Ridge At Top Of Bores

[peter_m7uk]

Gents,

 

I'm about to start the rebuild of my 2.0EFi Pinto, but there is a tiny wear ridge at the top of the bores.

I will be fitting new piston rings, so I'm not too keen on having this ridge present. I'm considering

using a ridge reamer to cut this away, but I wanted to hear if anyone else had tried this? Any comments in general on

ridges in the bore and what to do?

 

Cheers,

Pete

[Guest john]

Or you could try the honer, available at most motorfactors for less.

[Guest Ian & Carole]

Wether you remove the ridge or not the bores need to be "honed" anyway.

 

Your new rings will not "bed in" and you might wind up with oil smoke problems other wise.

 

HTHs

 

Ian J

[peter_m7uk]

Or you could try the honer, available at most motorfactors for less.

 

 

I have access to a honer at work for free! But surely it's the wrong tool for the ridge removing job?

I can't get a ridge reamer from work and no one knows much about it either, as we only work with

brand new engines..

 

Pete

[Guest john]

Pete, I did mine with a honer , three stones on an expanding mandrel, also good for taking the shine off the bore, I'll see if I can find a advert .

[Guest old_timbo]

Can you still get Cord re-ring sets? I remember fitting a set to a Midget engine. They had a notch in the outer top of the top compression ring to avoid the step on the cylinder wall, so all you had to do was glaze bust the cyclinders. I did this with some fine wet and dry to give a nice matt finish for running in the new rings. I think the oil ring was in three parts and was designed to take up wear in the piston ring groove and reduce oil consumption. Seemed to work well.

 

Tim

[Guest Alan_builder]

Gents,

 

I'm about to start the rebuild of my 2.0EFi Pinto, but there is a tiny wear ridge at the top of the bores.

I will be fitting new piston rings, so I'm not too keen on having this ridge present. I'm considering

using a ridge reamer to cut this away, but I wanted to hear if anyone else had tried this? Any comments in general on

ridges in the bore and what to do?

 

Cheers,

Pete

 

The current top ring and bore have worn together so the step shape and ring corner fit. The new ring will have a square top corner and may go bang in a big way.

 

I did hear about stepped top rings to overcome this.

 

How big is tiny? That is the big question!

 

What wear is in the bores and the pistion ring groves and the piston skirt? If there is wear in one that you have seen, how much is in the other items?

 

Just 45 years ago after a rering the dam thing jamed at TDC and broke 2 rings! I was just the apprentice!

 

I my

[johnlrichardson]

I fitted stepped top rings four years ago. The top ring has a step on it. so it misses the ridge, you could ask to see if theyare still available. I've fitted both rings and pistons complete with steps but the bore will still need honing.

 

john

[Andy Spencer]

I'm pretty sure Cords rings are still available. I didn't fit them to my rebuilt pinto as I had the bores honed but did fit them to a Chevette some years ago.

 

I think they are designed to give your tired engine a bit more life, but are probably not a great long term solution, particularly if tuning. As you need to glaze bust the bores anyway, honing is a good idea.

 

Be careful if you do it yourself, its easy to take too much off! My local pinto specialist did it for £20.

 

Andy

[Guest john]

Andy's right, remove the step and fit proper rings.

 

Cords rings were a good solution for tired engines, and really focussed on stopping you burning oil.

The bottom ring was a clever multi piece steel job that sealed a worn bore much better than the OE part.

The upper ones also had steps to overcome the oil loss and ride the ridge of a worn bore. ( Called a 'ridge rider' if I remember correctly )

 

I spent 20+ years as a Production Engineer with AE Wellworthy Hepolite and GKN manufacturing Piston Rings, and I recall Cords were not up there with the frontrunners of the industry. Their market was the man in the street with a smokey old banger who needed a fix for another 10k miles.

I've been there and met the boss but I think it may be all closed now, they don't show up on a yahoo search, so no website , and a search on ebay finds only parts for mainly pre pinto cars.

 

Ahh, the good old days

[peter_m7uk]

The current top ring and bore have worn together so the step shape and ring corner fit. The new ring will have a square top corner and may go bang in a big way.

 

I did hear about stepped top rings to overcome this.

 

How big is tiny? That is the big question!

 

What wear is in the bores and the pistion ring groves and the piston skirt? If there is wear in one that you have seen, how much is in the other items?

 

Just 45 years ago after a rering the dam thing jamed at TDC and broke 2 rings! I was just the apprentice!

 

I my

 

I got hold of a bore gauge and found the the biggest ridge was at the top of cylinder 1, with a step

from 90.83mm at the very top to 90.885mm just below the ridge (0.055mm in total). Using calipers

I also found that piston 1 had worn 0.1mm (can't be any more accurate) than the other three.

It does seem like s0d-all, but I'd be interested to hear the opinion of more experienced gents.

 

I am now half considering a rebore, hone, and oversize pistons and rings, though. Anyone know what

I should expect to pay for the rebore, hone and to have the old gudgeon pins pushed out and the new

pistons fitted?

 

Cheers

[Guest john]

Well you have two thou in the bores which will open up your ring gap by 6 thou, which is nothing to worry about, neither is 4 thou on the piston, as its the rings that do the sealing.

There's life in it yet IMHO, and the most I would do is fit new std size rings.

 

How hard are you going to treat it ? Do you want to race it ? and you will have to run it in if you go for a rebore and new internals.

[peter_m7uk]

Well you have two thou in the bores which will open up your ring gap by 6 thou, which is nothing to worry about, neither is 4 thou on the piston, as its the rings that do the sealing.

There's life in it yet IMHO, and the most I would do is fit new std size rings.

 

How hard are you going to treat it ? Do you want to race it ? and you will have to run it in if you go for a rebore and new internals.

 

Thanks for the reply, John When you say the most you would do is to fit new std size rings, do you think it would be fine to leave the ridge? Cylinder 1 is the only one where it's really noticeable.

Cylinders 2 to 4 you can feel a tiny hint of a ridge (0.03mm), but you can definitely feel it in 1 (0.055mm).

 

As for treatment of the car, I'm not intending to race it, but I'm going to have fun and maybe the

odd track day! I suppose I'm interested in piece of mind, as I don't want to burn loads of oil, be down on power or break the piston rings, but if it's a waste of £200+ to sort out this little bore wear, then maybe I'll just stick it all back together!

 

Cheers,

Peter

[Guest john]

Peter, take the step out with the honing/deglazing tool as was said early in the thread,

 

If your rings have got side wear, ie no longer fill the piston groove width when in the closed state, they will permit oil to seep past and burn, likewise loss of compression.

 

Check the fit of the rings in the grooves, and measure the groove widths too. In my case new rings virtually filled the groove width again, except for a tiny bit of wear in the grooves themselves. I reckon I got it back to 90% goodasnew like this.

 

As I can't see your engine, and don't know the mileage on it, I can only offer this advice in good faith. If you feel it is knackered then you have to perform more surgery on it. Not sure what the price of a rebore and new set of piston assy's is these days, but i could not justify the cost on my 3k miles a year. I'd probably put another S/H engine in it if mine ever failed , but I don't expect it to, Pinto's are tough old things as long as you don't starve them of oil.

 

HTH