1953 / 4 G3LS build

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
Post Reply
SPRIDDLER
Member
Posts: 8548
Joined: Wed Sep 01, 2004 1:00 am
Location: WEST SUSSEX UK

Re: 1953 / 4 G3LS build

Post by SPRIDDLER »

They were very particular at the factory.
Extract below from a very interesting article interviewing the designer of the 1950's AMC 350 engines regarding manufacture and tolerances.....
See here:

http://archives.jampot.dk/editorial/Roa ... _Baker.pdf

Component fit 2.JPG
You do not have the required permissions to view the files attached to this post.
'There is a tide in the affairs of men
Which taken at the flood............'
g80csp11
Member
Posts: 1577
Joined: Mon Jan 01, 1990 12:00 am
Location: WEST SUSSEX UK

Re: 1953 / 4 G3LS build

Post by g80csp11 »

Its common practice with modern engines to grade (measure crankshafts and conrods ) then to selectively fit bearing shells from a range of say 5 grades to obtain the correct clearance , the difference being that on our conrods a outer cage is fitted to the conrod . this is why when you fit a replacement BE assembly you have to 'hone' the outer cage once fitted to obtain the correct running clearance

Id recommend you fit a new BE assembly if you want to use the bike , There are cheaper pattern BE assemblies on the market but we have no experience on there reliability as they are only recently available . If you remember in the 70/80's Alpha tried to change the design and these all failed in service . they had to revert back to the Matchless original design

Id be very upset if I spent all the time rebuilding an engine , only to find the saving a few pounds on the BE made it un ride-able and I had to take it part again

though it pains me to say , sometime you just have to spend the money on the right parts
EddieDay
Member
Posts: 113
Joined: Sun Jul 23, 2023 7:33 pm
Location: Surrey UK
Location: Surrey and Nairobi

Re: 1953 / 4 G3LS build

Post by EddieDay »

Spriddler, thanks for that extract. Interesting that the components are graded in tenths of a thou and then paired accordingly.

Peter, I am sure that you are right that the safest approach is to fit new parts. It is just that £354 just for a crank pin was a bit of a shock and the Club parts store do not stock a conrod liner. I am not yet convinced that it is money well spent if the conrod liner is not new as well.

I have a new set of standard rollers and I am minded to order a set of +0.001" rollers as well. That should give me some leeway to have the crankpin sleeve and conrod liner honed a little. In the end although I am going to use the bike it is not going to compete in anything.
g80csp11
Member
Posts: 1577
Joined: Mon Jan 01, 1990 12:00 am
Location: WEST SUSSEX UK

Re: 1953 / 4 G3LS build

Post by g80csp11 »

the BE assembly comes with the con rod liner (outer race)
ChrisTheChippy
Member
Posts: 275
Joined: Wed Feb 07, 2018 12:02 am
Location: Essex

Re: 1953 / 4 G3LS build

Post by ChrisTheChippy »

Ahh now I see why you can't go down 5 thou . Every days a school day. However your plan of skimming 1 thou off and + 1 rollers is well worth a try as it might clean up . Don't think it will be perfect though definitely worth a try if only for the sake of your wallet!
EddieDay
Member
Posts: 113
Joined: Sun Jul 23, 2023 7:33 pm
Location: Surrey UK
Location: Surrey and Nairobi

Re: 1953 / 4 G3LS build

Post by EddieDay »

g80csp11 wrote: Fri Dec 29, 2023 8:11 pm the BE assembly comes with the con rod liner (outer race)
Oh thanks. It is probably just the photo on the spares web site that is misleading.
User avatar
Pharisee
Member
Posts: 1126
Joined: Tue Mar 15, 2016 8:51 pm
Location: Lincolnshire UK
Contact:

Re: 1953 / 4 G3LS build

Post by Pharisee »

ChrisTheChippy wrote: Fri Dec 29, 2023 10:58 pm Ahh now I see why you can't go down 5 thou . Every days a school day. However your plan of skimming 1 thou off and + 1 rollers is well worth a try as it might clean up . Don't think it will be perfect though definitely worth a try if only for the sake of your wallet!
If you're fitting 1 thou. oversize rollers, you'll need to reduce the crankpin by 2 thou.
I'm from the Fens.... Gimme six.
User avatar
Expat
Member
Posts: 1033
Joined: Thu Nov 12, 2015 2:22 pm
Location: Tennessee, USA

Re: 1953 / 4 G3LS build

Post by Expat »

:thumbup:
Keep shiny side up.

These are my principles, if you don’t like them, I have others. (Groucho Marx)
EddieDay
Member
Posts: 113
Joined: Sun Jul 23, 2023 7:33 pm
Location: Surrey UK
Location: Surrey and Nairobi

Re: 1953 / 4 G3LS build

Post by EddieDay »

Pharisee wrote: Sun Dec 31, 2023 2:46 pm
ChrisTheChippy wrote: Fri Dec 29, 2023 10:58 pm Ahh now I see why you can't go down 5 thou . Every days a school day. However your plan of skimming 1 thou off and + 1 rollers is well worth a try as it might clean up . Don't think it will be perfect though definitely worth a try if only for the sake of your wallet!
If you're fitting 1 thou. oversize rollers, you'll need to reduce the crankpin by 2 thou.
True. 2 thou off the diameter. 1 thou off the radius - a one thou cut. Unless something is skimmed off the conrod liner too!
User avatar
Duncan
Member
Posts: 2127
Joined: Thu Jul 10, 2003 1:00 am
Location: HAMPSHIRE UK

Re: 1953 / 4 G3LS build

Post by Duncan »

EddieDay wrote: Sun Dec 31, 2023 5:26 pm
Pharisee wrote: Sun Dec 31, 2023 2:46 pm
ChrisTheChippy wrote: Fri Dec 29, 2023 10:58 pm Ahh now I see why you can't go down 5 thou . Every days a school day. However your plan of skimming 1 thou off and + 1 rollers is well worth a try as it might clean up . Don't think it will be perfect though definitely worth a try if only for the sake of your wallet!
If you're fitting 1 thou. oversize rollers, you'll need to reduce the crankpin by 2 thou.
True. 2 thou off the diameter. 1 thou off the radius - a one thou cut. Unless something is skimmed off the conrod liner too!
I'm not following this if the roller is 1 thou over, it sits between the crank pin and conrod liner so surely that is 0.5 thou off of each to make the roller fit?
Post Reply