Dual capacity accelerator pump

[cobalt327]

I want to use a 1985 Q-jet 17085292 (NON CCC/NON computer controlled), but it has the solenoid for the dual capacity accelerator pump. Will the accelerator pump work "normally" w/o the solenoid operational? What I mean is, is the default accelerator pump position the normal pump shot or the decreased pump shot?

And finally if the pump shot is "normal" is this basically the same as a non dual capacity pump shot?

Great to see there's now a "basic" rebuild kit available w/the same quality as before! I've recommended them already at the Hotrodders.com forum.

Thanks, Mark

[Cliff Ruggles]

We remove the valve under the solenoid and fill that cavity with molten lead when building those here.  They work just like standard units at that point. 

One could just leave the solenoid unhooked, as the valve is closed, but we like to block off the entire system in case there is a leak at the valve.....Cliff

[cobalt327]

I'm wondering if there might not be something to retaining the function of the dual capacity accelerator pump.

My thoughts are to make the mods to gain pump shot volume (if/when needed), but to have the solenoid wired through a coolant temperature switch for a reduced pump shot under 'normal' driving conditions. Then have it also wired through a toggle that could be used to disarm the solenoid for track use.

Does this sound feasible, providing the reduced pump shot was found to be enough for normal driving?

Thanks, Mark

[Cliff Ruggles]

Most applications (high performance) are going to want improved pump shot with quick/heavy throttle movements.  This covers any potential lean spots till the main system is fully on line.  The only way one would know if it would like less fuel in these conditions for any particular application, would be to test it.....Cliff

[73 Z28]

That is an interesting idea to be able to switch the dual capacity fuel pump feature on and off as needed for performance use or daily driving.......hmmm may have to hunt up one of those carbs to play around with.

[cobalt327]

What I've seen on ebay and craig's especially, is there are guys who really don't know exactly what they have. And many among the carb buying public haven't really gotten the word on these carbs as being anything other than an "electronic" carb. What this means to 'us', is there's often little bidding competition for them- either because the listing calls it an electronic carb or guys just don't know exactly what it is they're looking at.

But the reality of it is, these are non electronic/non CCC carbs, although there ARE dual capacity accelerator pump-equipped CCC/computer controlled carbs. Those carbs are easily ID'd by having a TPS plug and an extra pair of wires coming from the side of the mixture control solenoid plug.

AFAIK a non CCC carb w/dual cap. AP will respond to mods just as any other single main AB carb would, and I believe Cliff has the kits for them as well. Worst case scenario is the dual capacity solenoid wouldn't end up being used and you'd end up w/an airhorn that had a plug or a plugged hole.

If anyone tries (or has already tried) this, pls. post the results.