The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Greybeard on 08.04. 2016 20:34

Title: Push rod fun
Post by: Greybeard on 08.04. 2016 20:34
If you ever meet the ghost of whoever designed the rocker box on these bikes will you give him a good kicking please.
Also same applies to the bloke who gave us that crappy comb device!
Title: Re: Push rod fun
Post by: BSA500 on 08.04. 2016 20:51
Add floating cranks to that list please
Title: Re: Push rod fun
Post by: RichardL on 08.04. 2016 21:30
If you ever meet the ghost of whoever designed the rocker box on these bikes will you give him a good kicking please.
Also same applies to the bloke who gave us that crappy comb device!

I just remounted my rocker box with the usual expectation that it was going to be a pain, but it turned out not that bad. The new thing I'm doing (new for me, at least) is to hold the ends of all four rockers in the up position by using rubber bands pulled back to one of the 4 long bolts. This way, once the comb aligns the pushrods with the cups and the box is pushed down, the pushrod ends stay in the cups. I think that's a fair part of the battle. I don't think it is any kind of news that putting gasket sealer on both sides of the Bid-D gasket and sticking it to the box rather than the head limits the schmearing of sealer with the comb.

Richard L.
Title: Re: Push rod fun
Post by: muskrat on 08.04. 2016 22:57
I do the same Richard. As I replace the end thrust springs with shims the rockers flop down. Elastic bands keep them up. the ex rods go straight in, it's the inlets that give problems. A piece of hooked wire helps them into the cup and the elastic bands hold them there.
Cheers
Title: Re: Push rod fun
Post by: Tone on 08.04. 2016 23:09
Oh no lve got that to come, if I can find the blinking comb. *eek*
Title: Re: Push rod fun
Post by: muskrat on 09.04. 2016 08:58
It's not too bad Tone. If I haven't got them in by the 6th beer I come back to it after another 6. *eek*
Cheers
Title: Re: Push rod fun
Post by: Greybeard on 09.04. 2016 17:13
If the comb would stay put it would help. I might try glueing it in place with gasket cement next time.

I thought I had the pushrods and rockers all located but realised that one of the exhaust pushrods was holding up the edge of the rocker cup; loosened off again; got that one sorted only for the other one to do the same thing!! I was trying to hold a torch while also manipulating a hooky wire and rocker arm. SUCH FUN!
Title: Re: Push rod fun
Post by: Rocket Racer on 25.04. 2016 01:30
I concur with Muskey and Richard,
with steel pushrods, I use the comb, with alloy ones I find I don't need it.

take out the plugs and carefully rotate the motor(using backwheel in gear) to check they are seated
Title: Re: Push rod fun
Post by: Rocket Racer on 25.04. 2016 01:40
If you ever meet the ghost of whoever designed the rocker box on these bikes will you give him a good kicking please.
Also same applies to the bloke who gave us that crappy comb device!

In their defence these twin motors designed in the forties were among the earlier enclosed rocker box design twins and better than the comparable triumph (too many bits to leak) and as bad as norton (really fiddly as the rocker box is cast in) . Certainly from the A7/10 came the A50/65 head which is far superior for assembly, so at least BSA learnt something, whereas norton and triumph twin heads were never improved upon due to lack of finances.

Like all these motors, once you've done it a few times you develop strategies to do it.
Title: Re: Push rod fun
Post by: hdawson on 25.04. 2016 08:00
I thought the comb looked dodgy from the start.
I just use a bent coat hanger wire  to manipulate the pushrods into position and don't seem to have any trouble.
Using Peramatex blue (while giving a oil tight seal) I always worry that, when removing it, that swarf may end up somewhere in the guts that may cause trouble.
Should I just use a gasket and put up with a  bit of weep?

Title: Re: Push rod fun
Post by: bsa-bill on 25.04. 2016 09:38
I have longish slim fingers, I can reach in from front and back to place a pushrod.
Now that would lead you'd think to an ability to master a guitar - not yet by a long way
Title: Re: Push rod fun
Post by: mugwump on 25.04. 2016 15:04
I was given an endoscope as a b'day pressie and its one of those gadgets that you wonder how you got by before. I found it comforting to be able to ensure the rods were in their relative cups. And, I find the naturally magnetized end of a screwdriver perfect for lining up the tops of the rods into the rockers. It helps as well to have an Ariel h'master rocker-box!!
Title: Re: Push rod fun
Post by: Greybeard on 25.04. 2016 16:03
It helps as well to have an Ariel h'master rocker-box!!
Well if you are going to cheat I'm not playing!
Title: Re: Push rod fun
Post by: Greybeard on 25.04. 2016 16:05
I have longish slim fingers, I can reach in from front and back to place a pushrod.

Can I ask for your help next time?  *smile*
Title: Re: Push rod fun
Post by: Greybeard on 25.04. 2016 16:07
I can see the benefit of the tip to use rubber bands to hold the adjusters up and the cups down; I just keep forgetting to do it!!  *angry*
Title: Re: Push rod fun
Post by: bikerboy on 30.04. 2016 01:44
To be honest I find no problem with this job whatsoever but I have a friend who does. His solution is quite easy.

