Engine: 289 Engine Changing Revs

[WayneXG95]

Just a question guy's

My 289 62 Hawk feels like it's not running on all cylinders but it appears it is?
It also changes revs up and down while driving, not a huge amount but noticeable.
I also have a electronic ignition and Edelbrock 500 cfm 4 BBL

I have to see my mechanic on Tuesday and would like to have some ideas on this

Anyone else ever had this problem?

Wayne

[Kenmike2]

Check the centrifugal advance flyweights in the bottom of the distributor. When they're worn they do strange things.

I have remanufactured ones for sale.

Ken Michael

[JoeHall]

Are you just going by the tac? Sometimes tacs get squirrelly.

[GTHawk]

Just a question guy's

My 289 62 Hawk feels like it's not running on all cylinders but it appears it is?
It also changes revs up and down while driving, not a huge amount but noticeable.
I also have a electronic ignition and Edelbrock 500 cfm 4 BBL

I have to see my mechanic on Tuesday and would like to have some ideas on this

Anyone else ever had this problem?

Wayne

I had this problem with my '62 hawk after I had installed an electric fuel pump. The pump pressure was 9 lbx. which turned out to be too much for the carp. The needle valve let in extra gas. I replaced the pump with a 3 to 4 lb pump. Could also install a regulator that would be better as you can control the ourput even with a mechanial pump.

[64studeavanti]

If it is a presto lite distributor. I have found that replacement rotors fit way too loosely, causing changes in dwell and timing when running.

[PackardV8]

I had this problem with my '62 hawk after I had installed an electric fuel pump. The pump pressure was 9 lbx. which turned out to be too much for the carp. The needle valve let in extra gas. I replaced the pump with a 3 to 4 lb pump. Could also install a regulator that would be better as you can control the ourput even with a mechanial pump.

X2 - I was about to suggest fuel pressure too high or too low; either will cause the engine to gain/lose speed at a constant throttle. Same with float level, which is affected by fuel pressure.

jack vines

[Mike Van Veghten]

Going with the fuel also.
I'd check into the possibility of a vacuum leak somewhere in the system. This will cause a lean condition that will cause the engine to surge, or cause a change in rpm.
A too lean setup within the carburetor is another...slim... but possibility.

Mike

[WayneXG95]

Are you just going by the tac? Sometimes tacs get squirrelly.

No you can stand there and listen to it rumble and change revs

[WayneXG95]

Float Bowl had crap in it - each time the carb would pump fuel in the dirt would block the jet - problem sloved