Onan P220 carb questions

[Brockport Bill 1,939]

Re: the Onan P220 carb --- Questions Re: the needle valve that is under the hinge for the float...... Is there a spring that is suppose to be around that needle ? Secondly, the needle itself has a tiny tab or almost looks like a button on top of the needle --- is that tab/button on top of needle suppose to be able to compress into the needle, or is it suppose to be firm and stationary??? I have a couple needles from a couple Onan carbs I have apart as well as a couple rebuild kits I have just gotten. Some of the needles have tab/button that compresses, the others don't compress -- are solid frozen? All advice appreciated.

[Handy Don 14,062]

The needles in the P218 and P220 that I've touched were both solid "button" with no spring. I would check the overall lengths since that's what determines the float height that closes the valve.

I've seen springs on other carbs where the fuel feed was gravity. I'm assuming no spring here because there is a fuel pump's pressure to open that needle valve.

[Brockport Bill 1,939]

25 minutes ago, Handy Don said:

The needles in the P218 and P220 that I've touched were both solid "button" with no spring. I would check the overall lengths since that's what determines the float height that closes the valve.

I've seen springs on other carbs where the fuel feed was gravity. I'm assuming no spring here because there is a fuel pump's pressure to open that needle valve.

i just received the manual emailed to me from Onan ( actually Cummings ) and diagram does NOT show a spring around the needle -- but there isn't any way of telling if the top of the needle  "tab/button" compresses?????????  I just ordered and received an aftermarket $17carb kit - ( to see what i would get ). It  included the needle - with NO spring for around needle - nor does the top of needle compress as i have found on others??? Thanks Don - any other insights are appreciated

[Handy Don 14,062]

7 hours ago, Brockport Bill said:

i just received the manual emailed to me from Onan ( actually Cummings ) and diagram does NOT show a spring around the needle -- but there isn't any way of telling if the top of the needle  "tab/button" compresses?????????  I just ordered and received an aftermarket $17carb kit - ( to see what i would get ). It  included the needle - with NO spring for around needle - nor does the top of needle compress as i have found on others??? Thanks Don - any other insights are appreciated

I looked in the one rebuild kit for which I still have some parts. Solid needle.

I am wondering if the "sliding" button permits the makers to use the same rubber-tipped needle "cylinder" with a variety of "sliding buttons" of different lengths to save on manufacturing costs.  Pretty clever, if that's it.

[Brockport Bill 1,939]

3 hours ago, Handy Don said:

I looked in the one rebuild kit for which I still have some parts. Solid needle.

I am wondering if the "sliding" button permits the makers to use the same rubber-tipped needle "cylinder" with a variety of "sliding buttons" of different lengths to save on manufacturing costs.  Pretty clever, if that's it.

hmmm............. interesting theory

[kpinnc 14,638]

The button is fixed. It provides a place for the float tab slot to both raise and lower the needle as fuel levels change in the bowl.

 

The Nikki carb (Vanguard manual) has procedures for setting the correct angle of the tab for a given application. Vanguards (14-18hp horizontal) sometimes have these carbs on them.

 

 

[Handy Don 14,062]

6 hours ago, kpinnc said:

The button is fixed. It provides a place for the float tab slot to both raise and lower the needle as fuel levels change in the bowl.

Yes, this is correct on all the needles I've seen personally, yet...

 

In this instance they are not fixed:

On 10/6/2021 at 10:08 PM, Brockport Bill said:

Some of the needles have tab/button that compresses, the others don't compress -- are solid frozen?

 

Clearly the "compressible" needles can't work in the Nikki carb you note or in the Tecumseh carbs I was working on last week since the falling float wouldn't be able to pull the needle loose from its seat. The P218 and P220 are the only fuel pump-equipped engines where I've been into the carbs so I don't have wide knowledge there but the mechanism doesn't "pull" the needle to open the needle valve. As I noted earlier, I suspect that pressure from the fuel pump is adequate to open the valve once the float lowers.

