13 replies to this topic

[wolfys_mini]

right some questions, dont ask why, dont give me rubbish answers, if you know the real answer, then say so. if you dont, stay quiet. simple

rocker assembly, what type of steel they made from? (do not say, the hard type!)

roller rockers, roller tipped, whats the advantages/disadvantages?

are they made from something different? never seen a set to touch, so excuse the daft question.

http://www.theminifo...x...?act=SR&f=6 <<<<< follow that advice

Edited by wolfys_mini, 14 March 2008 - 03:30 PM.

[miniboo]

thread edited.......already lets keep it about the question. as the old saying goes if you have nothing nice to say say nothing!! OR in this case if you have nothing beneficial to add then add nothing!!

[BoboGib]

just done a quick google search and managed to find this place that mentions their rockers are made of forged 4340 steel. Here is the link.


Clicky

[ginigwunkle]

which brand are you wanting to know as different brands will make with different grades, also which part in particulat as the shaft is made of diff stuff to the rockers.....

[wolfys_mini]

just a general overview.

unless you know all about a particular brand

all the different parts

[Dan]

The late standard rockers are made from what is known as sintered steel. This is a kind of 'steel chipboard' that is produced by pouring all the swarf from the factory into a forging die and compressing it, the steel chips act as a liquid and flow into the die then fuse together under the pressure into a fresh billet. I don't believe that Rover were particularly selective about what types of swarf were included and so there is no specific grade of steel for these rockers.

Earlier forged Cooper S rockers are made from EN8 and then hardened, as are the modern reproductions. The pressed steel rockers I know nothing much about, except that they aren't brilliant.

Roller tipped rockers have only one useful effect, which is to reduce side loading on the valve stems as they move up and down. This reduces internal friction in the valve train and leads to longer valve guide life. It makes the valve travel slightly more stable too which should reduce turbulence in the gas flow a little, but only a little. The valves don't exactly rock side to side very far with normal rockers, just a little. Interestingly the nose profile of the Cooper S rockers is better designed than that of the sintered rockers and does nearly as good a job of reducing side loading as a roller tip does.

Full roller rockers go one step further in reducing valve train friction. All this is good for reduing internal losses in the engine. The full rollers do tend to wear the rocker shaft more quickly though.

It has been said that roller tip and full roller rockers are louder than the originals but I don't think there's a lot in it. They are harder to set the clearance on though because the roller makes it much easier to slip a feeler gauge in to the gap, you have to be very sure you aren't compressing the spring by accident. Generally this is done by sliding the gauge in from the side rather than directly into the roller but you can still mess it up. You just need to be careful. A Click-Adjust should make this easier.

Generally speaking the aftermarket rockers are made from lighter alloys than steel. Various aluminium based types are used by the different manufacturers. The Mini Spares hi-lift forged plain rockers are made from EN16 steel and hardened.

Edited by Dan, 18 March 2008 - 12:16 AM.

[dklawson]

Dan, several years ago I searched the net for information for the composition of EN8, EN16, and EN40. I was particularly interested in the EN8 composition as I had dressed the tips of my forged rockers and I wanted to know the composition so I could get a local heat treater to re-harden and temper the faces. He refused without knowing exactly what steel he could compare the EN8 to. Do you have any information on what is in EN8?

[Dan]

I'm afraid not no. I'll try and find out though.


<<edit>>

A modern equivalent British grade may be 080M40, but you should verify that before you accept my word as I'm no expert.

In fact now that I've done a couple of internet searches using that new code it always seems to have EN8 written after it in brackets so I'm pretty sure. I've also found a reference (matweb.com) stating it is "very similar to American grade AISI 1040". AFAIK under the British grading 080 specifically means a 0.8%Mn alloy, the M in the middle means it's a mechanical grade of steel and 40 means it's 0.4%C.

Hope that helps.

Edited by Dan, 18 March 2008 - 01:11 AM.

[Dan]

Just bumping this for Doug to notice it.

[dklawson]

Thanks Dan.

It's been 5+ years since I was looking for the steel compositions. Since that time I've used MatWeb at work and never thought about using it to crossreference the EN series steels. 10+ years ago I bought a book for a previous job that was an international index to steel compositions. I wish I'd had access to that book when I was working on my car's rockers.

I'll take note of what you've found for future reference. However, I would have thought that the EN grade steels were "fancier" than our 1040. In our numbering system, 1040 simply identifies this as a medium carbon steel. Most often case hardened but with a certain amount of inherent toughness before heat treat.

Thanks again.

[morley]

Slight hi-jack but i'm thinking about my rockers for my engine build too, i have seen the cooper s BMC 12G1222 rockers on EBAY ,are these a direct replacement over the standard ones?

[dklawson]

The ebay link didn't work for me. Try going directly to www.ebay.co.uk and paste this item number into the search field: 130205900460

Those do appear to be the genuine article. As far as I know they should work on all A-series engines just like the listing says. However, they won't go cheap!

[morley]

The ebay link didn't work for me. Try going directly to www.ebay.co.uk and paste this item number into the search field: 130205900460

Those do appear to be the genuine article. As far as I know they should work on all A-series engines just like the listing says. However, they won't go cheap!

well i have just won these cooper s rockers (item no. 150224276798) on ebay, did i get them at a good price? and will i just have to remove the old rockers and replace them with these and job done?
and when setting up the tappets will i have to anything different?

[dklawson]

You got a deal but you only got half a deal.

The rockers you bought have been rebored with offset bushes. First... you aren't going to get a ratio of 1.5:1 with offset bored forged rockers. At most you may have 1.35 or 1.4:1

Second, and more importantly, you need offset pedestals to use these. Consider for a moment that the valves are in a fixed location. With standard pedestals, the distance between the valves and the fulcrum for the rocker arms hasn't moved. (That's 1/2 the lever arm which controls the amount the valve opens.) You will pick up a little more lift as the pushrod will now be working closer to the fulcrum... but certainly not much.

Write the seller and ask if he has the offset pedestals. If he doesn't, I wouldn't bother installing these until you've found, bought, or made some. If he says you don't need offset pedestals to make these work... he doesn't understand how offset bored rockers work. Don't let him insult your intelligence.

Still... if the pads are in good shape, if the adjusting screws are free to move, and the bushes were bored properly... you did get a deal.

by the way... the seller should NOT have pushed the one bush out. Hopefully you'll be able to press it back in pretty close to its original position.