Piston Questions

[Nigel Incubator-Jones]

After far too long doing nothing with my 100E's dismantled engine, I did manage to get around to replacing the piston rings tonight. So far so good, but my curiosity was piqued by a couple of things.

1) I couldn't help but get a few scratches on the pistons as I was putting the new rings on. Is this going to be a problem? They're too shallow to be perceptible by touch, and the old side-valve isn't exactly what you'd call a precision engine, so I'm thinking not but thought I ought to check. When do a few scratches cross the line from acceptable to unacceptable?

2) The tops of the pistons have what seems to me like some fairly heavy pitting on them, which only became apparent once the oily layer had been scrubbed off. I was wondering, for one thing, how that would happen and, for another thing, if this is also a cause for concern?

I appreciate pictures might help so if anyone should want to see some then I'll go and take them.

[stilltrying]

Pictures would help BUT, a few scratches on the pistons as you put the rings on is not uncommon and will not be a problem. Gouges on the piston would be a bit more of an issue. Remember the pistons don't do the sealing the rings do so make sure you gapped the rings first (you did do that didn't you?)

Pitting on the top of the piston is not a major issue on the engine you have but would be on something more revy and "precision" could have been caused by detonation in the past or just water damage from standing unused for some years.

I once had a hillman Minx 1500 and the top of the pistons were well pitted but the engine ran fine for many many thousands of miles, mine was pitted through water as the head gasket had gone and had been still running for weeks like it till I got round to replacing it

[roscobbc]

Used to get pitting on piston crowns of 2 stroke scooters. That was from broken piston rings when they used to seize up from lack of oil in petroil mixture. I blamed Bardharl oil. Advertising sail to use half the amount.......

[Nigel Incubator-Jones]

Pictures would help BUT, a few scratches on the pistons as you put the rings on is not uncommon and will not be a problem. Gouges on the piston would be a bit more of an issue. Remember the pistons don't do the sealing the rings do so make sure you gapped the rings first (you did do that didn't you?)

Pitting on the top of the piston is not a major issue on the engine you have but would be on something more revy and "precision" could have been caused by detonation in the past or just water damage from standing unused for some years.

I once had a hillman Minx 1500 and the top of the pistons were well pitted but the engine ran fine for many many thousands of miles, mine was pitted through water as the head gasket had gone and had been still running for weeks like it till I got round to replacing it

Thanks for that, sounds like I haven't got anything to worry about, then. Gapping the piston rings, though - I've not done that. I would have thought that they're all ready-made correctly gapped?

[Plumpcars]

They should be but the key with an engine build is 'never take anything for granted'.

[stilltrying]

They should be correct and as you are not to my knowledge fitting a blower or nitrous you will be fine.

A lot of people don't check as they go along just blindly fit what they have been given, however use this build as a learning curve, you should be able to basically throw it together and it will run, this will get you the basic's, next step is towards blue printing, manufacturers make the first engines to very tight tolerances but then when mass produced the tolerances get stretched and the engines are less than perfect, you then build the engine back to manufacturers original specifications, mainly for high HP or racing but done on a daily driver would ensure a bit more longevity.

One thing you will need to gap is the plugs, people buy a set of plugs for their car and blindly fit them because "they are already gapped correctly" this is far from correct, various vehicles/engines will use the same plugs but will need a different gap between say a Ford and a Nissan or a Land Rover etc. etc.

Keep up the good work.

[stilltrying]

Nigel, I have just seen your post on the other channel, you are a knob, probably a nice knob but a knob none the less. People on here and probably on the other channel would be very willing to help you get your engine back together, it is a very basic engine (has to be because of it's age and use).

Many of us are now old and decrepit but were once your age and no we were not all mechanic's nor did we have the correct facilities to do the jobs we did, I once did the head gaskets on my V6 Mk4 Zodiac in the railway station car park as we had no drive or garage where we lived. I also used to use the underground car park of a local block of flats when the weather was particularly bad (lived on the south coast). Look at your hot rod history Winston Sewell for instance.

I am not trying to be big by this, there are more determined people out there than me who have done far more and probably in more difficult situations, I would just like to kick you up the arse a bit to get you going. Yes doing this sort of thing on your own can be both boring and difficult but not doing anything is worse.
From your last post you have done the piston rings, so what else, if anything, have you done to this engione? Parts are not that difficult to locate or that expensive and I do know that finances can be an issue but with a head gasket set at around £20 and a full engine set for about £35 they are attainable items.

We don't care if you ask questions that you think are stupid, everyone has to learn at sometime and in your circumstances, without having a mechanical background the only way to learn is to ask and try to do it.

From your post on the other channel I would get the lad you know to come over to your place assess the situation with regards what is needed to get the engine back in one piece and then either tell your parents you are going to take the engine to his place and get it ready for dropping back in the car or just take the engine over there without them knowing, get it ready and then bring it back. Oh by the way the clutch will be fine, the rust will be easy to remove and you do not need to get the pressure plate spanking shiny, once in the car and getting used that will happen anyway.

The only "specialist" tools you should need for the engine repair would be a torque wrench (your mate will probably already have one) and a clutch aligning tool, feeler gauges. You can if good by eye do away with the clutch aligning tool.

So how about another go at getting your hands dirty

[cptpugwash]

Lol, was thinking that...just sneak it around your friends garage while they are out shopping. Once you have a plan and the parts though
Who dares wins..right..

Maybe doing a thread on the rebuild may help, but wish you all the best with it

[Nigel Incubator-Jones]

Sorry to have ignored these posts - hadn't had a proper look round the forum for a while and wasn't expecting such an old thread to be revived. Annoyingly, my dad arranged for the engine to go to a local engineering company to be reassembled while my friend's been spending two weeks in Yorkshire. I've got some money in the bank and am contemplating the wisdom of buying an old Cyclemaster or Trojan Mini-Motor as the most basic platform for learning.

[stilltrying]

Anything would be good to start BUT if it was me I would be looking for an engine that needs a rebuild for either something I already have (hillman or Ford) or one that I would like to fit in one of my vehicles, that way you learn but if anything goes wrong with either of your rides you have an engine ready to lump back in and get you on the road again asap.

If the Ford engine is getting built up then look out for a rebuildable 1725cc engine just to pep things up a little for the Hillman, not a great deal of extra power but they are a really billy basic engine and bits such as gaskets will still be available and cheap, plus you won't need to up grade the brakes or suspension as the 1500's and the 1725's used the same suspension and brakes (well certainly in the slightly later version than you have). You also don't have to go for twin carbs on the bigger displacement as a single will still be fine for general running around. I say this as you may find an engine that doesn't come with the carbs as some think they are worth money, they are not).

Whatever you do, remember two things, just give it a go, it's not like you will be breaking something worth tens of thousands of pounds and secondly have fun!!!!