Author Topic: conrod bolts  (Read 2302 times)

Offline chaterlea25

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 3253
  • Karma: 47
Re: conrod bolts
« Reply #15 on: 27.05. 2016 21:55 »
Hi Bill,
The bolts should stretch when tightened and return to original length when undone
Theres a sequence to tightening the ARP bolts, measure, tighten measure, release measure and so on
THe ARP bolts have a different torque setting to the BSA bolts, different thread pitch is one reason
From memory 28ftlbs when used in BSA rods?????
The stretch achieved is more important than the actual torque figure

John


1961 Super Rocket
1963 RGS (ongoing)

Offline edboy

  • Valued Contributor
  • ****
  • Join Date: Oct 2012
  • Posts: 434
  • Karma: 3
Re: conrod bolts
« Reply #16 on: 28.05. 2016 21:33 »
the point i was trying to make was that conrod bolts should be free to move in the conrod and not bind. if not carefull the rod will settle and you could end up with a loose bolt after milage. whatever torque you choose the rod must be free and in my opinion care over the rods is the most important part of the rebuild

Online bsa-bill

  • Wise & Enlightened
  • *
  • Join Date: Mar 2006
  • Posts: 5454
  • Karma: 62
Re: conrod bolts
« Reply #17 on: 28.05. 2016 21:44 »
Quote
The bolts should stretch when tightened and return to original length when undone

Cheers John - that's the bit I wondered about, I used bolts from a certain BSA expert (who may be here) they were made to his spec and torque was a bit higher than 22 and taken up to torque/stretch  three times, I wondered if after constant use they perhaps settled at full stretch
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online Triton Thrasher

  • Scotland
  • Wise & Enlightened
  • *
  • Join Date: Feb 2009
  • Posts: 1504
  • Karma: 20
Re: conrod bolts
« Reply #18 on: 28.05. 2016 23:27 »
Renewing the bolts was good practice when you could get original bolts.

Replacing originals with inferior bolts is bad practice.

Offline Tomcat

  • Valued Contributor
  • ****
  • Join Date: May 2011
  • Posts: 398
  • Karma: 2
Re: conrod bolts
« Reply #19 on: 29.05. 2016 07:28 »
Lots of relevant points to consider Olev. Here's my 20c worth, I'm an ex mechanic and have done a lot of 'Rings and Bearings' on cars and trucks. On all of these I have re-used the con rod bolts and nuts, with only one conrod ventilating the block, the cause of this was extreme revs not the re used bolts! None of the engines I rebuilt were performance engines so there was little need to go overboard like say, a drag race engine.
 As previously mentioned your bolts may have been re used many times over the last 50 years, so in this case new bolts and nuts are a good idea. When I rebuilt my YA7 engine 10 years ago I bought NOS bolts & nuts as I don't wish to see the inside of the engine again. Cheers Tomcat
'48 A7 '59 SR '74 850 Commando TDM900