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John;
(Hi Mario)
I presume you mean to elaborate on the road test to check mixture not the original hot start string.
Doing a road test goes back to not having a dyne at my disposal...and this technique is my own and based on my experience (with a number of stock and performance moded 122s and 1800s)...appreciate that it is tricky to relate and that everyone's experience, and car is different... having stated my disclaimers, I'll try to explain my technique...
Non-rolling tests:
I find that once idle has been set(once off choke and fully warmed up), blipping the throttle should result in a decent response and rise in the revs...(in this case the engine is working against rotational inertia load only...the best I can do without a dyne and parked, so there's also no need to hold it at high revs...Important - the point is: The info is gained while getting to high revs, not by holding it there!). [A car with a lightened flywheel would respond faster, etc.] While doing this test, a lean condition will cause a (noticible) delay in the response, and a very lean condition can even result in (really noticible delay ) and bogging, and possibly even a lean backfire...and don't forget, this test is somewhat air temperature influenced...colder air would push the results toward the lean side...makes sense (cold air is denser [huh] and SUs being a constant velocity design have no mechanism for air density compensation)...that's why I find myself adjusting the jets down three flats for the cold season and back up three flats for the warm season (but other than that, I dont touch my carbs except to check and add ATF to the dashpots once in a blue moon). BTW, I typically approach the optimum mixture setting (or at least a satisfactorilly performing one) from the lean side, and leave it set to where I get that satisfactory perf....so I won't cover the rich mixture result too much except to say that if you think you might be rich, back off on the jets in half turn steps, and redo the test...I think you'll find those (noticable) lean results fairly easily (and a road test would sure confirm this).
Road tests:
For checking the midrange mixture (probably the most interesting operating condition to me), I'll take the vehicle out on the road, and at a steady midrange speed, quickly floor the throttle (this is probably the maximum load I can put the engine under - up the steepest hill around is even better as it allows a prolonged highload condition...if I get a slow response, that suggests lean again (see above) and I'll richen both carbs by three flats. Obviously, this assumes ignition (including timing and advance) fuel system (including balance, float height, fuel pressure, metering needle selection, fuel delivery [i.e. no obstruction by sediment in bottom of bowl or some other wierdness - I've seen it!]), and other little details like that are all under control and mixture is the only parameter in question at this point. Once you're close to being satisfied with the pref., pulling a plug after a prolonged run of a particular operating condition which you want to check, cheching the color against the published charts, will give you more info to base additional diddling upon...
Its clear to see that experience, judgement, and discretion play a huge role in this adjusment business...doesn't that make a great point for all the things a modern fuel injection/engine management system does for you...sniffing all the temps, pressures/vacuums, your throttle input and whatever else, and looking up and dispensing just the right amount of fuel for each cylinder...most impressive when it works...then again OBDII never got anybody home when something crapped!
Cheers
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