The V8 Owners Forum -

With regards to the roller rockers they do seem like a good idea, I nearly bought a set from a recent car show, in the end someone else purchased them, once they were fitted they seemed to reduce the rev range of the engine. It might have been because they were heavier than standard and this may have been causing the valve to float but I can't remember the outcome.

The principle is sound I know- and the friction loss will add up to a certain energy burden relief but I simply do not believe it will be more or even near then 1000watts! They are said to be stronger- but if you are not going with a very aggressive cam profile and high revving then could they be just a waste of time

You will not need roller rockers on your engine for what you want to do in the Landy mate.
You will not need to rev to 6500 either. And I dont think you need to waste time coating all the bits in ceramic stuff either.

From what I understand you want the landy to be a good road vehicle with the ability to shine a bit on the track with some nitrous on the go.

You need to get it on the dyno and do two pulls. One NASP and one on Nitrous.

This is the only way you will get some baseline data to work from.

On the NASP pull you should get enough data to see if its running ok. And I suggest that you should re tune NASP until the engine is doing its best.
On Nitrous you will get some more data. This Should show an increase in torque at a lower rpm.

Once you have this data the improvements or tuning required will become obvious.

After this point you can decide on how best to make any improvements.

DaviesDJ wrote:The principle is sound I know- and the friction loss will add up to a certain energy burden relief but I simply do not believe it will be more or even near then 1000watts! They are said to be stronger- but if you are not going with a very aggressive cam profile and high revving then could they be just a waste of time

I agree, if they are claiming to release 1kW of power there is no way that I believe that. 1kW is a one bar electric fire and there is no way that the standard Rocker gear loses that much power in friction it would be like having an electric fire in your heads!

In my humble the best thing about roller tipped rockers is that they don't pull the valve back across the heads when using a high lift cam, the 'pull back' is what wears out the valve guides.

Began disassembly- and was looking at my rockers etc, shafts are like new as are the to let internal surfaces, but 2-4 of the rocker pads are worn quite badly, should I replace these (will be a bit of a pain as the posts were an interference fit!) or could you get away with smoothing off the surface and polishing them?? See picture below

Ooh, nasty. I would get new rockers. And pushrods.

Bit odd mind - any clues as to the cause?

Chris.

Unsure- will have a closer look tomorow when it's light- they are "Brit" part items so it may be just that;-) the push rods "appear" ok but I will check them for straightness and change them if there is any doubt, want to look at the lifters and cam lobes also- as the lifters were Rhoads = bloody dear. That is the worst one, some have a little indebted wear on the circular spot. Have not over revved it- cod be too much pre-load perhaps??? Anybody seen this??

I've never seen one that bad !!
The worst I've seen is about 1mm but it was smoothly worn and not sharp like that. Its either no oil to that rocker or just soft material I think.

The sharp metal edges look horrible?

If you have the odd soft pad, you may also have the odd soft cup on the other end?

How does the top of the valve stem look?

I cant see it being excess pre load to be honest. You would have heard loose tappets rattling I think. And if you set the pre load by shimming they should all have been very close with tappet clearances. Mind you, that tappet must have been loose as hell and you still didnt hear it

Or do you mean too little pre load giving a tight clearance? If this was the case and the lifters pumped up enough the engine would lack power at high rpm and you could end up with burnt valve seats.

This was how Rover built in a sort of rev limiter. I've only ever seen it work once though, on an old MGB V8 with the low comp V8 fitted. It would rev and pull under load to just under 6000rpm at which point it started fluttering and losing power as the valves were all held slightly open? Crude but effective eh?

I guess you are using standard push rods?

Sorry, what I meant is too little preload - and clearances too small etc. the lifters are roads bleed down lifters and so are a little noisy at idle normally - and then pump up giving higher lift at 3000+ I have a feeling that when this occurs the extra pressure etc along with the double valve springs caused this. It is crap doing this in the winter on the drive - but the seven chassis is in the garage
- so it was bloody dark so could t asses valve tips!
Plan 1) inspect heads and valves (taking over to my good freinds workshop at rugby to spend a few hours with them, hoping an hour on the valve master will solve it), will also check the seats and everything and re-cut if needed on serdi).
2) check the cam - this is a bit
More of a pain as i don't really want to take the rad and timing case off! I will take some pics and post them, if the cam comes out then out it comes! It's all in the game, but hope to save it. Remember after shining
Looming down and thinking
- ohh that's a little more then last time (gap to the circlip). But the all was the same from the last rebuild so thought it would probarbly be ok. But has new driven hard.

In the last 7000 since the heads have
Been off I
Must say it always felt quick even off gas, and pulled up hills past much more modern metal, so was surprised to find this. Standard lifters next time!

Is that actually metal that is sticking up off the rocker pad or is it oil/grease?

As an aside I noticed that you are running JE outriggers, I also run these but I did not like the way that the rocker could float about sideways if no wavy washer was used and I felt the if a wavy washer was used then there was too much side load on the rocker, in the end I used a flat washer and created about 10 thou clearance by rubbing the side of the rocker on wet and dry paper in order to thin it down a fraction.

I'm with Perry on the way that the pre-load acts as a rev limiter, it is quite clever how it works but obviously as soon as you change anything in the valve train such as the valve springs then the point at which the valves float and therefor the lifters pump up also changes. The oil pressure alone will never pump up a lifter, the valve has to be 'floating' before the lifter can pump up. When they do pump up the preload setting can become important because the valve is being held open this distance X the rocker ratio and whats more the valve is held open that extra amount just when it is very close to the piston, you could end up with contact which is why I only run 20 thou preload set using adjustable pushrods. (I just run bog-stock lifters)

Ok guys- top now off- valves are salvageable! Heads are good- but aqua blasted them today and blasted vales ect and re-face for rebuild with new seals. (Assembly tomorow) with tiny skim.

Bores look good as do pistons - happy with bottom end. 2 of the lifters are shagged! As are a few cam lobes- now malfunctioning just heavy wear! Obviously uneven preload and too much pressure on gear. Will re assele with care. Standard lifters this time- think the Thomas's are not worth it in my engine as I want mid range. And I never rev above 6300. And they are cheaper. Now which cam???? Really would like suggestions. Currently Kent 885 and would really like something similar but more mid range. Any suggestions. This cam did work well- but always looking to move forward.

Valves aqua blasted and refaced! Ready to go
- head also inspected and fine - no skim required - new stem seals fitted.



Now for the cam??? Thinking about the real steel viper options?? Or crower 50232??? Wod like more mid range then the 885 perhaps?

Got the heads and started prepping them - thought they needed a bit more de-shrouding, so gently took a tiny bit from around valves- keeping inside fire ring etc. smoothing off- I will the mceramic coat and polish.

Interesting stuff, I might have missed something here but what are you going to do about the blown head gaskets?

Cheers mate! Heads are dead flat so just emery clothed gently, new elring gaskets sprayed with copper gasket spray as perry mentioned, progressive nos control etc and bring back the timing 2-3 degrees. Part of me is glad the gasket went as the weak tvr piston would be next - sort or a safety valve - thinking about the cam though which is a dilemma! And done some modest work lifting the ports that I will post later today (not complete). Keeping same volume but raising with epoxy