The 505ci is officially done, in the car and ready for summer👍👍
I have a Holley 750 HP on the engine just to get it running and broke in. Now it's time for a big boy Holley !

The question is 850?? 950?? HP? XP? Lot's of options out there

What is your valued opinion?

This car is 80% street 20% strip

505 ci RB

E heads Ported

10.7 comp

244/250 duration @ .050. 540/ 556 lift. 107

Indy dual plane ported

727 TF 3000 stall 9.5"

3:23 gears

Challenger. 3700 with me in it.

👍👍👍👍

I would guess a 950HP 4150, or a 1050HP 4150, or a 1050 Dominator, preferably custom built for your combo.

Proform 950 or a 1050 in 4150 will be almost dead on out of the box....We have had very good luck with their calibrations on the Mopars. We just bought our 3rd Proform for our little 392 +.040 Hemi we are working on.

We have a 950 I won the championship on in 2013 where all I did was keep it clean and fattened it a tad...And we have a brand new 1050 we put on our stroker A body 484 Hemi right after making a pass with the 950, and it picked up, right out of the box. Great carbs for Mopars...I wish they made a 4500 carb.

Ummmm... kind of an odd combo, IMO. Those 3.23 gears just look "wrong". The last cars I drove w/ 3.23s felt like they never got moving 'cuz the long gears pulled the engines down for so long while accelerating.

If you're stuck on a new-gen Holley HP/XP, then I'd expect the 950 w/ its large venturi & downleg boosters is going to be an unresponsive piece on what you described.

The 850 HP/XP "should" work better (smaller venturi)... but I haven't heard of them working that well out of the box in the real world, although I think they've shown decent results in the controlled environment of an engine dyno.

I'll be interesting to see what direction you take, and how things work out.

Annular 1050/4150 QF body carb would be my suggestion. And custom isn't any different in cost than an out of the box. If you are stuck with the new Ultra carb line get the 850, do not get the 950. It has a flow and signal issue with the body,

It's a poor-man's overdrive.

I run 3.55's in my 500" Duster and just installed 3.23's yesterday. I wouldn't want to drag race every weekend with 3.23's in a 3700# car(Challenger) but I drive my car ALOT, and steep gears get real old real fast(to me).

I'd leave the 750 on there for a while to see how you like it. If you really want to know what to do then hook up a little vacuum gauge and keep an eye on it as you drive. If the vacuum gets above 2 inches at WOT throttle then you know you need a bigger carb. I'm guessing with the 3.23 gears you might not want to put a bigger carb on there.

Thumperdart can set you up with a nice piece that will be razor sharp.

Yes,

To Brads point, the 3:23 gear seams wrong however I do enjoy the lower RPM's while on the highway and contrary to popular belief, my Challenger runs great with the 3:23 gear. If I feel the need to teach someone a lesson at the track, I have a 3:91 pig ready to bolt in. Thanks for all of those who responded.

I tried four different rear gear ratio in my old Duster from 3.73, 3.91. 4.10 and finally 4.30 with a 31 inch tall rear tire. That stupid car acted and ran like it didn't know I had change the rear gear ratio That is the second time I've seen similar results in meduim weight A body Mopars with both SB and BB I would really like to see you run your car at the track with the 3.23 and then switch to the 3.91 and see what the exact results are Let us know the results also please

Your playing with a street car.. and I will
guess very little track... keep the 750 on it
and tune it properly.. you will be much happier
with the throttle response

Anyone out there running a 3:23 gear with a 505ci??

Me.

http://508charger.yolasite.com/

Pretty similar to yours. Mine is heavier, less converter.

I've track tested and tuned both a 4781, and a 950 hp (1.375 venturi). They both drive about the same. The 850 is actually a littler cleaner at low rpm because the 950 is a little fat down low. It is in the idle circuit/IFR and fixable, just have not done it.

At the track, the car ets and mph betters with the 950. When you dissect the time slip, you conclude that the performance advantage in the 950 is at shift recovery.

There's a maroon Dart here on Moparts that runs mid nines with 3.54 gears, 540 cube big block with efi. I'm anxious to test my 3.23's on the street this week.

That's impressive!!! 11's with a 3:23 gears !!! Once I get some WOT vacuum readings and some A/F readings I will choose my new carb. Based on the few WOT blasts down the road I had on a 62 degree day in Michigan this past weekend, the car is going to need a bigger carb.

