I think my carbs are Rochester 4 Jets? Both have idle mixture screws, the rear has a choke and pump. Should all 4 screws be fairly close in adjustment, like 1- 1-1/2 turns out for starters, or is it less with 4 screws? Here is a manifold pic off ebay, can't tell what ports share what cylinders.
Those are WCFB not 4 jet. 1 1/2 turns from lightly seated, some say the front plugs will run lean and rear plugs a bit rich. So, richen up the front and lean the rear .
It's been 46 years since I ran one but what Big Deuce said sounds right for a starting point. From there you dial it in until you feel you have it right.
After skipping through some more reading, 3/4 to 1 turn open after lightly seat seems popular. At that point, closing them until RPM drops off and back out 1/8 turn. Have they been freshly gone through, or operating as found?
Thanks duece. It was idling smoothly till I messed with it.. Oddly it would start and idle low and smooth, from dead cold, no fast idle, no choke. I figured that meant it was too rich and washing the rings, so I checked the screws. Backs were out a turn or more, fronts about a half turn. I think someone just played with the fronts as they are easy to get to. All seem to be working, changing idle. I put them all out one turn. Idled rough but I quit there seeking advice. I'll start with your suggestions tomorrow. They look like hell but work great otherwise, except the pump doesn't work. Don't know if they've been apart, not on my watch.
Pull a couple plugs maybe and see if they are black. Maybe 3/4 turn is a sweet spot, or a fouled plug could cause rough idle. If it still runs rough with the mixture screws in tighter, and you know its running rich, fuel is coming from somewhere else.
I was looking for the fuse box location in the Operators Manual just now, which oddly isn't mentioned, but came across carb adjustment. Didn't expect that, nor a lot of other mechanical stuff you won't find in new glove box manuals. Anyway looks more complicated. Byp*** screws? Byp*** what?
You need one of these. Summit sells them. I rtv’ed a plastic adapter to the Holley protector top I bought at the same time. There is nothing available for the small top air horns of the early carbs. I idle on both run on the back. If original carbs the front has no choke or holes for it. There are are longer adjusting screws available that your can turn with a 1/4” wrench to make it easier.
Thanks. I have a Unisyn from motorcycle tuning. Good idea. Yes, no choke or pump on the front carb, mechanical linkage kicks it in at some point. It's actually a surprising peppy engine. The mixture screws do have 1/4" hex, only way to turn the back ones really.
If the top photo is your set up you have a front pump as I can see the linkage. All WCFB’s do.. if it’s not pumping because it’s bad you need to replace it with a ethanol friendly one. The longer mixture screws make the rears easier to adjust. I bought mine at Danchuk since I live close. The Carb King on the HAMB is great for help and has kits available for all these.. good luck.
Yes you're right, sorry. I checked those byp*** screws this morning, like the mixture screws they are far apart from each other. Didn't mess with it, waiting until I make up an adapter for the Unisyn. Do the pumps come out by just removing that 2 screw cover?
Nope. That will remove/adjust the metering rods but you can take it off with the engine running to check and see if the metering rods are down in the jets from the vacuum. With the engine off they are sometimes hard to get back started in the jets. There is a small spring in there that needs to be in the correct position also. The top will need to come off for the accelerator pump. I’ve done it on both of mine at times on the car but better To do it on a bench.
By all means, remove the carb from manifold and dis***emble on the clean workbench. Don't want to take a chance on dropping anything into engine. Let's see if @carbking has any advice for OP.
Would be nice to know the numbers on the tags. There is a HUGE difference from the 1956/early 1957 carbs to the later 1957 / 1961 carbs. The manifold pictured is for the 1956 / early 1957 set-up. The mounting gaskets for the later units are quite different. No guesses on idle adjustment until I know which carbs you have. Jon
Hi Jon, didn't notice your reply. I've been fixing other things, and today decided I need to get to this. Here's the tags, should be 1956. The byp*** and mixture screws were far apart from each other as I mentioned, but it idled smooth. I set them to one turn, now it idles rougher, of course.. I'd like to change the pumps without removing the carbs. I've done Q-jets, Strombergs.. but if there's a chance of losing something, even with the ****erflies closed, I'll take them off. Thanks, Paul
Those can be tricky. I would try the mixture screws at 1 1/4, and then set the idle RPM with the air screw. Not saying you cannot change the pumps on the car, but I wouldn't. Jon.
Thanks Jon, I got it warmed up this morning, mixture screws seem to like 3/4 turn better than 1 1/4 but still need to fine tune. Curious why both carbs need idle circuits. since the front doesn't kick in the main circuit until you stomp on it. I may put off the pumps again, it does just fine after a few minutes warm up without them. Really seem to be well mannered carbs. Paul
there is a test you can do. Turn in both mixture screws on the front carb and then close the idle ****erfly. After doing that, keep adjusting the rear carb to idle the engine. I couldn’t do it worth a dam on mine with WCFB’s so I went back to both and with a vacuum gauge and a UniSyn got mine to idle perfect at 550 with an automatic in gear.
As far as the shared cylinders every other cylinder in the firing order. I would run the front carb completly closed but you will still need to adjust idle mixture on it. Adjust idle speed off the back carb
You can also do an easy check on the float levels. There are two small plugs on the side of the carburetors, one for front chamber and one for the rear. With the engine idling remove a plug and the fuel level should be just at the bottom of the port. No float adjustment is needed. If you can't see the fuel, the level is too low and if fuel runs out of the port, the level is too high. In either case the floats will need to be adjusted.
And just think folks think Whooly’s are the only ones that have that feature. Adjusting is pita but the WCFB’s are great.
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