The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Roadrocket649 on 18.04. 2011 13:12

Title: In dire need of divine inspiration
Post by: Roadrocket649 on 18.04. 2011 13:12
Guys,

I would appreciate your ideas on this.

The bike is a 1958 BSA Super Rocket, which has ?Spitfire camshaft?, and  a 67-1549 cylinder head (1960-1963 Super Rocket Head and 1962-1963 RGS)

The engine has been totally re-built

The cylinder head, new valves & valve guides

The rocker box is on and lubricated with Castrol XXL40

The oil tank has not been filled because of the  following problem,

On operating the kick start, to set the tappets, on every 2nd stroke/ depression of the kick-start, I hear a ?TAP?

First thought to be from the rocker box, inspection covers removed and inlet & exhaust valves re-checked ? They were OK

I am using the inlet & exhaust valve clearances as of Page 46 Haynes Manual, where it states,
      Inlet      Exhaust
1960-1962   0.008?        0.010?

Not page 10 (Routine Maintenance & Capacities data where it quote 0.0008? for both inlet & exhaust valve

The I thought it might be something to do with the gearbox/ kickstart, and filled it with Castrol GP50

It is still there

I do not wish to start the engine, in case of doing damage

Any ideas Guys, I am in dire need of Divine Intervention?

Roadrocket649

Title: Re: In dire need of divine inspiration
Post by: bsa-bill on 18.04. 2011 13:30
Hi 649
Have had a few problems of my own that were accompanied by a (tap or click), so a few suggestions that MIGHT be helpful

Valve sticking momentarily, the tap or click is when it moves again and takes up the slack in the tappet or cam follower
Front screws on the primary cover, if too long they catch the crank web when it comes around
Tappet catching the the rocker box cover

Others will have more suggestions I'm sure

Good luck with it
Title: Re: In dire need of divine inspiration
Post by: Roadrocket649 on 18.04. 2011 13:48
Hi BSA-Bill

Your input much appreciated

Definately not the front screws on the chain case - unwound them and "Tap" still there

Tap still there when rocker box inspection covers are off

Roadrocket
Title: Re: In dire need of divine inspiration
Post by: MG on 18.04. 2011 14:56
The timing gears, expecially when mixed up from unmatched sets, can produce some sort of "clicking" noise (backlash in the gears).
Title: Re: In dire need of divine inspiration
Post by: dpaddock on 18.04. 2011 16:04
Put the bike up on its center stand and rotate the engine via the rear wheel in 4th gear. If you have a helper, you can easily observe the valve action. A sticking valve is a prime suspect as posted by Bill and can be readily seen in this way. This method will also eliminate kickstarter noise from the list of suspects.

David
Title: Re: In dire need of divine inspiration
Post by: RichardL on 18.04. 2011 17:40
649,

MAYBE, take a look at this thread,

http://www.a7a10.net/forum/index.php/topic,3619.msg24950.html#msg24950

where our member Anji, in India, was having some valve noise. Don't know if yours is similar, but there is a lengthy discussion. Have you isolated the geography from whence the noise comes from by using a noise probe? Hopefully, not seen as self serving, I mentioned this in a post here (not like I am the only one to bring this up or use this technique):

http://www.a7a10.net/forum/index.php/topic,3619.msg24772.html#msg24772

Regards,

Richard L.
 
Title: Re: In dire need of divine inspiration
Post by: muskrat on 18.04. 2011 20:38
G'day Roadrocket649,
                             I'm with MG on this. Both mine do it. When winding over slowly there is a spot where the pressure of the valve springs force the cam backwards and takes up back lash in the gears. Once it's running it doesn't happen.
Cheers
Title: Re: In dire need of divine inspiration
Post by: MG on 18.04. 2011 21:05
I've just had another thought:

Did the full rebuild maybe include new conrod bolts and nuts?
I've recently rebuilt a bottom end with original rods and an ARP-made bolt and nut set (supplied by SRM). Unlike the older version they used to sell (supposedly for Triumph rods?), those bolts they are selling now are of the correct length and everything fitted perfectly well, but after assembly of the cases, I noticed that the nuts are slightly longer than the original ones and would hit the t/side crankcase around BDC!!!  *surpr*
A small chamfer on the nuts cured this. The new nuts have the hex over their full length, while the old ones had the smaller diameter locking ring on top, that's where the problem comes from.
 
