The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: 0116harley on 14.12. 2011 20:41

Title: cylinder head
Post by: 0116harley on 14.12. 2011 20:41
Hi all
Need a bit of advice on this one, ive got a cylinder head i want to fit on my A10.The problem is there are some deep marks which looks like someones had a go with a file, the deepest mark is at a guess about 15 tho deep.Asked at the local motorcycle shop about this they suggested to use a metal glue.Not sure about this.               cheers neil
Title: Re: cylinder head
Post by: Beezageezauk on 14.12. 2011 21:04
Yes Neil,

It's sometimes referred to as Plastic Metal.  Apply it like putty and after it sets you can file it to shape.

The instructions often say that it can be drilled and tapped but I've never been brave enough to go that far with it.

Read the instructions before you buy it and satisfy yourself that it's fit for purpose.

Beezageezauk.
Title: Re: cylinder head
Post by: wilko on 14.12. 2011 21:20
J B weld is your friend, nothing else will do!
Title: Re: cylinder head
Post by: t20racerman on 14.12. 2011 21:25
Alternatively, strip the head and get 15 thou skimmed off the head surfaces.
Also, don't use bought in gaskets as they all seem to be rubbish - buy some 0.8mm gasket paper and cut your own. Make them a bit wide and trim to size after assembly with a sharp blade.
Title: Re: cylinder head
Post by: bsa-bill on 14.12. 2011 23:33
Quote
Also, don't use bought in gaskets as they all seem to be rubbish - buy some 0.8mm gasket paper and cut your own

Yep, I totally agree with that
Title: Re: cylinder head
Post by: 0116harley on 15.12. 2011 20:58
Thanks for the advice guys. Think i'll get the surfaces skimmed seems more of a permanent fix
cheers neil
Title: Re: cylinder head
Post by: RichardL on 15.12. 2011 23:20
Unless you are worried that you might not be judged a 94 at the next Concours d' Elegance, in my opinion the skimming isn't worth what it's going to cost. After all,  the objective is to hold in the oil, and JB weld would serve that purpose. Hell, maybe even a thick slather of Permatex would do. Back to the JB Weld, it's black and should not show up on the painted cast iron head. Anyway, unless you do the vibration-damped head steady (described elsewhere on the forum) , chances are you'll leak a little anyway. Finally,  maybe you won't have to remove the valves.

Richard L.
Title: Re: cylinder head
Post by: chilblayth on 15.12. 2011 23:32
yes  i agree !  jb weld or similar will be fine i think , i remember a head repair on an xt500 where someone had been porting overenthusiastically and gone through into rocker area , oil was being sucked into the inlet port !!!!!!    looked like a james bond smokemaker  *smiley4*     turned up a alloy base plate secured it with ARALDITE    and it was perfect  *smile*    these modern epoxy adhesives are really  good  *ex*
Title: Re: cylinder head
Post by: BSA_54A10 on 16.12. 2011 11:37
The magic goop is Davcon.
It was designed for temporary repairs in places like ship engines and mining equipment.
Not cheap but works perfectly.
I have used epoxy putty sold as a radiator repair for fixing holes in crankcases for years and it works very well .
SR500's have a bad habit of popping the brake lever toe through the case if they fall over.
I had one repair last for 11 years of abuse as a courier bike.
Title: Re: cylinder head
Post by: beezermacc on 18.12. 2011 18:30
I definitely would not skim the top of the head. This will alter the angle of attack between the rocker arm and the valve stem. It may not make a lot of difference but its surprising how one thing leads to another.........
Title: Re: cylinder head
Post by: muskrat on 18.12. 2011 19:09
 G'day all,
             JBWeld would be my choice. But if you do remove the guides to skim the head I'd be replacing them as well. And the amount taken off the head and/or box can be compensated by using a thicker copper gasket from Lanni. http://www.coppergaskets.us/MCExamples.html
Cheers
Title: Re: cylinder head
Post by: bsa-bill on 18.12. 2011 19:41
Well it will do that to some degree right enough beezermacc, as will using thicker gaskets, a compression plate, skimming the other side of the head and changing the camshaft or using reground followers.

Going off at a tangent here but thinking about compression plate (surely that should be decompression plate) will it have the effect of softening the cam
Title: Re: cylinder head
Post by: 0116harley on 18.12. 2011 19:54
Thanks for all the feedback on this. Change of plan,never used j b weld or any kind of metal glue before. So i'm gonna give it a go. It does save all the hassle of taken the guides out. Maybe a good idea to wait till the weather warms up. As i should imagine this stuff dont work that well in freezing conditions. And the wifes getting fed up of bike bits in the house (women i'll never understand them).
cheers neil  *smile*
Title: Re: cylinder head
Post by: rockthedog on 26.12. 2011 16:17
yes jb weld did it for me been ok for last 5 years now *smile*
Title: Re: cylinder head
Post by: RichardL on 26.12. 2011 18:15
Neil,

Test a small amount (say 1/2 teaspoon) of the JB Weld on a piece of cardboard set to cure outdoors. Being a two-part filler, low temperature should not prevent curing, just make it take a long time, but probabaly a lot shorter than waiting for the weather to change. The manufactturer suggests a heat lamp to speed things up.

