The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Roadrocket649 on 30.03. 2011 12:16
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Can anyone help!
I am pulling what little hair I have out!!!
I am re-assembling a 1958 A10 Super Rocket, which has a 67-1549 cylinder head, and the one piece rocker box cover
I have tried everyway to come at positioning the rocker box, (front, back, &sides but the stud from the rear rocker box cover is constantly hitting the top of the frame, and stopping postioning over the holes, so the studs cannot be inserted in the holes in the cylinder head
I have the BSA service tool push rod holder to assist
I performed this operaton 20 years ago without a problem, which seems to imply the engine is higher in the frame, but I cannot see how that is possible
Everything from the bottom up appears OK
Anyone any ideas??????????
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In my doing this, I found the only way I could get it done was to remove the one offending rocker cover stud and reinstall it after the box is in place.
Richahard L.
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G'day,
I had that problem when I converted the cafe from A7 to A10 (taller barrels). I found that by twisting the rocker box to clear that stud and frame I could get one rear stud just started in it's hole and then by lifting the front a little could twist it back to get the other rear stud in it's hole, then lower the front. I've done it that often I don't even think about it now.
If all that fails, Richards method is easier.
Cheers
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Hi we just had the same problem last week,only way to do it,is unscrew stud,move the rocker over into position,and rescrew stud in.-strange but true.
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Removing one (or both ) of the rear studs helps, but it can be done whilst they are in place.
It also helps to tuern the engine over, until the tallest (exhaust) pushrods are both at their lowest points (cam lobes at bottom).
This results in more precious clearance.
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Yes remove the studs then it,s easy. Also when fitting have a good torch and dentist mirror handy. Using the torch from the rear of the engine you will be able to see the engagement of the exhaust rockers into the pushrods and using the dentist mirror and torch you will be able to see the inlet rocker and pushrods. It helps if you have three hands. All the best.
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Yep, torch ("flashlight" in my neck of the woods, but that is sylablicly inefficent, though, never sets the engine ablaze if one should get it confused with the propane-fired variety) and dentists' mirror is what I do. I know Muskrat (aka, "Ondatra zibethicus") must have great skill at this, but all that twisting with the gasket sealer in place bodes to be messy when the likes of myself is doing the twisting.
Richard L
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Hi Roadrocket649 and welcome to the (fit an alloy head and increase your vocabulary overnight club)
It's the rear top centre stud that is the problem as you now know, recommended strategy is to remove the stud from the box, fit rocker box then screw the nut onto the stud using loctite and let it set before refitting the stud.
Don't go daft tightening it up, thereafter any time you have to remove the Rockerbox the stud should come out with the nut
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Or, if some liberty re the purity of appearance is OK, remove and replace that stud with a 1/4-20 X 3/4 UNC socket head cap screw upon reassembly. I've done this with all four studs and it looks fine to me.
David
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Hi Guys
Thank You all for your comments
I did not remove the rocker box cover stud as it had a crack which looks like its ben there since the rocker box was built
I will remove the lower studs as suggested.
I suppose the problem will be tring to ascertain where the screw should be loctited to - although, I suspect the stud will have a mark
Once again many thanks to you all
Roadrocket 649
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From BSA Service Sheet No. 204 -
"On 650 cc models it is necessary to remove the top stud for the rear inspection cover and flats are formed on the stud for this purpose. The box can now be lifted clear of the cylinder head."
David
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David,
What a great archival find. One interesting question would be: Does anyone still have the stud with the flats?
Richard L.
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Yes, I got it on the Flash. When rebuilding the bike, I was wondering why someone would bother to machine flats on that stud. I soon found out when fitting the rockerbox on the engine in the frame... (although I can wiggle it on with the stud still in place as well, but removing it makes it much easier).
I can't remember the actual size of the flats, but I think it was one of those tiny BA spanners that fitted.
Another nice little feature for the rivet counters to look for *lol*
Cheers, Markus
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I just had to check. Yep 1 off 67-343 and 7 off 67-280. Got 4 box's but no 343. 3 might be A7 but one is the over stamped SR box.
Cheers