Hi Guys,

I have a 512 stroker and was wondering what people were running for jet sizes in their 6 packs? Motor was dynoed but we were still a little lean at 55 to 6 grand. My builder wanted to leave things alone while the dyno guy was insisting to do more pulls but we were on the dyno for a while and fought a phasing issue and I was pretty happy with the power 610 hp - 649 torque however the builder was shooting for 650 hp. Maybe left something on the table using this intake?

Motor is 11.2-1 compression, Promax cnc'd heads 330 flow on the intake side at 600 lift, Eagle 4.25 crank, Eagle rods 7.1, 260@ .50 solid flat tappet cam-crane-.600 lift, 1.5-1 roller tip ss rockers-crane,CP flat top pistons, 1969 aluminum 6 pack with vacuum secondaries-66 jet on the main and 81 on the end carbs all corners with promax metering plates. I am at 3500 feet above sea level.

Thanks for your input.

jet up on the center

My low deck Eddy dual plane six pak intake 400 block 512 C.I. 9.25 to 1 compression liked .092 on the drivers side and .096 hole size on the passenger side on both outboard carbs running and testing on 91 octane CA pump swill years ago I did run a set of 1970 440 carbs modified with the stock outboard metering blocks modded so I could change the set screws in the bottoms to bigger or smaller I.D., I used Holley #63,64 and finally 65 jets in the center carb. That motor had a custom ground solid roller cam with 260 @.050 intake side and 266 @ .050 on the exhaust ground on 108 LSA installed at 107 ILC with a set of Harland Sharp 1.6 ratio roller rockers. It made 612 HP and 644 Ft lbs with a set of large valve ported iron 906 heads back then, it ended up making 727 HP with similar torque after changing the heads to a set of Indy SR M.W. heads and single Indy 400-3 inatke with a 1050 Holley dominator carb, this was with 518 C.I.(4.300 stroke to raised the pistons up to zero deck height to increase the compression ratio) and 10.78 to 1 compression I love Mopar Wedge strokers, not so much with Hemiroid motors

mopars bulletin#2 june 1971 440 6bbl race setup: throttle side dia. side

front- .093" .089"

center- #65 #65
pvcr- .052" .052"

rear- .093" .099"

Cab - what elevation were you at with that motor? I'm at 3500 feet. I have plans to chassis dyno tune the car when I find some time this summer. I welded bungs in when I installed the exhaust. Thanks for the feedback.

Was any work done on the intake to improve the flow? Those old 2-plane Edelbrock intakes are capable of making some prodigious amounts of power, especially if you do some deep porting on them.

I have one on my 493" wedge with the mechanical secondary carbs making 715 hp at 5500 rpm. It was deep ported by Hughes Engines, and is bolted to a set of Hughes Stage 2 ported small port Indy EZ's. I'm running a smallish hydraulic roller.

The wide band was indispensible as far as dialing in the jetting and squirters. I found no need for a chassis dyno and dialed it in on the street using the data logging feature. It makes it pretty easy to do. My hat is off to the guys who dialed them in by the seat of their pants and reading the plugs. Now, that takes some skill!

Intake was port matched and also some extensive porting as well. Whether the builder did a good job - who knows? I never thought about installing a wide band gauge. Dialing it in on the street would be a lot more fun!! We thought with this cam and heads the motor would put out a little more hp...however it is just a street car that will never see the track but even so, making this thing run correct is important.

When I built and dynoed it the first time it was in Ontario, CA which is right at 800 Ft. I lived up in Hesperia,CA which is around 3500 Ft. I moved to Bend before the car was driveable and did most of the final tuning up here in Bend,OR between 4300 ft and 180 ft at Woodburn drag strip. I did put a wideban on the car and used it for testing the timing, spark plug heat range and the outboard jetting I never had to change the jetting for different elevation, I should have, but it ran fine so I didn't

Like Cab said 65 or 66 jets in center carb and this big engine likes fuel and respond to it so go up 2 to 4 steps on the sqirter on center carb ! You will feel the differens. On the outer carbs i ended up with 82-84 jets so i gues Cab reved his engine more than i did. If you realy whant to have fun with the six pack set up look for the mecanikal carbs that whas sold thru Direct Connetion whit list number 82&83 or if you can find the BG carbs that i run now that respond way better !

here is my 2 cents.....(take it for what its worth)
440 stroker 500ci 11.2. comp ported eddys hughes custom 650 lift ported six pack 70 center front 84 choke 88 throttle
rear 88 choke 90 throttle...when the six pack opens it pulls like a freight train

I read the BG carbs are significantly smaller than the Mopar Holleys. I love the DC mechanical carbs, but you have to know how they like to be driven. Nothing mysterious, but you can't mash them open at 2000 rpm and expect the port velocity to be high.

