Rocker arm bushes

[Lebro]

I I am In the process of fitting rocker shaft spacers to my '3.  The kit came with a bag of shims, but no instructions, so question is what sort of clearance should I be looking for between rocker & spacer, & what about the flat springs at each end on the shaft (next to the end caps) are they removed & replaced by shims or left ?

Bob

[Lebro]

Anyone got any views ?

Bob

[Chilliman]

Bob, I use them on all my engines, I just use the shim washers to equalise the play between the pedestals making sure they don't bind & allowing for expansion when hot - I can't give you a definitive figure as I don't have one. I still use the spring washers at either end under the alloy caps.

I have ten's of thousands of miles with this set up plus some very hard track use & never had an issue, hope that helps.

[Motorsport Mickey]

I used to allow 4 thou clearance on either end of the tubes/washers Bob on the race cars.

Mick Richards

[Lebro]

So 8 th total. What about the spring washers at the ends, shoul I replace those with solid spacers(thick washers)

Bob

[Motorsport Mickey]

No, I wouldn't want thick washers there, the thin shim steel hardened washers dissipate heat easily and so helps prevent heat bind up. 

Mick Richards

[Lebro]

I seem to be having trouble making my question clear ! As standard there are springy washers between the end rockers, & the pinned end caps. I am replacing the long springs with solid spacers (set to give a small clearance using shims) but the end rockers can still move sideways against the sprung washers at the end. Surely the end rockers should have the same controlled clearance as the others.

Bob

[Ian Vincent]

16 minutes ago, Lebro said:

I seem to be having trouble making my question clear ! As standard there are springy washers between the end rockers, & the pinned end caps. I am replacing the long springs with solid spacers (set to give a small clearance using shims) but the end rockers can still move sideways against the sprung washers at the end. Surely the end rockers should have the same controlled clearance as the others.

Bob

Bob,

I had an issue with a tapping noise from the top end which I eventually tracked down to the end rocker moving back and forth and slapping on the pillar so I removed the end cap and opened up the flat spring a bit before putting it back together. The noise has gone. If I were going down the route of fitting spacers, I’d put them on the end as well. Can’t help with the clearance though.

Rgds Ian

[Lebro]

Yep, the gap currently taken up by the sprung washers is too big to be taken up with the shims provided, which is why I suggested thicker washers

Bob

[Motorsport Mickey]

AAaahhh ...at the end of the rocker shaft not end of the solid spacer, I should have read your original post which defines it, thanks for the clarification. Yes, I used a spacer at the end between end rocker and shims, same clearance.

Mick Richards

[BlueTR3A-5EKT]

Sorry I am a bit late to this discussion.

My thoughts are that all the springs should be replaced by spacers and shims including the double coil thackery washers at each end before the plugs.  Moss/Triumph Tune used to sell a kit of spacers and washers and that I am pretty sure included 2 thick washers for each end of the shaft, along with spacer bobbins and shims.  The bobbins and washers used to go away for heat treatment prior to being built into kits, for selling.

I cannot find reference to that action in any of my tuning TR books, just advice to replace the springs with spacers.  I would say that the flat spring washers at each end are 'springs'.  The replacement of the springs with spacers is to ensure the rocker arms cannot wander along the shaft in use.

Those who have raced these engines will advise accordingly.

 

It sounds like the classic TR spacing is required - 0.004" to 0.006"  You know that off the top of your head as you have just done your half shafts.

Edited January 10, 2023 by BlueTR3A-5EKT

[Lebro]

Great, glad we are all on the same wavelength.

Will now get on with the job !

Thanks

Bob

 

[Hamish]

We need pictures before you refit the rocker cover.

Question how does oil get to the shaft etc with spacers. What do the spacers do ? Just keep the valve rockers in the right place ?

[Lebro]

Doh !  Now I will have to take it off again !!

Here we go:

    

Click on images to enlarge

It was a fiddley job, I removed 3 of the push rods (the ones sticking up) so I could drop the shaft down on the studs without depressing any valves.

Stripped the shaft from the forward end, leaving the rear pedestal, rearmost rocker, spring washer, & end cap in place. Then re-assembled using the spacers with no shims in place of the springs. Placed on the engine & partly tightened the 4 nuts. checked the sideways movement of each valve with a feeler gauge, & noted which would be the best way to move the rockers to get them centered over the valve stems.  Removed from the engine, dismantled again, & inserted the supplied shims (10 thou) where required to achieve a sideways movement of any of the rockers to approx 10 thou.  Sounds straight forward, but in practice the pedestals are not a precise fit on the studs, & they can themselves move sideways, so you have to check the rocker clearance on both sides of a pedestal, then tap it left or right (with nut slackened off) to even up the clearances. If they don't come out right then you dismantle again & re-arrange the shims till they do !

