carb synching possible problem

[Anonymous]

I synchronized my carbs yesterday at about 2500 rpm, and then shut the engine off and disconnected the manometer. However, after I put my manifold plugs back in, and restarted the engine the rpm's were down by about 1000. This is without adjusting the idle knob setting I used during the synch. Does this mean I had an air leak at one of my connections, and therefore need to resynch?

Thanks for any input,
Billy Miles

[redliner1973]

Did you by chance remove the fuel tank while doing this sync? if so, did you have the vacuum line plugged off when you synced? if not, rpm's can go higher, and when you put the tank back on and hook back up the vacuum line your rpm's go down.

[Anonymous]

yes I did remove the tank, but I extended both the vacuum and fuel lines.

[earlfor]

If you extended the fuel and vacuum lines, ran the engine from the tank to do the synch and now have reinstalled the 4mm screws, and the engine rpm is different from what you set, then the only cause I can think of is a vacuum leak. Probably at the adapter for the carb stix. Did you use the rubber washers and turn the nuts on the adapters down tight?

Set the vacuum levels at 8-10 in Hg at 1200 rpm. Reset the Idle adjustment knob between each adjustment for vacuum so that the engine never varies from 1200 rpm during the whole process.

Earl

yes I did remove the tank, but I extended both the vacuum and fuel lines.

[mcconnell]

I find using the throtle cable adjuster near the throttle instead of the adjuster at the carbs makes the idle adjustment much, much easier while synch'ing (big hands). Just be sure to set it back to the original setting when you are done.

[rodcwer]

EARL KNOWS OF WHAT HE SPEAKS. HE JUST SYNC MY CARBS LAST WEEK
and it runs great

[Anonymous]

Thanks Earl. Yeah I tightened the nuts down, probably tighter than necessary, displacing the o-rings. Was that your thought also?

[earlfor]

You only need to snug them good. A 3/4" drive breaker bar isnt needed. :-)

Earl

Thanks Earl. Yeah I tightened the nuts down, probably tighter than necessary, displacing the o-rings. Was that your thought also?