Worn rockers

[D Murton]

Hi all

 

The rockers on my 4a are worn on the face that contacts the valve stem so it is difficult to set the tappets.

There is also some wear in the rocker bushes/rocker shsft.

 

I could grind back the rocker face to get rid of the groove, rebush the rockers & replace the shaft or replace the whole set.

 

If I rebush the rockers do I have to ream the bushes to fit the shaft? or if I buy new rockers do they come with the bushes fitted & reamed to the correct size?

 

Any advice would be welcome.

 

Thanks

 

Dave

[RogerH]

Hi Dave,

the bushes are £2+ and you need 16 = £32+

 

The rockers are apprx £7 each and you need 8 = £56+ check with the supplier that the bushes are included

 

The bushes need reaming whereas the rockers are pre-reamed

 

Inserting and reaming the bushes will take all day and depending on your engineering skills may be iffy!!

 

The old rockers can be refaced (lightly) I use a circular sanding pad as they are gentler and produce less heat.

 

However, I would go for a new shaft and 8 new rockers.

 

Roger

Edited September 22, 2010 by RogerH

[D Murton]

Thanks Roger

 

I have access to a lathe so I could easily make up some stepped pins for removing the old bushes & pressing in the new ones but what I dont have is any reamers and I cant find any reference to the shaft diameter.

 

I was intending to grind back the faces by hand with a slip stone but also have a dental handpiece to polish up the faces.

 

I guess its a a case of a few hours vs ££ notes.

 

I will have to give it some thought

 

Thanks again

 

Dave

[RogerH]

Hi Dave,

the shaft is 0.625" +0.00/ -0.002.

 

I used an expanding reamer but it needs to be held quite steady.

 

I think an overly good running fit is more luxury than necessity as the bearing face is only ever at the bottom of the

bush so a standard 5/8" (0.625) reamer should sort it.

 

The bushes are split so put the split to the top of the rocker.

 

The bushes can be pushed out using a socket but purpose made mandrels are even better.

 

Dependinjg on the shaft diameter you may need to ease out the holes in the pillars.

 

Roger

[D Murton]

Thanks Roger

 

There is an engineering company opposite where I work so they may have an adjustable reamer I could borrow.

 

I may well wait till over winter when time isn't such an issue & strip the assembly out & make a decision based on how badly the rockers are worn.

 

Regards

 

Dave

[Ian Vincent]

If you buy new rockers from Moss they will come ready bushed. I suspect that the rockers are case hardened and if you try to reface them they will wear very quickly.

 

Rgds Ian

[88V8]

Or if you really don't mind a bit of wear in the bushes you could buy one of these, then you will be able to set the tappets regardless of wear in the contact face.

http://www.minispare...ku=MSA1001&tc=1

 

Here's a thread discussing it

http://www.tr-regist...?showtopic=6254

 

And just to balance things, an entertaining view from across the pond

http://www.minispare...ku=MSA1001&tc=1

OK, he is an MG owner so perhaps a few cucumbers short of a picnic.

 

I've had one of these gubbins for more than 30 years (I hate writing that) and it will be getting its annual outing this coming week.

 

Ivor

[TR 2100]

It's not difficult to count the number of threads per inch

on the adjusting pin and convert the valve clearance into

a number of degrees to back off from the gap being closed.

 

AlanR

[Badfrog]

Hi,

 

I use an old shaft with very fine valve paste for reaming.

BTW, why not consider roller rockers if everything is worn ?

 

Badfrog

[ChrisR-4A]

Hi Dave, I replaced the rockers and shaft on my 4A in 2005 and the cost was just under £90. I would not bother trying to reface the old rockers as the case hardening is fairly shallow and if there is a big step you are probably through it allready. The longest part of the job was removing the protecting grease (more like Tar) from 4 of the rockers which were very old stock". One thing I should have bought was the 2 roll pins which go either end of the shaft as new ones are much easier to fit than the ones you push out. Have only had to adjust the rockers once since and have done over 24,000 miles.

 

Chris

[TR 2100]

Hi Dave, I replaced the rockers and shaft on my 4A in 2005 and the cost was just under £90.

I would not bother trying to reface the old rockers as the case hardening is fairly shallow

and if there is a big step you are probably through it allready.

 

That's the way I would go - it really is the best solution,

especially when you remember that TR 4-pot are a bit tappety

anyway, so it's worth making sure the clearances are spot on.

 

AlanR

Edited September 23, 2010 by TR 2100

[D Murton]

Thanks for all the advice.

 

I dont think I could justify the cost of roller rockers so so I'll order a set of standard rockers & a new shaft.

 

Is it worth going for a tuftrided shaft on a standard engine that doesnt do that many miles?

 

Dave

[Alec Pringle]

Hi Dave,

 

roller rockers are an irrelevance unless you have a very seriously tuned engine, and they aren't worth a light unless they're top notch, and that is serious money. Don't even think about them.

 

On a standard engine you need standard kit, and the ready to fit stuff from Moss will do very nicely. Anything else is chucking money at a fashion statement.

 

Cheers,

 

Alec

[RogerH]

Hi Dave,

the standard shaft should last about 100,000miles apprx £30 from TRshop and the other usual suspects.

 

Roger

[Badfrog]

Hi all,

 

It's true that roller rockers are expensive (354 USD in me case) and the tuftrided shaft adds up, both being over the top for a standard engine doing moderate mileage at reasonable speed. However, both turn out quite beneficial when driving fast (4500 rpm average) and long range. They are silent, a cinch to adjust, do not wear and respect the valve stem.

 

Lately, I found a new advantage: when the prewar racer has its cylinder block on the bench and the TR has her nose up with a dismantled front axle, you can sit in the garage, shine a light on the rollers and enjoy the golden anodisation glow in the dark with a cigar and a malt. When you've just missed Spa, Beaulieu and Goodwood on account of no roadworthy car, it helps.

 

Badfrog, the stiff upper lipped amphibian...

[Tony Millward]

 

 

Lately, I found a new advantage: when the prewar racer has its cylinder block on the bench and the TR has her nose up with a dismantled front axle, you can sit in the garage, shine a light on the rollers and enjoy the golden anodisation glow in the dark with a cigar and a malt. When you've just missed Spa, Beaulieu and Goodwood on account of no roadworthy car, it helps.

 

Badfrog, the stiff upper lipped amphibian...

 

 

I know exactly what you BF, (just pouring another scotch and admiring my newly sprayed scuttles)....and roller rockers...

 

Tony