|
Oh yes, the definitely will need to be synched, that can be a source of the popping also (definitely a lean mixture will cause it). Here's how I used to do it with the Webers on my 914-6 when putting them on after disassembly and cleaning. (Note: This assumes jetting, etc. are all OK for the engine in question)
1. Carbs on engine, cross shaft between the carbs disconnected. On new installations you would need to eyeball down into the carbs and see if the butterflies are in more or less the same position, i.e. openings. When I rebuilt I didn't disturb the setting of the idle adjustment screw so that would be more or less correct.
2. Initial Settings: Make sure fuel pressure is correct, then set float level with the float gauge. Same thing with the accelerator pump discharge; set it. On the latter I found that the factory specs were 'way too much (again, for my particular car) and adjusted that down to something like .38cc/stroke (it's been a long time, that may have not been the number). Screw the idle mixture screws all the way in and then back them out about 1.5 turns. Close the little needle valves (air correction? Balance? I forget the term and don't have my books handy) at the top of each carb throat all the way. (These are the little bitty things with the locknut on them, top center of each throat)
On the accelerator pump discharge thing. If you romp down on it and you get an initial hesitation and it immediately clears and goes if you lift your foot a little, the pumps are lean. If on the other hand it bogs and continues to bog if you lift your foot, then clears after a few seconds on it's own with the foot still down, it's rich. What you want is an immediate and continuous response, foot on the floor.
3. Start car. First thing to do is to use your Uni-Syn (or whatever) tool to get the carbs more or less in synch from side to side and an idle speed of about 1200 or so. (Not too high here or you will get into the intermediate circuit) Then do an initial twiddling of the idle mixture screws. This should get you a more or less stable idle.
4. Now go back with the Uni-Syn and check each throat of each carb to see if the carb is pulling evenly. If not adjust all three throats on a given carb to pull the same, using the one pulling the most as the base; i.e. open the appropriate correction screws to make the low ones match the high one. Do this for both sides.
5. Now go back and using the idle mixture stop screws adjust the carbs to be pulling the same, and the idle speed again (probably need it)
While all this is going on you will probably have to "clear" the engine with bursts of throttle. Do this by just pushing manually operating the carbs together as much as you can; no need to hook up the linkage for this; just "blip" it with both hands.
6. Dress up the idle mixtures to get the smoothest running.
7. Recheck side to side synchronization.
If you're happy with the idle and synch, hook up the throttle cross-shaft. You may or may not have to adjust the length of the drop links. Keep checking the synchronization as you do this; some adjustment of the linkage will likely be required.
8. Just for kicks recheck/retwiddle the idle mixture screws. Also on my car I always found it better to be on the rich side here for overall performance.
9. Put whatever else needs to be reinstalled back on the car and go drive.
That's how I remember it. This worked for me for 18 year and probably six carb cleanings on the 914-6
|