Going to dyno - 6 pack jetting starting point?

Freshly built 440 based 505” stroker build going to dyno in a few days. Just looking for starting recommendations for the jetting. I have read quite a bit on anything i can find on jetting on this setup, but i se some very different approaches. I’ll give a rundown of what i have and please give me your recommendations:

505”rb - 4.350” x 4.25”
2618 forged Icon piston
7.0” h beam rod
Stock 71 block line honed, bored .030, torque plate honed, clean up decked
10.9:1 compr
Comp hyd roller cam by Dwayne P
235 /241 @ .050”
.589” /.571” lift. 112 lsa. (Power brakes)
Stock (untouched) Cast Iron six pack intake
Trickflow 240 heads with cometic .027”
Fully rebuilt 1990 vintage dc carbs.
(Both metering plates had staggered jetting and stamped 35 (.093” dr / .086” pass)
Metering plates were replaced with quickfuel jettable plates. I installed 81 jet dr / 77 jet pass.
Center carb left at 64’s
Pvcr’s were staggered at .052” and .043”
Automatic 727 with 2500-2800 stall
3.91 gear
71 cuda all steel body and factory.

This is going to be a street car only but run hard frquently.
So, what jetting woukd you start with and woukd you keep it staggered? I know we will look at plugs after each pull, but just looking for the best starting point for this setup, because as you know, pulling these carbs off with the steel lines is a PIA.
Thanks.

Set it up temporarily with rubber hoses, so you can tune it easier

I would start with what you have. You're right in the middle of what I ran on the dyno. I tried richer and I tried leaner. In short, despite seeing the changes in BSFC, O2, and mass fuel as you would expect, the power and torque numbers were all withing the repeatibility of the dyno.

I've run this set carbs on a mild 383, a hot 383, a mild 440 and a 500 similar to yours. It's surprising, for how often I changed jetting around in those applications, I settled on nearly identical jetting for all of them.

In another case, we ended up with slightly larger jetting all around. But this was on Impastato's dyno in Michigan and the engine draws outside air in. It was litterly 5°F outside that day. Plus the motor had open 2" primary tube headers and a cam with about 90° overlap. Even with all that, the jetting was still not that different.

Agree with that

For sure

Russ, when you dynoed your 505, what was the power difference between the Holley SD and the 6bbl?

NO experience!
But... the stagger is to correct manifold flow differences, and I would keep it staggered until you know otherwise.

Thanks for the replies. Ok, so i am going to make up some steel fittings to use rubber hoses for ease of making changes. And i guess it sounds like i should start where i have it set now. Ill pull all 8 plugs after runs and check to see how distribution looks with this staggered setup. I just was under the impression that only the rear was staggared , but when i think about it, the front and the back has shorter and longer runners feeding opposite sides of the carb. So i guess that’s the reasoning for differing the front and rear plates.
I have the outboards idle screws at 1/2 turn, and i’m showing just square on the transfer slot for center carb, which brought me to just about 1/2 turn on idle speed screw. The outboards also have 1/8” holes on the throttle plates already.

I made my old pump gas Duster with the six pack idle on the outboard carbs with the idle speed screw on the center carb all the way out so the throttle blades where on the idle circuit only completely closed, not exposing the transfer slots at all.
I had the outboard idle mixture screws between 1/4 and 1/3 turn our from gently bottom also, my carbs where original 1970 440 automatic carbs worked on by C&J Engineering in Whittier CA, they took some tinkering with to make them go as fast as I could Six packs rule
Try it like you have it and then go up a small amount (.001 to .003 per jet) on the outboard jetting only until it starts to lose power due to being to rich
Let us know your results please

Vince Impastato is one of the Best in the business IMO
Machining to Dyno The Man has great Knowlege.

When does it hit the dyno?

That is going to be a sweet running motor. I like the long rods and the DC carbs too. I started out with 78's in the outboards with 37 squirters and 67 in the center carb with a 31 squirter. I'm still running a 2.5 power valve.

Do yourself a favor and install a wide band to aid with tuning. I found it to be the best tuning tool I've ever used for tuning the jetting.

I just did a similar package. icon piston,7.10 rod, 440 source ported head, scotty brown hyd roller cam. outer carbs did not need any jetting just the center carb richer. 32 total timing pump gas made 605 hp 655+ lb trq.

About 20 hp maybe a bit more at peak in favor of the SD.

6 pack ahead until about 3600. About a tie 3600 to 4300, SD after that to 6000.

Average about 10 hp difference.

SD had a 1" open phenolic spacer, and I worked a little harder (more jet changes/more pulls) on it than the 6 pack.

Good luck. Hopefully the dyno has a wide band in each head pipe so you can see what is going on. EGT probes in each header pipe will also help you dial it in.

