the other (right hand) is ok which has clearance (.005"), now yes of course I have given clearance to the affected cylinder but i fear the seat or valve is damaged and will require repair so the head will need to be removed anyway but i'm trying to get my head around the zero lash.
I do to some degree understand the "coefficient of expansion" differences between cast iron and aluminium but I still believe you must have at least .001" clearance or risk what I believe what has now happened and damaged the valve seat, time will tell when the head is removed I guess but will keep looking at any further comments that may pop up.

MexicoMike said:

Setting zero clearance seems dicey to me because, just as in using a feeler gauge, some folks use a tight "X -thousandths" and some use a loose "X-thousandths." When there is actual clearance - say .008", that doesn't really matter. But with NO clearance, it could.

IF - as has been suggested - the particular combination of components actually increases tappet clearance as the engine warms up, then it seems logical to figure it's OK. But if the clearance decreases, like every other solid-lifter engine I've ever heard of/worked on, it would be a problem.

As suggested, I'd really want clarification directly from the manufacturer re this before setting to zero clearance. It will be interesting to see (a pic of) the actual instruction sheet or an email message from the manufacturer for the Maney setup.

Click to expand...

Yes exactly what I was after MexicoMike.

If anyone can provide a scanned copy would be great.

Hagarr said:

Now someone did make the comment i'm about to make, apologies don't recall the name but you will know who you are, the problem i have is with "zero" lash, sure when you have a hydraulic lifter like a Harley where the clearance is formed due to the nature of the valve train components this is acceptable but not with a solid tappet cam and lifters.

The cylinder i have low compression on (35 psi) is consistent with that cylinder having zero clearance (determined by compression and leak down tests), the other (right hand) is ok which has clearance (.005"), now yes of course I have given clearance to the affected cylinder but i fear the seat or valve is damaged and will require repair so the head will need to be removed anyway but i'm trying to get my head around the zero lash.
I do to some degree understand the "coefficient of expansion" differences between cast iron and aluminium but I still believe you must have at least .001" clearance or risk what I believe what has now happened and damaged the valve seat, time will tell when the head is removed I guess but will keep looking at any further comments that may pop up.

Click to expand...

On the subject of “zero lash” tappet adjustment, here is another data point to consider. Although this is a non-Norton application, I believe the fundamentals to be essentially the same as those being discussed here. For decades Harley Sportsters, XLH and XLCH, employed a near nil tappet setting where the factory tappet setting instruction stated that the pushrod could be “turned freely with finger tips, completely around, without trace of bind”. Thus, some minute amount of clearance existed in the valve train to allow the pushrod to rotate and the valve to seat. This was on an engine with cast iron cylinders/heads, solid roller lifters and steel pushrods, but with rocker arms in aluminum rocker boxes, and cams in aluminum crankcase, thus tappet clearance would increase with a warming engine due to coefficient of thermal expansion (CTE) differences between the ferrous components and aluminum components.

Perhaps we might be interpreting the “zero lash” setting a bit too literally, as we all know there has to be cold clearance for the valve to seat, thus “zero lash” has to provide some clearance so let’s just say “zero lash” means 0.001” lash, or the pushrod turns free or some such thing, but some minute amount of clearance has to exist cold. Thereafter, the “properly designed” warming engine provides additional running clearance in the valve train due to CTE considerations.

What I can tell you is:

A Maney cam with Maney alloy barrels and Maney steel pushrods is set at zero gap.

A Maney cam with Maney alloy barrels and alloy pushrods is 0.008”.

But you have an unknown Megacycle cam grind so I couldn’t even guess what you should aim for. And Steve’s scanned notes wouldn’t help you either sadly as he only refers to his cam AFAIK.

Maybe ask Megacycle? But you’ll need to know which cam you have first…