Tappets

[Tonyloz]

Hi all

I have noisy tappets due to the rocker faces having wear indents so setting the 10 thou clearances are a bit hit and miss

Question is can i lap grind them smooth again or are they just surface hardened

Any advice please

Thanks

Tony

[RogerH]

Hi Tony,

a very clever chap has said on here that the indentation is not wear as such but actually an indentation of the hardened

surface into the softer parent material.

 

So the hardened surface is still there but pushed in.

 

You can grind the metal away from the 'raised' area.

 

Roger

[Geko]

why don't you try setting the clearance with the engine running ?

[Ian Vincent]

Or use an SPQR tablet setting tool. They do work.

 

Rgds Ian

[Tonyloz]

Can you run the engine with the rocker box off without getting oil everywhere?

Don't want to cover my nice new engine bay with oil!

[Lebro]

It does splash a bit, but managable

 

Bob.

[Rem18]

I thought tappets were set from cold?

But surely noise is due to oversize spacing?

Is it just the slight noise your worried about?

[Tonyloz]

Ive sent for a tappet adjusting tool..i do like a gadget!

See how that goes first before taking it apart

[RogerH]

Hi Tony,

the usual tappet adjuster tool has not got a very good reputation.

 

If you have any tappets that are not indented then you could set them to the require gap and take note of the angular adjustment to close them up.

Use this rotation to set the others - it will be less than 90'.

 

 

Roger

[Ian Vincent]

 

the usual tappet adjuster tool has not got a very good reputation.

 

I have an old SPQR one and as I said above, it does work. It just needs a bit of care because it isn't idiot proof.

 

Rgds Ian

[Motorsport Mickey]

As Roger says the polished faces are impacted hardened surface material, that's what the tappets will seat on. The remaining surface material which stands up either side of the polished faces can be safely ground back making sure NOT to remove the polished seat face...easy. It's even recommended to do this in the David Vizard "Modifying Triumphs for the track" or whatever the official title is, something many Triumph owners try to adhere to.

 

Unfortunately I am one of the many idiots that Ian says can't operate machinery or even something as simple as a threaded bush with a screwdriver shaft and point running down the centre normally called a SPQR tappet adjustor despite a HNC in engineering and winning 5 TR Register race championships having built ALL my own engines and engines for others. I continue to learn.

 

Mick Richards

[TR 2100]

I still use an SPQR type approach.

 

Work out the thread tpi and you will find how many degrees

equate to, say, 12 & 14 thou.

So - tighten by hand to take up the play, then back off the

appropriate amount.

 

Can't say that approach would be accepted by engineers,

but I still do it that way.

 

AlanR

[RogerH]

Hi Alan,

the 5/16UNF adjuster on the rocker arm has 24tpi. - cal that apprx 0.040" for a full turn - so a 1/4 turn will give 0.010"

BUT the rocker isn't equal about its centre. The valve side of the rocker shaft is longer than the push rod side.

 

What is the ratio.

 

That is why I said on post #9 to work out the degrees on a good valve.

 

Roger

Edited May 8, 2018 by RogerH

[peejay4A]

1:1.55 nominally?

[RogerH]

Thanks Pete,

so 90 degrees on the adjuster will give 0.0155" of gap

 

6.45 64 degrees will give 0.010" gap. That could be fun to measure.

 

Roger

 

PS - who doesn't know where his decimal point is.

Edited May 7, 2018 by RogerH

[acaie]

Thanks Pete,

so 90 degrees on the adjuster will give 0.0155" of gap

 

6.45 degrees will give 0.010" gap. That could be fun to measure.

 

Roger

This isn't right. If you've ever adjusted a tappet to get the clearance right to .001, it does not take 0.6 of a degree on the adjuster to make .001 difference. On the basis of this sum it is 6 degrees to make .001, not.010, which sounds about right.

Rule 1 of mathematics for engineers is that it is more important to get the decimal point in the right place than to quote three significant figures.

[RogerH]

This isn't right. If you've ever adjusted a tappet to get the clearance right to .001, it does not take 0.6 of a degree on the adjuster to make .001 difference. On the basis of this sum it is 6 degrees to make .001, not.010, which sounds about right.

Rule 1 of mathematics for engineers is that it is more important to get the decimal point in the right place than to quote three significant figures.

oooops

yes it should be nearer 65 degrees. But you get the idea.

 

Roger

[TR 2100]

oooops

yes it should be nearer 65 degrees. But you get the idea.

 

Roger

 

Roger,

 

Ooops - |Yes, I need to change my calcs a bit!

 

AlanR

[Ian Vincent]

Unfortunately I am one of the many idiots that Ian says can't operate machinery or even something as simple as a threaded bush with a screwdriver shaft and point running down the centre normally called a SPQR tappet adjustor despite a HNC in engineering and winning 5 TR Register race championships having built ALL my own engines and engines for others. I continue to learn.

 

Mick Richards

Mick,

 

That's not what I said and you know it. the engineering principles behind the SPQR adjuster are perfectly sound but because it was probably made 'Down to a price' the execution is a bit dodgy. Nonetheless with care it works. Which is what I said originally.

 

Rgds Ian

[Motorsport Mickey]

Mick,

 

That's not what I said and you know it. the engineering principles behind the SPQR adjuster are perfectly sound but because it was probably made 'Down to a price' the execution is a bit dodgy. Nonetheless with care it works. Which is what I said originally.

 

Rgds Ian

Yeah...I'm thicker skinned than that Ian, just joshing.

 

Mick Richards

[Tonyloz]

Wow!

I can't wait to have a go when if arrives

I thought it sounded easy...i feel a headache coming on!