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Hi sage ones. I recently saw a set of roller rockers for sale that I was tempted to bid on (winters coming ) but was concerned that the seller was stating they would give a performance advantage but the rocker ratio was only 1:1.55 ie standard. When I enquired with the seller he stated that the tolerance of the standard set up was sooor that they were probably nearer to 1:1.45 so the roller rockers woul give more lift over standard. Anybody have any thoughts about that? I can see the design delivers less friction etc. I didn't bid in the end so no bling to fit this winter.

 

Regards Pete

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Pete,

 

I've never tried roller rockers but have talked to quite a few who have used them on Triumph 6 cylinder engines. There are some roller rockers out there that are prone to cracking. However, I know three owners who have fitted roller rockers from Goodparts in the USA and they have all been fine:

 

https://www. goodparts.com/

 

Take extreme care if bidding on secondhand rockers is my advice, you wouldn't want to end up fishing bits out of the sump.

 

 

Nigel

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Short of increased ratio I can't believe any measurable power increase would be in the offing. Friction losses on the rocker shaft have to be very small indeed. I'd hazard a SWAG at 1/10 HP tops.

 

In the event of increased ratio the entire valve train should be vetted for compatibility, especially the springs ;) .

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Hi Pete,

 

the performance benefit is marginal at best, until you have a highly tuned engine pulling telephone number rpm.

 

Irrelevant expense for a standard or modestly tuned engine.

 

I've nothing against roller rockers in principle, need I add . . . . we have them on the TR8 Drag Car.

 

But, and this is a significant BUT, a decent roller rocker set up costs serious money.

 

I've seen several broken rollers on Triumph 6-pots, and looking at the battered remnants I'd suggest that the quality varied from wouldn't-touch-'em-with-someone-else's-bargepole through to total cr*p.

 

They weren't cheap either, just not proper money and predictably proved to be not proper kit.

 

Cheers

 

Alec

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I should add a comment about some of the cheaper versions I've seen on eBay . . . . . I'd suggest the most efficient and painless way to fit is to bypass the engine bay and launch them directly at the scrap metal stillage, thereby saving a great deal of time, effort and grief . . . . and sod the expense. They should fit nicely in the scrap stillage.

 

Cheers

 

Alec

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If it ain't broke, don't fix it .... :lol: :lol: Alec sorry, but here you are not speaking about TRs..

 

After more than 50 years living with TR's I'm in for any positive modification as long as the appearance of the car is left unchanged..

Why not roller rockers, even without power increase,... as long as the quality is good... ;)

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If you decide on roller rockers - I would be tempted to use standard lift ones.

 

The idea of increased lift ratio may seem good, however this may well load the cam lobes and followers to a greater extent.

It can also cause the valves to be open earlier and close later which isn't always the ideal situation for combustion. You then have to increase the rocker clearances which in turn may move the stress to different parts of the cam lobes.

 

If what you want is a performance cam then fit one rather than use the rockers to try and achieve that.

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Hi Pete,

I have the feeling that you spotted something that looked tempting but not actually necessary - Christmas is coming and all that.

 

A couple of years ago I spoke to the chaps on the Cambridge Motorsport stand at an IWE and asked about their rockers.

Basically they said don't do it unless........... the unless equalled lots of work and £££££.

 

You can't see them when installed and you won't notice them until you have lightened your wallet.

 

Enjoy your car as is. I've done apprx 150K miles and enjoyed nearly all of them (I didn't enjoy the mile where the diff decided to throw a wobbly).

 

Roger

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http://www.flowspeed.com/rocker-tech.htm

 

This is worth a read if you interested in using roller rockers - note Harland sharp are basically designed incorrectly from the outset unless you massively lift the pedastal.

 

I put together a neat spreadsheet and worked out optimum geometry for my 2100EFI roller rocker equipped engine (Goodparts with 1.55 on the inlet and 1.65 on the exhaust and a hybrid cam - 289/284 duration and 0.300/275" lift

 

Raising the pedestals 0.090" and getting optimum pushrod length meant I could use overdrive top rather than direct up a 1 in 10 hill I drive everyday - and goodparts units seem better than most out of the box.

 

However this engine is just a wierd hobby of mine - virtually a half race engine used daily for commuting. I don't think a standardish TR6 would benefit

 

The USA is still a bastion of OHV so I guess it's not unexpected that they have given it some serious thought. This is good if you are interested - obviously for small blocks etc but the principles still apply

http://www.aera.org/ep/downloads/ep10/EP04-2010_20-30.pdf

Edited by Mk1PI
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  • 3 years later...

I have 1.55 ratio Goodparts and already with these had to release the valve springs.

I believe a lot of reported trouble with the rollers come from extended ratio and

from that resulting valve spring binding.

 

I took these rollers because I lost a new set from MOSS after few years.

It was the expensive new set with bushed rockers, unfortunately also

with not hardened tips.

 

They started eating itself and the valve tips and so I lost rockers and valves.

To avoid that in future I decided to use the rollers and already with these 1.55

things become pretty narrow in the head with the tubular pushrods.

 

I would expect much more rework with the 1.65.

 

Keep in mind that the total valve spring amount should not be higher

than original because the cam lobes will be eaten than if idleing more often.

The original springs seem to be not suitable because when released

to suit under full lift they might get loose when valve is closed.

 

Also the total lift is already pretty high with my 290 degree cam and 1.55.

 

That formed my decision for the 1.55.

It was my first summer with these rockers and they seem to work perfect.