Thanks guys.

Dyno day is Thursday. There are no wideband o2s, but 8 egt probes in each tube. Ill def post the results and findings. One thingbi didn’t nention here was the pretty horrible coreshift in the six pack intake. Not sure how much it will hinder, but it was the most i’ve ever seen on a manifold in my possession. About .175” on sides from what i recall. And the street diminator that is on it first for break in and first pulls has been very well port matched and plenum cleaned up along with smoothing of the runners. So, not sure how much of a true comparison it will actually be. But, i guess, stay tuned for the results.

Russ, was your six pack intake the one that was ported by hughes? Or was it untouched casting? And, was it cast iron?

Aluminum. No porting.

You should learn a lot with the 8 EGTs. Way more than guessing what to do with six jets and an O2. Can't wait to see what you learn.

Okay. I lied. Just checked. My 6 pack intake port windows are opened to match the standard port gasket.

Ok...thank you

I bet it wouldn't be too hard to find dyno numbers for a similar combo as this motor but with Edelbrock heads instead of the Trick Flow. will be some nice info for comparison.

Here is another comparison of a similar build with Indy EZ's and a hydraulic roller. Attached is the dyno run shortly before I almost had a catastrophic failure due to valve train instability issues due to insufficient spring pressures etc

I've since dropped the compression and switched to a solid roller with the help of Dwayne Porter. and run a valve train setup by Mike at B3 Racing. The replacement pistons weighed in at 528 grams to match the high compression ones I had in there, so it really spins up nicely.

I never did get it back on the dyno, but this latest motor is the smoothest reving RB I've ever had.

Notice how close the power is between the 4bbl Dominator and the 3 - 2's.

http://www.hughesengines.com/TechArticles/3dynotest684hp500cid6pack4bbljcross012007.php

The dyno testing I've done with a stock type six pack compare to a single plane intake and 1050 CFM Dominator carb was that the six pack made 8 HP more at its peak RPM and similar torque.
All the stock type six pack set ups I know of make peak HP around 5500 RPM and peak torque around 4500 RPM, the bigger single carbs on a decent single plane intake make peak HP and torque a lot higher nearer 7000 RPM
I had a SS Weiand two piece 440 six pack intake I never tried or used

526” FAST build....... ported 906’s, 6bbl........ peak hp @6100....... with HP ex manifolds and 2.5” pipes.

Hot street 505, stage 1 rpms, solid cam, dyno headers, 6bbl...... peak hp @5800.

Mild street 446, 346’s with very minor blend, hyd cam, 1-7/8 headers....... peak hp @4900.


My total guesstimate for Greg’s build would be for it to peak in the 5600-5800 range with the 6bbl....... provided there are no lifter function surprises.

Dyno day is done. Thankfully the engine is healthy and no problems, other than a pesky rear main seal leak. I give up with that. I was so meticulous and so careful. Just doesnt make sense how it leaks. But, i will be pulling the pan and windage tray off this fresh engine to try again.
Anyway, the results are as follows:
Street dominator intake with open 1” spacer with 850 carb: corrected peak 610 hp @ 5300 (might be higher-didnt get this printout, and screen cutoff at this rpm) and 634 tq @ 4600.
Swap to iron six pack: best pull after jetting up twice: corrected peak 576 hp @ 5400 and 608 tq @ 4300.
Ended up at 64 jets center, 88 driver side/84 pass side outboards.
Then bolted on aircleaner with old used fram filter: lost 4 hp.
Difference from street dominator with spacer to six pack= 34 hp and 26tq

Very nice. Your numbers are highr than mine. Not that you should compare dyno numbers.

So, 4 jet sizes up on the driver side for both the front and rear carb? EGTs led you to that, I presume.

To what rpm did you make pulls? Did you see much drop off?

What exhaust?

Thanks for sharing.

I believe there is significant power being left on the table due to the non-ported iron six pack intake. I sent my aluminum intake to Hughes and let them do as much as they knew how to do on it. They spent a significant amount of time working on it to push their envelope of porting knowledge and ate half the hours they spent to learn just how far they could improve the flow. They got the port to port spread much closer than it is in stock form and gained a significant CFM increase per port overall.

Here's an article they published years ago on a bunch of intakes including the six pack. http://www.hughesengines.com/TechArticles/4portedintakemanifoldsupdated08272007.php

I'm tempted to buy a another new aluminum intake, bolt it to my motor to transfer my port alignment to it and send it off to Wilson to see what they can do to it with their best effort.

Comparison

Russ....... Greg’s test was done using headers.
You had the HP manifolds?

Yes, I did.