I have reported that to SRM, and they promised to include a note to future sales. According to their workshop guys, this seems to happen on SOME, but not all cases, probably depending on wall thickness or something. Anyway, if it would just very slightly interfere, it could cause quite some noise without much resistance when turning the engine over.
Title: Re: In dire need of divine inspiration
Post by: Roadrocket649 on 19.04. 2011 09:54
Hi Guys

Thanks for all the suggestions

Hi dpaddock, I put it in fourth, and turned the wheel, and the "tap" is still there so it is not the Kickstarter

I am waiting to get a friend to turn the wheel while I watch the valve action

Hi Muskrat & MG, the timing gears have not been changed and are the originals (as far as I am aware)

I will ask a stupid question here, how can you tell it is backlash in the gears, I suppose you have to take a chance and put it together and try it? (I would love it to be that)
The camshaft is a new SRM "spitfire " camshaft

Roadrocket 649
Title: Re: In dire need of divine inspiration
Post by: Roadrocket649 on 19.04. 2011 10:01
Hi Manosound, I have read the thread you mentioned.

I have squirted oil along the rocker gear, and it is still there ( the oil pump has been re-built with new SRM parts)

The valves and valve guides are new

I have used your sound technique previously ( my father used to use a wooden headed screwdriver, but I was unable to turn the wheel and listen at the same time)

When my helper turns up, I will definately try it

Cheers

Roadrocket

Title: Re: In dire need of divine inspiration
Post by: muskrat on 19.04. 2011 10:09
Hay MG, great minds think alike. I thought about it today at work. I had a similar problem when I put a LJ crank in the '57 cases. But in my case the crank stopped when the nuts hit.
I'll still put my money on the back lash. The sound will be a "click, clock" coming from the timing side. To test wrap a bit of teflon (plumbers) tape around the idler pinion and turn the motor over. The sound will disapear or quieten.
Cheers
Title: Re: In dire need of divine inspiration
Post by: Mosin on 19.04. 2011 12:56
Just a random thought, but are you certain that the tops of all of the pushrods definitely seated correctly in the cups on the rocker arms? IF one were resting on the edge of the cup and you had set the clearance with it like that, you may experience a click as it dropped down into the cup and then came out again as you continue to rotate the engine...

With regard to locating the problem, I have always found the sense of 'touch' to be more effective than the sense of 'hearing' in these cases. It is perfectly possible to remove the tappet covers and place the tip of a finger on each pushrod in turn whilst rotating the engine on the kickstart You should then be able to 'feel' as well as hear the click as it occurs which will at least let you know exactly where it is coming from.

I have always found this to be an effective method, And incidentally, yes, I do still have all my digits intact!
Title: Re: In dire need of divine inspiration
Post by: Goldy on 19.04. 2011 17:29
I had a similar noise and it was one of the pushrods binding on the pushrod tunnel. When I dismantled I could see the mark on the push rod. They were alloy pushrods and I changed them for steel. All the best.
Title: Re: In dire need of divine inspiration
Post by: Roadrocket649 on 20.04. 2011 11:44
Hi Guys

The "tap" appears to be when the Right Hand Side Exhaust valve is closing, although I can see no sign of a valve sticking.
Hi MG/ Muskrat, before I remove the Timing case, would the "tap" not be on every valve if it was idle gear / backlash, as opposed to just one "tap" with every four valve movements?

