Smashed Valve Collar

[rocker21]

i have fitted the 357 cam to my A7ss and broke a pushrod , springs were getting coil bound so had to machine 20 thou off the base retainer and machine the valve were the collets go which in total gave me 60 thou more clearance so far no more broken pushrods,

[CheeserBeezer]

Yes, so referring to comments above, it would appear that using an SS head with the 650 alloy head valve arrangement, is a lash-up unless considerable machining has been undertaken. Generally, I find it difficult to improve on manufacturers' original specifications and, when 'improvements', have been undertaken there's a downside somewhere which offsets any benefit in the 'improvement'.

[berger]

rocker21 same here , i remember now as well as skimming the bottom keeper the super rocket valves were also machined to lift the collets and give me about 60 thou with the 375 cam on the berger build

[limeyrob]

Mine came with the iron head valves, collars and collets in an ally head.  Luckily there was a lot else wrong so I never turned the engine over as I'd seen enough.  I bought the whole set of correct valves, collars (top and bottom), spring and collets and was still very careful when I turned the engine over first time check the springs didn't bind.  Since I had both the iron and ally head sets I could put them side by side, they are very different.

[BagONails]

More good info for which I am very grateful. I am a relative newbie to the delights of classic bike ownership so the collective wisdom on here is WIWIG,but I have to say it is an interesting hobby and there's never a dull moment!

Now I have found out more so here goes:
The head is good, guides are OK. Its a 67-1106 with 70mm dia combustion chambers so not SS but a pre SR, alloy, twin separate inlet head, sold presumably to allow speed demons to fit twin carbs with suitable individual manifolds. (I'm running a single carb because KISS principle.)

All the valves fit the guides within service limits. They all have the same size heads, and the two inlets are marked 67-0967 making them SR exhaust valves so maybe correct? The collets as Radlan alluded appear compatible with the valves at least.

Pushrods all straight, rolling on a surface plate, ends normal polish only. Rockers appear OK and all move freely with no tight spots or play.

The rest however is junk, according to the guys last night fairly typical of a lot of the stuff coming over from the USA. (sorry Richard!) A dog's breakfast of mismatched, modified and I believe home made parts. eg. the lower cap under the suspect valve spring was 1mm thicker than all the others. The top caps all vary in thickness and in fact the RH exhaust top cap that hadn't failed yet... has only 2.3mm thickness of unknown grade ally to hold the plot together above the spring. The one that failed had 3mm. The factory steel parts are distinctly chubby in this area NOT pared away to the minimum. Basically, a hand grenade with the pin half out just waiting to be dropped.

I think if I can get 67-0884, 67-0960, 67-0886 SR spring set. upper and lower valve spring caps respectively I should be able to rebuild the head.

I will lift the barrels now to check the state of the cam and followers and it needs refinishing anyway as the existing paint has bubbled and is cracking off.
I've inspected the LH Ex springs and there is really no evidence of binding, I'd expect bright polished lines of contact, but nothing even under a 10x eye glass so maybe purely fatigue due to wrong part, badly made, excessive preload etc. and all of the above. I am then hopeful that this is it but won't know for sure until I check of course.




 

[limeyrob]

The SR collects can be tricky to get, sometime they are available, sometimes not.  I opted to get a whole set of springs top and bottom collars and collets from SRM. The top collars and collets are their own and not interchangeable with the BSA parts but they all work as a set and the price was about the same the BSA parts had they been available.  See what's in stock ten decide.

[groily]

Love your VSC BoN!
Great Minds (or Fools Seldom Differing  . . .)

[Radlan2]

Hi again B o'N 
  Good news that no further damage has been found. That twin carb head could well be one from the "Speed Equipment" catalogue which are rare and sought after, well any 70mm twin carb head is. Google Atlantic green BSA for more info. It could indicates that a previous owner loved that bike enough to buy such special parts. is there a chance the valve caps and cups were modified/thinned to achieve the correct fitted spring length and the position of those parts got mixed up and changed during a later stripdown? I had to resort to that after having unleaded seats fitted, though I would only mod factory steel ones not alloy aftermarket ones.
     Just a thought
                  Chris

[trevinoz]

Does your head have a date code on the rear along with the foundry mark?
If not, it is probably a speed kit head.

[BagONails]

Progress Report...

Got a lot done today with great help from one of our local guru's Dave Robertson, shout out for Davo! 

The head has been water blasted and is now looking like a new one, can't see any casting dates on it Trev.

I gave the part number to Mike Reilly at Mike's Classics in Queensland and he has told me "it is a 54/55 road rocket head, all alloy heads use the same springs, caps and collets etc" So I've gone ahead with an order for those parts from him as he had everything in stock (#arightresult!) At least if they turn out to be wrong for this head I can post them back to him for next to nothing...

