I've said this before, There is such a thing as too much idle timing. It may not be too much for the engine, just too much for the low-speed circuit sync. And then you get into tuning issues. And 18 is too much for your 218 cam.And heres the reason why: the Throttle blades get to be too far closed and port sync suffers to the point that you have to crack the throttle to wake them up. And in fact the transfer port can run dry and become an idle air bypass.
So The first thing you have got to do is check that sync. Take the carb off drain it by tipping it upside down over a cakepan or something. Dispose of the gas or collect it and put it into a closed container--Safety first!
Now flip it back right side up, and make absolutely sure that the choke is off and the curb idle screw is firmly against its stop. Hold it there and flip it upside down again. So you are looking at the butterflies.Find the front two. Orient them so they are the furthest from you. Now find the points of the mixture screws where they are sticking into those bores.Next find ,immediately beside them, the transfer slots. They are slots, running vertically up the bores. They are about a half a millimeter wide and maybe 3 or so, mm long. These are the ports we need to sync up.If you cracked the butterflies to find them, check the curb idle screw to make sure it goes back to the stop.
Ok so now you know what ports we're talking about. The one thats slotted concerns us. With the throttle closed that slot should appear as a very small rectangle, about 1.5 times as long as it is wide. On your engine it can be a little shorter; perhaps 1.25 times as long as it is wide. Make it so. Use the curb idle screw against its stop.Remember about the choke; You do not want to have the fast idle cam engaged. From now on do NOT adjust that screw. Ok so thats done.
Next flip the carb right side up. Again choke off.Check the secondary throttle blade opening. They should be as closed as possible, without sticking closed, and both should be the same closed.
Next, set your idle mixture screws to 1.5 turns from lightly seated. Lightly seated.Lightly.
Thats it we're done. put her back on. Fill the bowls through the vents and start her up. Warm it it up to operating temp.
Theres a good chance she will be idling fast.Do not be tempted to back out the speed screw.Instead bring the idle timing down a little at a time,to as low as 12* but no lower.Once the idle speed is down around 700 to 800, readjust the mixture screws as may be required, per Rustys method. If you have to screw them out much past 3 turns, we'll have to do something about that.Remember up to this point we have NOT adjusted the curb idle screw.
Alright I'll leave you to get that done. Then we'll continue.
Which fuel is in your tank?
More to come
