sas

I put it across as my theroy ??. I welcome your experiance.

All the heads I have seen have a 8mm (approx) hole through the brass insert.

sas

I missed the instal height bit, I sit them on pedistals but each is different, generally compress them as much as possiable without becoming coil bound.

With many cams tested, lots of porting on standard valves and many turbos tried, I have a proven combinations. However they are all ZVHs.

Lift is less important to duration, and I have not done one on less that A/R 0.63 exhaust housing.

Simon.

Rob_DOHC

iTrader: (4)

Chill man, you've helped me out on numerous occasions. When i poured oil though my oiling holes (one with out brass piece) i did notice a slight restriction to oil flow BUT a lot more oil ended up on the lobe, with out the piece the oil stuck to the walls of the hole much more and to the head casting rather than dripping onto the lobe i guess surface tension of oil is much higher than that of water so your tests may not have shown it.

Infact in the end i ended up with the best of both worlds as i opened up the brass inserts letting more oil through and directing the 'drip' onto the lobe. Its not irrelevant but i suspect the amount of oil being thrown around under the rocker cover is pretty sufficient to lubricate most things under there.

I think the rockers are probably breaking due to metal fatigue, maybe it would be worth getting a batch heat treated and shot peened to reduce stress.?

I'd be more concerned about valves bending, as this must mean the valves hitting the piston... so valve float?

Rob,

Rogeyboy

iTrader: (2)

That sounds like a good solution Rob, as Karlos says its just a shame the heads gotta come off to drill em out... Shotpeening or strengthening the rockers somehow sounds like good practice, esp if you are having other bits "uprated" etc anyway!

Rob_DOHC

iTrader: (4)

So far so good on the oiling front, i'd though about making up a spray bar to directly lube up the lobes but i wasn't brave enough to tap into an oil gallery lol im not sure if shot peening/heat treating the rockers would help as im not sure how/why they break but it might be something for stu to investigate?

As to billet rockers, i did a lot of research and unless you get the design very right you risk breaking them too, they are made/used a lot in the states and there are some really good sites explaining about rocker design, its not as simple as 'just' getting some made up. They need to go through stress analysis as well as frequency analysis to ensure no premature failure.



Rob,

russ rs

Is anyone using Janos rockers On here????

nigel b

Rob
If you use the right software to design the parts it takes it all guesswork out of it

Rogeyboy

iTrader: (2)

This is getting deep now lol...
I'll just stick to 6,500rpm @ around 20psi and hope for the best...

sas

Or how about this as an idea????


Use a black top Zetec bottom end, good oil supply and capacity with that?

Rob_DOHC

iTrader: (4)

Lol, not ALL the guesswork, just the majority, and you might end up with something that works. But at the end of the day, the software is only as good as the monkey driving it, i've spent weeks changing and analysing parts before and still end up with something unexpected, especially with frequency analysis, i treat it as more of a decent starting point.

Rob,

Rob_DOHC

iTrader: (4)

I don't see how that solves any top end problems though. The only time i would use a zetec bottom end is with a zetec head......

Rob,

SiZT

Not neccessarily, think about the way the rocker acts on the valve.

Rob_DOHC

iTrader: (4)

So you think the rocker its self may bend the valve stem? tbh the picture says it all

sas

My attempt at joke was lost on you.

studabear

This is 1 of the best threads on here for a while!

Rob_DOHC

iTrader: (4)

Lol, remind me not to come to any stand up nights you do

Rob_DOHC

iTrader: (4)

Heres a vid of a rocker being processed, only one region of the rocker has force applied to it so they were obviously only interested in that area.

http://www.youtube.com/watch?v=xMNkbrPVreg

Rob,

sas

Well I sniggered.


Back to the topic, sorry.

stuart collins

iTrader: (7)

how is it valve float ?? the cap snapped in half this time and i sum how broke a colet or it came off last year, ill send u a pic if u send me your number

Rob_DOHC

iTrader: (4)

Lol,

It depends, why did the valve bend? If it bent because the piston hit the valve head it 'could' have been valve float, ie) the valve was open when it shouldn't have been so the piston hit it causing it to bend, or it could have been bent when the rocker pulled out, or it could have dropped letting the piston hit it when the colet broke. To sum up.... it could have happened for a number of reasons.

If the rocker broke up and didn't do anything nasty you would expect the valve to close and stay closed (nothing opening it).

Not fussed about pics matey, just an interesting and unfortunately common topic.

