Steel Rockers.

[chris52]

Hi guys just a bit of advice on Steel Rockers. I have had two tips of the alloy rockers on my griff 500 Serp and both have knackered the valves. This then creates a big strip down and the cost is not cheap so I have decided to go for steel ones, I know I may loose a little power due to the extra weight but I think its worth the peace of mind.

So which are the best to get. There seems to be a few available at different prices I would prefer to spend a little more and have the best available rather than buy cheap and have to do the job again in a couple of years time.

I am replacing the cam aswell at the moment and all the lifters etc if I am also replacing the rockers would I be best going all the way with new rods, shafts etc.

And an opinion on roller rockers would be nice, The new cam is just the OE one so no upgrade there so I don't think roller ones would be of any advantage or am I wrong

Cheers again
Chris

[spend]

Rolling across the tip of the valve stem rather than grinding over it wastes less energy to do the job. Less metal grinding should also result in greater longevity.

Just look carefully how the rockers work, its not straight up & down but all sweeping angular motion...

[chris52]

Cheers Spend, I understand the mechanics of the roller rockers but do they justify the extra expense on a standard cam and also am I likley to get Valve Float with either the steel or the roller rockers due to the extra weight. I do have double spring's on the valves but I think that was standard on the serp engine.

Cheers
chris

[Barkychoc]

What cam do you mean by OE ?
Its not a range rover cam in there, I just wondered what you are fitting.

[chris52]

"Origional equipment" just the standard tvr 5.0ltr cam Part No TVR E0440.

Chris

[rev-erend]

These guys have the steel rocker arms .. quite reasonable at 71 pounds..

http://www.v8tuner.co.uk/category.php?id=32&pa...

Looks like it's impossible to get roller rockers at present .. and they also can foul the rocker cover .. and cost loads.

Occasionally these and Group A rocker arms come up on ebay but are usually more money than they are worth - around £300 usually (Kenne Bell and yella terra are the names to search for). I have kenne bell myself and have paid £50 for just one when it came unadjusted and stripped the thread on the adjuster.

The steel sounds like the best bet and as the griff runs out of puff at fairly low revs - the extra weight of the steel tips is really not a problem.

[350Matt]

This issue keeps floating around and there were tales a few years back of there being a bad batch of the ally rocker arms, all losing pads with high loadings / revs.

Equally there are many folks on the drag racing circuit all using the ally parts with no issues and some large lifts and revs!

I'm in two minds whether or not the steel ones are a no-brainer, as the mass increase is considerable as they're hardly a optimised part. This extra mass will limit the cam choice and valve acceleration that can be applied and therefore power (not just at high 5000+ revs). If I was to fit them I'd definitely go down the lightening route.

Another thing that should be mentioned here is push-rods, the standard rover items aren't that strong and many of you will have probably noticed little witness marks about 3" down from the rocker end where the rod has rubbed against the head whilst bending.

This is not good, loss of valve control / lift etc etc.

Real steel do a set of cro-moly pushrods which are lighter and stiffer than the standard items they just need the clearance holes in the head enlarging slightly.

I used them in my wedge and that regularly did 6500rpm with 14mm of lift and ally rockers and making sure the preload was within spec.

So the rocker may not be to blame rather the high cam loadings , poor or non existant preload setting and bendy pushrods may well be the cause.

[chris52]

I dought very much that the preloads were even checked when TVR did the rebuild certainley no shims have been found.
and judging from what the last owner said "the car has always sounded the same" I an guessing that the noise has been there for a long time probably very shortly after the engine was rebuilt. I'm now unsure which route to take, will probs just replace the brocken two and check all the others for cracks

chris

[Seasider]

Quinny said:

I used these pedestal shims to set the preload

All of em ??

[GreenV8S]

Quinny said:

I promise unless your car has had a serious amount of tuning and is running a really wild cam you won't tell any difference.

I suspect the issues would be worse with a mild cam, actually.

[GreenV8S]

Quinny said:

There are no "issues" you're just replacing an alloy rocker with a steel one.

I mean the issues of increased valve train weight, and everything that follows from that. Maybe the effects are significant enough to be a problem - maybe they aren't. My point is that other things being equal, the milder cam actually makes these problems worse because longer period cams tend to be easier on the valve train at a given rpm.

[hiltonig]

Quinny I like your fuel rail !!, is that new or painted ????

[clive f]

definately go for steel ones, I went through 2 sets of alloy ones within 400 miles, and the pads started falling off.

v8 tuner do a reasonably priced set, give him a ring, you will get loads of good advice.

as for pre load, tvr didn`t bother at all, I was told by a very well known powerful parts supplier that I didn`t need to check the pre load at all when fitting a new cam and lifters, it was just as well I did because the pre load was between 3 and 5mm
I know people argue that the lifters are hydraulic so it doesn`t matter, but to my mind it does, and not setting it is pure unprofessional laziness.

perhaps our valvetrain and cams would last longer if the proper adjustments were made in the first place

[clive f]

hav`ent you got a floor to clean

[Johno]

hiltonig said:

Quinny I like your fuel rail !!, is that new or painted ????

Rather than buy a new one, take yours off, have it shot blasted and then powder coated/sprayed. That's what I did with mine. Powder coating means it won't look shabby in days after cleaning.

Obviously you need to block the holes, flush through very well anyway and cover the unions really well.

Worked a treat.

[GreenV8S]

clive f said:

I was told by a very well known powerful parts supplier that I didn`t need to check the pre load at all when fitting a new cam and lifters, it was just as well I did because the pre load was between 3 and 5mm
I know people argue that the lifters are hydraulic so it doesn`t matter, but to my mind it does, and not setting it is pure unprofessional laziness.

perhaps our valvetrain and cams would last longer if the proper adjustments were made in the first place

I guess that goes to show that some parts suppliers are salesmen at heart and not engineers. In my view it's important to set the preload. There must be enough preload to prevent the lifter running out of travel, otherwise the clearances will all go out. But you don't want any more than necessary because this preload also defines how far the lifters can pump up and obviously you want that minimised. So the preload should be as much as necessary (to cope with thermal expansion etc) and no more.