I run 1:1 linkage on my dual carb setup, and it runs fine and idles clean. I think progressive linkages are adding complexity that you don't need. Just my 2 cents.
Edelbrock setup for dual quad
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TT5.9mag
Two atmospheres are better than one
When you double the available throttle bore area you effectively cut in half the signal to all of the fuel supply. You went leaner initially with rods and jets and you should have gone richer. Common misconception that a bigger carb (or multiple carbs) will drown an engine. It’s exactly the opposite. Make changes based on observations not on assumptions. Read your plugs.
Thanks for this, I am just about to install a dual quad, 1:1 setup on my 408, and did exactly that. I jetted carbs down thinking there would be more fuel. I will set them back to standard setting for initial trial.
TT5.9mag
Two atmospheres are better than one
Jetting (and all fuel/timing adjustments for that matter) should always be made because you observed something. Find a problem, Make a change, observe the result, repeat. You dont ever want to guess or assume.
Look at post #24, bullets 17 and 18. Thanks @toolmanmike
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Information on the 273
Hey there, Ive gone and done some reaserch and have read some articles about the 273 already but I am very intrested in what anyone who has owned or owns a car with a 273 in it has to say about them. What makes them diffrent from other mopar small blocks? What kind of issues do they have? I...
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I installed an AFR gauge in my car when I first put it together with the dual quads. Using the AFR gauge, and old school reading the plugs, it is easy to get your car running right. I recommend an AFR gauge to anyone with a couple hundred bucks to spare.
Agree, but when you are doing something new, you need a baseline with which to start. Can't observe, until you try something. Seems my intuition was wrong on baseline settings.
Same here, my assumption was 2 carbs=more fuel than single 4bl...plus mine is a 273 so overfueling seemed more than likely with 1405 and 6. Plus the exhaust would burn the everlovin' eyes right out of ya lol.
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A couple of Holley 450's would have been a sweet setup. 
Havent touched it since I posted this, but before I changed the carbs back to stock I thought I would ask this....
I'm not ignoring suggestions, but before I change rods/jets, what about changing main rods/jets to stock and leaving 2ndary jets in both carbs 1 stage lean?
Thanks
Steve
I'm not ignoring suggestions, but before I change rods/jets, what about changing main rods/jets to stock and leaving 2ndary jets in both carbs 1 stage lean?
Thanks
Steve
TT5.9mag
Two atmospheres are better than one
You don’t need to mess with the secondary rods/jetting at all right now. Leave those for when you get to wot tuning. Just make sure the secondary bores are closed. Then work on getting the primary right. You are popping through the intake because you are lean. You need more fuel.
Thanks, so heres what it looks like main carb 2ndarys with lid removed.
I'll replace main rods/jets tomorrow.
Double check float level and drop also.
Thanks.
I'll replace main rods/jets tomorrow.
Double check float level and drop also.
Thanks.
Tune the primaries first. You do this by disconnecting the link that connects the pri & sec shafts.
Just remove the circlip that holds the link onto the pri shaft & let it hang [from the sec shaft ]. Both carbs.
Just remove the circlip that holds the link onto the pri shaft & let it hang [from the sec shaft ]. Both carbs.
Sr4440
Well-Known Member
Hello, my name is Joe, and I own/run an engine dyno. I have done dozens of duel 4 barrels. 1st, don't worry about the secondaries, they will never open, unless you get to 5500. 2nd, all Edelbrock carbs are rich out of the box. 3rd get a a/f gage if you want to dial it in right, it will be quicker, and you will be a lot happier. Unless you like pulling a plug every 10 mins.
If it doesn't idle unless the idle mixture screws are way out, look for a vacuum leak by spraying carb cleaner on the head mating surface. Without data, everyone is just guessing.
PS Edelbrock carbs are so nice when they are dialed in!
If it doesn't idle unless the idle mixture screws are way out, look for a vacuum leak by spraying carb cleaner on the head mating surface. Without data, everyone is just guessing.
PS Edelbrock carbs are so nice when they are dialed in!
Getting closer.
Still open to advice?
Still open to advice?
TT5.9mag
Two atmospheres are better than one
Stop trying to run it and tune anything until you have all the vacuum leaks plugged. It won’t do a damn thing. And whoever told you to run the mixture screws all the way in is wrong. Bottom them all lightly and then turn them all out 1 turn as a starting point. Closing the choke on the secondary carb won’t do anything if you have the curb idle screw backed all the way out either. You’re getting there.
Thanks, vacuum leaks are plugged now. Front carb pcv plugged. Checked timing and its 17* with VA plugged.
I've never messed with a DQ before so a steep learning curve here for me. There was a reply by another member that said to back off curb idle all the way and screw in idle mixtures all the way, so I took his advice, he runs his DQ's like that all the time. Like I said I have no idea. But I did as he mentioned and it fires right up now and idles pretty good(after getting pcv hooked up and plugging open port on back of intake). Some of it looks like an abortion(coil bracket, return spring bracket, progressive linkage)but its functioning.
I have no throttle cable so I cant test drive it unfortunately.
Lol, yeah good point with choke on front carb. I'm actually surprised with how good it fires up and idles. I have choke linkage unhooked and not hooked up electrically.
It seems to be running rich as exhaust takes eyes right outta you lol.
I'll try 1 turn out on both carbs for idle mixture screws.
What about curb idle on 2ndary carb?
I've never messed with a DQ before so a steep learning curve here for me. There was a reply by another member that said to back off curb idle all the way and screw in idle mixtures all the way, so I took his advice, he runs his DQ's like that all the time. Like I said I have no idea. But I did as he mentioned and it fires right up now and idles pretty good(after getting pcv hooked up and plugging open port on back of intake). Some of it looks like an abortion(coil bracket, return spring bracket, progressive linkage)but its functioning.
I have no throttle cable so I cant test drive it unfortunately.
Lol, yeah good point with choke on front carb. I'm actually surprised with how good it fires up and idles. I have choke linkage unhooked and not hooked up electrically.
It seems to be running rich as exhaust takes eyes right outta you lol.
I'll try 1 turn out on both carbs for idle mixture screws.
What about curb idle on 2ndary carb?
TT5.9mag
Two atmospheres are better than one
Curb idle on secondary carb should be backed out for initial tuning. You may find that it needs a little curb idle from that carb later on but for now back it off. And in that case it won’t matter where the mixture screws are, bottomed is fine. But don’t bottom the mixture screws in the primary carb. Start one turn out.
Got it idling decent, still seems really rich, or blow by?
Sr4440
Well-Known Member
At idle, the "rods" are not used, all idle fuel is controlled by the idle mixture screws.
Thanks, I guess I'll have to improve on my idle mixture tuning. While the screws affect the idle and vacuum,
They dont seem as responsive as they "should"??
Of course they are a pita to get to wedged in between the 2 carbs lol.
What's your take on the soot? Blow by or excess fuel?
A compression test is on the list.
They dont seem as responsive as they "should"??
Of course they are a pita to get to wedged in between the 2 carbs lol.
What's your take on the soot? Blow by or excess fuel?
A compression test is on the list.
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