Preload all over the place...

[daveb500]

I'm trying to check my preload and it seems to vary alot. for example, one will be larger than 50 thou, a few are about right then 2 have no preload (the rods are loose). I've tried swapping a few rods around, I've check the pedestools on the head are level, I've checked the valves are level. So I can only assume it is the rockers. Looking at them, they don't appear excessively warn, but what I have noticed is that on the rockers with no preload, the inserts that the rods go into appear to be deaper in the rockers than the others.

Should I just get a full set of rockers? The alternative is adjustable rods (but that feels like I'm masking something that is not right).

Has anybody else come across this?

(and yes, this is what my face looks like )

[macdeb]

daveb500 said:

I'm trying to check my preload and it seems to vary alot. for example, one will be larger than 50 thou, a few are about right then 2 have no preload (the rods are loose). I've tried swapping a few rods around, I've check the pedestools on the head are level, I've checked the valves are level. So I can only assume it is the rockers. Looking at them, they don't appear excessively warn, but what I have noticed is that on the rockers with no preload, the inserts that the rods go into appear to be deaper in the rockers than the others.

Should I just get a full set of rockers? The alternative is adjustable rods (but that feels like I'm masking something that is not right).

Has anybody else come across this?

(and yes, this is what my face looks like )

I had the very same problem on a Griff' that I had, it made a rattling sound on overrun from 1800rpm down to tickover. Had a hell of a game to find out what it was as no-one knew after taking it to several places. Anyhow I replaced the whole valve drive train; rockers/shafts/pushrods/lifters/cam and I still couldn't get the preload correct over all lifters. Had the heads off in the end and found the valve heights were different. You could find if it's a similar problem if you run a steel rule over the tops of the valves without taking the heads off. [but, of course with the rocker gear removed] If it's the same, you may have to have them off and the valves/seats looked at.
Yours may not be as bad as mine [rattling] but the result was for preload.
Hope this helps.

Edited by macdeb on Saturday 3rd April 14:30

Edited by macdeb on Saturday 3rd April 14:35

[spend]

Did you check your rocker shafts were not bent & the diameters were constant. Plenty of tight/loose spots as you pushed the rockers & pedestals on?

Go solids all the way is my advice

[daveb500]

spend said:

Did you check your rocker shafts were not bent & the diameters were constant. Plenty of tight/loose spots as you pushed the rockers & pedestals on?

Go solids all the way is my advice

No I didn't, but I will now. I guess another test would be to swap the rocker that has too much preload with the rocker that has none. If the preloads swap with the rockers then it must be the rockers.

That's given me a few things to think about anyway.

[Precat]

Real Steel sell adjustable pushrods. These will allow you to solve the problem you describe.

Hope this helps.

Precat

Edited by Precat on Saturday 3rd April 17:45

[chris52]

I had exactley the same issue. I had 7 rockers that were dated 94 they had the HRC 1050 part no but as you say, the push rod end fits in much deeper so knocks the preload out.They were definatley a different batch of rockers as they had different cast marks. I manged to get some 96 dated rockers from ebay and that resolved the problem for me.
I am pretty sure I have some pictures of the the different rockers I can post them on here if that will help.

Chris

[chris52]

Found the pics

First up is the good rocker

This is the bad one (at least for my car anyway)


Its Plain to see by the picture That the second one sits in further


Dates on the rockers



Chris

[BeastMaster]

Think that if you go adjustable push rods, some head work may be required to open up the push rod holes. - Andy

[daveb500]

chris52 said:

I had exactley the same issue. I had 7 rockers that were dated 94 they had the HRC 1050 part no but as you say, the push rod end fits in much deeper so knocks the preload out.They were definatley a different batch of rockers as they had different cast marks. I manged to get some 96 dated rockers from ebay and that resolved the problem for me.
I am pretty sure I have some pictures of the the different rockers I can post them on here if that will help.

Chris

Thanks - very interesting. I can't read the date stamp on most of them....but I think new rockers and shaft will be the answer. Do you know what the number after the 1050 is? a batch number perhaps? This varies quite a bit.

[cinquecento]

Dave.. If you get new rocker PLEASE be careful abt the rockers you buy, especially with regard to the machined oil galleries in the rockers and the low oil pressure you experience with these.
Lots of details posted on PH,

[daveb500]

Ok, so a simple job seems to have suddenly become a lot more complex.

It sounds like even genuine LR rockers can cause pressure problems. What about the steel ones? Some people obviously think the weight is a disadvantage but presumably they don't suffer with wear issues and I assume they don't cause the pressure problems either....

Why is life never simple.....

[chris52]

Not sure about the steel rockers and how they perform but if I remeber correctly Quinny fitted them is his when he rebuilt his engine, so he is the man to ask.
They do seem to be a major issue at the moment trying to find decent quality rockers.

Chris

[spend]

I don't think its fair to put all the blame on the rocker arms, various folks have had as much tolerance problems with diameters of the shafts IIRC. The bush in the arm needs to be a close fit to the shaft otherwise it just wears an indent and pisses oil out the other side..

[macdeb]

I changed to steel rockers on my Griff' with pre-load probs' [earlier reply above]. It didn't solve anything, though they are a fit and forget item as opposed to the originals with their tendacy to break the pads. Put a steel rule along the length of the valve tops 1st to see any variation in height, if there is enough difference it will make it impossible to get all lifters within correct preload tolerance.

Edited by macdeb on Monday 5th April 23:02

[daveb500]

macdeb]I changed to steel rockers on my Griff' with pre-load probs' [earlier reply above said:

. It didn't solve anything, though they are a fit and forget item as opposed to the originals with their tendacy to break the pads. Put a steel rule along the length of the valve tops 1st to see any variation in height, if there is enough difference it will make it impossible to get all lifters within correct preload tolerance.

Edited by macdeb on Monday 5th April 23:02

Yeh, I've done that. As I said in the first post, I've check the valves are level, I've checked the rods and I've check the pedestools. I've also got a new cam and followers. The rockers are visibly different so they definitely need replacing.

I'm going to give Dom at TVR Power a call today to see what his thoughts are. And I might try V8D as well. Hopefully, that should give me a good rounded opinion on the quality of rockers available. And I'd rather pay a bit more for seomthing that will be right.

I'm not keen on going to steel because it feels like old(er) technology but if it is the only way to get quality, I will.

Edited by daveb500 on Tuesday 6th April 08:02

[daveb500]

Right, I've just spoke to Dom. He recommends the steel rockers so that's what I'm going to use.

[macdeb]

daveb500 said:

Right, I've just spoke to Dom. He recommends the steel rockers so that's what I'm going to use.

Cool, Let us know how it goes, good luck.

[daveb500]

Well, I just put the new rockers on and checked the preload quickly (I'm doing it properly later) and they are now all very similar so problem solved

[spend]

So what do you think now of all these folks that descry TVR (power) for not using shims because they see these discrepancies when they rebuild their engines

Looks like there is a lot more wear on the cups than the pedestals and their seats?

[daveb500]

spend said:

Looks like there is a lot more wear on the cups than the pedestals and their seats?

The cups were definitely deeper on some than others. Weather this was due to wear or manufacturing, I can't be sure. Personally, I think it looks more like manufacturing because the whole socket looks deeper. If that is the case, it has probably always been wrong.

Anyway, it is right now and I'm satisfied with the result. And I'm learning huge amounts as I go which is also good