It is a Rochester. 1971 Skylark with a 350 a/t p/s. I took my car out for a drive a few days ago. It started up great and idled pretty swell to my ears. It did just fine in the neighborhoods but out on the main roads it kept bogging down and dying in the middle of the road. Brought it back home and did some testing. I hooked up an old tach out of another car and it idles at 1000 rpm. The bogging and missing doesn't show up until about 2800 rpm, after 3500 it seems to roar and function well. I peered down into my jets and noticed only the primary was opening under throttle in park. A friend of mine who is a well known mechanic for over 30 years told me the secondary wont open unless under load. He also explained to me how to adjust spring tension on my secondary using a flat head and an allen wrench. I myself am very new to carburetors but am slowly coming to terms. I want to be able to drive my car without it dying or sounding like a disgruntled demon. There's a lot of good info on this site about quadrajets... I'm looking for a good solution for my 2 barrel that I can run for now until I get a quadrajet for my other intake. Thanks guys, Mike the man.
I'm afraid I don't understand. A Rochester two barrel carb doesn't have a "secondary" that will "open under load". A Quadrajet does, though... it has two primary throttle bores and two secondary throttle bores. Can you post a photo of your carburetor so we know what we're talking about? Devon
This is a picture down the throat of my machine. Another of the full carb. The butterfly valve on the top of the first picture seems to want to open, but doesn't.
Alright Mike, you do have a Rochester two barrel, but the flap you're thinking is a "secondary" is your choke, not a secondary air valve like the q-jet features. Might be time to find a a different mechanic, I'm afraid! Do you have a chassis service manual for your car or any other source of instructions for adjusting the choke, if that is your problem to begin with? If not, maybe we can dig up some online sources. Devon
I have the original repair manual. I'm not talking about the choke. The choke is the plate on the very topside of this carb. I guess to put it in better words: when you view the carb from the front of the car, looking straight down into it, the right hand barrel wants to open but wont. I see fuel spraying from both jets, but the hole just wont open. In my experience, aren't those two valves at the bottom of the barrel supposed to be connected and actuate identically? Or am I still thinking about all my friends with their 4 barrels...? Thanks for the continued help Devon.
The Rochester two barrel carbs have a single throttle shaft that opens both throttle blades at the same time. If you're only seeing one of the throttle blades opening, I'm guessing it's the side connected to the throttle linkage. If this is the case, the throttle shaft is broken and only opening one blade, the one on the left (driver's side). Can you confirm this is what you're seeing? Devon
That sounds like precisely my problem, however, it's the passenger side that opens, the driver's side is the one that isn't working correctly. Since the throttle linkage is on the driver's side why would it only open the passenger side? Could this be the reason it bogs and misfires around 2800 rpm?
Yep, in this case the left side throttle blade probably froze in the bore, breaking it's attachment to the throttle shaft, thus the right side is still opening fine. So now you're down to a one barrel, I'm afraid! Consider a four barrel manifold and Quadrajet upgrade unless you're planning to repair what you have. Devon
P.S. I'd not drive it anymore unless you can remove and inspect the carb. You don't want broken pieces of the throttle shaft to be ingested any more than they may have been already. Devon
I have a 4 barrel intake sitting in my garage. I just need to find a carb that fits my extremely low budget. I understand what has happened now. Very happy to have a 350-1 hahahah. :rant: Again, thanks for your help Devon. Mike the man.
wow, that's interesting. I have a bunch of 2bbl's if you need one. I may have a Qjet. I built most of them and sold them, but may have another somewhere if you are interested.
What would the pricing be like on the 2 barrels? You know, just shoot me a price on the quadrajet too. I may be coming in to a bit of cash in a few weeks. Are they just functional cores or have they been gone through? Mike the man.
