[6pack] Annoying Bucking/Stumble

Sally or Dick Taylor tr6taylor at webtv.net
Mon Apr 9 14:16:56 MDT 2012


Brian---Too many possibilities here to list, so let's do the easiest ones to check or change first.
Your symptoms could be either ignition or fuel related. Weak spark will generally show up when the engine is under load, at the lower rpms. The higher compression you have makes this more likely. You can try different points gaps from the std. .015, going to a =/- .005 for testing purposes. A more costly but effective alternative would be a CD ignition, such as the MSD6A, along with their (in-cockpit) timing control.

On the fuel side of this, try a heavier oil such as 20W50 in the dash pots. This oil viscosity comes into play below 3,000 rpm. If this doesn't help, raise the needle assy. a half turn on each carb., going to the maximum lift, if necessary.
As I said, you can always go back to the original settings if none of the above help. Write back!

Dick 


-----Original Message-----
From: brian at asmoothmove.biz
Sent: Monday, April 9, 2012 6:44 AM
To: 6pack at autox.team.net
Subject: [6pack] Annoying Bucking/Stumble

Hi guys,

Maybe some of you have a remedy for a problem that annoys me. 

When my engine is at operating temperature, the car will buck several times
when applying part throttle, under load, in 3rd, 4th or overdrive. It does
not do this when cold, nor if I down-shift. The carbs were re-built by
Paltech last year - air valves don't seem to be opening prematurely and I
have the proper oil in the dashpots. The plugs (clean), cap and condenser
are newer, wires OK, points clean, new rotor installed. Timing is dead on at
12BTDC when the retard is plugged off. Stock cam/exhaust and 10.1
compression - recent cylinder head rounding/polishing to eliminate pinging
(which it did). 

Any ideas out there would be greatly appreciated.

Brian J. Alwin
1972 TR-6
CC79085 

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