Thirsty beast! How did you tune yours if you don't mind me asking? Pulls like a freight train sounds good to me...I haven't had a chance to drive mine yet - I have been out of the country for the last 6 weeks and will be here another month or so. I think I will throw 84s up front and 88s in the back and hook up an AF gauge and go from there judging by what everyone else seems to be running. I was just checking on line and I see there is a remote one available usable through your smart phone if you don't want a gauge in the car - sounds kinda cool. Appreciate the input from everyone!

Stagger the jetting for the manifold, don't use the same size jets in the outboard carbs My carbs had the stock metering plates modded to accept # 6 brass set screws drilled to those numbers, which I opened up .004 on both sides to make it richer. If your using Holley jets or Holley air bleeds as your jets look at the hole size and go from there Remerber though it is way safer to start off richer than needed instead of to lean

You have been missinformed ! The flow are rated dry on some and wet on some so thats why the numbers vary but i have flow tested the outer stock Holley carbs that is rated to 500cfm and the BG carbs are only about 4 cfm under those BUT the center BG carb flow the same amount so al 3 carbs together in flow numbers the BG would be bigger and i can open mine from 1500 rpm to full in a 4 speed Challenger without any hesitation what so ever on a RB stroker of 505 cubes whit same cam as you use from Hughes so i gues you need to tune more then !?

First thing holley jets out of the box are no where what the number says.. Try to get a set of pins and gauge the jets.. I run 84/86 on a stock stroke 440 with 906 heads that are cleaned up with a good valve job.. 11.97 comp. with a hyd flat tappet cam..
For instants the 86 jet is my 84.. Sounds like you are very lean.. Good luck..

I think he is referring to the old DC mechanical carbs, those end carbs flow more than the stock vacuum 6 pack end carbs. They are basically a 850cfm DP cut in half, they have the slabbed throttle shafts. Flow is around 1050 to 1,100 true CFM.

I can floor my DC mechanical 6bbl off idle and no bog, cough, backfire.. Just acceleration!!! I do have it on a tiny 365ci maybe 400hp demon with a 4,400rpm stall and drag radials! My A/F meter still showes it lean at WOT 13.5 with 77/78's on the end carbs, 64 center.

Not how Holley`s work unlike BLP or maxi-jets where the number is the actual size.........two different animals..........

forgot to add I purchaced quick fuel metering blocks they make a kit for the six pack. Also didnt want to drill anything out and make a mistake ,and everbody I know that purchased the (other guys plates) had major issues. Im not saying my seup is perfect its working... ps cabis correct when mopar dynoed the six packs in the 69-70's they found staggering worked better.
thanks

Are you shore that the DC mecanical carbs list number 82 and 83 outer carbs have bigger venturi than the stock vacume !? i own two NOS sets of those and the throttel blades shore looks smaler on al 3 DC carbs ! Any way my BG six pack carbs as i stated before flow the same becaus they are same body and just about 4 cfm under the stock outer vacume carbs so they would have bigger flow numbers than the stock al 3 together as the stock center carb is way smaler than the outer carbs and they just work fantasic.

Perhaps there's a bit of a communication barrier between our posts regarding my statement. Opening all six barrels without a bog, hesitation or mis-fire at low rpm is not the issue. With the help of a wideband, I'm pretty confident my tune is pretty sharp at this point with the motor cranking out a respectable power curve beginning with over 500ft lbs of torque at 2000 rpm and culminating in 715 hp at 5500rpm. The drivability is excellent as well, especially with a Passon 5 speed and 3.73's.

In my comment about knowing how to drive them, I was referring to the concept of a driver keeping the velocity through the venturies at the maximum rate. Obviously, it varies depending on engine rpm and throttle blade positioning. You must be aware of this, and it's affect on power output during an rpm increasing throttle event. If the driver's ability to vary air velocity through the carbs isn't an issue, especially at low rpm, then why not adjust the progressive linkage to have all 3 carbs open at once?