Idle quality


http://209.208.111.198/Topic113119.aspx 		Print Topic | Close Window

By Rusty_S85 - 10 Years Ago
I want to ask this just incase if someone knows where I should go directly to correct this problem.

I recently topped off the transmission and was able to get the car to go into gear.  Problem is the engine tends to have a roughness to it at idle in gear vs in park at idle.

So far I have the engine set at 600rpm in gear and 800rpm in park.  The valve lash is set at 0.019" hot.  The point gap is set at 0.015" if I remember correctly.  The dwell at 600rpm idle is 29* which is 1/2* more than the factory spec.  I have not checked timing as I had the engine running really good up till I started to put the engine in gear and found the roughness.  The engine isn't missing, I am just wondering if age and mileage has gotten to the engine and I need to bump the idle speed in gear up some but I had the engine idling at 600 in park before and it idled smooth.

Has anyone ran into this before and know what should be checked out?  I wont be messing with the engine till next weekend which will probably be just me checking timing and maybe even playing with timing a little.
By slumlord444 - 10 Years Ago

First get a timing light and get that right. Second check for a vacuum leak somewhere. Had a similar problem with a 302 in a Mustang and finally got it to go away when I replaced the carb with another one with a fresh rebuild.

By Rusty_S85 - 10 Years Ago
I will be checking the timing.  I know spec is something like 6* but Ive seen a lot of people claim these y blocks love 10*.  I might play around with it, if that doesn't correct it then I might need to try dumping some atf down the carb as I do have a lot of smoke coming out of he draft tube and the filler/vent when idling.  It starts coming out after about a few minutes of running.  I am not sure how these draft tube setups work but when I turn the key off the engine stops pretty quick telling me the rings must be seated.

It probably is just a timing thing.  Or I might need to adjust the idle mixture some more seeing as this is a Autolite 2100.  I have had to set them with the engine in gear before on my 302 and my 351W to get a smooth idle in gear which also resulted in a smooth idle out of gear.
By Ted - 10 Years Ago
Assuming the engine is in good mechanical condition (even compression, valves set, timing in the ball park, etc.) then I would try another ¼ turn out on the idle mixture screws and see if that helps.
By Riz - 10 Years Ago
I would defer to Ted but also Sounds like a vacuum leak maybe even the trans mod valve.
Had one that went bad and was actually sucking ATF into the manifold--it did take care of every mosquito in central Ohio for the smoke bomb -thought I had blown a head gasket.