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Any NOS Poulan Countervibe 3400 Piston Rings!
- Thread starter seagiant
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kmcinms
ArboristSite Guru
how did those rings work out for you?
Has anyone tried the rings that Lil' Red Barn is selling?
I'm not sure why people don't just file fit an oversized ring verses buying one from another country.
Well, for one thing, finding anything made in America anymore is nearly impossible. In many cases, imports are your only option. That being said, I've always file fit my piston rings no matter where they come from. The ones I just installed were a good .010 oversized and would have fried themselves and/or ruined the piston if I hadn't. Of course, bigger is better than too small. I've read a lot of folks complaining that they're getting rings that are too small. Installing those would be a waste of time...
Not necessarily. A 015 or 020 gap is far better then no ring tension. A 030 gap makes more power then smoked rings.
Bottom line for me is simple ... if I'm going to go through the process of rebuilding an engine, I'm going to use the best quality parts I can find. Sometimes that means compromising on the quality but I rarely compromise on the fit or the function. I'd rather retire a saw and spend my time and money on something that has a future.
I'd never sacrifice quality for fit in this case. I know the best modern ring with a wider end gap will do more good then sources from 30 40 or more years ago. Rings have changed and the good old adage OEM is good enough is out so it went with my old wash water now days. The effectiveness of better materials in rings designed to update your ancient offerings from ten years ago are worth it to me. Nitro likes big end gaps so it's not uncommon to go a bit extra on even the smallest gas motors air cooled. You'll find your factory specs can vary quite widely for various reason among those being timing lead and cylinder pressure.
I'd like to add fitting the ring land area both vertically and radially is the most important thing to check first then check your end gaps second. Modern rings have different designs that directly effect how the ring rides on the bore surface.
kmcinms
ArboristSite Guru
That would be all fine and dandy if you could find rings with the correct axial height to fit the pistons designed for these Poulan saws. The correct ring tension plays a huge part in the equation too. You wouldn't file a ring that is designed for a larger bore diameter to fit a smaller bore without excessive wear/drag in the cylinder. These cylinders are bare aluminum, not plated.
yessir, the axial height does have to match the ring lands on the piston for optimal ring performance. That's where the dimensions on these pistons differ from common 1.5mm piston rings.
Factory ring lands on these pistons are set up for a ring with .062 axial height, where as 1.5mm rings are .0585 axial height. .0035 less than the rings designed for these saws.
Glue a fatter ring into a jig to lap them down to size. Aluminum bores are fairly tough and staying within a mm on ring size isn't going to change the radial tension enough to cause any issues. After a few heat cycles and it should seat in decent.
Have any off you looking for these rings bothered to call Total Seal?
Bothered? Someone has to know a company exists first. Rather than snidely asking if someone has "bothered" to make a phone call, why not just offer up the information about the company and make a POLITE suggestion to check with them?
kmcinms
ArboristSite Guru
What? Who is trying to fit a thicker ring into a thinner ring land? Have you ever rebuilt one of these saws, or had one apart to mic anything inside one, or are you just guessing? Seriously, I wouldn't want to put a .040 oversize ring into a standard bore inside an aluminum cylinder, even if it has been file fit. The problem isn't finding the correct bore diameter to fit the cylinder. What the problem is that most rings for chainsaw pistons are 1.5mm, the rings for these Poulans measure .062.
Say what? Total Seal? You lost me. Those rings aren't designed for pistons with locator pins in the ring lands. Are you using custom pistons in your saws? Besides the fact they would laugh at the inquisition, that's not cost effective on hobby saws, is it.
The rings I just received measure .061 in height, and .079 thick. That's significantly thicker than the old, worn rings I removed and I don't have a spec on how thick they're supposed to be but they look to be just about the right thickness for the groove depth. When placed in the bore of a good cylinder, they fit the bore properly, leaving essentially no gap between the ring ends, which is what I was hoping to see. Of course I'll file them down to accommodate the width of the pins and remove a few extra thousandths for expansion but I'm thinking I should be good to go. Are they made of great material? Time will tell I guess but they appear to fit properly and that's half the battle.
kmcinms
ArboristSite Guru
Factory rings are .062 thick (axial height). What brand of rings did you buy?
If you can get thicker rings lap them down. If you can't then take your piston to a machine shop to widen the ring groove. Cut the top of your land area not the bottom of the ring land.
What one will solve your problem if your not looking to use a -0.015 under or file fit down from +0.040 overbore sized rings?
You guys asking about pricing need to just stop. It is an antique not available for the past few decades. Get real.
Now what is your next excuse?
Metric sizes?
Check the depth by simply installing the ring backwards after you fit it to 0.0012-0.0009 installed clearance. Back clearance should be a minimum of 0.003 not to exceed 0.010 according to me not some number plucked from the sky or a manufacture. But, no wait, most rings are installed to those specs factory on just about everything made that burns fuel and has pistons with steel rings, how convenient.
You've been given all the answers.
What one will solve your problem if your not looking to use a -0.015 under or file fit down from +0.040 overbore sized rings?
You guys asking about pricing need to just stop. It is an antique not available for the past few decades. Get real.
Now what is your next excuse?
Metric sizes?
Check the depth by simply installing the ring backwards after you fit it to 0.0012-0.0009 installed clearance. Back clearance should be a minimum of 0.003 not to exceed 0.010 according to me not some number plucked from the sky or a manufacture. But, no wait, most rings are installed to those specs factory on just about everything made that burns fuel and has pistons with steel rings, how convenient.
You've been given all the answers.
