Quadrajet power piston

[SRU1436]

I’m rebuilding my quadradjet (7043202) on my 72. While watching videos on the rebuild, I noticed my power piston (the rod coming out of the bottom) is significantly shorter than what I’ve seen in videos. Mine appears ground away. I measured mine and it appears 3/32 in length. See attached photo. I don’t think it should be that short, based on pictures I’ve seen. See photo from quadrajet power.com

Is the rod coming out of the bottom making a difference in the performance of the power piston?

Thanks.

[RustyPile]

High manifold vacuum "sucks" the piston down in the bore, along with pulling the metering rods deeper into the jets. This effectively leans out the F/A mixture. As vacuum is reduced, the spring lifts the piston and metering rods, enriching the mixture. That rod is the stop for the piston.. Why anyone would cut it off is anyone's guess.. I'd be replacing it.

[SRU1436]

Thanks, it appears it’s worn done over time. It’s original to the truck.

[Rust_never_sleeps]

I believe it's the later models with APT that have the pin at the bottom
Yours is a 73 by the casting number, APT showed up in 75

[RustyPile]

Originally Posted by Rust_never_sleeps

I believe it's the later models with APT that have the pin at the bottom
Yours is a 73 by the casting number, APT showed up in 75

I was thinking APT showed up later.. That was so long ago for me to be trying to remember, but I do believe you're correct.

[Rust_never_sleeps]

Originally Posted by RustyPile

I was thinking APT showed up later.. That was so long ago for me to be trying to remember, but I do believe you're correct.

More accurate to say APT showed up in 76
75 had a one-year-only version of APT with aneroid adjuster that....was not universally loved

[SRU1436]

I bought another power piston with rod in the middle, should be longer based on the picture. Once it gets delivered, I’ll measure the difference. I might run the current one and then swap it out for the one with the longer rod to see if I can notice the difference. Thanks for the help.

[Rust_never_sleeps]

Originally Posted by Rust_never_sleeps

I believe it's the later models with APT that have the pin at the bottom
Yours is a 73 by the casting number, APT showed up in 75

I had this wrong: Definitely a skinny pin on the side of the piston for APT, BUT
The fatter pin on the end of the shaft is absent on at least some APT carbs