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FE Technical Forum / Hanging valve?...NO, and another update
« on: January 12, 2020, 05:00:49 PM »
Recent build, 390 with Edelbrock heads, morel roller lifters, adjustable Ford iron rockers, PI intake. Motor is in a nice 1970 f100 I built for my daughter. My initial valve setting was one full turn after zero lash.
Maybe 5-600 miles on the motor. It has run fine, but always ran a bit rich at startup. Once it started getting cold here, I noticed it started sounding real fat with a bit of a burble. I finally modified the EFI tables to lean it out a bit at cold startup. Oddly, that didn’t make much difference. It got worse as it got colder.
Finally, I decided to investigate a little more and listen closer as the motor was warming up after a dead cold start. What I hear is the distinctive sound of a valve (or two) hanging open, not a fat burble. Once the coolant temp gets above 125 or so, it starts to clear up. At temperature, the motor runs great.
So, it seems I have one or two valves that are a bit tight? Haven’t pulled the covers yet, but looking for other ideas and things to look for before I reset the valves. I thought about pulling the plugs before it gets to temp and look for a couple wet ones. If it was distinctive and only one or two, I would back off the adjuster 1/4 turn on those.
With hydraulic lifters, wouldn’t they have to be REALLY overtightened to overcome the full travel?
Maybe 5-600 miles on the motor. It has run fine, but always ran a bit rich at startup. Once it started getting cold here, I noticed it started sounding real fat with a bit of a burble. I finally modified the EFI tables to lean it out a bit at cold startup. Oddly, that didn’t make much difference. It got worse as it got colder.
Finally, I decided to investigate a little more and listen closer as the motor was warming up after a dead cold start. What I hear is the distinctive sound of a valve (or two) hanging open, not a fat burble. Once the coolant temp gets above 125 or so, it starts to clear up. At temperature, the motor runs great.
So, it seems I have one or two valves that are a bit tight? Haven’t pulled the covers yet, but looking for other ideas and things to look for before I reset the valves. I thought about pulling the plugs before it gets to temp and look for a couple wet ones. If it was distinctive and only one or two, I would back off the adjuster 1/4 turn on those.
With hydraulic lifters, wouldn’t they have to be REALLY overtightened to overcome the full travel?