2.8 riddle

[todd reid]

Here is a question that has puzzled me for a long time, that I would like to run past the collective brain trust of club members.

BACKGROUND: I put the complete drivetrain from a 74 Capri in my Alpine back in the early 90's. The engine was rebuilt to stock spec except for an overbore to clean up cylinder taper (cam, pistons, bearings all new). The stock 2bbl Motorcraft carb was rebuilt, and all polution equip was removed.
This situation has been present since day one (15+ years) and has not changed.

QUESTION: When fully warm, the engine will pull stongly in 1st gear up until about 3500 rpm, at which point it it become reluctant to rev higher and occassionaly spits a little bit. In 2nd and 3rd gears it pulls stongly and smoothly to 4500+ rpms, and in 4th it pulls stongly to 4000 or so before wind resistance, etc start taking their toll.
So what's going on in 1st gear? I've always attributed it to some combination of carb setup and vacuum advance (lighter load in 1st gear?).
What do you experts think?

 

[Bill Blue]

Todd, all in all, it sounds a lot like my Pinto 2.0 was acting. Turned out to be a bad condenser. I think with a marginal spark, the engine will run fine until the engine load reaches a certain point. The load varies with gear selection, throttle position and road conditions, so the exact rpm problem occur seems to be constantly changing.

I'm pretty sure all 2.8's used pointless ignitions, but electronic ignitions can produce symptoms similar to points. Have you ever changed the "box" and coil and did it make any difference?

Bill

 

[V6 JOSE]

Hi Bill,

The 1974 Mustang II' and Capris came with a points ignition, so he could be experiencing what you describe. Electronic ignition was introduced on these cars, in 1975.

When I read the post, ignition was my first impression too. That is where I think Todd should start looking.

Jose

Todd, all in all, it sounds a lot like my Pinto 2.0 was acting. Turned out to be a bad condenser. I think with a marginal spark, the engine will run fine until the engine load reaches a certain point. The load varies with gear selection, throttle position and road conditions, so the exact rpm problem occur seems to be constantly changing.

I'm pretty sure all 2.8's used pointless ignitions, but electronic ignitions can produce symptoms similar to points. Have you ever changed the "box" and coil and did it make any difference?

Bill

 

[todd reid]

Thanks to all that took time to reply. '74 Capri was a points & condenser setup (in a Bosch Distributor). Hard to believe that I have been running on a bad condenser for 15 years, but its certainly easy enough to swap it out. I will report back if I find anything.
TR