• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

Do I have the wrong rings?

Share this page

Basil said:
On a related question - if my ring gaps are too wide (and they seem to be), could that cause excessive blow-by into the crank and thus account for the strange oil leak I've had since having the engine rebuilt? When I shut the motor off, I would get a few seconds of oil coming out the back in a stream....just a few secs after shutoff, then it stops.
Click to expand...

Yes. When my 1500 blew a piston and spoiled the rings in that cylinder (4 years ago), one of the symptoms was a leak out of the rear main seal. Otherwise, it actually ran OK. The piston I pulled out can be seen below.
It doesn't take much to breach the rear main seal on these engines.

1500_piston.jpg
 
Using a digital caliper to measure the inside diameter of the bores (measured at the top), it appears they are standard bore. Using one ring inside the bore, the gap appears about the same near the top as it does 3" down the bore. Also the top of the pistons is stamped STD so it looks like I have standard pistons in a standard bore, yet the gap seems excessive. I think I will call APT Monday (tomorrow) and talk to then about new rings. When I had this engine together I pulled it twice and put new rear seals in trying to stop this darned leak, but it persisted. I hope I am having the same issue Nial had with his damaged piston - excessive blow-by. Wish me luck...I'll keep you up on my progress in this thread.
 
F.W.I.W.
What I know about it:
Excessive ring gap will deffinately cause excessive crankcase pressure {blow by}
Just a W.A.G. but I suspect whom ever did your rebuild instaled the wrong rings or cut them back way too far to ensure ring gap.!
The closer you can get to the SMALL end of the specified ring gap the better.
This is jusy my opinion on the subject:
I think you need SOME ring gap to allow for expansion of the rings as they acquire heat. No ring gap at all {In my opinion would cause excessive ring and cylinder wear.}
You may be able to purchase one set of rings for one piston { you used to be able to in the distant past}
you could then check the ring end gap using this set in all cylinders to see what you have in the way of wear or taper and go from there.
It is obvious the rings you have are not going to work properly with that much end gap.
 
Basil, if you move the rings to the bottom of the bore,or, below where the piston rings stop on the downward stroke, there will be zero wear, so if the block is standard, and the gap is over specs, you have the same problem I have seen. If you put AE rings in, you will find the gap is perfect. However, that is the only rings I have seen that are perfect out the box. Most of the suppliers try to get you to use offshore rings anyhow, telling you everything will be alright, and you are the first one who has complained, offshore is better, and it ain't. If the block has been bored, say, .020, you will know, because the gap will be tremendous. There is a formula for knowing how much say 2-3 thousands cylinder wear will increase the gap. I used the formula, and put the new rings at the bottom of the bore and check gap, then moved up to say 3/4 inch down, and measured the difference between the two. Use a piston to make sure the ring is square in the block.If the block has any miles on it at all, there will be taper, but you cannot measure it with calibers. This is one way to get how much taped a block has. Since the pound is down below $1.55 against the dollar, ordering from the UK is starting to look very attractive. Usually takes less than 5 days to the East Coast. BPNW and Engel have had AE parts in stock recently.
 
AweMan said:
I think you need SOME ring gap to allow for expansion of the rings as they acquire heat. No ring gap at all {In my opinion would cause excessive ring and cylinder wear.}
Click to expand...
Yes, exactly. The rings get a great deal hotter than the cylinder wall (even hotter than the piston); and if the gap disappears due to expansion, the force against the cylinder will increase dramatically. The wall can be ruined almost instantly when the rings micro-weld (gall).

However, none of this solves Basil's problem, which is to know what size rings he needs. A telescoping gage set is cheap enough, but getting accurate measurements with them depends a great deal on proper technique (and still requires a micrometer or caliper to make the actual measurement).

In this case, since you are only trying to distinguish .010", using the piston as a gage, and an ordinary dial caliper to measure the piston, should give you all the accuracy needed. Use feeler gauges to check the piston-to-wall clearance (which you should check anyway, since you suspect the wrong parts were used), then measure the piston with the calipers.
 
TheSearcherMan said:
If you put AE rings in, you will find the gap is perfect. However, that is the only rings I have seen that are perfect out the box.
Click to expand...

Where do I find these wonder rings?
 
what is the total mileage that this engine has done?I would accurately check the bore size and check the bore for ovality and taper before going out and buying rings.could be that you need to rebore the cylinders.Take it to a good machine shop or beg borrow or steal an internal micrometer and accurately measure.On an older engine seems strange you have no ridge at the top of the bore
 
mikespain said:
what is the total mileage that this engine has done?I would accurately check the bore size and check the bore for ovality and taper before going out and buying rings.could be that you need to rebore the cylinders.Take it to a good machine shop or beg borrow or steal an internal micrometer and accurately measure.On an older engine seems strange you have no ridge at the top of the bore
Click to expand...

<span style="font-weight: bold">See my first post</span> - rebuild has probably 2000 miles max on it. The ring gap measures identical (nearly) using the rings inserted in the bores at the top of the bore and again 3 inches down. I
 
Drat! BPNW thought they had some (AE Rings) but none were on the shelf. Moss doesn't have them and neighter does Spitbits. Any other suggestions where I might find them?
 
You really should read my posts... Anyhow, if you have a 1500, Engel has 3 std. sets of AE rings in stock. 1 800 900 2826, ask for Jean, she looked them up. However, I don't know if you have a 1500. Also, sell them some advertising?
 
Remove the used top ring, look very close, see if you see std, 020, 030, on one side of the current rings. Also, look at the top of the piston and look for the same. If you don't find it, use your calibers to check the piston size, then compare with the shop manual. If you have an oversize piston, it will be larger than the standard size bore in the block, which is in the shop manual.
 
Pardon my ignorance here. the rings could only be stock or oversized. If the rings were oversized the gap would be narrower wouldn't it?
 
sorry I think you have miss understood my question,I realise it is only 2000 miles since rebuild but when I asked what the total mileage of the engine was ,I think it could have quite a significance as yes it has only done 2000 miles since the rebuild but the rebuild was done using standard pistons and bores ,If the engine had had a reasonable amount of mileage on it ,I would expect to find some kind of lip at the top (however large or small)if it has not then it makes me think that the bore has been honed to remove the lip,hence taking the bore oversize thus giving you your excessive ring gap.That is why I agree with the importance of checking the bore with an internal micrometer for size,ovality and taper,just have this hunch your going to find the same with the new rings-hope I'm wrong.
 
Yes, however if the block has been bored and the rings are std. the gap will increase..........then Basil will be stuck with a set of std. rings.
 
Back
Top