22 replies to this topic

[59 Speed]

I've just checked the tips in my rocker arms (where it meets the top of the valve) and most seem quite worn / pushed in where it has been pushing the valve down.

I have two sets and was going to pick the best ones and grind them down with a fine grit disc so they are equal and smooth like I did with the end of my rush rods - would this be okay or will I be reducing the hardness of the tips?

My other option is to buy a set of 1.5 roller rockers, but as I'll be running a Kent 286 cam I've heard there won't be a benefit of using them apart from the reduction of side loading to the valve guides.

I wasn't planning on getting them replaced just yet as I'd much rather spend my money on a pre verto ultra lite flywheel / clutch setup as the last time the engine ran it was with a very heavy verto type.

Can I get away with the grinding the rocker tips, or is it essential that they are replaced?

Thanks in advance,
Ian

[Dusky]

Will ruin the valve opening ratio. let them be..

[Gremlin]

Will ruin the valve opening ratio. let them be..

Why, if you just grind the face down

To be clear I'm not saying it will be fine I'm just curious as to how Dusky thinks this^

[Alex_B]

 

Will ruin the valve opening ratio. let them be..

Why, if you just grind the face down

To be clear I'm not saying it will be fine I'm just curious as to how Dusky thinks this^

 

The rocker ratio is a product of the height of the rocker arm and its length, by grinding down the face you will reduce the rocker ratio, albeit not by very much 

Edited by Alex_B, 23 April 2014 - 09:25 PM.

[SMP]

I did this on mine using various grades of wet and dry wrapped round a bit of metal. I only dressed the unworn part of the tip down so that it was flush with the worn part. This made it easier to get feeler gauges in to set the tappets. This will affect the rocker ratio a bit but no worse than than if I just used them as is. I used paraffin as a lubricant for the wet and dry.

[Gremlin]

Yeah exactly, I can see what he's getting at but he'll only be taking off .5-1mm so it'll be fine as long as the rocker is strong enough once been ground down by a mm, I don't know enough about hardening to answer confidently

[Alex_B]

Yeah exactly, I can see what he's getting at but he'll only be taking off .5-1mm so it'll be fine as long as the rocker is strong enough once been ground down by a mm, I don't know enough about hardening to answer confidently

I am 99% sure the valve tips are not hardened and im not even sure the rocker arm is hardened, however if it is I would imagine it will just be surface hardened and taking up to a mm off would remove the hardening entirely 

[Captain Mainwaring]

 

 

Will ruin the valve opening ratio. let them be..

Why, if you just grind the face down

To be clear I'm not saying it will be fine I'm just curious as to how Dusky thinks this^

 

The rocker ratio is a product of the height of the rocker arm and its length, by grinding down the face you will reduce the rocker ratio, albeit not by very much 

 

Think about that again.....

 

 

Stone off the tips a bit but you may well go through the hardening

[Mighty made]

Rockers are usually hardened on the surface, by heat treatment.

 

You can usually see the colour change at the surface as it could just be the tips

rather than the whole rocker.

 

The original forged ones I think had some gas carburising process done to get to the same effect.

 

Typical hardness depth is about 60 thou from memory on the powder rockers the core material remaining softer to improve toughness, fracturing etc.Removing this layer could you back to the original material hardness (and so it'll wear faster).

 

All of the gears have a similar treatment on them .

[Alex_B]

 

 

 

Will ruin the valve opening ratio. let them be..

Why, if you just grind the face down

To be clear I'm not saying it will be fine I'm just curious as to how Dusky thinks this^

 

The rocker ratio is a product of the height of the rocker arm and its length, by grinding down the face you will reduce the rocker ratio, albeit not by very much 

 

Think about that again.....

 

 

Stone off the tips a bit but you may well go through the hardening

 

Am I wrong on the rocker arm? 

I was under the impression that the arm itself is where the rocker ratio comes from, and by modifying the rocker arm tip you will affect the ratio ( I am aware it wont have much of an affect) 

[59 Speed]

Cheers for the feed back guys.

By the sounds of it it's not worth messing with the rocker tips so I think I will be going for some roller tip ones. I was looking into into buying the rocker spacer kit and thicker rocker shaft anyway.

I was just concerned whether they would reduce power as I'm going to use a Kent 286 cam.

Does anyone have any recommendations of manufacturer?

[dklawson]

The ratio is determined by the distances between the pushrod, rocker shaft, and valves.  You are not going to significantly alter the arm ratio by regrinding the valve contact tip on the arm.

 

The process was somewhat common years ago.  It was typically referred to (at least over here) as resurfacing or reprofiling.  I cannot comment about the later sintered arms but the forged arms were heat treated and there you had to worry about removing the heat treated contact surface by grinding off "too much".  The stamped steel arms had separate contact tips and I assume those were also heat treated... though the arm was not. 

 

More info on DIY resurfacing is in the link below should you decide to recondition your rocker arms and perhaps keep them as spares.

http://www.zcar.com/...ocker-arms.html

 

As always there will be lots of stuff on YouTube if you search for "rocker arm resurfacing"

[Dusky]

Cheers for the feed back guys.

By the sounds of it it's not worth messing with the rocker tips so I think I will be going for some roller tip ones. I was looking into into buying the rocker spacer kit and thicker rocker shaft anyway.

I was just concerned whether they would reduce power as I'm going to use a Kent 286 cam.

Does anyone have any recommendations of manufacturer?

Get 1.3 rollers, otherwise you 'll lose alot down the rev range.. 1.5 only gains at high revs..

[Captain Mainwaring]

 

 

 

 

Will ruin the valve opening ratio. let them be..

Why, if you just grind the face down

To be clear I'm not saying it will be fine I'm just curious as to how Dusky thinks this^

 

The rocker ratio is a product of the height of the rocker arm and its length, by grinding down the face you will reduce the rocker ratio, albeit not by very much 

 

Think about that again.....

 

 

Stone off the tips a bit but you may well go through the hardening

 

Am I wrong on the rocker arm? 

I was under the impression that the arm itself is where the rocker ratio comes from, and by modifying the rocker arm tip you will affect the ratio ( I am aware it wont have much of an affect) 

 

I think it's been addressed above, but the ratio comes from distance to fulcrum/distance to fulcrum so if you resurface then these effectively remain unaffected - 

[Dusky]

How do they make the difference between 1.3 and 1.5 then?O.o