Roller Rockers vs Originals

[debaron]

What are the thoughts on rollers over the standard TVR/LR setup?

[Goaty Bill]

debaron said:

What are the thoughts on rollers over the standard TVR/LR setup?

Expensive in the extreme.

Otherwise
different engine, different times mind you

[CHGRIFF]

Fitted Rollers to my Griff. Waste of money IMO. Didn't notice any difference and they they lasted 40K before rollers fell apart. Money would have been better spent on a decent audio system, even if you cant hear it when your driving, but everyone else would appreciate it with the roof off. Unless lifting power limits to 400+, dont bother, nothing to be gained.

[debaron]

CHGRIFF said:

<snip>
Fitted Rollers to my Griff. Waste of money IMO - Unless lifting power limits to 400+, dont bother, nothing to be gained.

Fair enough - that coupled with the fact that they also seem to be extremely hard to get hold of plus the cost as Goaty mentioned- it's not looking good for rollers!!

I appreciate they are better design wise - rolling over the valve top must be more efficient than grinding over it as the originals do - but looks like the cons outweigh the pros with the rollers.

I did see 'reverend' had a nice set of PEP chevy shaftless rockers but bet they were pricey not to mention modification to the heads to mount them.

Now to get hold of a decent set of originals.

Steel or Alloy though?!!??

[Goaty Bill]

debaron said:

Fair enough - that coupled with the fact that they also seem to be extremely hard to get hold of plus the cost as Goaty mentioned- it's not looking good for rollers!!

I appreciate they are better design wise - rolling over the valve top must be more efficient than grinding over it as the originals do - but looks like the cons outweigh the pros with the rollers.

I did see 'reverend' had a nice set of PEP chevy shaftless rockers but bet they were pricey not to mention modification to the heads to mount them.

Now to get hold of a decent set of originals.

Steel or Alloy though?!!??

Ahh, yes, well, there is little if any real power gain from simply installing roller rockers (that I am aware of).
Certainly no direct gain worth the cost IMO.
With a mechanical lifter cam, I don't recall them being any quieter either.

[Brummmie]

On my LS engine, (its still basically the same) roller rockers induced valve float, it wouldnt rev past 6200rpm, i went back to standard and it was good for 7000. All that weight on the tip has alot of inertia..

[Goaty Bill]

Brummmie said:

On my LS engine, (its still basically the same) roller rockers induced valve float, it wouldnt rev past 6200rpm, i went back to standard and it was good for 7000. All that weight on the tip has alot of inertia..

Or, provides less resistance to your massively powerful valve springs made necessary by the towering lift and steep ramps of your roller lifter camshaft.

They have their place, just not on most engines

[Pupp]

Just use outriggers on the shafts and the OEM alloy rockers are fine

[debaron]

Pupp - can you elaborate on the outriggers? Not familiar with those.

Ta

Ryan

[Pupp]

debaron said:

Pupp - can you elaborate on the outriggers? Not familiar with those.

Ta

Ryan

Sure, with the standard pedestals, where the 'outers' are still inboard of the end-most rockers on each shaft, the typical mode of failure with extended rpm/big cam usage is for the shaft to fracture, presumably due to flex and resulting fatigue.

Accordingly, the likes of JE etc can provide machined billet replacements for the outer pedestals, that are forked so that they support either side of the outer rockers. They mount exactly the same to the heads but make the entire assembly much more rigid. Essential if you're contemplating an engine that can buzz...

...I'll see if I can find an image

ETA there you go

Edited by Pupp on Tuesday 6th December 22:22

[debaron]

Excellent - many thanks Pupp. They look just the ticket. The whole rotating assembly has been balanced and going with stage 3 heads and stealth cam so yes - it'll be buzzing alright!

Cheers to all who replied.

R

[haircutmike]

Interesting.

I bought a set from JE and couldn't get them to fit, even heating the pedestals in boiling water as instructed made FA difference!

Now I'm taking it apart again and it's winter, I think I'll have another try, (or find a man who can!).

[Chris71]

Just to throw something else into the mix, a common point of failure for the standard alloy rockers is the hardened pads. They detach from the rocker, damage the top of the valve and potentially go through the rest of the engine. It happened on my (factory standard) engine and I was surprised to see several other people on here have experienced the same thing.

The JE pedestals sound like a good idea, though, if that's another failure mode.

Without wishing to hijack the thread, has anyone got any further thoughts on the steel rockers? They sell for about the same price as the cheaper (non-Land Rover) alloy sets and opinion seems to be really divided on them.

[debaron]

Hijack away - I'd like to get a definitive answer on steel vs alloy once and for all!!

[domV8]

Pupp said:

....Essential if you're contemplating an engine that can buzz...

debaron said:

Excellent - many thanks Pupp. They look just the ticket. The whole rotating assembly has been balanced and going with stage 3 heads and stealth cam so yes - it'll be buzzing alright!

What is the sorts of rpm are people equating with "buzzing" here? I seem to recall M.Adams reckoned the safe limit for standard pistons/rods was ~6500rpm...

Are we talking extended revving below that, or are people talking about higher rpm levels than that..?

(Will be having heads replaced shortly and cam timing changes for a little more BHP at higher revs, so wondering if these pedastals will be applicable to me...)

Thanks,

Dom

[Alexdaredevilz]

I rev to 6500 no problems yet,

Seen it a few times to 6750

Im on stock alloy rockers

[Simon says]

I seem to remember the pistons being the weak link on the pre/intermediate Serp motor ie 3.9 long skirted LR/RR piston after 6k+, looking at the 4.0/4.6 Serp pistons i have at the shop they look far more suitable for higher revs i would imagine, i am sure the likes of V8 Racing or Spend etc can give some input here of course i would imagine the stock rocker gear is going to start throwing a wobbler before 7k if we are talking spiky cams too, the stock con rods would be making an appearance at some point over 7k for long periods i would say just my cents worth in saying all this there is a guy on another well known forum who during drag racing as been well over the 7k mark with the 3.9 piston with nothing happening...... yet,but it all comes down to how valuble you think your engine is, just food for thought but i don't think i would take the chance and say ruin a perfectly good set of big valve heads amongst other valble engine parts trying to chase that extra 500/1krpm and one of the rods lets go with devastating consequences

Edited by Simon says on Wednesday 7th December 17:06

[domV8]

Alexdaredevilz said:

I rev to 6500 no problems yet,

Seen it a few times to 6750

Im on stock alloy rockers

Hi Alex,
Brief duration is usually OK AFAIK - its prolonged running at higher rpms where you can come a cropper, as mentioned by Pupp..

Pupp said:

...the typical mode of failure with extended rpm/big cam usage is for the shaft to fracture...

What rpms (hit regularly) would people suggest these items would become appropriate at..? Have we seen regular occurences of these failures happening when people are revving to (say) 6500 on a regular basis - or have the failures had a common thread of being at higher rpms than that..?

I can't see myself going past 6500 - but could be in the 5000-6500 quite a bit post-rebuild (track days etc), so would like to have some idea of where the "safe zone" ends... if anyone knows!

Thanks,

Dom

Edited by domV8 on Wednesday 7th December 18:27

[Alexdaredevilz]

domV8 said:

What rpms would people suggest these items would become appropriate at..?

Thanks,

Dom

Only one way to find out

I will let you know when I try to crack 170

[jesfirth]

when my engine was rebuilt earlier this year 2 of the hardened pads on the alloy rockers were actually missing and had ended up in the depths of the engine - probably helps explain why it was knackered and had to be rebuilt! I have steel rockers now