Dual quad info

-
I saw that on your channel, sounds great, thanks Rob.
If I went new carbs, I'm looking probably $1000 Cdn....at least lol.
Tempting to get one more Eddy 1405 to go with one I'm using now.
rumblefish360 said:
My buddy setting up my old set up. 600 x 2 AFB on a 11-1 - 360 w/a solid comp 294S, Edelbrock heads 1-3/4 super comps headers. Minimal tuning, ram very good.

Linkage is the Edelbrock stuff.

Click to expand...
 
The exact numbers of the carbs I don’t remember.
I messed with so many of them and that was so long ago. It may have been an electric choke carb at one point.

It doesn’t matter either way. The choke plate(s) were wired open or removed. In your case, (Canada cold days) an electric choke on at least the rear carb would make for an easy warm up and drive.

As far as netting goes, you’ll need to tune them per engine for best results. It doesn’t matter what it started out as.
 
I started with Summit twin Holley 390 dual quad package, that's just the carbs.

Needed to also get the Holley Vacuum Secondary Carburetor Accessories 20-73, as well as an air cleaner setup.

Then went to 600s, bought used and rebuilt. Far cheaper than the 390s and a huge difference.

Always had 1:1 linkage. Although the tr has a crossover built in, never used progressive.

Not sure how a regular dual quad intake works, whether each carb feeds all or 4 cylinders.
Either way, is there a potential for some to run richer/leaner with progressive?

20220708_010859.jpg
 
I'm in the process of putting together dual quads for a 318 - am using the paired progressive 500 AVSIIs from Eddy. They came with an instruction manual that shows the differences between the primary and secondary carbs. (avaliable on line) No reason you can't modify the one you have to Eddy's specs and then buy the other one to match. Mine will be on a Edelbrock D-66. I have had a few progressive DQ users suggest that you use the rear cab as primary. That puts the primary two barrels on the primary carb closer to the center of the system and leads to better distribution at low throttle between the front and back cylinders, rather than feeding the back 4 cylinders by drawing fuel all the way from the front of the manifold.

PS: I'm running two Eddy 500 AFBs on my 340 with an STR-12. You can't run the carbs progressive on the crossram so they are set up opening simultaneously and they run great. Since opening is controlled by demand on AFBs an AVSs, I think that that helps with potential overcarburation. If that is true, you might get by with putting your set up on the 273 to see what it does.
 
Steve, I found that linkage. It'a a Mr Gasket part. Still sealed in the blister pack. It will do progressive or 1:1. Let me know if you want it.
 
Good info, thanks! I'm hoping to be able to use another 1405/6. To mate to the one on 273.
Everything I've read/been told states the rear should be main one. Makes sense, as you describe those primaries are closest to center of intake.
Did your AVS11 come with linkage?
I'm not sure the terminology, this DQ is single plane, but its isolated side to side.
Thanks again!
str12-340 said:
I'm in the process of putting together dual quads for a 318 - am using the paired progressive 500 AVSIIs from Eddy. They came with an instruction manual that shows the differences between the primary and secondary carbs. (avaliable on line) No reason you can't modify the one you have to Eddy's specs and then buy the other one to match. Mine will be on a Edelbrock D-66. I have had a few progressive DQ users suggest that you use the rear cab as primary. That puts the primary two barrels on the primary carb closer to the center of the system and leads to better distribution at low throttle between the front and back cylinders, rather than feeding the back 4 cylinders by drawing fuel all the way from the front of the manifold.

PS: I'm running two Eddy 500 AFBs on my 340 with an STR-12. You can't run the carbs progressive on the crossram so they are set up opening simultaneously and they run great. Since opening is controlled by demand on AFBs an AVSs, I think that that helps with potential overcarburation. If that is true, you might get by with putting your set up on the 273 to see what it does.
Click to expand...
 
back in the day i ran the offy intake on my mild 383 in a 65 coronet 500 with holley 4010's (discontinued) with 1:1 linkage. then on my 440 in a 68 coronet r/t with comp afb's. both using threaded heim linkage with the idle speed adjustment screw removed from the rear carb. I used a drop link with jam nuts (cut down pushrod tapped to fit the stock cable end on the bottom and heated and flattened at the top for an eyelet to put the carb to carb rod through and adjust to cable length) no chokes. As stated, the carbs will only pull what's needed. strip kits were a must but i only had to upsize the mixture rods one size to get a good idle afr. driveability and performance was great on both cars
 
Thanks for posting, looks great! Which Eddys did you use?
Thanks for the info!
PA Dodger said:
Mine is a '74 360 HP stock compression, Hughes Whiplash cam, headers. Nothing crazy. It had a Performer RPM intake that was changed to the same dual quad you are putting on. The performance difference is unnoticeable.
Fuel line is similar to - Edelbrock 8088 Edelbrock Dual-Quad Fuel Line Kits | Summit Racing

View attachment 1716028741

View attachment 1716028742
Click to expand...

