super rocket valve spring installed height problems

[mikeb]

Dutch - thanks heaps for all your figures!!!  very helpful. I'll sit down with the calipers tomorrow and compare.
how did you get those keepers so low in the caps??? how did you re-size the stem groove? any concerns about fatigue?

I've been re-measuring the inlet rocker ratio again this time more accurately with dial gauge etc - but it still works out wrong so I'll try again in the weekend and post back. a guy on a britbike forum post said he measured .340 travel on the collar with a 357 cam but the lobe pushes that much without a ratio I wished I'd measured this before i took the bike apart

Klaus - I don't quite understand why spring pressure will help resolve this. don't i have to know the travel distance first?

cheers

Mike

[duTch]

 Mike- just be aware that all those measurements are kind of arbitrary and inconclusive and not necessarily right or correct, I was just measuring stuff for the heck of it out of curiousity, figuring it may be stuff I'd need in days of the future- passed ...the rocker measurements were a fair bit of calculated guesswork...

how did you get those keepers so low in the caps??? how did you re-size the stem groove? any concerns about fatigue?

  Just lucky I guess, it was a headfar-que for a while but took them to my mate and explained and he sorted it on his lathe or something- I had cups of tea and bikkies with his Mum... , didn't really think about fatigue,
 but my eyes did almost fall out once or twice ...and hadn't considered stress on the valve tips until you mentioned it 

 I've also been looking at the way the valve-lash adjusters(some call 'em 'tappets') engage on the valve tips; as per pic ->and compared to previous pic (last page), having trouble with photos since I threw the last phone up the driveway resolution is all different

[mikeb]

So Dutch all those measures pretty much match what I have, and I’ve compared my old and the new srm.

On the bench I’ve set up the head/rockerbox/light springs/barrels/pushrods and with dial gauge measured valve travel against lift under the cam followers (on the correct angle) using a range of drill bits to match the height of a 356 and 357 lobes. With lots of measures there’s a fairly linear relationship between the two (I had though the change in rocker angle would shape the curve). The summary is between 0.291-0.352” cam lift the rocker ratio is about 1:1.135 on the inlet and 1:1.119 exhaust. This means for my 356 cam at 0.305” --> 0.346” inlet valve travel + 0.95” (spring compressed) +060 gap = 1.356” install height. That’s more than Eddie Dow says for a 357 (1.3125”) and less than srm say (1.375” for 356) so either these springs are longer than Eddies when compressed or I’m still missing something  .

Does anyone have a measure on the outer spring when fully compressed? If so do you know the brand?

Apart from springs, the keepers don’t sit deep enough in the caps. The keeper ‘bump’ is a bit squarer than the shape in the valve stem, tho otherwise appears to make good contact with the stem – no movement. Maybe the keepers are too fat or the taper in the caps too tight.  Can anyone recommend how I could get all these to fit better?

Or maybe I could try your trick Dutch and have tea and bikkies with a friends Mum and see if that works ?

[duTch]

 

Or maybe I could try your trick Dutch and have tea and bikkies with a friends Mum and see if that works ?

  ...well it's worked for a variety of things i the past, but won't be with Kels' Mum anymore, she's since departed....

 Mike, I'm absolutely no engineer or other 'expert', but unless I'm missing something, I can't figure how the compressed spring length at rest (valve closed) is going to affect anything other than a possibility of binding if too many winds for the amount of travel...?

 If the valve is closed, it's closed- and will perform its duties as shafted by the cam to the lift available (hopefully consistent L<>R, which is more important the way I see it  ), whatever the spring length... 
 
 Did you put the keepers in the collars and measure between the 'bumps', and at the same time the virtual stem measurement which will vary depending where they sit in the keeper??               

[mikeb]

Dutch i'm certainly no engineer either... don't quite know what i'm doing most of the time, especially on BSAs. this is all about avoiding coil binding when the valve is fully open. between the top of the seat and the underside of the top collar i need at least enough for the full amount of valve travel (hence my measures) + the fully compressed spring (coz thats when its not getting any smaller) + a bit of a gap (for good luck). at least i think i do. i might not be understanding your point, nor this bit:

the virtual stem measurement which will vary depending where they sit in the keeper??

??? time for a sleep here in NZ

[duTch]

 

this is all about avoiding coil binding when the valve is fully open. between the top of the seat and the underside of the top collar i need at least enough for the full amount of valve travel (hence my measures) + the fully compressed spring (coz thats when its not getting any smaller) + a bit of a gap (for good luck).

 Oh yeah that's right, so I was kind'ov on the page ..got lost in translation   

i might not be understanding your point, nor this bit:
Quote

    the virtual stem measurement which will vary depending where they sit in the keeper??

