just had the valve stem seals done on the 429 with the passenger side head coming off due to a broken bolt.
That is all done and back together. Now one problem leads to another. The engine will not idle
or idle adjust as it should. If I screw the main large idle adjust screw in on the carter the engine still
runs - if I turn the drives side smaller idle air adjust screw all the way in the engine does not stop.
There is a noticeable flat spot right at bottom of idle on take off and the engine just is not right at least
Is this an indication of a vacuum leak? The problem is still there if the PCV valve is off and blocked,
same with other vacuum lines. Hope that makes sense and I can get some advice.
"Brains Trust" required at the front counter please.
Are the throttle plates closed? take off the carb linkage and see if the problem goes away. The idle circuit stops controlling the engine once the plates open, so it seems most likely to me that when reinstalling the intake, that the carb is now in a slightly different position and that this has disturbed the linkage adjustment.
Did you put the metal shim back under the Carter carb? It will not idle with it removed. Was any sealant used between the metal shim and the base of the carb?
There is a choke idle adjustment screw, but not an idle adjustment screw. The idle is accomplished with the bleed air screw and fuel mixture screws.
Quick question, should there be gasket cement (sealant) on both sides of the shim?
The sealant should be applied to the surface that mates up to the carb, but I out it on both sides.
Thanks Russ. I’ve neglected to reinstall the shim when I put the manifold and carb back on, probably explains why the idle is very up and down.
Yup, the carb was modifies to not idle with the shim missing. Good find.
thanks all to start lots to think about. Tony the car is running Petronix 3. Before the head came off and on (left only) of course there were no issues -- car idled perfectly. I will get back on it today or when I get time and investigate further and update.
OK went back to timing - put in more advance from where it has just been set. That is the problem solved.. It seems to have more advance than recommended but I remember reading in another post that using more advance in these engines as they get older is necessary is that right?
Anyway car is running as it was before and no more blue smoke out the tail pipe!