vac gauge to adjust carb By tvnacman (Read 592 times)

[tvnacman]

I watched someone adjust a carb with a vac gauge . We had good conversation about fuel injection . I did not want to over stay my welcome , so I did not ask .

Does anyone here know how to do this and is able to explain exactly what was going on ? I did not ride the scooter after it was complete . I'm still up in the air if it is a good way and how precise it is .

John

[alleyoop]

Here you go:
Actually no different than getting the highest Idle using my METHOD(HAHA).
Alleyoop
classicinlines.com/Vacuum.asp

[tvnacman]

Nice Al , I guess I posted at the correct time . We should talk to JR and get that link put into the tech section .

John

[imnts2]

That used to be a very common tool to assist the tune up of carburetor equipped automobile engines. I used it many times. I also used it to synchronize carburetor linkages until I go flow gauges to measure flow.

I have not done a carb that way since Carburetors largely disappeared from my cars in the early 80's. but I will try to give you some idea Understand, tuning a carburetor or an engine is a bit of an art. The idea is that the best ignition timing at idle will be just a little retarded of highest vacuum (lowest intake manifold pressure and and the best idle mixture will also be a little richer than the highest vacuum. Both of those little's are really very little. But in addition, as you get familiar with the engines you are tuning and your instruments, you will get a sense of the condition of the engine (ring sealing, valves leaking or not adjusted properly , leaking vacuum lines, etc. You can also get a sense of the condition of each of the cylinders by shorting out the plugs one at a time.

Now I suspect a little search on the net will yield a more detailed instruction sheet and a better explanation. If you don't have luck. let us know and I will try some more.

Good idea I think. Frankly, I'll bet the artist would be flattered to let you ply him with food (and/or drink) and tell you all about it.

Thanks for the question

lefty2

[tvnacman]

I learned to do by ear with my dad , carb and timing . retard it till it ran rough then bring it back . then get on the hwy if the band played we slightly advanced it . then continued till band was very faint or gone . We checked for hot starting , we might be done in the morning it had to cold start well . The light sat in the tool box it came out to be taken out of the way while looking for another tool .

john

[justbuggin2]

i had done tune ups on my old vw with a vac gauge but it had been so long ago i dont remenber how i did i do remenber that if the needle was jumping around you need to adjust the timing until it got steady then you adjust a/f and idle settings