The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: SimonHolyfield on 10.01. 2019 12:13

Title: Engine Tolerances
Post by: SimonHolyfield on 10.01. 2019 12:13
Chaps,

I've completed the teardown of my 1955 Ariel FH engine, which will be rebuilt into its original 1958 form with the help of a new crank & flywheel, purchased with the help of this very forum.

Whats the best place to find the dimensions & tolerances I need for inspection?
Title: Re: Engine Tolerances
Post by: chaterlea25 on 10.01. 2019 16:33
Hi Simon,
The data you need is in the BSA service sheets,    https://www.bsa-oc.com/en/service-sheets-2/

https://www.bsa-oc.com/wp-content/uploads/bsk-pdf-manager/58_SECTIONA_BSASERVICESHEETNO216.PDF

https://www.bsa-oc.com/wp-content/uploads/bsk-pdf-manager/63_SECTIONX_BSASERVICESHEETNO702.PDF


John
Title: Re: Engine Tolerances
Post by: Greybeard on 10.01. 2019 16:37
If the FH is mechanically the same as the A10, and I believe it is, then this may also be useful: http://www.bsawiki.com/
Title: Re: Engine Tolerances
Post by: SimonHolyfield on 10.01. 2019 17:50
If the FH is mechanically the same as the A10, and I believe it is, then this may also be useful: http://www.bsawiki.com/

It is, though the FH doesn't keep pace with the A10 upgrades - it never got the thick flange barrel, for example. Until BSA gave all the A10's the large journal crank in 1958, you can think of the FH as a Gold Flash spec engine with different castings - the head, barrel, timing cases and even crankcases (I think) are different - though the crankcase may just be machined differently for the Ariel primary drive.

Anyway - many, many thanks for your help Gentlemen.

As you can see from the attached image, today I have been removing sludge trap plugs!
Title: Re: Engine Tolerances
Post by: Swarfcut on 10.01. 2019 18:16
 Simon... That is a class act, caught just in time and with the main bearing location on the flywheel cheek untouched  from new.

    YOU LUCKY MAN!!!!!

  Swarfy.
Title: Re: Engine Tolerances
Post by: Greybeard on 10.01. 2019 20:23
Quote

As you can see from the attached image, today I have been removing sludge trap plugs!
Now that looks like a great way to get those plugs out!
Title: Re: Engine Tolerances
Post by: SimonHolyfield on 11.01. 2019 08:46
I wrote a bit more here:

http://ariel-square-four.blogspot.com/2019/01/small-journal-crankshaft.html?m=1