Tillotson Carb diferences

[gink595]

I have a stock 880 with a few tank fulls through it, it started giving me fits and wouldn't stay running for more than a few seconds, I tore the carb off and cleaned it. I probably had than thing apart 10 tens. Nothing ever changed and it went from runnning fine to crap just like that.

So I finally said screw it and went digging through old threads and found out that the HT-7A is a non-limited carb that will bolt right up to the 880, so I ditched the HT-12E and bought a 7A, it showed up tonight and I started comparing them and I can't see what the differnce is in them, but it seems to difenatly run stronger with the HT-7A.

So what is the difference between these carbs?

 

[Jacob J.]

Apparently the HT-12e has an internal governor speed valve? Does yours have both high and low adjustment screws with caps?

 

[gink595]

Yeah the 12E has the caps and a plastiic block between the carb housing and jet heads. Visually I can't tell any difference. How does that governer work?

 

[gink595]

Is there a way to modify the 12E so it is non-governed?

 

[Jacob J.]

Is there a way to modify the 12E so it is non-governed?

You know, I'm not sure. I did get a bunch of Tillotson HT and Walbro WG carbs in a box from a guy a few weeks ago and I think there's a 12e in that batch. I'll play around with it and see what I can find out. I know we used to be able to block the governor in the old HS and WR carbs with some epoxy.

 

[gink595]

Where is that passage at? I've read at another place about a brass plug but I'm lost to where it is at? Does it direct flow after a certain RPM, I don't understand how that works?

Yes it would be intersting to see what you find.

 

[JasonBmac]

Not sure on the tilly governor, but the Walbro one was kinda like a main nozzle check valve, but in reverse... There was a check ball forced onto its seat by a spring. THe spring and ball weight were such that at a certain RPM, the ball would begin vibrating on its seat, allowing extra fuel thru to the main jet. This would richen the mixture and effectively cap max rpm's... Crude...

I'd imagine that the Tilly unit is similar... But don't have documentation for that.

J