>Thank you, PO. You installed an aftermarket cam but
>didn't bother to replace the Strombergs' needles-- you
>just cranked the mixture all the way to "rich," so now
>she idles like sh*t.
Hmmmm, I think there is a problem here.
Others probably know more than em about this, but......
Certainly, changing the breathing of the engine will alter its fuel needs,
but the beauty of the Constant Depression type of carburetor is that
for the most part they have just the right mixture all the time.
The needle is to fine tune the mixture, but it ought to be pretty close
as is. With the new cam, you did not change the engine's mixture requirement:
The proper proportion of gas to air is unchanged.
Except at high revs, you will not exceet the flow capacity of the stock carbs,
so the
carbs OUGHT to be able to deliver the proper mixture despite the new cam.
I think the problem is more basic. Maybe the cam is not timed correctly. But
it might
be more basic than that. Hot cams have a a lot of valve overlap (to have time
to get
the mixture in and exhaust out. At low rpm, the valve overlap makes the engine
have poor
vacuum and it can not draw the mixture in adequately. Excessively hot cams
idle like crap.
Or don't idle at all.
The PI engines were able to tolerate a rather hot cam because the injection
made it
possible to get the right mixture even with low vacuum. It did SPEW unburned
hydrocarbons at idle
due to the valve overlap. That is why we got the carb version. It was not the
PI, but the cam
that caused US emissions problems. But with the "normal" cam, there was ne
need for the expensive
PI system.
What you should do is take a long run on a freeway, then pull off somewhere and
shut down
the engine without idling (kill the engine and coast). Then pull a few spark
plugs when it cools
sufficiently and look at their color. You can judge the mixture somewhat based
on that.
-Tony
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