Weber jet swap

[slorocco]

Finally go the 88 out to Cody, Wy. Altitude here is about 5,000 ft. Going to attempt to swap out the main jet tomorrow on the Weber carb. Can really find any good manuals or instructions. Is it really as simple as removing the top, swapping the jet and re installing the top ?

Any helpful tips would be greatly appreciated.

[bfishel60]

I've only pulled mine out to clean crud out of it. There is a circlip that might fly away is the only thing I remember watching out for.
Otherwise pretty straight forward from what I remember. I didnt need a new gasket either.
Bill F

[knac1234]

slorocco--

If it's a 34ICH Weber, then yes, just pull the air cleaner elbow off, pull the top off (I found it easier to take 2 more minutes and disconnect the throttle linkage so the top can pull completely away), and replace the jet. The main jet is at an angle, so a little fiddly, but an easy and quick job. 10-15 min tops.....done it a few times when I was rejetting for the altitude I live at (9100 ft).

Julian

[slorocco]

Yup 34 ICH. Thanks for the tips. Gonna tackle it in a couple hours.

[TeriAnn]

When you are done have a CO2 sniffer put up the exhaust to check your air to fuel ratio. Too lean and you can burn a valve if you are lucky a hole in a piston if you are not. Too rich and you are throwing gas money out your tail pipe.

It probably would not hurt to get a reading before you change jets just to see what your start point is.

[crankin]

Teriann, can you suggest a brand? Everything that I have seen seems to want you to weld in a bung and install the O2 sensor so that the heat from the exhaust is there to get a good reading. In your experience have you had a strong reading by sticking the sensor in the tailpipe?

[TeriAnn]

I was thinking of just taking the truck to a shop that does emissions testing and just ask them to check CO2 levels and let you know what the air to fuel ratio looks like. Way cheaper than buying a system but it is just a pay your money for a one time look kinda thing.

But yes if you want to get really serious about tailoring a carb or EFI to a particular engine over the RPM range a CO2 sensor on a bung just behind the exhaust manifold and a gauge is the way to go. I occasionally think of doing that to my Triumph TR3A for fine adjustments to the twin 45DCOE Webers. But so far the price has kept me from doing it. Well that and not knowing where to put the gauge.

I was just thinking a one time check at a shop could let you know if you are in the air to fuel ballpark and not running lean enough to burn up parts.

But if you are serious about dialing in your fuel delivery system and want to know at a glance if a problem you are experiencing might ne the fuel deliver system a built in gauge is worth having. Right now I think Summit racing has a gauge that would work.

[slorocco]

definitely a good idea. I swapped the jet out from a 165 to a 155 based on recommendations from other users on this board at similar altitudes. Truck is now running hotter than it was. temp gage needle now runs about half way between the middle of the gage and the red zone. Before the swap it used to run right in the middle pretty much all the time.