Before - 289/ rebuilt original heads/cap,rotor plugs,wires,filters(air,fuel,oil) changed/upgraded Performer cam/Aluminum Intake/600cfm 4v Edelbrock carb./and pos exhaust w/standard exhaust manifolds.

Ran very well. Would squeek the tires w/out using the brakes. Good pulling power.



Now - Just had someone put on a custom 2" exhaust w/Flowmaster Mufflers and Nickel plated Tri Y headers.

Runs pretty good except (1) I can't even squeek the tires now and (2) Will stall sometimes when the pedal hits the floor at a standstill.


Not that I'm out racing or beating on this 40 year old car, but was just doing some testing and comparisons. I was expecting 15-25 hp gain, but it almost feels like it has less pulling power than b/f. Doesn't make sense to me. The only thing I can think of is that the carb. and timing need some adjusting????

Thanks for any help and or advice you can provide.

 

Sound's like it's running lean after the new exhaust. I'd re-jet the carburetor starting with a two or three size increase.

 

Will adjusting the carb. (re-jet) affect the timing?

 

No.

 

OK, why did you go with only 2" exhaust??? You need a minimum of 2.25 with your set-up, but I went 2.5 in case I ever want to stroke my engine, or even go with a 351 down the road someday. Sounds like, but I can't see why, the timing got moved. Did anyone play around in the engine compartment??? You could rejet your carb as recommended too, Auto Zone has the kit, for 75 bucks I think is what I paid for mine. Try and re-set the Air/Fuel ratio screws out front of the carb. Turn them all the way in, then come back out 1 and 1/2 turns each screw. Be careful going in to not force them, they will bend something inside there, and it's a mess.

 

what are the cam specs, and does it require a stall or a larger exaust? If not I would start with adjusting the carb and go from there. How does the car idle? What rpm, any smoke or smell? Most likely the cam is to big for your app or you have a bad fuel/air mix.

 

Pull one of the spark plugs out and see if plug is a tan in color, if tan carb mixture is good. If plug is white the carb is to lean.

 

"OK, why did you go with only 2" exhaust??? You need a minimum of 2.25 with your set-up" - Then why did it run well before when it had a smaller diameter POS exhaust and standard manifolds?

"what are the cam specs, and does it require a stall or a larger exaust? If not I would start with adjusting the carb and go from there. How does the car idle? What rpm, any smoke or smell? Most likely the cam is to big for your app or you have a bad fuel/air mix. " - Car Idles well. No smoke/smell etc. If the cam was too big, why did it run great before? The cam was already installed. All that was changed was headers and exhaust. Plus it's not like it's a real aggressive cam.

Edelbrock Performer RPM
Designed for street high-performance applications, Performer RPM cams provide power from 1500 to 6500 rpm. These hydraulic lifter camshafts are dyno-matched to Performer RPM manifolds for high-rpm horsepower while maintaining acceptable low-end torque. With 10 to 12 inches of manifold vacuum at idle, Performer RPM cams have more lift and duration than most street camshafts. In the manifold section you’ll find horsepower graphs showing the power levels obtainable when the Performer RPM package is used with the right combination of engine components.

Performer RPM; Camshaft Kit; Ford 289-302; Hydraulic; 1500 To 6500 RPM; Valve Lift Intake .496; Exhaust .520; 7122

"Pull one of the spark plugs out and see if plug is a tan in color, if tan carb mixture is good. If plug is white the carb is to lean. " - Good idea. I will check the plugs.

I'm no expert, but logic would lead me to believe that if the air/fuel mixture was good before w/restricted air flow. Now, it is breathing much better and needs more fuel to burn to compensate for better air flow???