any one else have big problems with brakin things in the cvh head , im always brakin rockers in half most of the time its 2 at a time inlet and exhaust , last year broke a colt at 7200 and bent a valve at fastford fight club pulled the tread off 1 of the rocker stud nuts and then pulled the rocker stud out the head, turns out id run a 12.9 on 3.5cyl, and then thurs this week snapped a cap straight in half and bent another valve, is there anythin uprated out there apart from roller rockers that i can use or has any1 else had/ got the same problem and what have u done

 

Mines nothing like the power of yours but had loads of problems with ripping the rocker studs out the head on full boost & splitting solid lifters apart!

 

I'd imagine nms and maybe c+b would be the ones to speak to if they'll give you any info.....karl norris seems to be able to make them hold together for more than five minutes at 300+ but you never know what problems they have!!
Mine was only 260 odd running 2 bar but didn't have the problems you're having lol.

 

This is where you need to be looking at roller rockers as i don't think there are any uprated items other then them and i am sure its because of how high the CVH engines need to rev to make big power.

speak to jano (oddkiddcreations)

 

i know that karl and a few others have tried roller rockers and all gone back to std set up

think karl would be worth a chat tho as he is pushing the cvh way beyond anyone else

guess i have all this to come when my boost is turned up
MK only had this happen the once tho and his little fiesta was given huge abuse

 

havent even got any boost in it and powers only at 340ish atm

 

o

maybe worth a chat any hows

 

Timecert threaded inserts in the cylinder head for a start.
Also monitor (measure) valve spring pressures carefully.
If valvetrain becomes unstable (too low spring pressures at high revs and high boost)
rockers, lifters, etc can and will break.

 

it was the same with single valve springs and now with doubles, lifters are solids

 

Like canada above says, i would be looking at Timecert (helicoil) inserts which are a steel thread opposed to ali. I can't comment much about the rocker though, any pictures of a broken one? be good to know where they break.

Rob,

 

they break everywhere usallly straight through the middle in to 3-5 pieces, helicolin the head is only goin to stop the studs coming out and id rather it did that then keep bendin valves

 

Helicoils are ok but there is another type that work even better that we use in hubs on aircraft engines
Billet rockers would be the way forward

 

It really doesn't matter if the springs are single, double or tripple - if the pressure closed and open is not enough stuff breaks.
The Kent and Piper singles and double springs for the cvh are terribly weak.
7000+ rpm with the heavy rocker arms and valves etc.. is a disaster waiting to happen.

The recommended (by Kent) spring pressure of 70 lbs closed on a cvh is a joke.
Well over 100 lbs closed is needed for high revs and high boost levels.
Sure the cam and lifters will wear faster, but we aren't talking about a 30,000+ km lifespan engine here anyhow.

I had emailed David Baker (cvh guru) some time ago, and his valvesprings are far stiffer than
Kent, Piper, or Newman recommend.
The low spring pressures recommended are to (try to) ensure a long camshaft life.
Baker recommended 115 to 120 lbs closed pressure.

As far as camshaft and lifter wear - please remove that silly oil resrictor on the head.
I have no idea why most shops leave those in.

 

I had a rocker go on mine while it was being mapped. Just the rocker broke, no studs pulled or valve damage. The rocker broke into 3 or 4 bits but didn't cause any damage. I was missing one bit which I found resting in the sump when I took it down to check.

I searched about and concluded there wasn't a tested upgrade available so replaced it with standard and so far its held together.



Edit to add. My rocker broke when I was running a piper 285t2 cam, hydraulic lifters and kent HD springs. Now running newmans ph4, solid lifters and standard springs.

 

Stu whats the reason for you not wanting to use roller rocker set up?

Gus id imagine karl stopped using roller rockers due to cost?

 

not that i dont want to its where can i find the fuckers

 

Oddkid does them stu

 

karl use to get them made in small numbers i know but im sure he had reliabilty problems
(could be wrong im few beers in)

 

As said jano oddkidd is going to be having a batch of roller rockers made stu could have a word with him?

