The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: jachenbach on 25.05. 2015 13:53

Title: Head/rocker box problems/questions
Post by: jachenbach on 25.05. 2015 13:53
So, I've got my pistons/cylinders mounted up and yesterday installed head/rockerbox and huh???????????? Background- A10 engine, no numbers, alloy head, partially disassembled when purchased with a pickup truck load of parts. Anyway..... No problem installing head, though I couldn't find a torque value in my Haynes manual. Somehow, thought I'd read 22 lb/ft, so that's what she's at unless someone here knows different.
   Fitting the rocker box was a pain. Not getting the pushrods in the cups, just used a hook and managed that. Fitting it between frame and valve springs. I had to grind off the taper in the stud ends and file just a hair off the top rear cover boss, and at that still scraped paint from frame tube (no big deal). So I assume I have the longer studs I've read about here on the forum. My parts lists from '54 to '63 don't show the nuts for the rocker box studs, except for A7S/S, which shows long sleeve nuts for the rear studs. Looks like what I should use on the A10 as well?
   The head will probably need to come back off. I had disassembled to inspect valve seats and faces, measure guides etc. and all seemed good, but with rocker box on, my rocker adjuster screws to valve clearances are a mess. The right intake is backed all the way out, to where the valve stem may be contacting the rocker rather than the screw, while another (can't remember which) had to be screwed in quite a ways and the other two seem about normal. There was no apparent valve recession in the head, but that was just an eyeball judgement. I'll get down to the shop after I walk the dogs and look at the rocker/valve angles to try to figure out if the problem is in the head or the rocker box before I pull the head back off. Looking at parts books and several rocker boxes and rockers I have, I don't see that there were any variants that should cause a problem. Any other ideas what may be going on?
Title: Re: Head/rocker box problems/questions
Post by: muskrat on 25.05. 2015 14:09
G'day jachenback. The top rear cover stud should have flats on it so it can be removed to get the box on easier. The problem pushrod isn't in it's cup properly. Yes you need the long nuts *eek*.
Title: Re: Head/rocker box problems/questions
Post by: bsa-bill on 25.05. 2015 15:15
Had my box off the Flash several times lately (iron head tho) there is a certain way to put the box on that does make it easier, difficult to explain tho, but approached the head from the drive side, inlet end first diagonal, not quite 180 degrees, so the central web on the inlet side dissects the pushrods so you have two on each side then twist it clockwise to it's intended position then drop it down .
my fingers are just long and slim  enough to feel the rocker caps so can verify the pushrods are in them, I agree with you jachenbach about the hook, by far the best way that I've found
Title: Re: Head/rocker box problems/questions
Post by: jachenbach on 26.05. 2015 00:49
Thanks fellas. Right again, Muskie. Found 2 needed sleeve nuts, got it all on nice and neat, installed head steady and adjusted valves.
Went ahead and temporarily mounted the siamese pipes and lightly hung the carb and drip tray(?) just to see how it'd look. She's getting pretty!