# I think my carb lacks a venturi ... is this possible?!



## DanielWilson (Feb 2, 2009)

During the summer, my 960 started losing power ... reminding me of the time I'd blown a head gasket. It went from mowing just fine to sputtering and backfiring in the course of about a minute.

So I limped it to the garage where, over the months, it got:
* a head gasket replacement (probably not necessary)
* a radiator repair (definitely necessary)
* a partial paint job (waste of time, but it looks a little better)
* a cleaning of the centrifugal spark advance mechanism after the above failed to get it to run any better
* re-setting of points (necessary after the previous step)
* and today a carburetor tear-down

Prior to the carb tear-down, it ran OK at idle speed, but attempts to rev it up would sometimes stall it right there (no load, just opening the throttle) or sometimes provide a little more power, but not enough to run my mower.

So ... my next guess being the carb, I tore it down. When the shop manual said to remove the venturi ... I checked the diagram ... OK, a funnel-shaped thingy ... and that part wasn't in my carb.

Now, it's possible I was so clumsy I dropped it as I removed the fuel bowl from the top half of the carb, but I don't think so. I was keeping track of much smaller pieces like the idle jet!

Is it possible that the venturi has been missing for some time ... even when the tractor was running OK? Or ... that it somehow disintegrated? I would assume they were originally made of some type of metal and that even a plastic replacement (I've seen them listed for the N's) would be of a gasoline-friendly plastic.

At any rate, I really think I'm going to need one in order to re-assemble the carburetor ... and I'm not finding them for a 800/900 series.

Any ideas?

Thanks!


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## ErnieS (Jun 1, 2011)

Post pictures of the disassembled carb and the manual page, if possible. I don't believe it would have run without a venturi.


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## Mickey (Aug 14, 2010)

I'm with Ernie here.


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## Big_T (Dec 1, 2011)

If your manual indicates that the carburetor should have a venturi, my guess is that it should have one. Probably won't run without it. A tractor carburetor rebuild shop may have one. Try to get manufacturer and numbers off the carb as it may have been replaced sometime in the past, and may be different from the carb in your manual?? I looked at a more recent Ford tractor carburetor, and it doesn't have a venturi listed in the parts breakdown. 

The sudden change in performance as you described would cause me to check slug of dirt in the fuel supply to the carb. Was the tank low on fuel when the problem occurred?? Do you have a free flow of fuel at the carb?? A trickle flow is not good enough. There are 3 screens to check: inside the tank (attached to the shut-off valve), at the sediment bowl, and at the inlet elbow to the carb. 

The only other thing I can think of is a jumped tooth in the timing gears. I had this happen many years ago. 

Or maybe a jumped tooth in the distributor drive - have you put a timing lite on it?? 

Do you have a hand operated vacuum pump? If so, apply a vacuum to the distributor advance mechanism and confirm that the advance mechanism is working.

When you open the throttle, watch the governor to see that it is operating.


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## DanielWilson (Feb 2, 2009)

Here's the page from the Parts Manual:


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