[Brockport Bill 1,939]

thanks Don --- 

[Brockport Bill 1,939]

7 hours ago, kpinnc said:

The button is fixed. It provides a place for the float tab slot to both raise and lower the needle as fuel levels change in the bowl.

 

The Nikki carb (Vanguard manual) has procedures for setting the correct angle of the tab for a given application. Vanguards (14-18hp horizontal) sometimes have these carbs on them.

 

 

I've seen that float adjustment technique on a You Tube -- thanks for the graphic

[Handy Don 14,062]

47 minutes ago, Brockport Bill said:

thanks Don --- 

YMW

[Brockport Bill 1,939]

got the needle issue resolved -- the 520 HC is running --- thanks all for info

[Handy Don 14,062]

19 minutes ago, Brockport Bill said:

got the needle issue resolved -- the 520 HC is running --- thanks all for info

(any pictures?)

[Brockport Bill 1,939]

On 10/8/2021 at 1:42 PM, Handy Don said:

(any pictures?)

yup - in  a couple days

[Brockport Bill 1,939]

here are two photos of the back end of 520 HC that I disassembled,then cleaned debris, grinder to remove corrosion, etc, primed and top coat. Also removed the lift cylinder and used rebuild kit ( $17 ) to correct leak. I'll send some engine and carb project photos in couple days. 

[Brockport Bill 1,939]

I should note this is condition I got the new to me HC - I don't abuse equipment like the way i got this one few months ago - thats why I'm doing the various repair and rehab projects on it.

[Brockport Bill 1,939]

Don: here is the breather unit I took off and cleaned, plus replaced the gaskets

[Brockport Bill 1,939]

here's the HC lift cylinder rebuild with new O rings kit

[Handy Don 14,062]

1 hour ago, Brockport Bill said:

I should note this is condition I got the new to me HC - I don't abuse equipment like the way i got this one few months ago - thats why I'm doing the various repair and rehab projects on it.

The '95 520 chassis I'm using got all of the HC upgrades except the higher final gear ratio in the transaxle that boosts the top speed. Wouldn't mind having that!

[Brockport Bill 1,939]

this HC is an 88 yr model -- my 14 yr old grandson's HC we got is an 89 -- he used his phone app to time the speed driving around the yard he was so impressed with how fast it went

[Brockport Bill 1,939]

my son has the Toro version they developed in later yrs -- he has the 1998 Toro 520 Lxi -- its a huge beast 

[Handy Don 14,062]

Yeah, that LXI is something, for sure. Brawny (except for that front axle pivot!) and lots of grunt.

 

[Brockport Bill 1,939]

we became aware shortly after getting the Lxi this spring of the pivot issue and the fix -- he isn't  using it much yet since we got it but i suspect soon he'll be looking at that issue

[lynnmor 7,815]

8 hours ago, Brockport Bill said:

this HC is an 88 yr model -- my 14 yr old grandson's HC we got is an 89 -- he used his phone app to time the speed driving around the yard he was so impressed with how fast it went

 

The C in the model number stands for commercial.  The 520H was intended for all markets and was kept to a slower speed for safety and liability reasons.

[Handy Don 14,062]

5 hours ago, lynnmor said:

 

The C in the model number stands for commercial.  The 520H was intended for all markets and was kept to a slower speed for safety and liability reasons.

Understood, and, selling in a country as litigious as ours, valid. Nonetheless, 10mph on a straight run would be kinda fun! (That's me, cheap thrills from the guy who took a Jag XKE up to 150 on the NY Thruway in his invulnerable youth).

Edited October 12, 2021 by Handy Don

[Brockport Bill 1,939]

I have an H and HC  -- maybe I should do a side by side street race  -- check out the real time difference?? haha......... Boys and their toys !!!!!!!!!!!!!!!  the listed spec is 7.5 versus 6.4 mph