My wagon, 4600lbs, 526 inches, unported rpm heads, 10.6 compression, mild cam. 2600 stall, 3.73's.
had a rpm w/ 850 holley. ran ok. changed to an M1, and a 1000cfm 4150 quick fuel carb.
HOLY CRAP. a difference of night and day. car feels like an animal now.
go with the M1.

Do you think the 150 CFM bigger carb. didn't help?
I haven't seen or heard of any BB Mopar, B or RB , that didn't go quicker and faster with a bigger carb

I'd say some. But considering the actual flow difference between a 850 and 1000, is not near 150 cfm, ,I'll say not that much.

Yea, the coronet did seem to like the open exhaust.
The exhaust system is full 3" to the bumper with Flowmaster's
I guess the cam is somewhat healthy so i've been told


When i went open header i also put on 16" extensions
But i just used 3-1/2" for the extensions as thats the collector size.

You need to remember that not all carbs. of the same CFM size built by a different company flow the same, some flow more and some flow less as another company same size rated CFM
The true test is either on the same bench the same day tested by the same tech or tested back to back to back to the original carb. at the track within 1.5 hours of each other at the track tracking the weather changes and adjusting for that
I had three carbs flow tested by the same tech on the same bench within 30 minutes of each other, one barrel at a time and the B.G. Stage # 3 modified Holley 750 CFM flowed 1020 CFM The stock Holley 950 HP #80496 flowed 880 CFM and the stock Holley 4781-2 850 CFM D.P. flowed 880 CFM also
The B.G. was the fastest of the three at the track

IMO You’re kidding yourself. These two manifolds are very very close by all accounts including Dyno tests. Going from a standard 850dp to a quickfuel 1000 is light years. I’d guess the difference in that swap is 90% carb. In fact, In a heavy wagon, I wouldn’t be surprised if you’re still leaving performance on the table with the single plane.

Lightyears?

I don't see lightyears. Just my .02...

On my junk...i saw exactly .07 difference between a 40 year old 800dp and a high dollar carb 950 carb. Just my experience.

Yes. I know...every combo is different...

If we're talking 4150 to 4500, then I would agree, no doubt.

Fair enough. Do you still have the RPM? Just like I mentioned to Ohio, I’d love to see a back to back test with no other changes with these two manifolds.

Sorry to hijack one more time, but...Silver was is the LSA of your cam?

I can say we had a pretty good comparison on my sons Dart between the RPM and the Holley street Dominator. But his eng is only a .030 over 400 (406 cubes). But you could really see the RPM was much better in the 1/8 and 60 ft. I know in the 1/4 he ran at that time 11.59 @ 117 with the SD and 11.55 @ 116 with the RPM. The single plane SD had more mph in the 1/4 but the RPM still had the better et. And you could see in the timeslip how the RPM won all over in the 1/8 and how the SD was coming on in the 1/4 but ran out of realestate. So if had a bigger eng like a 499 or something then the SD may have won in the 1/4 with an eng with more cubes and torque. Course much depends on the combo as we all know. I run the Indy dual plane on my 493 and it looks to have larger ports then the RPM. I do want to try a single plane one day but a friend I know with a combo very close to mine ran 10.98 with the Indy Dual plane and then he switched to a single plane (Victor I think) and ran a 10.90. So he picked up almost a tenth. But then he took his 850 DP off and went to a Dominator and then ran 10.60's as it really liked the more carb.
So to me it all depends on the combo as the dual plane is better down low and may be faster in the 1/4 on some combo's until you have enough eng , gear and converter so the single plane will be the best and fastest. Ron

Sorry to hijack one more time, but...Silver was is the LSA of your cam? [/quote]


No worries bud,
.585/.600 1.5 rocker
260@50-268@60
109 lsa
104-105 installed

I would definitely run the M1 single plane on that motor.

Love the SuperBee by the way!

run the M1 and a good annular booster carb, best of both worlds???

500+ inch motor = single plane intake.

My only on track comparison that might be somewhat relevant here was on a mid 11 sec stock stroke 440 combo in a 3700 lb cuda. I tested the RPM vs. a Holley SD and the timeslips were almost identical.

Merely because Cab and I talked about it the other night and I respect his opinion and experience a great deal. Just getting some opposing views on it. I feel that the M1 is the best fit for my car, but I would like to put them both on and do some street duty with both and possibly find time to do a same day shootout with both intakes.

on the street my 512, max wedge ,Indy 400-2 ran great, 3.54 gear.