I’ve got a couple of ‘pre-owned’ conrods for my Domi 99 rebuild to replace the battered ones I took out of the engine. The ‘new’ ones are in good used condition but the casting webs on the sides of the I-beam section of each are quite rough - almost like horizontal grinding marks. Should I remove the marks to make the areas smooth? Also, how much polishing should I do to the rest of the conrod surface - I’ve never been sure of that.
I polish so it shines like an outer cover except in the depression where it's a bit difficult to get the polishing wheel in, prep by removing butts and casting flash.
If not, then personally I wouldn't bother. Only really necessary in high stress (high revs) situations. Worst time for a rod is an early downshift when braking going to very high revs with a closed throttle. (No compression to load/slow down the pistons at tdc).
Then again, if you want to keep up with R1's and Fireplaces you might need to get them shining like a mirror!
Thanks for the replies. I’m not intending any racing, just plodding around the local roads with the odd motorway run. So it sounds like I’d be wasting my time trying to get the rods super-smooth. I’ll save my polishing elbow grease for the timing and gearbox covers.
You need to polish, or file out then polish, any nicks so it's always worth putting the rods against your buffing wheel if the rods are old like us! Even if you are only "plodding" you might as well polish them as not. you know it makes sense with old nails like ours!
Hello Well I would say get them clean first get out any nicks and marks but I do not polish rods clean then and smooth them out with fine stainless wire wool then clean them again then wipe clean oil on them before fitting make sure you have the correct shells fitted and there the right way around As some shells have oil holes IE SIX START OIL PUMP, and some have NO OIL HOLE IE 3 Start Oil Pump . and this includes 650 and early 750 engines from bracebridge street have No oil holes, now all Plumbstead Engines have oil hole after September 1963, so do your research on your engine and Do keep all internal parts very clean before fitting and make sure there is No grit or Filings anywhere before fitting any parts Clean Clean every where Yours Anna J
If you can afford it, buy some new rods from Thunder Engineering. They are polished to a level whereby they look to be chrome plated. Top class engineering in every respect.