 

-Not unexpected when spending 1000 bucks-

 

They run with the additional oil feed and rubber caps on the valve guides.

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Read all the links at post #13 and let us know what you conclude.

 

What do you think is an acceptable duty range, 1 season, 2 seasons, 3 years, 5 years?

 

What is the rest of the engine spec to go with 1.65 rockers?

 

Al

 

Hi Alan.

Engine is currently standard to my knowledge (at the moment).

 

If I can't get more than 5 years of general use at my average of 3000 miles a year then I'd be quite unhappy.

Edited by ShaunC
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Thanks for the feedback Andreas.

 

I've had the current rocker assembly off and three are starting to pick-up around the bushings so I will need to attend to that pretty soon.

 

My initial thoughts were as you describe, and keeping as close as possible to the original lift.

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BPS are selling 1.5:1 rocker sets for around £300, I have no idea of quality and anybody would be wise to do some research before purchasing, and also do some checking of correct angles etc, but 1.5 should be a sweet spot with little further mods required.

 

When you say starting to pick up around the bushings? do you have bushed rockers?

 

Alan

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Lads:

 

I have used both roller rockers and conventional rockers with high ratio designs.

 

There is no doubt that they improve performance. They increase duration, lift at the valve, and valve overlap all of which are proven ways to add power. How much power they free through reduced friction, I cannot say. Roller rockers eliminate the side load on the valve stem, so in addition to reduced drag across the valve stem tip, the valve has much lower frictional loading as it reciprocates in the valve guide.

 

Downsides? Aluminum has poor fatigue resistance, hence cracking issues. In a street motor they should probably be replaced after 50,000 miles. Designs are always improving, as are the alloys used, so perhaps this is less of an issue these days. High ratios may mean that valves springs may need to be replaced in order to avoid coil bind. Valve guides may need to be machined to avoid the spring retainer crashing into the guide, or crushing valve stem seals. There is a possibility that the valve may crash into the piston because of the increased lift, although this is wildly unlikely with any cam you would care to drive on the street. Fuel economy, idle and emissions are adversely affected.

 

All of that said, in my case I later removed the high ratio rockers, be it roller, non-roller, aluminum or steel. Why? Because they were part of a total engine makeover including a cam, and I found that they increased idle roughness unacceptably and increased emissions (my cars get tested where I live). In one case I went from 1.6rr aluminum rollers to 1.5rr aluminum rollers and was happy with the motor at that point. I want fully streetable motors and did not like the additional idle/emissions/economy tradeoff - especially with the mild cams that I was using at the time.

 

Unlike changing a cam, high ratio rockers do not change the lobe center angle. And a decent, streetable cam can turn into a bit of a burping, fuel gulping annoyance with the addition of high ratio rockers. Depends on the cam, and what other modifications have been made.

 

I would say if your existing cam has lobe centers of 110 degrees or less, proceed with caution when using higher ratios, you may find the engine gets a little too beastly for a street driven car. OTOH, they are easy-peasy bolt on power if no other changes are needed. They are roughly equivalent to going up one "step" in your camshaft design.

 

Your car, your choice.

 

Vance

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There is no doubt that they improve performance. They increase duration, lift at the valve, and valve overlap all of which are proven ways to add power.

 

Whilst they can increase lift, they can't increase total duration, the physical cam profile sets duration, a higher lift rocker doesn't start the valve opening any sooner (quicker maybe) and it will shut at exactly the same point. Like wise it can't increase valve overlap duration, all they can do is have the valves slightly more open during the period of overlap.

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These type of things

 

Triumph TR2-4A Roller Rockers 1.65:1 https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F183084412727

 

 

Are they really that much cash ?

Are they worth it ?

H

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Are they really that much cash ?

Are they worth it ?

 

 

Yes they can be that much and more!

 

Bling factor definitely, unfortunately hidden by rocker cover, always been surprised that some enTeRprising supplier hasn't made perspex rocker covers so that people can show them off! At higher lifts and without a lot of further checking and engineering the most likely benefit is that you will smash up your cam lobes and followers quickly, allowing you to spend even more money and time on improving your engine. A fair bit of research will also show that some (not all) are perfectly engineered to actually increase valve opening speeds where its not required, and slow them down where it is, and also to carefully push the tip of the valve stem just where it shouldn't be.

 

However it is likely true that slightly increased ratio rockers (including rollers if engineered correctly) may be beneficial (worth it? only you can decide) at higher ratio's they definitely drop into the here be dragons territory and IMHO should't be regarded as a bolt on goody without a lot of careful measurement and probably expertise (which I don't have), Knowing what you need to know, and knowing that you don't know it, can sometimes save costly mistakes! :)

 

Alan

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Errr, that not quite true Alan about the increased durations,

true, it opens an closes at same point, BUTT, its got moer durations both side of the lift curves

efta aboot 200-300-thou lift,

as is the case, its no just a case of fitt,n em, its acase of getting most lift frae em

 

M

 

Give it time t,show up, its slow, scroll doon a fair bit, it,ll come up faster that way !!

for some strange reason, site will no let me post the image frae me comp,

or frae the source of it either.

 

https://www.google.co.uk/search?q=do+high+lift+roller+rockers+increase+cam+duration&client=firefox-b&dcr=0&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjNwNXG18HZAhVkJMAKHZT3BT0Q_AUIDCgD&biw=1320&bih=828&dpr=1.25#imgrc=l_t0IdA4rFCesM:

Edited by GT6M
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