Hi Goldy, the bike did have four alloy barrel push rods in I got it
When I first took the head off 20 years ago, one was badly abraided to the depth of about 3mm
Definately rubbing against the channel
The others were OK
I changed that one for a steel push rod, and replaced them all in that order.
When I too the head off 10 years later, there was no further abrasion on the other three.

Cheers

Roadrocket649
Title: Re: In dire need of divine inspiration
Post by: bsa-bill on 20.04. 2011 16:27
Hi again 649.
If you take out the spark plugs ( already out I bet ) and then remove completely the tappet adjuster for the right hand exhaust valve, fix the pushrod clear so it can't get into trouble while you kick the engine over, this would eliminate the valve or the click.
Funny thing it was the right hand ex valve that was sticking on mine *spider* (remember the Bruce)
Title: Re: In dire need of divine inspiration
Post by: Roadrocket649 on 20.04. 2011 17:39
Hi BSA-BIll

Good thoughts
I have screwed down the tappet so there was no clearance
Result: "Tap" still there
So I screwed down all the tappets so there were no clearances
Result: "Tap" still there

Looks like the Timing Chain cover and the inner cover will both have to come off

Cheers

Roadrocket649
Title: Re: In dire need of divine inspiration
Post by: Jim on 20.04. 2011 18:52
Hi Roadrocket 649

You say that the cam is new. I recently had a bottom end rebuilt with a new spitfire cam (not from SRM) and the cam lobes were not spaced properly meaning that one lobe was trying to lift two followers, I had to grind it back in the end. Could it be the edge of the cam lobe clipping something? *eek*
Title: Re: In dire need of divine inspiration
Post by: bsa-bill on 20.04. 2011 19:11
Quote
I have screwed down the tappet so there was no clearance

Not what I meant exactly, no take the adjuster out altogether so that the valve does not move, then if the click is still there it's definitely NOT the valve
Title: Re: In dire need of divine inspiration
Post by: chaterlea25 on 21.04. 2011 00:57
Hi All
Jim may be onto something !!
If the camshaft gear is not fittd correctly and the gear is not fully home the cam can move inwards and catch on neighbouring followers *eek*

HTH
John O R
Title: Re: In dire need of divine inspiration
Post by: Roadrocket649 on 04.07. 2011 09:36
Hi Guys

Just an up date on the saga

Where I last left you, on the ever continuous story of the mysterious ?tap?, seemingly  from one of the valves, that occurred when I rotated the re-built engine over, either with kick start or in 4th gear & turning the back wheel

I had screwed down the tappets so they connected with the valve heads to eliminate excessive clearance some of the guys had suggested may have been the problem, and still had the mysterious tap ? so it was not the tappets and clearances ? I thought

Feeling positively dejected, and visualising the engine casings coming back off, I went down the pub, and consoled myself with a few beers.

Got up next morning, said try one last time and went and turned the engine over with the back wheel whilst in 4th gear ? tap still there

I thought I would just re-check the tappets were fully turned down, and found a bit of clearance on the LHS inlet valve ? screwed it down

The ?tap? was now only one in eight valve openings instead of one in 4

Checked again and found I could turn the RHS down very slightly
-   noise gone completely

I reset the tappets to correct clearance ? no noise!

Engine completed

It turned over 2nd kick, and runs beautifully ? sounds great!!!!!!!!!!!!

The engine re-build included a new camshaft, and new cam followers.

The toolmaker from the WSBSAOC that re-built the engine told me that he had had to grind the cam followers to get them to locate in their position. Whether this was part of the problem, or what I do not know

All I can say, is many thanks to all who helped me through this situation

Kindest Regards

Roadrocket649




Title: Re: In dire need of divine inspiration
Post by: A10Boy on 04.07. 2011 17:05
I love a happy ending. Well done.
Title: Re: In dire need of divine inspiration
Post by: Mosin on 04.07. 2011 22:02
Now is the moment to try and store the memory of how good it feels when a problem is easily solved... Just so that you can remind yourself that not everything is always bad next time you strip a thread in an inaccessible place!  *smile* *smile* *smile*