Racing w/dual quad - A NSS

I'm setting the car up to be able to run NMCA rules. My goal is A NSS so I'm going dual Edelbrock performer carbs & indy modman. I'm figuring on shifting at about 7K, not launching on a 2 step, & launching at 5 to 5500. I haven't played with an ebrock carb in a bunch of years, & thinking 2 600s
This is a 470 w/SRs, 456 gears, 3.08 1st gear
So am I opening a bad can of worms?
600s ok?
anything to be done as far as playing with the counterweights on the secondary air door? (It looks like no AVS for my car, but not sure)

We've had good luck with the 600's on the smaller motors, 750's on the bigger stuff. In years past I watched guys with sticks take the air door completely out. Stock jetting is very close. You may want to swap the step-up springs so the metering rods stay seated in the jet at idle. I think that these carbs biggest down fall is there transition from idle/leave rpm to WOT. Whether it is lack of pump, air door to quick/slow I haven't figured out yet. They're not terrible but there is room for improvement. I see a few AVS but they don't appear to be any better. Even the 800's on a big motor. My 572 A/FX car runs 2 750's at 113 square jetting. I've moved it around a couple of times with minimal change. My buddy's 440 (N/SS D) runs stock 600's and stock jet, same deal runs about the same. With a stick I'd use the two step in a heart beat. I can't with an automatic or I would.
Doug

Thanks Doug,
W/r to the 2 step. I've been gun shy since I had a switch fail and launched at 7500. I was planning on bringing it up to where the 2 step just starts acting and then backing off. Thinking this will give some pump shot left. I'll probably work my courage up again and give it a try w/pedal to the floor.
Thanks again
Greg

what car and what does it weigh? What are your engine specs?

I run a modman with a pair of 600s on a 499 with SRs and a small indy flat tappet cam at 12.5 to 1 comp. My car weighs 3550 and I ran a best of 9.99 with mine in NSS trim. Not enough room to work in bad weather. I backed mine up to B due to that.

68 barracuda, 3200 to 3250 depending on the day on new england dragway scales, solid roller, .646 lift, 11 to 1, MW port SR heads by Dwayne. 470ci
It will typically run 9.90 to 95 at new england until the temp gets over 85 then will be up to 10.0 to 10.05 w/1050 4150 version. This is with no tuning for weather. Planning on raising the compression ratio, not too much left in the heads, will be a cam change. Going for 9.80s when hot.

I'm planning on testing the modman and edelbrocks with no other changes to see the effect from just those.

Did you ever try a before and after with the modman?

Thanks

Why the ModMan rather than the Indy X ram? Is the X ram not legal in the class?

The ModMan might work better than the Edelbrock dual carb intake just because the Modman is single plane rather than dual plane, but the ModMan is a weird intake. Basically just a big box with little short runners. You might need to do some serious tuning to get all 8 cylinders happy at WOT.

I never saw a low deck cross ram listed by Indy

Is there such a thing?

Didn't realize it was a low deck. Yeah, not many choices for low deck intakes. Gotta run what you can find I guess.

STR-15

I don't have good data on the swap. I went 9.91 @137 with the indy single plane and 950hp with a fuel delivery issue.

We fixed the fuel problem and went to the modman and 600s at the same time. I saw .08 slower with the modman without tuning for best et. We got a base line and tuned for consistency. We were on a short time table for the first NMCA race a few years back. Honestly, we have just left it alone and let it work for us.

To answer Andy F... It fit under my hood, so I went with it over the indy bathtub.