Don't know if it's the same one I'm thinking about out of S. Illinois. I saw it at I-57 run 6.01 IIRC. I had seen it come by a couple ties and just happened to be on m trailer when it made a pass. I remember when it left thinking it wasn't really going anywhere, but when it got to the stripe I about fell off the trailer. I'm thinking at the time it had a 8 3/4 with 3.23s, could be wrong it's been several years ago.

I think the car I saw has a blown Hemi n it now.

The 499" that was in my Cuda was very similar to yours. I started with an 850. Then went to a 950. And then tried a Dominator.

The Dominator was a full MPH faster in the 1/8 and ETed better, too. And the mid range on the Dominator was awesome.

My car is primarily a street car like yours. The Proform 950 took the least tuning of any of the carbs. While the Dominator took the most.

It was a 68 or 69 Dart with a 3.54 Dana, said he drove it on the street so he preferred the 3.54 gears. I cannot remember his name.

Probably the same car, pretty stout piece for sure.

Twin Turbo Mower is his screen name here.

Yea that's it! Very cool car. And he is from Illinois.
He inspired me to go with more cubic inches so the rest of the car could be built more streetable.

Big cubes, smallish cam, tall gears.......I would steer clear of "race" calibrated carbs if you're going to buy something off the shelf.
That type of combo just doesn't need the same type of low speed calibration a more race oriented combo would, and it can sometimes be a chore to get them to run clean in the part throttle cruise mode.

While it contradicts what Russ's results were in his car, I like the plain ole 850 double pumpers in that type of application.
Custom?? I'd probably try and have something done out of the QFT "950" style body with the 1.450 Venturi.

I also like the old Demon RS combo with the 1.420 sleeves and the 1.750 base plate...... The "825", although the calibration they came with ootb was awful.

Being a dual plane intake distribution will be much better with an annular booster. Quick Fuel has 1.45, 1.50, and 1.59 venturi bodies available, I would use at least the 1.50 with an annular or a 1.59. I use BLP baseplates in my builds, the t-slot are smaller like the Holley bases and control transition fuel better, so ideally a custom is a better way to go. BLP also has billet bodies available if you want the look of billet, in either a shiny silver or a coated black version.

I would agree that if you're going to use annular boosters, a 1.50 Venturi is probably the smallest you'd want for that displacement.

FWIW, my BG set up w/ 1.425" venturi sleeves & downleg boosters ran just as quickly at the track, and noticeably cleaner on the street, than when I tested it using 1.56" sleeves & BG's optional annular boosters.

Just my opinion from limited experience, but I don't think annulars on street-driven big blocks -- even lowly 440s -- are a good match w/ venturi sizes under 1.56". Maybe I'd try something different now if I hadn't sold my annular boosters to another Moparts member, but I found that configuration hard to tune to run clean down low and it came on the main circuit too soon during part-throttle street driving.

my 512 is very close to your engine, I also have 3.23 gears 68 charger, I bought a holley 950 hp & the cruise afr was down in the high 10s, it took a lot of tuning to get it mid 13s, changed the primary metering block that has adjustable IFRs,but that was another $120.00 it works ok.

what IFR did the holley have and what did you end up with?

the adjustability of the QFT carbs is pretty appealing.

There is a 1050 QF annular for sale in the race parts section. I've never driven one of those on the street but it might work okay. If you have the patience you should be able to tune it if it doesn't work right out of the box.

the best i could tell it had .035 IFR & 70 IAB, now .028 IFR, .058 IAB

Boy, lots of options!!!!! I have the ability to get a Holley at cost so my options for other brands is a no go because I'm a cheap Mopar guy.. Does Holley make a HP series vacuum secondary carb in a 850/950? Their listings are all over the board?????

This is why I prefer to use "street" calibrated carbs for that type of application.

ANY carb(except svo`s can be tuned for the street quite easily......do it all the time even into the 8-second zone but agree the QF and newer Holleys w/billet features are nicer, lighter and better over all...........

Not that I know of. There is a 870 cfm Avenger carb #80870 but I've never used it. Might work okay on a street driven stroker. There is also the 850 Speed Demon carb which Holley sells. Not sure if your at cost deal includes Demon's or not.

If you are on a tight budget, buy a used 4781 and a rebuild kit. For less than $225 you'll be very close for a bunch less money. I did run mid 11.70s at 119.5+ mph with the 850.