Richard L.
Title: Re: cylinder head
Post by: 0116harley on 26.12. 2011 20:23
Hi everyone back to work on the bike soon. Im gonna make my own rocker cover gaskets as suggested, Is it a good idea to use a gasket sealent as well, as i find no matter how hard i try these always tend to leak a small amount of oil from the covers
cheers neil
Title: Re: cylinder head
Post by: RichardL on 26.12. 2011 22:23
Neil,

Some info here about leaks at the rockerbox joint and a clever way to avoid them.


http://www.a7a10.net/forum/index.php/topic,2912.msg19879.html#msg19879

Richard L.
Title: Re: cylinder head
Post by: berger on 08.04. 2020 20:15
well you bsa chaps while I have had lots of time to do things I have lightened two inlet rockers this afternoon for the berger build,  weighed at 95.2 and 91.2 g they are now 82 and 80.3g , I don't want to take any more off. musky or any of you racer chaps out there has this been worth doing and is there enough weight  been taken off, any way to the point about rocker arm angle, I took the covers off betsy the beezer to check clearances and then discovered this thread *computer*. I looked at the inlets and one valve was open , the adjuster tappet screws nearly fully out and the angle shocked me *pull hair out* I looked at the exhausts and adjusters about right in the middle and open / closed angle ok. the bike runs fine --- well it will it's a beezer. then the penny dropped, the barrel has been skimmed the two faces of the head and the rocker box, if only I had had a computer years ago I would have been edumacated on this topic. I just wondered why it doesn't really effect the exhausts as such, is it because they are longer arms and the inlets are little stumpy's *dunno* thick me *bash*
Title: Re: cylinder head
Post by: muskrat on 08.04. 2020 21:02
G'day berger.
At half lift of the valve the adjuster should be dead in line with the valve stem. If one adjuster is out along way compared to the other it could be the pushrod is sitting on the edge of the cup.
Cheers
Title: Re: cylinder head
Post by: berger on 08.04. 2020 22:50
hello musky built it back up in a hurry a couple of years ago ,  they are both in the cups, done lots of miles like this and I just looked again and took a feeler to the rocker arm and I can't get a 2thou between spring keeper and rocker arm even though I can set tappet clearance .rocker is possibly just interfering with keeper, this is the result of losing about 45 thou from top of barrel all the way to the rocker box  [ be warned *problem* ]. or I have picked up a couple of longer push rods not realising when in that rush to get it done *bash*  it has to come OFF!!! *pull hair out* *pull hair out* if I find the push rods are proper it has to be the vast  skimming in which case I will be making a thick copper gasket set for it *work* but why are the exhausts perfect *conf2* I will find out tomorrow, ps is  10 or 12g off rockers about right or is more lightning needed.
Title: Re: cylinder head
Post by: berger on 09.04. 2020 12:22
just before I attack this rocker box here is a piccy of inlet valve, I am still on my old phone so piccy isn't too good but you can see how close rocker arm is to valve spring keeper, you can just blow air through the gap I tried my new phone for this but I need to drastically reduce and I haven't mastered that yet, thick me *computer*. following is a picky of the exhaust which is normal, I haven't mastered putting more than one piccy in the same thread sorry, thick me *computer*
Title: Re: cylinder head
Post by: berger on 09.04. 2020 12:24
exhaust which appears normal investigation needed me thinks *work*
Title: Re: cylinder head
Post by: RDfella on 09.04. 2020 12:36
Is the valve seat badly recessed? That's let the valve stem come higher and have same effect as a too-long pushrod. Arm is only close to collar because tappet adjustment is almost right out.
Title: Re: cylinder head
Post by: berger on 09.04. 2020 14:49
RD fella I thought about valves aswell, i'm trying to scratch my brain cell as to how it was after I built it up from scratch when I had oil pipes on wrong and this latest time when I just did top end in a desperate hurry after it locked up coming away from bulldog bash, I am on it now and who can tell me the difference between rocker spindle thrust washers 67-60 six of and 67-61 two of is it the thickness because I have just measured some spares and there isn't a definite conclusion  cheers
Title: Re: cylinder head
Post by: berger on 09.04. 2020 17:36
think I have it, I rebuilt it the last time with four push rods that came with loads of bsa bits saving mine for the berger build. the inlet tappets have taken a bit of a hammering *bash* I will change those, and the valves have survived. so this is what I have found all valves sit in the head with only 5 to 10 thou difference in the height of the top of the stems.  the inlet push rods I fitted are 8 and 1/8th long . the ones I had in for years are 8 and1/16th. the reason the exhausts looked ok is because those push rods were just 9 inch, my old ones are 9 and 1/16th, the bit longer inlet push rods plus about 3/64ths taken from all surfaces of barrel / head etc has combined to create this problem *problem* now I think I will have a cuppa tea and stop scratching my brain cell. I live and learn again ,
Title: Re: cylinder head
Post by: Swarfcut on 09.04. 2020 19:19
Bergs. Yes, no, maybe.....