I'm not surprised with your numbers. If you had used a performance intake such as a Victor or Trick Flow the 610 number probably would have been a touch higher. A 30 hp drop when bolting on the six pack intake seems about right. Did you do a weight comparison? You probably added 30 lbs when you lost the 30 hp.

My pump gas 496 with TF240 heads and a hyd roller cam that is fairly close to yours makes roughly the same numbers using a port matched Trick Flow intake and a Holley Sniper EFI unit. I would guess that a good intake would put you in the 620 hp range if the carb is correct. The six pack intake can probably be improved although not too many folks like grinding on cast iron. If it is a hot rod then switching to the aluminum six pack intake and having someone like Hughes Engines do a deep port match would narrow the gap.

Russ, the jetting increased 7 jet sizes in both putboards and both sides. We left the 64s in the center. The last pulls with each manifold was to 6000 rpm. Peaks seemed to be well below that. And this was with their 1-7/8” dyno headers. Tubes come straight out wuite a few inches. I’m sure it would have killed a bunch of power if it was run with factory ex manifolds, like you ran.

I think when Greg gets the sheet from the run that had the 610@5300 rpm on it, the peak might end up being a little higher than that.
On the screen shot he has of that run, which as I understand it went up to about 6000rpm, only shows the data through 5300......... and to that point, the numbers were still going up.
The dyno printout should show the whole run, so the actual “peak” may not have actually occurred at 5300(but..... then again, it may have).

I don’t recall all the details of the conversation he and I had about the power expectations when we were discussing the cam choice....... but I think it basically did what was expected.

With the 6bbl, the numbers are within 7hp from 5200-5900.

Jbc426. Thanks for the references to porting the intake. Nut, like your cuda, this guy’s 71 Cuda is also a numbers matching 440-6 car. That’s the teason for this whole build. To take out the numbers matching block and tuck it away. So i didn’t want to touch his orig intake. And, he didn’t want to spring for a new alum edelbrock. He will never race this at the track. Just a street car he will hammer on ocassionally and do some burnouts with. I will definitely check out that article since i’m in the whole researching anything to do with six packs. Thx.
Btw, love that engine shot.

Andy, You are correct about the weight savings. That iron intake is redicilous. I believe it is 57 lbs, although i haven’t actually weighed it. So 30 lbs sound very resonable. But, the owner was not really looking for evey horsepower. That is more my goal and i influenced him to an extent. However, he was dead set on keeping his original iron intake and carbs on this new motor, so we lnew it would land wherever the power / torque landed. I think it did what it was expected to do. In a street car that prob had 325-350 hp at this point in life, it will be an awakening for him.

Yes Dwayne, i will get that sheet from the shop, but i don’t think it will be for a few weeks. I will send it your way and try to post it on here whenni get it.
And as far as our conversation, i think the cam choice was perfect for the intended usage. We knew it would never be raced at track. And his converter is not matched with a high horsepower build. So, you tried to keep it very streetable for power brakes and torque production from lower down. He thinks his converter is around 2500-2800. The sixpack was also a given from day 1. I am extremely pleased with the cam choice.

One thing for sure is,, That car will be a HANDFUL on the street !!!!! better warn him to be careful , especially if he has plain street tires.

Thanks. As shown in my previous post with the attached PDF, my jetting was less than your's on the 6 pack. I was running at about 13.0 on the A/F on that run. All of my best 4 bbl runs were recording A/F more like 12.3 to 12.5, so my 6 pack set up might have been a little lean in hind sight.

I pulled mine to 6000 too. I wish that I would have gone to 6300. My numbers were so flat from 5100 to 6000 that the "peak" power would change from 5300 to 5900 rpm on back to back runs with little or no change. I think its because of my cam. Just curious as to how your power tracked after peak.

Here’s a 10.9:1 505 with prepped/blended RPM heads, 6bbl, a 252/260-112 solid cam and my dyno headers(2-2 1/8 x 4).
The intake had some work done to it by a friend of the engines owner.
Timing was 35*, jets were 87/87 front and rear, 66 in the middle.
It doesn’t really have much of a power “peak” either.

On a cold water hero run it made just over 650tq/600hp.

I would take those numbers any day. Is that a Roller or flat cam? Prob a little too much cam for this application though, right?

That was a SFT cam........ def rowdier than what you just tested.

It’s important to keep in mind these motors weren’t tested on the same dyno.
And not only were they not the same dyno, but between your build, Russ’ build, and the one I tested...... they were tested on 3 different makes of dynos, using 3 different data acquisition systems.
Sure...... it’s possible they all agree with each other really closely........ but I wouldn’t trust them to be close enough to consider the results as truly “apples to apples”.

Exactly. From a comparison stand point, mine seems to be a bit high relative to your example and Greg's. But you know that I'm not about the dyno numbers, but the learning from changes. I do think the shape of power curves, change in power from motor changes, and jetting information is transferable.