The sprung washers at the ends are removed, & these are replaced with a solid washer of the correct thickness to get the correct sideways clearance of the end rockers. No such washers were provided, so I raided my washer draw, & found some suitable ones, which after reaming out to 5/8", & adjusting the thickness (lathe) were fitted behind the end caps. Again, the clearance of the forward rocker (No.1) can be varied by nudging the front pillar left or right, which also affects the clearance of the rockers behind that pillar. So, as you see it is an iterative process !  Anyway got there in the end, & finished off by checking the valve clearances, which had not really changed much.

If I have to remove the rocker shaft in the future then on re-assembly care will have to be taken to get each pillar in its optimum position to ensure correct sideways clearance of each rocker.

Bob

 

Edited January 10, 2023 by Lebro

[Ian Vincent]

2 hours ago, Hamish said:

We need pictures before you refit the rocker cover.

Question how does oil get to the shaft etc with spacers. What do the spacers do ? Just keep the valve rockers in the right place ?

Hamish, the oil passes up the end rocker shaft pillar and along the drilling up the centre of the shaft to drillings at the rocker positions. Every time the rocker rocks and opens the hole a squirt of oil goes into the bearing before emerging as a little fountain through the drilling in the top of the rocker. Hence the splash lubrication to the rest of the valve train. 

Apologies, if I’m explaining the obvious. 

Rgds Ian

[BlueTR3A-5EKT]

Bob,  Is that an original rocker shaft?   If so it is an hollow tube without end plugs and the end caps are fitted to stop oil spilling out either end, as well as hold nos 1 & 8 rocker in place.    Will your roll pins be oil tight compared to original solid Mills pins?    If you have a repro rocker shaft they invariably have core plugs fitted into each end of the tube to seal them.

 

Q 2.   Where do the 2 carb breather pipes go to after the Y piece?   Mine are just capped off at the carbs.

Edited January 10, 2023 by BlueTR3A-5EKT

[roy53]

I could send you photo's Bob but i use the racetoration ali mounting blocks which do away with the end caps

Roy

[Lebro]

1 hour ago, BlueTR3A-5EKT said:

Bob,  Is that an original rocker shaft?   If so it is an hollow tube without end plugs and the end caps are fitted to stop oil spilling out either end, as well as hold nos 1 & 8 rocker in place.    Will your roll pins be oil tight compared to original solid Mills pins?    If you have a repro rocker shaft they invariably have core plugs fitted into each end of the tube to seal them.

 

Q 2.   Where do the 2 carb breather pipes go to after the Y piece?   Mine are just capped off at the carbs.

Complete shaft + rockers etc came from TR shop.

The roll pins were fitted to it when it arrived.  Plenty of oil in & around it.

Pipe from rocker box to Y piece, then to both carbs. The ports on the carbs were originally capped off. But I realised  many years after fitting the ex Cox & Buckles carbs that they were intended to connect to engine breather. Seems to work ok.

Bob

[Hamish]

1 hour ago, Ian Vincent said:

Hamish, the oil passes up the end rocker shaft pillar and along the drilling up the centre of the shaft to drillings at the rocker positions. Every time the rocker rocks and opens the hole a squirt of oil goes into the bearing before emerging as a little fountain through the drilling in the top of the rocker. Hence the splash lubrication to the rest of the valve train. 

Apologies, if I’m explaining the obvious. 

Rgds Ian

 

[BlueTR3A-5EKT]

2 hours ago, Lebro said:

Complete shaft + rockers etc came from TR shop.

The roll pins were fitted to it when it arrived.  Plenty of oil in & around it.

Pipe from rocker box to Y piece, then to both carbs. The ports on the carbs were originally capped off. But I realised  many years after fitting the ex Cox & Buckles carbs that they were intended to connect to engine breather. Seems to work ok.

Bob

I failed to view the 5 th photo where it is all reassembled.

[Z320]

Hi,

I had a closer look on the rocker shaft and rocker bearings

on my 4A because a sudden loss of oil pressure last year (other post), found all OK I let the construction with springs.

Each rocker has 2 bearings, between is a gap. On the rocker shaft there is a flat area at the rocker position, guiding oil to the bearings and gap.

In my opionion the oil suply is always "open" but limited by the drillings. I not noticed an oil mechanism

Ciao, Marco

Edited January 10, 2023 by Z320