All Small Six Tuning with AFR gauge need help.

[ActionYobbo]

Here is where I am at now.
I have a 63 jet now and cruising it’s 13’s with 14 to 16 on hard acceleration depending on incline but idle and coasting is still 11’s.
Going slight down hill it shows 16 on hard acceleration not wot and going back up that hill it shows 14’s from a 30mph rolling start at the bottom and doing 50mph at the top, distance just under 1/4 mile.
It’s running the best it’s ever ran so I fell like ignoring the AFR gauge and calling it good for now.
Also I think my fuel pump just did its last drive. It’s making a knocking noise and it is having trouble keeping fuel in the filter before the pump.

 

[Frank]

fuel pump just did its last drive. It’s making a knocking noise and it is having trouble keeping fuel in the filter before the pump.

Change the filter first! Filter on the suction side of the system is sensitive and can cause gas starvation from boiling the gas due to the vacuum created if the filter is clogged. The knocking noise can also be cause by a clogged filter on the inlet-side.

Unless the tank is dirty, filters should be on the output side

 

[ActionYobbo]

Change the filter first! Filter on the suction side of the system is sensitive and can cause gas starvation from boiling the gas due to the vacuum created if the filter is clogged. The knocking noise can also be cause by a clogged filter on the inlet-side.

Unless the tank is dirty, filters should be on the output side

Tank is rusty. Have a new filter before the pump and change it when it looks dirty.
I went for a good drive today and it’s running really good. Ran along at 60 for a few miles. Still only just a bit of fuel in the filter so after reading what Frank posted I might take it out and put on another filter. Never know it might be a dud filter not allowing flow.

 

[xr650jkallen]

You may also want to check and make sure that your AFR gauge is configured to the correct fuel. Mine has several options to select from and adjust the scale accordingly.

 

[ActionYobbo]

Looks like it was the new filter. I changed the filter and I have 120 miles on it with no problems.

 

[ActionYobbo]

Update and questions
Got to drive it on real hills and it did good no noticeable lack of power or anything. Speed was mostly 40 with some 55 sections. The AFR gauge at idle is 14 to 14.5 and driving on flat or light load 13 to 15 but uphill it’s going to 19 and down hill foot off the gas 11. This was consistent with the engine at 2200 rpm in drive 3 uphill at 55 AFR was 17 to 19 all the way up the hills and 11 on the way down with no gas and some brakes. Along the flats and through town and the 40 mph areas it was around 14+/- this is is a big bore autolite 1100 on a stock large log 200 with a 63 jet.

 

[pmuller9]

What is the WOT afr?

 

[ActionYobbo]

What is the WOT afr?

Don’t think I ever get to wot.

 

[ActionYobbo]

So today I changed the jet to a.064 just for the fun of changing jets. I changed no other settings. Went for a 30 mile drive with some nice hills and it ran at 12.5 most of the time with a 13 now and then. Power up the hills was noticeably better but it’s a bit on the rich side. So I put the 63 back in and did the same drive and got 11.5 down hill 14.5 on the flats and 19 up hill. This .064 jet came out of a used carburetor so now I am wondering if it’s been drilled. The drill bit that fits the .068 won’t fit into it so it’s smaller than that.

 

[Frank]

thanks for the update and that is helpful info. Modified jets and jets not specific to the carburetor will not meter correctly. The shape of the jet from the top taper/no taper, jet height/depth and the shape through the bore of the jet are engineered with the rest of the components. I recommend getting a correct new jet now that you got correct metering and a solid baseline from the #64.

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