Damn polly. If you want to be SURE you get this right, bring the pistons with NEW rings to me and I'll get the block machined/honed for you. Its about £100 but I can guarantee it will be done to better than OEM tolerances.
You can then rebuild it and carefully gap your rings to the specs I also give you.
ooh thx so much for the kind offer Ed
I might have previously had 3 bad lucks with the engine blocks for these pistons:
- first block from Noddie was too loose,
- 2nd was too tight and reused old rings with prob bad honing from my cousins machinist,
- and although this 3rd block has good tolerances, it might be bad honing finish by the same guy?
knowing your quality of work, starting all over with new bores, rings, bearings machined by a different expert seems to be the best chance of getting it to work this 4th time.
the current engine block is already at the perfect 71.5mm dia so honing any more would just make it even looser won't it?
think its best to start over from a smaller dia stock engine block to be able to machine it spot on to JEs min spec.
asked myself if I'd prob need to obtain another spare block for the re-bore and re-mod the girdle cage to fit my windage tray cos I heard the girdle cages can't be interchanged else the crank bore alignment could be offset n cause binding?
but then whilst driving home I realised HEY what bout my recently broken stock 1.3 block that just had a fractured piston #3 ringland?
that block could be machined to the exact forged piston spec PLUS I've already modded that girdle cage for the windage tray
good thing I didn't just scrap it.
btw would it be a good thing to drill more oil drain back holes on the forged pistons oil ring groove, allowing scraped oil to drain off the rings faster rather than build up?
alright so provided I have the time off work and enough finance, the plan would be:
- send Ed the spare stock block and head to be bored,honed,decked & skimmed perfectly and forged pistons to have more oil drain holes drilled.
- then I reassemble with new rings gapped (I found as frank prev said that the gaps actually increased then stabilise after bed-in, so I should prob gap em slightly tighter than spec at first? so that after bed-in they'll be absolute perfect?),
- use the 72mm oil expanders to scrape harder,
- new bearing shells,
- fit windage tray onto already modded girdle cage.
what mineral oil?
how do you bed ur engines in Ed and what method would you recommend?
- bedding-in the engine on an engine dyno before fitting is prob the ideal scenario but I'm guessing it's likely to be very expensive.
- what bout fitting the engine in the car, trailing it over to ur place and then do the initial start & bed the engine in a controlled environment ie. ur rolling road?
apologies for the many Q's