Greg,
My experience this past season has been similar to what dvw stated about the transition off idle to wot. It works but could be more responsive at the hit. Overall it still was consistent & reliable, but not as good as a holly. This is with 2 eddy 750cfm afb, mod man,493 rb,3700lb auto.Don't know how it would act with your stick shift combo.
Steve

PS- I think the mod man is a good compromise manifold for performance & fitting under a stock hood. Went 10.70's & 80's with a ch-28 & 500cfm afb's 2 seasons ago & 10.40's & 50's last season with the mod man & 750's

Maybe a dumb question but I know the A bodies with a wedge are legal with a single 4 intake and the NMCA will allow you to run a Holley. Why complicate your life? Unless you are looking for that look then I understand.

can't run a holley single four barrel on a mopar unless your in the fx 9.75 and quicker classes I'm pretty sure.

Correct Russ. 9.75 you can run a Holley (c/fx). You can run a single afb in the slower classes though.

Casey

Thanks Steve, good to know. Hood clearance is an issue. It will be interesting. I may have to leave with the pedal all the way down. This is going to be a learning process. There will be a bunch of clutch adjustments to get everything working.

Yes, AFBs it is for NSS. I didn't think I'd be able to run the 10.00 index with one. Maybe someone more clever than me could.

Give Damon at Diamondback Engines a call. He is the man when it comes tuning the Edelbrocks. His website is http://www.diamondbackengines.com/

I know a few years ago Heath Shemwell ran a 68 cuda with a 440 and a holley carb. He lobbied the rules committee to allow the holley carb and they allowed him to run it. I see the current rules do not I would call the NMCA and ask. Also I know the 422 guys allow it.

I guess I'm not surprised that the rules aren't necessarily the rules,
but the die is cast. 2 4bbls it is. Something new

Two AFB's aren't nearly as bad as everyone thinks. My bet is 2 Eddys will run every bit as well as a single 4150 Holley. The tuning window has been a no brainer. My car has been 9.12@147.7 On box stock 750 Eddy's with the chokes removed and nothing but one step up in jets and a spring change.
Doug

oldiron,

I also run NSS, and use 2 of Damon's modified 800 Eddies on an Eddie STR-15 intake, with a Jerico. I launch on a 2 step at 5400. Combo is a 496" with INDY -1's. With screens it fits under the hood with the scoop.

Love my carbs. Engine is making more than enough steam for what I want to do with it. Last season was my first in a car this quick, and I was fighting 60' issues. Looking to keep it at a 10.0 this year and will have to slow it down.

-Dave

I do make a throttle linkage for the dual carb mod man intake so if you go that way I have the linkage kit.

http://arengineering.com/products/mod-man-dual-carb/

My brother runs two Eddy AFB carbs on his 400/511 eng in his NSS 64 Fury and he also uses the Mod Man intake. He went to it also for hood clearance issue's as he was using an old tunnel-ram but had to run the taller modern 64 Hemi type scoop even with the lowblock. He wanted to go back to the stock height scoop so thats one reason he went with the Mod-Man intake. His 64 weighs about 3600 lbs with him in it and has run a best of 9.96 using this setup but it normaly runs 10.0's to 10.20's. I dont remember all the jet and spring specs he uses but he had a little stumble issue he had to work with but he has them working very good now as he is very happy using them. His line of thought on the Eddy cars is as he says to me.........I like to run the dual Eddy carbs but on a single carb for racing he prefers a Holley. They are working very well for him right now and I can always get more info on his carb specs as I knew them but dont remember them off the top of my head. Ron

Hi Dave,
Thanks for the info. Sounds like Damon is a good man to talk to. Two 800s?

Ron, thanks to you as well. Its good to have a comparison.

Andy, your website is down at the moment. Will check it out when it comes back

Happy Easter all.

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Hi Dave,
Thanks for the info. Sounds like Damon is a good man to talk to. Two 800s?

Happy Easter all.

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Yep,
Two 800's. They are heavily modified, as are all of his carbs. He will ask lots of questions. Different mods depending on stick or auto ect... Since we bolted them on, we adjusted the idle twice. Thats it. Never had them back open yet.

Intake is STR-15 Cross Ram modified to run the carbs inline. There are other mods to it as well, but not willing to give those away hehehe.

Happy Easter to you as well!

-Dave