PA Dodger said:
Air Cleaner is Edelbrock - Edelbrock 1235 Edelbrock Pro-Flo Series Air Cleaners | Summit Racing
The air cleaner base has a slightly longer spacing than the carb's spacing. I made base gaskets that still seal it. The carb air cleaner stud holes had to be slightly modded.

View attachment 1716028745

View attachment 1716028747
Click to expand...

PA Dodger said:
Linkage is progressive. - Edelbrock 7094 Edelbrock Throttle Linkage Kits | Summit Racing
The throttle cable and kickdown is Lokar.

View attachment 1716028749

View attachment 1716028750
Click to expand...
 
They're Eddy 1405's. The progressive linkage makes the throttle a real smooth transition and the Lokar throttle and kickdown cables and bracket take a lot of headaches out of the setup.
 
I think you bring up an interesting point with it having front to back common and side to side isolated... My tunnel ram is wide open to all eight from anywhere... Either way I think it's still allows for progressive carburetors if that's what you want... Now if it was isolated front to back obviously that would be a different scenario...
I went back and forth with progressive and one to one and ended up in the long run just leaving it one to one...
These are some old photos from 5 or 6 years ago. You can notice on the rear carburetor I have a little extra space for under the air cleaner to make it pop up above the front one to get a little of that direct air...
The first picture I'll post is of the reason I didn't want to do the sideways mounted carburetor the linkages much more elaborate...

Screenshot_20221231-091256~2.png

1 here you can see where I attached a slider to the front carburetor. But I attached it a little lower than the rear carburetor has to give it a quicker throw...

Screenshot_20221231-091344~5.png

2 here I'm just pointing at a stop that pushes the front carburetor throttle back close but both should be spring loaded anyways it's just a safety measure.
Screenshot_20221231-091330~3.png

3 okay a few things to notice here but I'm pointing at the throttle stop for the front carburetor or should I say throttle go LOL..
This is in the closed throttle position and that stop that I'm pointing at is set in the full throttle position when both are pushed all the way back. You can see now how much throttle you get on the rear carburetor before the front one starts grabbing but since it's point of contact is closer to the fulcrum point it will catch up and be full throttle at the same time as the rear carburetor...
Making your true adjustment being how far you put it from the fulcrum point...
Screenshot_20221231-091344~4.png

4 hear my pointer finger is right on top of where the rear carburetor is connected and basically all you have to do is put that bolt in that position and put your stop right up against the spot where my middle fingers pointing and you'll have one to one..
Screenshot_20221231-091330~2.png

This is just simple everyday buy it anywhere dual quad linkage for 20 bucks or so...
You may or may not also notice the rear carburetor is an old competition series and the front one is a 1406... The car ran great with that setup..
But I had to go new and fancy and got some Holley Street demons... I got them on a Christmas sale and by the time I sold these carburetors I think I was into the new ones about $250 or less... What I did for the 750 Street demon on my truck was got put on a waiting list with Holley for a factory second and paid half price for basically a new carburetor.. which one I opened it up to set the float bowls and had some trash in it and I told Holley and they sent me a brand new one..
I don't know if I would recommend the Holley Street demon for dual quads though as they do not have as many options for jetting as edelbrocks that have been around many years. They were never made for a dual quad setup...
IMG_20200613_194321.jpg


Screenshot_20221231-091344~3.png


Screenshot_20221231-091344~2.png
 
I worked on a 409 factory dual quad set up recently and it had progressive linkage. Secondary front carb had no mixture screws. The intake is set up so that 1 barrel of the primary choked rear carb feeds 4 cylinders and the other primary feeds the other 4 cylinders. IMHO
your intake design determines what style linkage you should run. A tunnel ram probably shouldn't run progressive linkage. I run 1 to 1 on my TR 440.