He has two long studs that he slips into the rocker box (inlet side) to give him something to push the comb up against.. He then slides the rocker box down the last inch or so with these studs making sure it drops straight down. The comb is in the perfect position (also located on the studs) and they drop in every time.

Unscrews the studs by hand and drop the bolts in their place. He reckons it saves him so much grirf
Title: Re: Push rod fun
Post by: Greybeard on 30.04. 2016 09:03
He has two long studs that he slips into the rocker box (inlet side) to give him something to push the comb up against...
Sounds good; I'll give that idea a go next time.
Title: Re: Push rod fun
Post by: Billybream on 30.04. 2016 19:18
Being so careful today when changing my tappet screws, and they were well worn, got to the last one and yes you guessed it the push rod slipped out of the rocker cup, really felt let I had let myself down, but fortunatey with the help of some bent wire got it back in. So no major drama, started her up after winter lay up, having had the mag overhauled by Priory and fitting SRM clutch cover with top hat and bearing, resulting in two finger clutch operation, so pleased, shame you cannot see this great piece of machining.
Title: Re: Push rod fun
Post by: Gasket4450 on 30.05. 2016 13:05
        I use the two removable threaded rods technique too, and have done for a few years now.  It seems to get easier each time I do it...... each to his own, I suppose.

Norman T
Title: Re: Push rod fun
Post by: RichardL on 30.05. 2016 13:45
I don't get it. Is there some reason you guys don't think the actual rocker-box bolts are studly enough, thus requiring surrogate studs to step in as stops for the comb?  The bolts work fine for me.

Richard L.
Title: Re: Push rod fun
Post by: Gasket4450 on 31.05. 2016 20:28
Richard,
                                I use a couple of threaded brass rods about 5" long for no other reason than their extra length allows me to keep the rocker box right up against the underside of the frame tube while I sort everything else out underneath it, before sliding it down the rods into place. Gives me more room than the rocker box bolts do. Just personal preference, I s'pose...

Norman T
Title: Re: Push rod fun
Post by: TT John on 01.06. 2016 11:52
If you ever meet the ghost of whoever designed the rocker box on these bikes will you give him a good kicking please.
Also same applies to the bloke who gave us that crappy comb device!

I did have success with the comb after seeing a post on the forum somewhere, I think there may have been photo's also, the idea is to bend the comb so that you can clamp it to the cylinder fin with mole grips, it made it so much easier, and with the copper gaskets, this stops all that frustration of the compo gaskets popping out of line, I think the photo's may be on this forum somewhere.

Regards John
Title: Re: Push rod fun
Post by: Greybeard on 01.06. 2016 16:50
...the idea is to bend the comb so that you can clamp it to the cylinder fin with mole grips...
Sounds like a good plan; I'll try that next time. If the comb would stay put it would make a big difference.
Title: Re: Push rod fun
Post by: bsa-bill on 01.06. 2016 18:02
Quote
you can clamp it to the cylinder fin with mole grips..

Sharp intake of breath
Title: Re: Push rod fun
Post by: TT John on 02.06. 2016 10:45
I did see one useful method of getting these in easily, that is with the comb, by bending it (stepped)  so that you get a flat piece on top of the cylinder which you can clamp this with mole wrench, keeps it in place. HTH

Regards TTJohn
Title: Re: Push rod fun
Post by: bsa-bill on 02.06. 2016 10:50
I'd be happy with a screw up clamp for sure but Mole grips or any over centre type clamp on a brittle fin - be very careful
Title: Re: Push rod fun
Post by: nimrod650 on 02.06. 2016 19:11
a magnetic comb to keep it in place  *????* *????*
Title: Re: Push rod fun
Post by: bsa-bill on 02.06. 2016 19:26
great for Flash, not so good on Rockets

Sorry lads I'm fulfilling a long desire to be a damp squid today
Title: Re: Push rod fun
Post by: Greybeard on 02.06. 2016 20:32
great for Flash, not so good on Rockets
Just need an aluminium magnet.
Quote
Sorry lads I'm fulfilling a long desire to be a damp squid today
I think that's damp squib actually   ;)

Title: Re: Push rod fun
Post by: bsa-bill on 02.06. 2016 20:40
Quote
I think that's damp squib actually 

 ;)  I think that's right, but squids are more often damp than not - but lets not carp on about it *smile*
Title: Re: Push rod fun
Post by: cyclobutch on 03.06. 2016 08:49
The fish gags are getting to mi nnow.
Title: Re: Push rod fun
Post by: TT John on 03.06. 2016 10:01
a magnetic comb to keep it in place  *????* *????*

I am not talking about the common mole grips, I was referring to the ones you use when welding etc, with the flat thin jaws.
Title: Re: Push rod fun
Post by: bsa-bill on 03.06. 2016 16:51
Quote
I was referring to the ones you use when welding etc

Oh ok sorry, know the ones you mean, yep mole grips can be confusing referring to a Make really I believe, similar Vice gripe which are actually Vise grips
Title: Re: Push rod fun
Post by: nimrod650 on 03.06. 2016 18:33
great for Flash, not so good on Rockets

Sorry lads I'm fulfilling a long desire to be a damp squid today
two long mild steel studs on alloy head  to use a  magnetic comb that could be made for a few squid shoaly or mussel down  or take a dab and make one in your own plaice and save a few squid but i wont carp on about it any conger