'67 V8 Down on power?

Recently noticed the '67 283 down on power. Barely can crack 60 om the freeway. Doesn't want to chirp tires like it used to. Seems peppy off idle and at low speeds, but a dog above about 20 or on steep hills.

Well, went through the usual suspects: timing ok, vacuum advance ok, heat riser valve ok. Suspected fuel starvation (from the symptoms) and replaced fuel filter. No change.

Then I pulled the air filter and checked the throttle linkage.  Aha! The throttle was barely opening the butterfly valves, and binding about 1/2 through its rotation (at least). Disconneced the accelerator pump linkage - throttle works normal. Waiting for engine to cool before I pull the carb apart to see what's up with that.

Fuel filter was only $5 and a snap to swap out. I think my instincts were right... the engine was starved for fuel, just from a different cause. Glad it's not the fuel pump.

Stay tuned....

Pulled top off carb, saw that the accelerator pump sping retaining clip might have gotten displaced. Crimped it a bit to make it have a better grip on spring, reassembled, and


HOLY SHIT!!!

The motor is transformed. Now it feels like a real V8. Burns rubber on turns in 1st if you push on it. Got up to 75 on freeway easily. Rush hour traffic in the way! 

Weee!

Good work, after all these are pretty simplistic   

Space Truckin wrote:Good work, after all these are pretty simplistic    

Thanks.

That they are... pretty simple...

Also addressed a certain lack of throttle pedal travel by taking off the gas pedal, removing the angle link, putting it in a vise, and gently bending it in the direction of higher pedal position. This now allows the gas pedal to give about 80% full throttle at the carb when pedal is floored.  The remaining 20% will need another session in the vice. 

The reason why this is necessary, I think, is that at some point before my ownership the master brake cylinder was replaced, with a model that sticks out too far, such that it interferes with the throttle linkage rod coming back to zero. To compensate the throttle linkage had to be adjusted to the point where the pedal was never high enough and full throttle was only a fond wish. Took me a while to realize that bending the angle link at the pedal was the only solution that wiould work, short of replacing the master cylinder with a shorter one - something that probably isn't too easy to find.  Anyway, now the gas pedal sits noticeably higher at zero and gives nearly full throttle when floored. A little more bending will finish the job - but for now the engine power is more than enough.

Turns out the accelerator pump push rod pulled out of the lower portion again... barely made it home a month later... went ahead and got a new pump... more details here...

https://vintage-vans.forumotion.com/t40336-more-fun-with-carbs