With the head all clean and shiny I have been able to properly evaluate the state of the valves and guides etc. consequently I am now talking to SRM about a set of new Colsibro oversize guides. I will get these fitted as the old ones virtually fell out with a few light taps with my exercise mallet (without heating the head too.)  We can reuse the valves as they are in good condition and made of stainless. Then I'll have the seats re-cut. and reseat the valves.

Barrel is off and the bores look pretty good, the pistons/rings too. They appear to be +020's Hepolites fitted with 3 piece OCR's and will go back in with a light hone. Piston to bore min clearance is about .005". The barrel has been acid dipped by our local engineers and now looks like a new unpainted one. They will deck the barrel if necessary but it probably doesn't need it.

The cam and followers appear to be in very good nick, bright and shiny with no sign of heat, scoring, ridges etc, I might try to put a clock on it and measure the lift on the suspect exhaust cam just to be sure as I've only eyeballed it from above at this stage.

That's about it for now, good progress so far, could have been a lot worse.  I will just have to wait a week or two for parts now.

I'll probably order an SRM gasket for the RB while I'm at it as that was the whole purpose of the initial teardown!

As ever if you think there's anything else worth checking out while we've got the thing in bits by all means pitch in.
Cheers guys.




 

[BagONails]

The SR collects can be tricky to get, sometime they are available, sometimes not.  I opted to get a whole set of springs top and bottom collars and collets from SRM. The top collars and collets are their own and not interchangeable with the BSA parts but they all work as a set and the price was about the same the BSA parts had they been available.  See what's in stock ten decide.

Yes, I was a bit concerned until I checked out Mike's Classics, he has helped me out with a few hard to find parts to date. Shout out for Mike too!

Love your VSC BoN!
Great Minds (or Fools Seldom Differing  . . .)

Indeed, You just have to work with what you have Groily. This works very well, actually much better than one of those bendy over centre jobs. You can really feel how much pressure you've applied and it keeps everything nice and square. It worked a treat.

Hi again B o'N 
  Good news that no further damage has been found. That twin carb head could well be one from the "Speed Equipment" catalogue which are rare and sought after, well any 70mm twin carb head is. Google Atlantic green BSA for more info. It could indicates that a previous owner loved that bike enough to buy such special parts. is there a chance the valve caps and cups were modified/thinned to achieve the correct fitted spring length and the position of those parts got mixed up and changed during a later stripdown? I had to resort to that after having unleaded seats fitted, though I would only mod factory steel ones not alloy aftermarket ones.
     Just a thought
                  Chris

To be honest Chris, its all immaterial now but you are probably right. We are pretty sure the aluminium caps were home brewed and done to achieve the correct height but the lower caps were such a mix of sizes it almost looks like they scraped the bottom of the toolbox and threw in whatever came to hand!

[chaterlea25]

Hi BON,
I am assuming you have ordered oversize guides so they will be a tight shrink fit in the head?
Colisbro guides will need to be honed to size as it does not cut easily or at all with a reamer
Not everyone has the facilities to do this job.

John

[trevinoz]

Ian,
If there is no date code on your head you can be pretty sure that it is a speed kit head.
The code is a letter followed by 54 or 55.
If you post a picture of the rear of the head behind the manifold area all will be revealed.
I have done some jobs for Dave Robertson, a genuine nice bloke.
Trev.

[BagONails]

Hi BON,
I am assuming you have ordered oversize guides so they will be a tight shrink fit in the head?
Colisbro guides will need to be honed to size as it does not cut easily or at all with a reamer
Not everyone has the facilities to do this job.

John

Thanks John, good tip I will check with our engineers before pulling the pin with SRM. 

Ian,
If there is no date code on your head you can be pretty sure that it is a speed kit head.
The code is a letter followed by 54 or 55.
If you post a picture of the rear of the head behind the manifold area all will be revealed.
I have done some jobs for Dave Robertson, a genuine nice bloke.
Trev.

Hi Trev, Yes Dave is very active in our club here in Adelaide and he does what he can to help the members out. Very appreciative.
I already posted that picture by the way, have a look in I think my third post above it reads. 67-1106 and under that 'AM' all cast in raised lettering.
I can't see any other codes. So would a speed kit head still be factory? and would it still take the standard Ally head components in terms of collars, caps and springs?
I hope so!

[trevinoz]

Hi Ian,
Without the date code I am pretty sure that it is a speed kit head.
As far as I know they are factory, they have the same foundry mark AM.
I have one for my 1954 Road Rocket, if it ever gets done. The original head was too far gone for economical repair.
All of the jewellery should fit.