Nice numbers Chargerfan68. I have a few questions, what hyd roller lifters are you using, what spring retainer pkg on your trick flow heads and whose rocker arm assembly did you use? I’m planning on building a very similar engine build. Thanks.

I used Howards Max Effort hyd roller lifters. Part no 91774. (Incidentally, i was concerned about the weight of oil i would use, since some hyd lifters are specific to weight. So i called Gaterman, who makes these, and the engineer said i would be fine using 10w40 or 15w-50 conv or synthetic....no problem at all). As far as the retainers, they are installed by Trickflow with the hyd roller spring option. So, I have no information on what retainer they are. The spring i believe is 1.545”. Maybe Dwayne P might chime in and give info on retainers. For the rockers, i used the Comp Cams Ultra pro magnum Rockers (steel) par no 1621-16. Very nice rockers. This is the second time i’ve used them. First on my own 505” in my ‘73 charger. Roller tip lands almost exactly in center of valve tip with both sets. These are bushed.
Good luck on your build. And thx.

Looks like trickflow lists the retainers as: TFS-21400425 as far as i can tell.

Does anyone here know what the factory set up was on the jetting? I’ve got a stock 440 that has 64’s in the center and the outboards are marked .082-Pass and .083- Dr.
With the throttle completely closed on all 3- (idle screw not touching even) it’s idling at 1,000 rpm and slobbering rich. I’m guessing the outboards are to big. Any recommendations? This is my first time tuning a 6 Pak. Thanks for any help.

What about the setting on the outbiard idle mixture screws? Are the lead plugs removed so you can adjust and if so, what are they adj to? Also, are you sure the butterflies are all really closed? Have you looked down the carbs at idle and confirmed they are not being held slightly open by wrong gaskets, etc.. and the linkage for the outboards to the center carb...is it incorrectly adjusted, posdibly holding oitboards open? ( although now that i think about that, the slot in the center linkage arm might not allow it to do that. Let us know what you find.

I believe your jetting is in the ballpark. I tjink stock was 62 or 63 center. And outer metering plate orifices were around .083”-086” or so.

The outboard linkages were 1/2 turn to long. And I would’ve swore all day long the butterflies were completely closed. It’s idling down around 800 rpm now. The outboard carbs lead plugs have been removed the needles seem to be all the way in and have been staked from the bottom of the throttle body. I’m way closer now than I was for sure but it’ll still make your eyes water behind it. I’ve heard that just how 6 Paks are?
Thanks for the help. It’s appreciated.

Another thing to think about is: if the center carb idle speed screw is screwed too far in, it will expose the transfer slot and the idle mix screws will become ineffective. So right now, if you screw the center carb idle mix screws in all the way, does it cause the eng to stall?

Adjuts the outboard idle mixture screws so they are between 1/4 to 1/2 turn out from gently bottom and then try from 1 complete turn to 2 full turns out from gently bottomed out with no idle speed screw contact at all to the idle stop on the carb body on the center carb. to see if that will get you a cleaner, leaner, idle mixture at 800 to 1100 RPM in neutral or park

If the center carb mixture screws are turned in all the way it does stall. It seems best idle is about 1 1/2 turns out. I’m still thinking the outboards will need to be jetted down. The Quick fuel plates looks like the way to go. This is a bone stock ‘70 440 HP, so I’m thinking .082 is to much.
Since the outboards idle screws were staked, was that something the factory did or someone along the way?

Have you confirmed that there is no vacuum leak by testing with your hand over the center carb?

Does the idle speed wonder or slow back to idle rpm after you give it throttle?

Just looking for staggered Jet ingo and I ran across this
Am surprised you lost HP with the air cleaner
I picked up !

Heres my Dyno sheet results

Stil curious on other peoples Data on Six Pack Stroker jetting
and Still looking for results on the Hughes max port
six pack intake .

My dyno session - unported aluminum intake
64 center
84/88 outboards
TTi 1 7/8 headers
Max Power was WITH air cleaner base and KN air filt.
Back to back dynoruns indicated more hp with A12 base on .

Everything changes when in bolted into car . Wish i had current 1/4 mile time slip.

Real Street results with tti’s , h pipe and 2 1/2” full exh Magnaflow muffs
5 speed passon od and 354’s kept up with my hellcat SEVERAL times and is fast as hell
after 3rd gear . Loves Hi RPM
Low end , not so much . Cant figure out yet even after recent 4:10 swap. Its quicker , but slower .. bye bye 140 mph blasts . Which is probably good for my own well being ..

X pipe swap next …

Heres the dyno pull without Air cleaner
Picked up 6-7 hp with attached .

Cam Specs