 In my archives I have          A7        Inlet  Push rod   8 1/16"         Exhaust Push rod     9"

                                          A10       Inlet                8 1/2"           Exhaust                 9  1/2"


 See how this stacks up with official published data and what you actually have.

 Swarfy.
Title: Re: cylinder head
Post by: berger on 09.04. 2020 19:55
swarfy one thing for sure my old inlets are correct and I will put the 9" exhausts in , very strange the other sizes , the exhausts at 9/1/16th have been in and never changed while I have owned the bike up until I changed all 4  saving mine for the berger build, its a mystery to me but I am pretty sure my original inlets will sort the job, I will find out in the coming days cheers
Title: Re: cylinder head
Post by: berger on 13.04. 2020 20:01
said I was thick , lost the plot somewhere. it hit me straight away when building up the two rocker boxes regarding the spindle washers *doh* two are smaller hole size *red* , amazing what you forget when the pubs more important *beer* . so now I have the berger build box done and have also got the lovely jubly home made gaskets fixed to the underside of the rocker box that is going on tomorrow with the old CORRECT push rods, and of course two different tappets because the others were a bit fed up, after being at the wrong angle. still confused as why the push rods I had put in were 8/1/8th inlet and 9/1/6th exhaust *conf2*
Title: Re: cylinder head
Post by: berger on 14.04. 2020 19:05
betsy has now got her lid on *yeah* the photo just about shows the difference 1/16th of an inch makes on push rod length regarding angle of inlet rocker, on a previous post I could only get fresh air through the gap of rocker arm and spring keeper and found it had made a mess of the two tappets - valve tops were ok they must be well ard *bash*.I have learnt a lot with putting in what I thought were A7 push rods on the previous top end build.
Title: Re: cylinder head
Post by: Rex on 15.04. 2020 09:29
Five minute job on a mill. Goop of some sort may work but doing it properly will last forever.
Title: Re: cylinder head
Post by: Swarfcut on 02.07. 2020 11:22
Bergs Hits the Jackpot!!!!

  Building up a rocker box for my Plungy, noticed that the rocker spindle oil feed ends were being drawn below the level of the casting face when the acorn nuts were tightened. With the spindles located correctly, so the spindle annular oilway to the rocker  coincided with the oil hole on the underside of the rocker, there was a definite gap between the casting and the shoulder at the threaded acorn nut end of the spindle, like space for a washer.

  My early parts book indicates all the plain washers are the same, but later '54-'57 edition shows a pair of 67-0061's to be a different washer fitted at the Acorn Nut end of each spindle. This will bottom against the inner face of the casting and prevent the spindle being drawn too far  towards the timing side. I reckon I have never seen different washers on this bike, just a set of 8 big hole washers. So looks as if I have a pair of small hole washers missing, and big hole standard washers in their place. Drags catalogue confirms the ones required  as being "Small Hole".

 With a small holed washer added, the acorn nut will draw the shaft to its correct position...... and may solve the problems of the leaking banjos for some of you folks, and worth checking you have small holed washers here  next time the top comes off.  It's one aspect of the rocker gear we take for granted, but as these bikes have been through hell in some cases, assembly mistakes and mis-matched parts are an answer for some of the strange faults experienced.


   Without them the spindle will move further into the rockerbox, displacing the drive side thrust washers tighter against the rockers, which ain't so good, as well as removing some of the positive location for the banjo/rockerbox sealing washer.  There is also the possibility of the rocker spindle rotating slightly as without being pulled hard against the casting by the acorn nut, it is just suspended between two threads, rather than being positively located and clamped tightly in place.

 So searching for information came across berg's note above, and that helped me find the answer.

 Thanks bergs.

 Swarfy.

 


Title: Re: cylinder head
Post by: terryg on 02.07. 2020 12:43
Useful information indeed. I’ve often wondered why there was no hard stop when tightening the acorn nuts.
I’ll know what to look for next time.
Title: Re: cylinder head
Post by: berger on 02.07. 2020 13:25
cheers swarfy, I knew I might be useful for something . I also found that the spring washer next to the small washer can be a bit of a pillock and trap itself on the shaft not letting the shaft pull fully home to the small bore washer, a bit of screw driver pokery was needed to make sure everything was in situ. oh and a bit of what's up with this ******* thing NOW!!!