Rcoker covers with roller rockers

[hiltonig]

I have a set of yellaterras, anyone know if these will fit under the standard rocker covers ?, is there such a thing as a spacer if they dont fit ??

[spend]

Depends on the covers, theres proper TVR ones or Rover ones...

Pasco has some spacers he'll sell on if you need some.

[Markh]

hiltonig said:

I have a set of yellaterras, anyone know if these will fit under the standard rocker covers ?, is there such a thing as a spacer if they dont fit ??

Yella terras fit under the cast TVR without any problems

[spend]

Out of interest do the YT's have the pushrod - valve stem offset correct. I was quite surprised when I drafted head locations, valve stems, followers / pushrods and then the Kenne Bells that everything lined up perfectly


Its about 2.4mm offset left/right on the rocker arms for perfect alignment by my reckoning.

[cinquecento]

I put YT rollers into my 96 Griff in early January.. so I can assist here. I have the std TVR rockers and this excerise was part of my Stealth cam change and dealing with poor quality replacement rockers.

In short, you need to extensively grind both rocker covers.. AND raise them. I did this by siliconing together two black rocker cover gaskets.

I did err on the cautious side as with empty lifters, you need to allow for the extra lift when they are primed.

I got to the point that with emtpy lifters, I was able to bolt down the rocker covers, rotate the engine and have enough clearance so none of the YT lifters hit the cover.. then added the two gaskets to allow for the additional lift the primed lifters would give.

The main areas to remove are around the round strengthening where the oil filler/breather go.. however you need to do both ends of the rocker cover. I used a Dremel. The covers are made from really soft alloy material so they are easy to grind

Don't forget you will need longer rocker cover screws as well. Have done quite a few miles now, no leaks and all's quiet in the engine.

[cinquecento]

spend said:

Out of interest do the YT's have the pushrod - valve stem offset correct.

They are aligned with the help of spacer washers to ensure the valve stem is centred on the roller. With this OK the pushrods are centred However interestingly, the pushrod cup in the rocker is some mm closer to towards the shaft: causing some concern as this then means the push rod runs so much closer to the rocker body, I was very careful... there is just enough clearance btween the push rod and the rocker assy.

[spend]

cinquecento said:

spend said:

Out of interest do the YT's have the pushrod - valve stem offset correct.

They are aligned with the help of spacer washers to ensure the valve stem is centred on the roller. With this OK the pushrods are centred However interestingly, the pushrod cup in the rocker is some mm closer to towards the shaft: causing some concern as this then means the push rod runs so much closer to the rocker body, I was very careful... there is just enough clearance btween the push rod and the rocker assy.

That seems strange, if I understand you correctly: if the shaft - pushrod moment is shortened I can't see how you get the correct rocker ratio? it would effectively reduce the valve opening..

The proper TVR covers are a lot higher internally than the Rover ones you have so will not be a problem in the way you have. I found the problem with the TVR ones is that the thickness of the casting near the 'indent / cut-out' needed relieving internally to clear the middle rockers - but there was plenty of casting to grind away without issues. Having said that my rockers are wide (&square) so your YT's being angled may make that OK.

Not sure there will ever be a definitive answer, more a case of placing the covers on loosely and turning the engine. I made them fit without gaskets and then use the gasket as extra clearance (personally find a single gasket hard enough to fit - 2 would give me nightmares I'm still working on a stud arrangement... to make easy)

I think its still important to check the shaft height as part of the installation, when you are looking at how the roller sweeps over the valve stem. Also the angles the pushrod is making. I guess many are just 'slapping them in'

I've got a couple of sets of KB's here and some 'others', the geometry of the 'others' is bloomin awful but I am most impressed with the way the KB's line up with everything.

[cinquecento]

spend said:

I think its still important to check the shaft height as part of the installation, when you are looking at how the roller sweeps over the valve stem. Also the angles the pushrod is making. I guess many are just 'slapping them in'

Agree. I did go to a lot of effort checking the geometry. Even when using replacement pedestals (see my posted picture) the rollers were sweeping perfectly across the valve.