Dual quads

[chance]

Hello, just joined  the forum. I just bought cliffs book on rebuilding and modifying q jets... lots of good info awesome read!! It didn't have any info on dual quad applications so I'll ask here. the carbs will be going on a mopar 383 with 10 to 1 compression flat top pistons with no valve reliefs  906 heads with steel shim head gaskets , offenhauser 3614 low risedual quad intake. Engine pulls between 7 and 8 inches of vacuum. I have several carbs to work with. Just wondering about idle and main jetting, and choke pull off time in this application.
Thanks guys!
God bless!!!

[Cliff Ruggles]

Not enough information.  Need to know the carburetor number(s), and camshaft specifications.  One q-jet would be more than enough for that engine, but they work fine using two of them even though it doesn't need no where near that much cfm due to the design of the secondary system.

I've set up quite a few for dual quad applications.  The best carbs to start with are Chevy side inlet units with the divorced choke set-up from 1969 to 1977.  For sure it is best to find two with the same part number, but not a requirement.....Cliff

[chance]

Thanks Cliff. I'm currently building an 800 cfm single q jet based off of your book. it will sit on  a single plane Mopar M1 intake that's on the car now with a 750 holley. I ran the dual quad manifold for a while with 2 450 holleys but the et's went down by 4 to 6 tenths so I went back to the single holley as I could never get a q jet to perform correctly with that cam. I have a bunch of q jets that the haters club has given to me over the years and I buy them at swap meets for little or nothing. I would like to try the dual q jets because a friend of mine has a Buick Riviera with a factory 425 with 2 q jets and its the best running dual quad set up I have ever driven, it works well on the street as well as the drag strip. Any ideas on main jets and rods and choke pull off for running 2 of them?
I love your book! Found out a lot I didn't know about q jets and I've been rebuilding and running them for years.
Take care and God Bless!!!

[Cliff Ruggles]

I owned, drove and drag raced a 1970 Roadrunner for many years.  Started out with a 383 and rebuilt it with the Mopar 284/484 cam.  I tried several intakes on it over the years and it ran quickest in ET with a stock spread bore intake topped with an 800cfm q-jet.

I ran the factory square flange intake with an 850DP Holley and it was close in ET but less MPH due to the smaller plenum area.

I tried several single plane intakes on it and it really slowed the car down.  I was running a 3000 stall converter and 4.56 gears in it.  Probably needed more converter for the single plane intakes because it "felt" stronger at full throttle, but the time slips showed that it really slowed down in 60' times.

I ended up replacing the 383 with a 440 and it ran half a second quicker at the track with the same basic set-up.

[chance]

That's awesome! Almost identical situations, I have a 68 charger B body, same engine, 3500 stall 4:30 gears. The only reason I never went with a dual plane manifold is a buddy of mine had a 66 cornet with a 440, 484/284 purple shaft cam and the mopar M1 dual plane manifold 3000 stall converter 4:10 gears, and my car was always quicker than his. His 60' times were quicker, 1/8 mile was within couple hundredths, 1/4 mile I'd take him by 3 to 4 tenths. So the stock iron dual plane worked best for you? I don't think I have any of those any more...lol. Guess Ill try to round one up.
Thanks Cliff!
God Bless!!!

[Cliff Ruggles]

Locate a stock intake for one of the later engines that had a spread bore design.  They are superior to the square flange earlier versions.

The P-Parts catalogs even recommended them as part of a "package" for those engines.

What ET and MPH are you running with the 383 set-up now?.....Cliff

[chance]

I'm running 12.8 at 106 mph at 1700 feet above sea level on 26" tall tire. thinking of going to 27.5 tire?

[Cliff Ruggles]

ET and MPH are good for the combination. 

I ran mostly 1/8th mile with mine when I raced it, as we had a track about 10 miles from the house.  It typically ran around 8.0 to 8.2 in the 1/8th mile depending on weather and track conditions.

The big 440 was much quicker, running 7.7 to 7.8 for most outings.