20221118_112756.jpg


20221118_102656.jpg


Screenshot_20221117-130945_Chrome.jpg
 
Thanks guys, some cool helpful info. Budget restraints meaning do it as cheap as I can with it still looking good, so another Eddy on the front or rear will be the "plan".
Thanks for detailed pics Jason. I checked the Eddy website out, it doesnt look like they offer refurbs like Holley does?
Very cool 409 setup, never see an intake like that!
66Valiant528 said:
I worked on a 409 factory dual quad set up recently and it had progressive linkage. Secondary front carb had no mixture screws. The intake is set up so that 1 barrel of the primary choked rear carb feeds 4 cylinders and the other primary feeds the other 4 cylinders. IMHO
your intake design determines what style linkage you should run. A tunnel ram probably shouldn't run progressive linkage. I run 1 to 1 on my TR 440.

View attachment 1716029022

View attachment 1716029023

View attachment 1716029024
Click to expand...
j par said:
I think you bring up an interesting point with it having front to back common and side to side isolated... My tunnel ram is wide open to all eight from anywhere... Either way I think it's still allows for progressive carburetors if that's what you want... Now if it was isolated front to back obviously that would be a different scenario...
I went back and forth with progressive and one to one and ended up in the long run just leaving it one to one...
These are some old photos from 5 or 6 years ago. You can notice on the rear carburetor I have a little extra space for under the air cleaner to make it pop up above the front one to get a little of that direct air...
The first picture I'll post is of the reason I didn't want to do the sideways mounted carburetor the linkages much more elaborate...

View attachment 1716028975
1 here you can see where I attached a slider to the front carburetor. But I attached it a little lower than the rear carburetor has to give it a quicker throw...

View attachment 1716028976
2 here I'm just pointing at a stop that pushes the front carburetor throttle back close but both should be spring loaded anyways it's just a safety measure.

View attachment 1716028977
3 okay a few things to notice here but I'm pointing at the throttle stop for the front carburetor or should I say throttle go LOL..
This is in the closed throttle position and that stop that I'm pointing at is set in the full throttle position when both are pushed all the way back. You can see now how much throttle you get on the rear carburetor before the front one starts grabbing but since it's point of contact is closer to the fulcrum point it will catch up and be full throttle at the same time as the rear carburetor...
Making your true adjustment being how far you put it from the fulcrum point...
View attachment 1716028978
4 hear my pointer finger is right on top of where the rear carburetor is connected and basically all you have to do is put that bolt in that position and put your stop right up against the spot where my middle fingers pointing and you'll have one to one..
View attachment 1716028979
This is just simple everyday buy it anywhere dual quad linkage for 20 bucks or so...
You may or may not also notice the rear carburetor is an old competition series and the front one is a 1406... The car ran great with that setup..
But I had to go new and fancy and got some Holley Street demons... I got them on a Christmas sale and by the time I sold these carburetors I think I was into the new ones about $250 or less... What I did for the 750 Street demon on my truck was got put on a waiting list with Holley for a factory second and paid half price for basically a new carburetor.. which one I opened it up to set the float bowls and had some trash in it and I told Holley and they sent me a brand new one..
I don't know if I would recommend the Holley Street demon for dual quads though as they do not have as many options for jetting as edelbrocks that have been around many years. They were never made for a dual quad setup...
View attachment 1716028983

View attachment 1716028973

View attachment 1716028974
Click to expand...
 
I'm not saying you can't run a progressive set up on a tunnel ram but I think the design will make the front two cylinders way lean. Now you could jet up the primary side on the rear carb but I think 1 to 1 works best on a tunnel ram. That Chevy 409 had a carb base gasket leak and the front 2 were so lean the engine was skipping. And you can certainly fab up some linkage no matter which way you go. Good luck.
 
66Valiant528 said:
I'm not saying you can't run a progressive set up on a tunnel ram but I think the design will make the front two cylinders way lean. Now you could jet up the primary side on the rear carb but I think 1 to 1 works best on a tunnel ram. That Chevy 409 had a carb base gasket leak and the front 2 were so lean the engine was skipping. And you can certainly fab up some linkage no matter which way you go. Good luck.
Click to expand...
With a carb base leak you're going to have lean problems no matter what.. that's not even any kind of an ideal situation....
When I had progressive I had absolutely no issues with the front cylinders when I ran the rear carb primarily...
It sounds good in theory but what it is is a perpetually spoken mith because it seems to make sense but in reality it's not true...
 
You must log in or register to reply here.
-

Back
Top