Piston rings issues

[alexmcguffie]

The good thing is that if these rings don't work for you then you can do the job twice

[bmcecosse]

We don't all have bottomless pockets - so sometimes it's worth trying what's on hand - it may be fine !

[alexmcguffie]

We don't all have endless time either

[MarkyB]

If you don't have any spare time and don't have any spare money, something is going wrong somewhere.

[bmcecosse]

Money V time - an eternal balancing act!

[alexmcguffie]

Never forget the classic car rule of 'it'll cost twice as much and take twice as long as edtimated'

[bmcecosse]

Can't argue with that one !

[swampy42]

Earlier in this post the subject of glaze busting was mentioned. I've had a go with 240 grit emery paper on the end of a stick! The effect is, unsurprisingly not massive - the cylinders are still very shiny and nothing like the dulled, honed cylinders that Google will bring up. So, how important is it, to get it looking dull and un-glazed like? I don't mind attacking it with coarser emery paper if I know I'm not going to be doing any damage.

[bmcecosse]

80 or 100 grit...need to be a thick stick to approximate to the bore diameter... perhaps wrap it tightly with old cloth... The idea is just to put numerous light scores on the surface at a 45 degree 'cross hatch' pattern. It's not really 'honing' which would require you to purchase (surprisingly) a 'hone'. It is just 'glaze busting' and should suit your purpose nicely.

[swampy42]

Thank you. That's today's job sorted.

[swampy42]

Ok, pistons all in and cylinders honed. I've tightened up the big end bolts to finger tight and am noticing the reluctance of the crank shaft wanting to turn. New bearings (both main and big end). The bearings were cleaned and oiled well and certainly the shaft was rotating on the main bearings without issue.
Q1. Can I assume this new stiffness is purely down to the new rings against a relatively rough cylinder wall?
Q2. When the engine is first started, in what is bound to be another 12 months, is it simply a case of removing the plugs and hand cranking 20 or 30 times, to get the oil pumping? Is there anything else I should be aware of to avoid ruining a rebuilt engine?

[MarkyB]

Can I assume this new stiffness is purely down to the new rings against a relatively rough cylinder wall?

Probably, the amount of friction increases a lot with the pistons in on freshly honed bores.

[alexmcguffie]

How are you turning the crank shaft? If you fit the flywheel and use that to turn the crank then once the initial 'sticktion' has been overcome you'll be able to keep it moving. You will feel the drag of the piston rings but you should notice that reduce towards TDC and BDC as the piston travel is less per degree of crank rotation.

Some engine builders keep torque figures that are needed to turn a crank at various stages of an engine build. This can be used as a good reference rather than just by feel.

[swampy42]

I was just turning it by turning the flywheel mounting flange. No leverage or anything, just by hand. If I know all is well, then I'll tighten up the big end bolts. Just wanted to double check at this point rather than finding out I had missed something and having to strip it down again.

[les]

It's usual to install the crank first and be happy it spins ok, then one piston and turn, then another etc etc, that way you get a better idea of where any excessive tightness, if any, is. Of course you may well have done it this way.

[swampy42]

That would make sense indeed. I was so happy that I managed to get a piston back in, that I just ploughed on with he other three. At it spins easier at top and bottom of the stroke, then I guess that's a good sign that it should be OK

[bmcecosse]

Plenty of oil! And I assume you have put the caps back on the rods they came off - and same way round with 'tangs' together. And yes - one piston at a time ! If the engine is to stand for some time - you should put an oil + vaseline mix in the oil pump. When you do start it - oil down the bores - and crank it with plugs out (use jump leads from a car with running engine) until the oil pressure comes up - if no gauge, then crank till the oil light goes out and then another 20 seconds or so. Only then - fit the plugs and start it up - NOT revving it up as you do so!

[swampy42]

Many thanks for this concise reply. Yes caps have gone back on same rods, tangs are together, but I don't know if the caps are the same way round. If tangs are together wouldn't the caps automatically be the same way round? Jumping ahead a bit here, but once it starts is it best to let it idle for a while - how long does it usually take for the rings to bed in?

[bmcecosse]

Well yes - a nice fast idle while you check for oil and water leaks up to operating temperature. Then when it has cooled down, but not necessarily 'cold' - retorque the head to 44 ft lbf and then regap the valves. You will then probably want to restart it - warm it up and swing the dizzy to get the best idle - and twiddle the carb also with the aim of best idle - checking with the 'lift pin' as you go. And then a nice test run! Rings will take a few hundred miles - but just drive normally without hammering it...

[swampy42]

Excellent. Many thanks indeed.