Guys, I have been chasing a stumbly/miss type idle for years. I'm wondering now if the cam itself is a possible culpret. Is their a proper install position for this cam? I had the bottom end professionally rebuilt and the place re-installed the cam. I thought I remember them saying they set it at 0 degrees but I would have to find the original paper work to verify.

 

Do you have an adjustable timing set? I would assume that installing it straight up should be OK, as the cam grinder is the one who sets the timing of the valve events. If you have a non-adjustable timing set thats compatible with what the manf. recommends, then the cam may not be the issue.

That cam is the single pattern w/ a 112 LSA, correct? What kind of vacuum does the engine pull? If the engine doesn't pull good vacuum, and there is enough overlap for exhaust scavanging, then you can run into the issue of the injector pulses being pulled out into the exhaust. This is a problem with the old batch fire systems like TPI when running cams with overlap. The end result is that the engine runs lean.

Are you still running closed loop at idle? What do your BLMs look like? How do the spark plugs look after the engine has been allowed to idle for awhile? Are they white/grey? sooty?

 

74219 219/219 duration @ .050 .560"/.560"

Pulling 13" of vacuum. I even bought a Smoker and have checked for leaks over and over.

Still running open/closed loop. Car idles bad when first started as well as when hot. Blms show rich. Number 8 spark plug looks rich, others seem to be OK. Been through 2 sets of injectors, new disty, sensors, checked AFPR etc. No luck.

 

112 deg is correct...