Needle & Seat - How Swollen is Too Swollen?

[TylerFrankel1]

Good evening everyone! I just wanted to get y'alls opinions on Needle & Seat Valves, and when they must be replaced. On smaller Briggs & Stratton/Tecumseh Engines, I've often the Seat is a Rubber Insert and the Needle is Metal, as opposed to most larger engines and Hondas where the seat is brass and the needle is rubber tipped. Over time, the rubber seats have a tendency to swell and the float level is forced to be a bit lower. I've had several engines that run great even with a slightly swollen needle & seat, but I end up replacing them if they're noticeably swollen. I'm working on a mower now where I can't decide whether I need to replace the needle and seat, so I decided to see what the consensus of the community is on this issue. The mower runs good, I was just checking the carb bowl for debris when I noticed this one was swollen:


I'm refurbishing this unit for resale and don't want to spend more than is necessary. I figure they will run about the same except maybe on an extreme hill, until the float level drops at/below where the jet picks up gas. Let me know what y'all do with these and if you have any thoughts on the matter. Thanks!

 

[bertsmobile1]

In the beginning was th word & the word for that carb is stuffed
When ever the throttle butterfly opens up the engine will surge & run lean because the fuel level in the carb will be too low for the "signal" ( why can't they call it a venturi ) to life sufficient fuel.

 

[Born2Mow]

I tend to agree with Bert, somewhat.

The true indicator to me is NOT the physical float position, but rather how the engine runs on the available mixture that fuel level produces. Do you feel or hear engine surging ? Is the spark plug white or colorless ? Yes, that float needle will produce a somewhat "leaner mixture" than probably intended, but is that always a bad thing ?

If your 10 year old son is wearing size 14 shoes, a lot of moms might freak out and consult 10 doctors. But there's another side of the coin.... He might grow up to be 8 feet tall and become a billionaire in the NBA. So "out of spec" is not necessarily a bad thing.

In this area, I'm more of a "results" guy than a "by the measurements" guy. There's more than a single, hard measurement that works. There's always an acceptable "range" of measurements.

Hope this helps.

 

[Scrubcadet10]

for the price of a Abraham Lincoln ,i usually replace the needle and seat.

 

[Rivets]

Bert hit it on the head, time to replace the needle and seat. You will have to do it sooner or later, why not do it now when you have the carb off. If you’re in the business to repair, then fix it right, if you are just fixing your own unit go ahead and take the gamble. Remember it’s always nice to see the DIY guys have a breakdown when it’s cold and you have a foot of snow, and then it won’t start and/or surges. All depends on who’s doing the repair and who’s paying the bill. Measurement techs will say fix it now and not risk a comeback.

 

[Born2Mow]

Measurement techs will say fix it now and not risk a comeback.

You are correct.

Customers always appreciate mechanics trying to save them money on any job, until the unit breaks again 2 weeks later. Then they become downright abusive and you loose a customer. It's a delicate balance.

If I had to run the risk of doing this job again for free if I didn't replace it, then it would get replaced.

 

[TylerFrankel1]

Cool, thanks for the input everyone! I actually work for a shop, and refurbish/repair stuff on the side for extra cash flow. The only reason I didn't replace it without thinking twice is because we're out of the 398188 needle/seat kits, and I was hoping I could get this thing fixed and sold fast. Oh well, I guess I'll be waiting for next Friday to roll around when parts come in. From the limited testing that I've done, it ran appropriately without surging, but I didn't have it in very thick grass. I run out of grass to test mowers on with the amount of stuff I turn around lol.

Another school of thought may be that I sell it as-is without a guarantee, but I'm too nice of a guy to do stuff like that generally.

 

[Rivets]

To sell it as is, will come back to bite you 95% of the time.

 

[TylerFrankel1]

Afraid

To sell it as is, will come back to bite you 95% of the time.

Too true. Patience is a virtue, I'll have her for sale by the 10th.

 

[TylerFrankel1]

for the price of a Abraham Lincoln ,i usually replace the needle and seat.

You can buy the seats aftermarket in bulk online too. I once got a 10 pack of the Briggs seats for 5 bucks. Technically you're supposed to replace the needle too but I really have never seen one that's bad/has any noticeable blemishes. I used about 5 seats out of that pack before I lost it. All 5 worked great. I think I may buy more of those...

I was wondering, do you watch any of Taryl Fixes All's videos? He's the only other guy I know of to call cubs "scrub cadets" lol