 

Oh right probly so then gus

 

There were a batch of rockers made in the USA a few years ago.

 

any1 make strong caps then ??

 

What causing the rockers to break, i was led to believe it was 7k+ rpm as opposed to boost levels...

Canada - what oil restrictor in the head do you remove?

 

Stu, well I use std RS turbo valve springs and a cam with 12.6mm lift, have no problems reving to 7500. I have had the odd rocker pull off in the past, but not since I torque the rocker down at 28ft/lbs. Basicly at that torque if the tread is damaged it will pull the rocker stud out, meaning a repair is required rather than running it and it comes out at a later date.

Never had a snapped rocker!

I repair with a keenserts.

 

I can't understand why people suffer from snapped rockers. I can't understand how it actually happens unless the valve spring goes coil bound or they are suffering some kind of resonant vibration causing them to crack.

 

SAS

What power level are you t with 7500rpm

I could not get 6500 and 300bhp/26psi out of my standard springs

Do you use standard installed height etc?

 

try standard rst rate springs, not double,

 

All of this spring confusion would be cleared up if spring set up was made more clear.

We need a valve spring chart - installed heights, as well as spring pressure (lbs) at the installed height for a few different spring sets.

Dual springs set up with enough closed pressure would certainly work as well as a single with the same closed pressure - but what are those pressures? Has anyone measured?

 

I have attached a picture.
This is the large hole in the head which oils the camshaft/lifter lobes.

As you can see there is no brass restrictor in the North American heads.
We have never had cam wear issues.

 

Do they need drilling out of our UK heads does anyone know?
I would like to remove mine as increasing oil flow to the cam lobes and lifters can only be a good thing but I cant be arsed to take my head off to do it! lol

 

Im not sure that the little brass inserts are actully restrictors?
If you watch the quanity of oil pumped up around the follower and spills out onto the little platform with the brass insert, you will see that is not much, my opinion is the brass insert is to direct the oil to a more accurite position to drip onto the cam.

Just my theory.

 

The 7500rpm was my old ZVH engine now going into a customers car. I didnt have a dyno during that time. But estimate 420bhp.

However I have 3 engines out their that rev to 7100 making power upto their revs limits. An example is Bezo 2.0l ZVH van -

 

Interesting theory, could well be.

 

Sas why do you think I couldn't even get a pull at 6500 on STD springs with standard install height?

Even creeping the boost in it would not have it

Hydraulic lifters I'm on and quite a big cam

 

They are brass inserts that look like they have been pressed in. I agree with sas, i can't see how they restrict anything and believe them to be there to direct oil onto the lobe.

Rob,

 

Care to share? (about the inserts)

Rob,

 

What material are the rockers made from?

Has nobody considered shot peening them?

 

Do what you want.
The little "pin hole" that is in the UK head certainly restricts oil drain back to the cam lobe.
You can't even get much water to drip through that hole.

The north american CVH engines have never had an issue with early cam wear problems.

My cvh engine had 270,000 km on the same camshaft - the lobes and lifter bottoms show almost no wear. One has to assume the extra volume of oil getting on the cam lobes helps??

Just trying to help. I guess I will keep my big mouth shut!

 

^^^ i have heard before about the oil restrictions in the head,exactly how Canada has said,

what differences do North American heads have other than the brass oil ways restriction??

Stu.....maybe you should get hold of one of these heads and have a try

 

Im willing to give the "drilling out" technique a go, i mean a large quantity of oil all over the cam is better than a drop or 2 in the right place surely? But i can see SAS's point also, if there is no oil getting the the platform in the 1st place then maybe the problem lies elsewhere!
270,000KMs on a cam speaks for itself surely? There can't be many people in the UK with that sort of mileage on a CVH cam, i got nearly 130,000Miles on my last cam (standard ford), but whos to say it was the original cam when i brought it?

Back to topic... Surely the power output of the engine doesnt effect the rocker arms, it must be a rev related issue that causes them to fracture or snap completely!