Quadrajet Irritations

[MrSony]

Rebuilt a 17058241 qjet, (78 800cfm Buick 350 carb, same model and year yadda yadda as the one currently on my car) put it on, runs like sh*t. Won't idle worth a damn. Above the idle circuit it's fine, but the thing won't idle below 1100 without stalling or idling at 300rpm. It was an ebay find, and for giggles I tried it on the engine right when I got it, ran like *ss. Gotcha. Fast forward a year to today, finally got time to rebuild it. Found the passenger primary metering rod tip was broken off, either by me or someone else. I used a set of rods from a 17057252 Olds 350/403 carb. I could also basically cover the choke tower with my hand and it'd idle up about 300rpm higher, indicating it's lean... right? The two Buick carbs (old one and new one) are exactly the same, minus the primary rod change. I bolted the old one back on, flick of the key (bowl was still full) and she turned over like butter and burbled at 800rpm dead.

Tomorrow I'm gonna take the jets and rods and powerpiston/spring out of the old carb, put them in the new carb, and see if it changes anything.

Wish me luck.

Any input is appreciated.


Yes I checked for vacuum leaks.

 

[pontiacgp]

are you sure the carb has the right gaskets?. I would get a rebuild kit for the carb and replace them

 

[Zspoiler]

To tune Q jets you need a knowledgeable touch .There are a couple of books from SAE books that may help you.

 

[DRIVEN]

Wishing you luck.

Covering the air horn and getting more rpm does indicate lean. I'd be looking for vacuum leaks but you said there aren't any. How is the throttle shaft for play?

Swap the parts and keep us posted.

 

[olds307 and 403]

All those carbs are very lean on the idle circuit. What are your motor specs?

 

[MrSony]

All those carbs are very lean on the idle circuit. What are your motor specs?

Stock 350 Buick crower level 3 cam. 276/281 adv. duration 112lsa. 18" vacuum at idle.

 

[MrSony]

are you sure the carb has the right gaskets?. I would get a rebuild kit for the carb and replace them

I did. Its freshly rebuilt.

 

[MrSony]

Wishing you luck.

Covering the air horn and getting more rpm does indicate lean. I'd be looking for vacuum leaks but you said there aren't any. How is the throttle shaft for play?

Swap the parts and keep us posted.

No play, moved throttle whioe spraying brake cleaner, no rpm change. Both sides.
And yes there are no leaks. Car wouldn't run perfect with the other carb if there were.

 

[pontiacgp]

I did. Its freshly rebuilt.

I'd take it apart to see what the problem is then, could be a passage is blocked. I don't see how that carb in it's original form would be running lean on a small block unless the engine is seriously modified. The 800 cfm carbs were used on big blocks