I didn't know nearly as much back then as I do now.  My Ventura in full street trim with less gear runs low 7's at 95-96mph.  So far best 1/8th mile ET has been 7.18 at just under 97mph.  Most outings it runs 7.2-7.3 around 95-96mph.  It could really use more gear and converter, but I like the 3.42 gears for the street and the converter is a very tight 10" unit that acts pretty much like a stock converter for "normal" driving........Cliff

[chance]

What's in the ventura? 400,455, destroked 301. I only mention the last one because a guy at our local track has one and that thing is nuts it turns over 8000 rpm. I'm building a 400 for my 77 TA. That leads my to my next question. the q jet  I've been trying to make work on the charger before I got your book is a 7045333 XM. I haven't had a lot of luck with cracking that number, probably not going to the right web site. This carb is clean and kitted ( not one of your kits ) and very low miles.  Anyway I also have another 77 TA carb 17057274 ARN I know these are a good carb to build but this one looks like it rolled around in the trunk for 25 years, nothing is broken mind you the vent is bent over and closed off and the plug for the mixture control broken but all the hard parts are not broken like the base plate or the air horn. My question is. Is it worth it to go through the TA carb or just do some of the mods to the other one like notching the secondary air doors ect.

Thanks!
Chance

[Cliff Ruggles]

Not familiar with a 7045333?

I use a 17057274 on my engine.  To date it has outran, dyno and at the track every carb we've tested against it, Demon, Holley, Edelbrock AFB and AVS.  They are excellent carburetors and plenty for what you are doing.  Mine is completely "stock" as far as the castings, never touched with a grinder or sanding roll.  It is recalibrated with a few simple tuning mods from my book.

My current engine is a 428 with a 4.21 stroke crank for 455cid.  It is topped with KRE heads and 236/245/112 HR cam.

Makes over 550hp/600tq, smooth idle, and strong/broad/flat power curve.

On 1/4 mile tracks I retard the timing 4 degrees, short shift at 5000rpm's, and add 200lbs weight to stay roll bar legal:

https://www.youtube.com/watch?v=6zVdoLR-VzM

......Cliff

[chance]

Ok, thanks cliff. I'm still going to do the dual quads just because it looks cool for the street and I have all these carbs and manifold changes for a BB mopar are really quick. If I lose performance I'll just change them out when I want max performance.
Thanks for time and knowledge!
God Bless!!!

[Ethan1]

 Chance,
 7045333 is a Champion Carburetor. So, a reman carb. I would look for a different carb. Like the one, Cliff, suggested.

 God bless you!

 Ethan

[chance]

Oh ok, thanks for letting me know! I wasn't having much luck cracking that number. So do they change the numbers on the reman carbs is that why it's hard to find? I'm going to use the TA carb like cliff suggested . It's pretty beat up so I'll take it all apart and look it over closer to make sure it's usable.
Thanks Ethan!
God bless you too!!!
P.S. I have a son named Ethan

[Ethan1]

Oh ok, thanks for letting me know! I wasn't having much luck cracking that number. So do they change the numbers on the reman carbs is that why it's hard to find? I'm going to use the TA carb like cliff suggested . It's pretty beat up so I'll take it all apart and look it over closer to make sure it's usable.
Thanks Ethan!
God bless you too!!!
P.S. I have a son named Ethan

Yeah, they did change the numbers, Chance. If I remember correctly, the part number for that carb is also 4-488. If you need parts on the TA carb, I am sure, Cliff, may be able to help. And you are very welcome, Chance!

 God bless you too! And God bless your son, Ethan, too!

[chance]

Cliff. I finally, got to watch the video you sent with the ventura. That thing doesn't sound like a 550 HP car.... but it sure runs like one. That's quite a combo! What's the compression ratio one that engine? Do you have to run catalytic converters where you live on that car? I don't have to in the small town I live in....but I know the cats defuse  the thump of a high compression engine. That's a wolf in sheep's clothing right there. It's all business when you hit pedal on the right. I might be hitting you up for more info on that later for the TA engine. I do kinda the same thing with the Charger it doesn't look like much it's got primer and old faded paint, but it sure is fun leaving a  guy at the stop light with a $50.000 car.....LOL