Picked up a q-jet this weekend. What's this thingey?

[Recian]

So yeah I picked up a quadrajet this weekend. The truck I got it from was a 80s with 305, EGR, no AIR injection. Identical to my truck just a 4bbl. What's this weird sensor in the bowl? It sticks out the top. I have the connector/harness. It just plugged into the engine harness and grounded to the engine.

[chengny]

That is a mixture control solenoid.

If your truck has no ECM don't bother installing that carburetor - without an input signal to the MCS it will default to full rich.

[Recian]

No way to get around it?

[Recian]

Wonder if I could take the electric choke off it and swap it to this instead

http://www.ebay.com/itm/ROCHESTER-QU...b430c9&vxp=mtr

[chengny]

You know what, that might not be a mixture control solenoid under that connector cap. You might be able to use it as is afterall.

Big questions - and I can't tell from the picture:

1. Is the plastic connector blue?
2. Is there a TPS?

If the answer to both is NO - it is not a MCS type.

It is a dual capacity accelerator pump design and you should be fine to mount it and go. A dual capacity Q-jet will run without input from an ECU. All you need is the basics (i.e. an accelerator cable, fuel supply, etc.).

Basically nothing needs to be done to have the carb perform just like the earlier single capacity accelerator pump carbs. The plug and solenoid can be left intact, the default setting (with no external wiring or electrical source supplied to the plug) is such that the accelerator pump will deliver a normal pump shot.

Differences between the two types:

[Recian]

Mine is identical to your first picture. That solenoid is the only wire and connector on the whole carb

[Desert1957]

Probably one of the worst Q-jets ever made, most of them are in some land fill.

Desert

[t5noel]

Originally Posted by Desert1957

Probably one of the worst Q-jets ever made, most of them are in some land fill.

Desert

Which? The first or second?

[jimboh247]

The carb on my 85 is identical to the 1st picture, and my dual capacity accelerator pump is not hooked up. The wiring harness connector for it melted on the manifold.

[Recian]

I think he's referring to the 2nd one with all the sensors. I heard they're worthless which is why I've been avoiding those and why I snagged this one as soon as they dropped the truck in the yard. thought this one was better since it didn't have sensors and crap all over it. Jimboh I've got the connector harness from my carb. snagged it with the truck if u need it

[jimboh247]

Are you in New Bern, NC?

I'd love to have it. PM me with what you need for it.

[t5noel]

Originally Posted by Recian

I think he's referring to the 2nd one with all the sensors. I heard they're worthless which is why I've been avoiding those and why I snagged this one as soon as they dropped the truck in the yard. thought this one was better since it didn't have sensors and crap all over it. Jimboh I've got the connector harness from my carb. snagged it with the truck if u need it

Yes, I agree. I was fortunate enough to be given one identical to the first. Got it rebuilt and put it on a crate 350 from summit in a 74 GMC stepside. It runs like a dream without a single adjustment except for the high speed idle.

[chengny]

Sorry for the gloomy initial response. The color of the plastic cap is a dead give-away.

Blue = MCS - always with a TPS - (ECU required)
Green (or brown or gray - I'm color blind - just not blue) = Dual Capacity Accerator Pump - (not ECU dependent)

[Recian]

so that sensor will pretty much just sit there and plug the hole in that carb, it will run like a standard quadrajet, adjustments work the same and all that? If so I don't need the connector pigtail and it can go to someone who needs it more.

Yes jimboh I'm in New bern, NC