   I mean measure the internal diameters with the keepers in the collars with no valve in place (virtual)- keepers at max insertion (when the two halves meet), and/or keepers/collars flush at top of collars

[duTch]

  Just had a thought re;

I mean measure the internal diameters with the keepers in the collars with no valve in place (virtual)- keepers at max insertion (when the two halves meet), and/or keepers/collars flush at top of collars

  (If you haven't already done it), while the collets/keepers are in the collars, you could slip the valve tip into the keepers so the 'bumps' are sitting on the tip, and see how far in the taper they are, and even invert the valve and do the same, but with the keepers in the grooves and something to simulate stem thickness at the pointy (bottom)side- might be able to see how the tapers match. but if there's not improvement, I say there's not much can be done...so long as the collets are fully in the groove , and I suggest minimally deeper and wider grooves will be better than 'snug'...hope that makes sense?

  Going by the photo ahlf way down page one, they aren't too bad, but can see further in would be better I guess

   

[mikeb]

I thought I'd post up the happy ending to this story for the next person sweating over a lack of installed height on a alloy head a10. I rang SRM and they said if I sent the caps and keepers back they'd turn out the inside of the caps so the caps sit higher on the keeper (why not size them before mailing I wonder?). the inside angle of their caps they say is 10 degrees. being 12,000 miles away I got someone local to do the job - my maths said at 10 degrees +.020" diameter would raise the cap by .100". hence the pics below - you can see the cap sits much higher and I have +.100" more installed height and enough for my measurements of valve travel (for a 356).

in case you are wondering the springs are soft ones for a test installation

[duTch]

  Just a follow up post;

  How'd you get on Mike? I had to hunt for this to follow up

 Sorry guys, I realized I took over up theer ^^ didn't mean that 

I hadn't forgotten, but when I checked my valve gaps the other day, I finally forced myself to check the actual valve travel with dial gauge as promised:

 Actual Valve travel (with a 357 cam as below) measured with dial gauge on valve caps, as best I could;

   L Ex  0.3575”      R Ex  0.3605”       (0.003"  variation L/R)
   L  In  0.371"      R In  0.3675”       (0.0035" variation L/R)

 This is with reground 357 Cam lobe; two different readings(?)
(1)      0.348”   0.350"      0.3565”      0.347”
(2)      0.3455”   0.3515”      0.350”      0.3455"
 * not sure what the two different readings are…maybe dependent on tongue angle
   
Strangely, the cam lift of the 357 I'm using are greater than the new (aftermarket/pattern?) cam I bought somewhere in UK '81 

Lift on New 357 *may well be pattern copy;
Cam Lobes- new 67-357     from base circle to top of lobe;
        LIn                LEx         R Ex         R In
(In")       (0.3285 )   (0.3415)      (0.3375”)      (0.3505)

Hoping that makes sense to someone, It was confusing that each cam had a variety of readings in the course of their revolutions

[bsa-bill]

how did you get those keepers so low in the caps???

has someone also said this - Rocket and Flash keepers are of different design (I have both) think the Rocket one do sit lower

[duTch]

 

has someone also said this - Rocket and Flash keepers are of different design (I have both) think the Rocket one do sit lower

    Dunno if it's been said Bill

  I'm not sure if there's an easy answer, as (obviously) the caps/collars are different profiles, and I think the RR/SR valves are longer(?), so may appear to sit different 

 Just another thought that I wonder if Mike was supplied mismatched collars/collets from RR/SR?SS ? (Shooting Star different p#'s)

  Note; I've amended my above post, realized I had stuff where it shouldnea been- I think fixed now .

This is the relevant stuff in answer to Mikes question;

Actual Valve travel (with a 357 cam as below) measured with dial gauge on valve caps, as best I could;

   L Ex  0.3575”      R Ex  0.3605”       (0.003"  variation L/R)
   L  In  0.371"      R In  0.3675”       (0.0035" variation L/R) 

 ** Note that this is lifted with a reground 357 may have slightly different specs from standard.

[mikeb]

hi Dutch
good to have your data posted - its gonna help some other poor sufferer of a10 valve height weirdness. I've had people say "its just a low-spec a10, it should just work", but mine would not have without the extra effort. getting the collets re-machined (as per the post above) did solve the problem and leaves me thinking that no matter how much money you spend at whatever flash shop you've still got to check them all in detail. i did Plasticine tests and all.  the supplier (see above) only sells alloy head ones, so i assume no supply mix ups re Bill's comment about flash vs rocket

the bike is now back together and as of yesterday road legal    - sounds awesome. shakeout run this weekend. can't wait. i might even finally get a picture of it on the pictures forum....!

[duTch]

 Congratulations, have fun on the 'shakedown' I hope not too much shakes off

the supplier (see above) only sells alloy head ones, so i assume no supply mix ups re Bill's comment about flash vs rocket

 The Shooting Star is the A7 version with alloy head, and I've got mahself carried away and found all the numbers(except springs ). It's not to say somediffreent numbers aren't the same part, but why would they be(BSA )
A7,A7S/S,A10    29-0410 Collet*
A10 S/R             65-1624 Collet       Also RR 56/7

A7,A7S/S, A10    67-0034  Collar*
A10 S/R              67-0960   Collar       Also RR 56/7

'A' Group to '57   67-0033  Valve cup (bottom)also later Models;
A7,A7S/S, A10    67-0033 Valve cup (bottom) except S/R
A10 S/R             67-0886 Valve cup (bottom)        Also RR 56/7