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Ring Gap Table Instructions
1. This table is in inches. If you are measuring your bore in millimeters, you will need to convert to inches by dividing your bore size by 25.4.
2. Multiply your inch bore size by the “Bore x” column for your application to determine the end gap.
Example: For the top ring with a 4.0” bore, multiply 4.0 X .004 = .016
Application:
Top Ring Bore x .0040”

2nd Ring Bore x.0050”

Scraper Ring Bore x.0050”

Note:
1. The above is a general guideline. Each ring should be fitted to the particular cylinder in which they are to be installed.
2. The gap on the second ring should always be larger than the top ring end gap, this will help to reduce top ring flutter or lifting.

My apologies for previous post.

Thanks James, I stand corrected!
 
pistons and rings arent the same as other parts ,when you rebore you bore to your new piston size ,which may be several thou different to manual data ,when they do blocks in factory they have graded pistons (in size )and graded blocks to match sizes ,tdis run at about i thou diametrical clearance at bottom of skirt ,rings usually come with too small a gap that you file to suit ,obviously if bore is worn this will alter gap ,if you push ring with piston as far down as practicable where bore isnt worn you wont run the risk of gap been too small as it travels down
 
This is what it says in the 200tdi workshop manual. Which bit should i be paying attention to?

200tdipistonrings.jpg
 
jamesmartin said:
pistons and rings arent the same as other parts ,when you rebore you bore to your new piston size ,which may be several thou different to manual data ,when they do blocks in factory they have graded pistons (in size )and graded blocks to match sizes ,tdis run at about i thou diametrical clearance at bottom of skirt ,rings usually come with too small a gap that you file to suit ,obviously if bore is worn this will alter gap ,if you push ring with piston as far down as practicable where bore isnt worn you wont run the risk of gap been too small as it travels down
Click to expand...

Thank you for the explanation. So basically, I am going to deglaze the bores with my three prong honing tool. Then, I will open a single pack of rings and push them about 3/4 of the way down the bore using the piston to ensure that they are flat. I will then use my feeler gauges to check the gap and if it needs opening up a bit, I will run the ring up and down a file. Those rings will then be installed onto the piston to suit that bore, is this the correct procedure?
 
presuming you bought std rings which are best and not cord **** rings,yep thats what you do but remove to file and take burr of edge of ring with one sweep of file and then fit each right way up if marked
 
jamesmartin said:
presuming you bought std rings which are best and not cord **** rings,yep thats what you do but remove to file and take burr of edge of ring with one sweep of file and then fit each right way up if marked
Click to expand...

Okay, thank you. There's a lot to consider really. It's all relatively straight forward and it does make sense but I need to make sure I keep my wits about me! I've ordered standard sized rings from AllMakes 4x4 so I have no idea who the manufacturer will be.

-Tom
 
it is staright forward ,you may find gaps are larger in which case unless we not talking thou dont worry about it ,its the too small that is,allmakes should be good
 
Okay, pistons came out today and I have deglazed the bores. They have gone from this:

borewear.jpg


to this:

glazebusted.jpg


glazebusted2.jpg


It doesn't have the same cross hatching as a proper hone would but will this suffice? It has etched into the cylinder wall nicely. In the third picture you can see a vertical score mark in the bore. I really didn't want to de-glaze any more than I did, so I am going to leave them be, this being the one and only mark remaining amongst all four bores. I now have a new question:

There appears to be some vertical score marks / scratches around each piston here and there. Is this quite normal or should there be absolutely no sign of the piston touching the cylinder walls?

Thanks,
-Tom
 
Last edited:
jamesmartin said:
your supposed to go up and down fast enough to give cross hatch ,a few faint scratches is fine
Click to expand...

I did go up and down fast but my drill's slowest speed is 1200 RPM and it's not too easy to match. Would you suggest I borrow a cordless drill and do it again to get cross hatching?

-Tom
 
Marks on the piston wall are probably from contamination of the engine oil and not necessarily the piston contacting the bore. Pistons are soft and easily marked by grit or metal filings caught between the two.

I'd say you need a slower drill to get the factory finish hatching effect. Just be careful not to overdo things or your pistons will be like waving a broomstick in the Albert hall. Remember you are working in thousandths of an inch when it comes to piston clearances.
 
far too fast you want to be looking fo 40-45 degrees .i would ,but they have apart from that come up well, did you lube it at same time ,diesels fine or similar
 
jamesmartin said:
far too fast you want to be looking fo 40-45 degrees .i would ,but they have apart from that come up well, did you lube it at same time ,diesels fine or similar
Click to expand...

I will see if I can get hold of a cordless drill tomorrow then, at least they have a truly variable speed so I can get a good cross hatching. Do you think it's possible that i have taken off too much metal at higher speeds? I gave each bore about 10 seconds. I had my dad spraying the bores with paraffin as I was deglazing yes.

Thanks again
 
Shifty1962 said:
Marks on the piston wall are probably from contamination of the engine oil and not necessarily the piston contacting the bore. Pistons are soft and easily marked by grit or metal filings caught between the two.

I'd say you need a slower drill to get the factory finish hatching effect. Just be careful not to overdo things or your pistons will be like waving a broomstick in the Albert hall. Remember you are working in thousandths of an inch when it comes to piston clearances.
Click to expand...

Thanks for that Shifty. I gave each bore about 10 seconds up and down with the drill, there is a very slight cross hatching effect but the angle is extremely obtuse. Do you think I might have over done it? The pistons pushed out by hand when I removed them. It took a good shove, but not one of them required a wooden stick and a hammer to remove. Would it be safe to leave them as they are or would you strongly suggest I give them another quick scour to get a cross hatch?

Thanks,
-Tom

-Tom
 
very unlikely you cant get that much pressure like machine hone,with the one i used to use you could hone a block +20 if you could keep a straight bore , its better to loose 1/2 a thou size to get good finish
 
jamesmartin said:
very unlikely you cant get that much pressure like machine hone,with the one i used to use you could hone a block +20 if you could keep a straight bore , its better to loose 1/2 a thou size to get good finish
Click to expand...

Alright then, I'll try and acquire the necessary tools tomorrow. What would happen if I was to fit new rings and leave the bores in their current, de-glazed, un-crosshatched state?

-Tom
 
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