Rattle

[berger]

Mr greybeard nothing to write home about as regards measurements then. is the distance you measured between guide and spring cap with spring on or off? I imagine on and if so even having the bottom spring keeper upside down it doesn't really make a difference . I will stick me neck out and say again - bad follower to start with

[Greybeard]

Mr greybeard nothing to write home about as regards measurements then. is the distance you measured between guide and spring cap with spring on or off? I imagine on and if so even having the bottom spring keeper upside down it doesn't really make a difference . I will stick me neck out and say again - bad follower to start with

It's Neil BTW.
I measured the distance between top of guide to bottom of collet without the spring fitted.

I have a new set of followers on order.

[berger]

ok Neil when you get it back together make sure there is about 60 thou spring gap at full lift, some say 80 but I think that is boy racer clearance 

[chaterlea25]

Hi GB,
Reading Bergers thread about removing the blanking plugs of the oilway to the cam trough , I thought about your engine problems
Make sure to check that it is clear before rebuiding the cases
As this oil feed depends on the prv opening I would check it out too

John

[Greybeard]

Righto lads, thank you for your patience. I need advice again. I've re-read the mail I received from Gary at SRM.

Gary Hearl <[email protected]>
   
Wed, 26 Sep 2018, 10:48
   
Hello Neil,

Looking at your pictures of the damaged cam follower, this is a classic case of valve springs coil binding.

The valve springs should have a fitted free length on a 356 Super Rocket camshaft of minimum 1.395” (Measured between top and lower cup) and be able to be compressed a further 0.080” ( 2.0mm) before they coil bind. If a valve seat has been replaced in the past, its possible the seat has not been cut down to its correct position, in effect holding the valve further down which would make the valve springs wrong fitted length, also pattern valve springs with wrong wire section and number of coils could cause the same issue. I would check all the valve springs for this problem, if it isn’t checked and rectified , any other cam followers fitted will have the same wear issue. Also look for bent pushrods and excessive wear on top of the valve stem, these will all be a result of coil binding valve springs.
...

Regards Gary

 
I have the valves assembled with the head on the bench. I've been measuring the distance between the bottom and top spring collars as Gary suggests. On the Inlet valves, I have 1.323" and 1.345". This means I have 72 and 50 thou less movement than he says I should have! The 72 thou is the one that has the follower that's been most affected.

The exhaust valves have  1.372" & 1.390", so 23 & 5 thou less than recommended. You can see in the picture that the best valve has the collet seated lower down. I did go around the collets with a pin punch to check that they were fully seated.

I have at least 2mm gaps between the spring coils.

The valve seats are I believe the originals. The valves were changed a couple of years ago, the collets and springs were changed last year.

Now, what can I do about this? I don't have sophisticated workshop tools. What about using my lecky drill, running emery cloth on a mandrel in the valve top collars? As it's a taper the required measurement should increase fairly rapidly, (I think)

The valve springs fully compressed in a vice are about 23mm

[berger]

hello GB I would find a decent lathe turner [not me, but I once found one at a local model engineers club who was very helpful for the price of a donation to the club] and have 1mm or whatever it works out to be to get correct set up taken out of the valve stem/s at the top where the top of the collets fit. this is what older brother had to do to mine to get a decent clearance on the spring coils when I was playing with a 357 camshaft.This was even after he had turned down the bottom keepers as per SRM instructions, but shooting star valve gear wasn't meant for a 357 hence me once having a problem like yours but cured it by having the valve top relieved a bit. edit my valve springs compressed are 24.6mm so its not your springs its when its all together you are losing clearance

[Greybeard]

I just ran out to have a look at the collets to see if they were touching each other at the end. There is clearance between the ends.

[berger]

GB its a bit of a headache but I would be having the valves machined out where the top of the collets sit to raise them up the stem a tad, i'm not doing the maths for how much will be required for each valve because I only drink black&tan 

[Greybeard]

OK, I solved the problem by grinding some metal off the boss on the back of the bottom spring cups. I held the cup on a scrap bolt while lightly pressing the cup to the side of the bench grinder. The cup was turned by the grinder, I just braked it. Leather glove and frequent qwenching required. The finish looks quite professional.
I've installed a new set of Stellited cam followers that are longer than the last ones. I have the barrel and head torqued up. Tomorrow morning I'll fit the rocker box and I hope to see tappet adjusters that are at the correct height. If all goes well you may hear the engine fire up about mid day. Keep em crossed!

[muskrat]

 

[chaterlea25]

Hi GB,
It looks like some of the new collets are "thicker" than the one nearest camera ?
Or ??? if the collet's inner diameter is too small then they would not sit snugly around the valve stems ??
To work there must be a gap between each half of the collets, are all the gaps equal ?

John

[duTch]

 In the photo, the top left collar (Left Inlet?) looks to be on a cock-eyed angle....unless it's my cockeyes...
 **edit....and whether it makes a difference the Left Exhaust collets are proud of the collar, whereas the Right ones are 'set in' 

[Greybeard]

In the photo, the top left collar (Left Inlet?) looks to be on a cock-eyed angle....unless it's my cockeyes...
 **edit....and whether it makes a difference the Left Exhaust collets are proud of the collar, whereas the Right ones are 'set in' 

The one that looks set in is actually flush. That is the only assembly that was close to the magic figure quoted by SRM. None of the others are cock-eyed; must be an illusion.

[Greybeard]

Hi GB,
It looks like some of the new collets are "thicker" than the one nearest camera ?
Or ??? if the collet's inner diameter is too small then they would not sit snugly around the valve stems ??
To work there must be a gap between each half of the collets, are all the gaps equal ?

John

Yes John, the collets all have clearance between the two halves. The collets all look the same to me and they fit the valve stem properly.

[Swarfcut]

GB  Before you put the top back on, compare my quoted dimensions  (6/4/19) with what you have now.

 Overall fitted length top valve cap, fitted spring and bottom collar, i.e. bottom face of bottom collar to top edge of the top valve cap, inlets, I measured 41 and 42mm.  From the top face of the inlet valve cap to the mating face of the head/rocker box I measured 20 and 21mm.

Swarfy.