I am having a problem fine tuning a 261 and describing the "hesitation' ...puff....rumble... by email is difficult but here goes....

Totally rebuilt 261 (truck eng. with solid lifters)with less than 50 hours of running.

Oil at 40 psi...
vacuum at 22 in. and steady
....idles well around 425-450 rpm
Pertronix ignition....
not running hot...
revs up good.....
Std Rochester B carb totally rebuilt and adjusted on a flow bench
Using clean gas from a removable outboard motor plastic tank and a filter in line...
10W30 DIESEL MOTOR OIL with two remote
PH 8 oil filters

Symptoms...

slight ticking sound from valve train probaly one of the front cylinders on the loose side..

...the part that annoys me no end is a slight rumble hesitation in the exhaust pipe.....not a steady hesitation but a slight puffing sound that comes and goes without a specific repeat pattern... almost as if a cylinder was not firing completely...

Could I have a valve adjustment problem.... if one is clicking could I have one not closing properly but then it has to be interminently...?

I have tried removing one plug wire at a time but did not noticed any significant changes... now to be honest I may have to repeat that process with a pair of appropriate rubber gloves as the extra voltage from the Pertronix coil gives you repeated wake up calls....

Am I missing something else...overlooking the obvious...?

Comments suggestions...?

Bob C.

Last edited by RAC1812; 08/10/2010 8:46 PM.
Bob C.
CMP Heaven
The Hammond Barn