Trouble shooting today and found badly clogged inline fuel filter. When I looked down into the small butterfly chambers I saw this. Seems a small brass jet is missing from one of the throats. Is this going to badly affect the running of the carb ? Do I need to hunt down a spare carb for parts. Don't really want to replace it seeing as it had been re-built at some stage --- good ones are hard to find and expensive.
I've literally have done hundreds of qjets and never seen that missing,also never seen Phillips head screws in the center either. Yes I'd look for a different carb.
I don't know where that carb came from, but that is not a factory primary venturi...looks like a badly rebuilt hack-job. The air-horn screws are not stock either...sorry to say that whole carb is likely a poorly re-manufactured unit which won't do anything other than pass emissions testing. The jets are down inside the float bowl, the parts in the photo are supposed to be brass metering orifices for air bleeds & such and are pressed into the casting. Reputable shops know the dimensions, and know how to replace missing orifices rather than tapping/screwing in some mismatched replacement parts which won't function correctly. I've had some high-dollar "rebuild/tuning shops," do similar things on my cores...and return me with a beautiful-looking Q-Jet that leaked everywhere & ran worse than my friend's POS holley double-pumper that blew out both of his mufflers. There are a number of reputable builders on this site who can likely furnish you with a proper replacement which won't be overly expensive. https://www.everyday-performance.com/
That's a accelerator pump discharge nossle that it missing. The only effect of that not being there will be a bigger pump shot into that Bore of the Carb and that throttle Bore will run out of pump shot sooner. Jetting and cruse will not be effected. The question is who's motor did it go thru if it feel out when a motor was running? Is that a 4Bbl, because I have never seen that type of accelerator nossle in a pre 1981 Q-jet before.
The carb is off a Chev 350 truck. Cliff R. said it's a good choice of carb. Got in contact with Quadrajet Power and they can supply the new air bleed nozzle. I'm going to persevere with it for now ----- because a Nailhead specific QJet would be impossible to find here. After I get all the teething problems sorted with this hot rod build ( and there's plenty of them ) maybe I can then start hunting down something else if it doesn't work out.
UPDATE ! Went to a local car and parts swap today and got a 1980 800 CFM QJet , appears to have had little use. Got these different idle mixture screw adjusters. Will have to get a special tool I suppose --- or make one. Will change out carb and see how we go, after sorting other issues.
Yes, it takes a different tool. The hole to the side of the hole the screw is in was drilled in order to be able pop out the factory-installed cap that prevents people from tampering with the settings. You won't need to get caps, I hope.
