Rebuilding the Carb- To gasket seal or not to gasket seal

[Poulan K100]

I have a vintage (read old) Poulan that I'm restoring and recently rebuilt the carb with a new Tilltotson HL carb kit (Thanks Butch). I pulled it apart and cleaned the body with mineral spirits and hit the hard gasket buildup areas with 700 grit sand paper (very fine) installed the gaskets and reassembled. I got the saw to fire-up and am in the process of adjusting the carb. However, I see a bit of gas coming out from around the gaskets in the body and where it meets up with the intake. The rebuild kit involved me putting to gaskets over each other in some cases and I don't have experience in this. I tightened the assembly screws down firm (not over tight) with some loc-tight to hold them in place. I know if there's excessive air getting in it will make the saw difficult to adjust and perform. Should I pull it apart and use a gasket sealer? If so, do you have a recommendation on what type of sealer? (Hard vs. Pliable)

Thanks,
Scott

 

[Lakeside53]

Assuming we are talking abut the intake block and NOT gaskets internal to the carb, use a very thin smear of Permatex HPF on both side so the gasket. It's a flexible gasket repair compound.

 

[Poulan K100]

Thanks, Lakeside. I am talking about both internal gaskets to the carb and the intake to the block. All gaskets were replaced when the carb was rebuilt. Why the distinction between the two?

 

[Lakeside53]

Thanks, Lakeside. I am talking about both internal gaskets to the carb and the intake to the block. All gaskets were replaced when the carb was rebuilt. Why the distinction between the two?

The internal gaskets are designed to be put in dry - the gas will swell them slightly and make a seal. Any gasket goo will eventually get into the carb and block the jets... Try tightening the carb screws again (assuming it's been a day or so with gas it the carb). If it leaks after a couple of attempts, you have a problem with the carb body or covers.

 

[Poulan K100]

Thanks again. It's been a couple days since I rebuilt the carb and tested it for the first time. I'll test again tonight.

Scott

 

[buck futter]

You can also use 2 stroke oil smeared over the gaskets, it may be enough to seal things up if you don't happen to have permatex handy. The oil of course will not harm anything.

Lucky

 

[Dadatwins]

Some carbs have alignment pins on the covers so the covers will only fit one way. As for the seal on the intake I would also use a flexible gasket material before assembly, it helps keep it place when putting on the carb. Good luck.

 

[slowsuki]

seems on some of the tillotson carbs the new intake gaskets are thinner than the original, though it could be do to swelling over time.some of the gaskets on my mcculloch intake gaskets are made out of leather, they seem to work good. when i rebuild those carbs i use two gaskets for intake.

 

[Poulan K100]

Interesting point. The original gaskets that I removed were only one per carb section. In other words, there are three pieces to the carb body lower, middle and upper(main). The new rebuild kit showed the three carb body sections, but between the lower and middle section they now require three gaskets "sandwiched" together which would seem to increase the possibility for more leaks. Here is the picture of the carb I'm working on and placement of the new gaskets: http://www.acresinternet.com/cscc.ns...8?OpenDocument

I did some extra reading on engines racing after a carb rebuild and will follow someone's advice of starting the engine and spraying carb cleaner on the carb while running to see if the engine dies. It would be a positive check for an air leak. The other possibility is the new needle I received in the rebuild kit was shorter than the original and so the main intake never closes when the trigger is released. Life's little mysteries I guess. I'l start with the simple and work to the complex.

 

[Lakeside53]

If you pressure test the carb you can eliminate most of what your are unsure off...

 

[slowsuki]

there are many diffrent hL carbs. you need to make shure that the needle and seat are for your applocation. most of the gaskets are the same the needle and seat are not. i have ran into the same problum when buying rebuild kits. the needle and seat is what determens how much gas flows .it's how you can use a single carb for 60cc to 120cc aplications.sometimes people selling rebuild kits do not know much about them.

 

[Poulan K100]

Carb rebuild success- Now to adjust

Thanks guys. I have never pressure tested a carb before Lakeside so I had to do it the hard way. I pulled the carb apart and sealed the intake with permatex and followed us with a look at the needle and seat. This was the problem. The needle spring lever that came with the rebuild kit had a "V" in it that the needle fit into. The old needle and lever wasn't designed this way. I was able to fix the problem by not locking the needle into the "V" and it now seats properly. I tested the saw this morning and thought I had a problem because after a couple of minutes the saw would kick over. Just before getting ready to tear the carb apart again I checked the gas tank. Sometimes we forget the simple things (gas). Anyways, saw now runs and idles. Next question is how to tell if the carb is too lean or too rich? Do you measure a saws rpm to tell? What tool do you use for this?

Thanks,
Scott

 

[v8titan]

Thanks guys. I have never pressure tested a carb before Lakeside so I had to do it the hard way. I pulled the carb apart and sealed the intake with permatex and followed us with a look at the needle and seat. This was the problem. The needle spring lever that came with the rebuild kit had a "V" in it that the needle fit into. The old needle and lever wasn't designed this way. I was able to fix the problem by not locking the needle into the "V" and it now seats properly. I tested the saw this morning and thought I had a problem because after a couple of minutes the saw would kick over. Just before getting ready to tear the carb apart again I checked the gas tank. Sometimes we forget the simple things (gas). Anyways, saw now runs and idles. Next question is how to tell if the carb is too lean or too rich? Do you measure a saws rpm to tell? What tool do you use for this?

Thanks,
Scott

Give this link a try if tuning by ear. If you have a tach, that's the best way to keep from exceeding the no load speed.

www.madsens1.com/sawtune.htm

 

[Lakeside53]

Give this link a try if tuning by ear. If you have a tach, that's the best way to keep from exceeding the no load speed.

www.madsens1.com/sawtune.htm

Be very careful on an old saw you are bringing back to life... and be very conservative (rich). Let it idle for a tank (with a "rev up" every few minutes). Crank seals, rings, pitting on the bore etc etc all need a gentle touch...