Rob,

stuart collins

iTrader: (7)

last tme the the colet went valve dropped hit the pistone and the valve bent up in to the combustion chamber brakin the guide, i expect it has done the same thing again will see when i take head off , its just a good job im on standard valves if i was using stainless big valve im sure the valve head would come off and fuck the whole engine

stuart collins

iTrader: (7)

rite titan will make roller rockers for cvh and prob the caps , 1 set if goin to be 1500+ and if i get 3 sets made goin to be around 1100 each

great

crazycage

fuck that lol

Joshy

just a small imput,

the brass inserts are threaded and unscrew with an allen key

Rob_DOHC

iTrader: (4)

Jesus! To get one set made up (if you already had the drawings) would probably cost 2-300 pounds so the other 1000 or so must be their development price?

Bit on the pricey side!

Rob,

creator

Stu iirc the price of what jano said he could possibly sell them at was about half that price

gus

iTrader: (1)

dont think titan have the drawings anymore

MO' BENT RIMS

this is why i prefer zetecs even though i hear cvh is the way to go

SiZT

Ignore what I said about the rockers bending the valves, realised it's the valve heads your on about

Raj_FRST

lets say hyperthetically, someone already had drawings for roller rockers and was in the process of producing a set, what woube be the best way in which to test their integrity etc??

Rogeyboy

iTrader: (2)

Joshy - R u sure? I thought they were pressed in? I'll have a play with a spare head i have...

Rob_DOHC

iTrader: (4)

The first port of call is decent design by an engineer, correct measurements are one thing, material spec and saftey margins are another. This step goes hand in hand with stress analysis, which lets you see the effect a certain force will have on your rocker.

Then you should have a prototype batch made up, i'd estimate this to cost between 3-500 depending on how much machining each rocker needs and who does it. These should then be tested to destruction, by that i mean 7-8000 if not more (you don't need a bottom end to do this), then they should be real world tested.

And after all this, if nothing broke when it shouldn't have then you could sell them and be confident with your design and untarnished reputation.


OR

You could guess, sell your guesses and hope they don't fall apart and come back to bite you.

If you go for the latter, really over spec everything.

Rob,


EDIT

3rd option, and probably the best... buy a decent set like titans and shamelessly copy them....

Rob_DOHC

iTrader: (4)

In all honesty the only reason i have a cvh fitted to mine was because i already had one and wanted to keep the cars original engine.

Zetecs IMO for an RST will always be the way to go... combined with equal length shafts and an MTX your onto a winning nice to live with formula.

Rob.

Versus_Creations

iTrader: (1)

Some info i dont mind sharing.

Back in 1985 Titan made these rockers at a cost of Ł575 a set retail.

The Titan rockers have already been copied by me to exact replicas. To have other engineers and machinist make them works out over Ł900 a set.

Titan will remake them for me and Burtonpower only (Thanks to Andy who has spent lots of time with me regarding these items!
With my drawings and my master set that i have ready for this job its possible for us to make them again.
It costs (this is not an advert Ł650 each set) for a batch of 10 sets to be made. This is not a money making exercise and no profit will be made. For me to spend Ł6.5k out of my own pocket just so we get to have Roller Rockers again i need to make sure that a home can be found for each set before production can happen. I dont want Ł3k worth of stock sitting on the shelf.

I have 6 people already who have paid almost in full for a set each. Myself included in that list for 2 sets. As you can see not many engines or cars are worthy of these components.

I also make new studs which are m12 on the head side and the std m8 on the rocker side. The thread is rolled instead of cut which also makes them stronger. These are heat treated and have never snaped or caused me issues. So anyone who has had them pull out the head etc this is the perfect fix for ever.

I have lots more relevant info regarding rockers and strength etc. Some of which i wont discuss on an open forum. Some of you have already had this info off me via phone. Id appreciate it if you kept it to yourself

Rob_DOHC

iTrader: (4)

Thanks for sharing the info Jano, i hope you get another 4 people willing to give them a try

If you ever need info or alternative machinists give me a PM, im confident that you could reduce the machining costs an awful lot should you ever need to.

Rob,

rickbartlett

interesting thread

gus

iTrader: (1)

i want em just cant afford em

jamie rst

iTrader: (1)

Nice one Jano and no worries fella my lips are sealed,

so come on boys get in touch with Jano for a sweet part.

Rob_DOHC

iTrader: (4)

The following is not a joke:

YOU BUNCH OF BASTARDS, if this thread hadn't have been started im positive my car wouldn't have just had its first break down lol

First time its seen 5500 (raised the rev limit), 12psi of boost, going better than its ever gone before (it was 18psi and 185bhp) and CLONK.... limp home on three thinking the worst and kicking my self for being horrid to a newish engine, compression test later, spark test and a bit of head scratching because both are fine....

Take of the oil filler cap and no.4 exhaust rocker is floating around

I think the stud has pulled out.....

NOW,

What type of helicoil would people recommend using, nigel_b mentioned an aerospace variety earlier on.?

Im temped to replace all the studs but don't really want to take the head off

Rob,

studabear

chemical metal

gutted for you rob. hopefully thats the only damage