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Going to dyno - 6 pack jetting starting point? #2826080
09/28/20 03:06 PM
09/28/20 03:06 PM
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New York, USA
Chargerfan68 Offline OP
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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.

Last edited by Chargerfan68; 09/28/20 03:08 PM.

1.50 60Ft. , 10.75@ 127MPH Hauling 3900 LBS.
Re: Going to dyno - 6 pack jetting starting point? [Re: Chargerfan68] #2826104
09/28/20 03:38 PM
09/28/20 03:38 PM
Joined: Aug 2011
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Pattison Texas
CSK Offline
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Originally Posted by Chargerfan68
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


1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392 Stock 11.79 @ 114.5

Re: Going to dyno - 6 pack jetting starting point? [Re: Chargerfan68] #2826161
09/28/20 05:05 PM
09/28/20 05:05 PM
Joined: Feb 2005
Posts: 4,310
Prospect, PA
BSB67 Offline
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Originally Posted by Chargerfan68
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.


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.

Re: Going to dyno - 6 pack jetting starting point? [Re: CSK] #2826163
09/28/20 05:06 PM
09/28/20 05:06 PM
Joined: Feb 2005
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Prospect, PA
BSB67 Offline
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Agree with that

Re: Going to dyno - 6 pack jetting starting point? [Re: BSB67] #2826195
09/28/20 06:21 PM
09/28/20 06:21 PM
Joined: Jan 2003
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So. Burlington, Vt.
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fast68plymouth Offline
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Quote
Set it up temporarily with rubber hoses, so you can tune it easier


For sure

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


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Going to dyno - 6 pack jetting starting point? [Re: Chargerfan68] #2826228
09/28/20 07:43 PM
09/28/20 07:43 PM
Joined: Oct 2007
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New York
polyspheric Offline
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NO experience!
But... the stagger is to correct manifold flow differences, and I would keep it staggered until you know otherwise.


Boffin Emeritus
Re: Going to dyno - 6 pack jetting starting point? [Re: polyspheric] #2826276
09/28/20 09:38 PM
09/28/20 09:38 PM
Joined: Oct 2006
Posts: 1,264
New York, USA
Chargerfan68 Offline OP
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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.


1.50 60Ft. , 10.75@ 127MPH Hauling 3900 LBS.
Re: Going to dyno - 6 pack jetting starting point? [Re: Chargerfan68] #2826326
09/29/20 02:41 AM
09/29/20 02:41 AM
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Bend,OR USA
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Cab_Burge Offline
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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 wrench grin Six packs rule up
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 scope wrench twocents
Let us know your results please thumbs


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Going to dyno - 6 pack jetting starting point? [Re: BSB67] #2826337
09/29/20 05:56 AM
09/29/20 05:56 AM
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N/E, Michigan
RATTRAP Offline
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Originally Posted by BSB67
Originally Posted by Chargerfan68
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.


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.



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

Re: Going to dyno - 6 pack jetting starting point? [Re: Chargerfan68] #2826382
09/29/20 10:10 AM
09/29/20 10:10 AM
Joined: Jan 2003
Posts: 14,492
So. Burlington, Vt.
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fast68plymouth Offline
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When does it hit the dyno?


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Going to dyno - 6 pack jetting starting point? [Re: Chargerfan68] #2826418
09/29/20 11:41 AM
09/29/20 11:41 AM
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West Coast, USA
jbc426 Offline
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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.


1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
Re: Going to dyno - 6 pack jetting starting point? [Re: jbc426] #2826461
09/29/20 01:32 PM
09/29/20 01:32 PM
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Shelby mi.
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JAKE68 Offline
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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.


JAKES AUTOMOTIVE
Re: Going to dyno - 6 pack jetting starting point? [Re: fast68plymouth] #2826485
09/29/20 02:46 PM
09/29/20 02:46 PM
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Prospect, PA
BSB67 Offline
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Originally Posted by fast68plymouth
Quote
Set it up temporarily with rubber hoses, so you can tune it easier


For sure

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


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.

Re: Going to dyno - 6 pack jetting starting point? [Re: Chargerfan68] #2826490
09/29/20 02:55 PM
09/29/20 02:55 PM
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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.

Re: Going to dyno - 6 pack jetting starting point? [Re: AndyF] #2826538
09/29/20 05:24 PM
09/29/20 05:24 PM
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Chargerfan68 Offline OP
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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?


1.50 60Ft. , 10.75@ 127MPH Hauling 3900 LBS.
Re: Going to dyno - 6 pack jetting starting point? [Re: Chargerfan68] #2826603
09/29/20 07:33 PM
09/29/20 07:33 PM
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BSB67 Offline
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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.

Re: Going to dyno - 6 pack jetting starting point? [Re: BSB67] #2826617
09/29/20 07:47 PM
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Okay. I lied. Just checked. My 6 pack intake port windows are opened to match the standard port gasket.

Re: Going to dyno - 6 pack jetting starting point? [Re: BSB67] #2826763
09/30/20 08:30 AM
09/30/20 08:30 AM
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New York, USA
Chargerfan68 Offline OP
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Originally Posted by BSB67
Okay. I lied. Just checked. My 6 pack intake port windows are opened to match the standard port gasket.


Ok...thank you


1.50 60Ft. , 10.75@ 127MPH Hauling 3900 LBS.
Re: Going to dyno - 6 pack jetting starting point? [Re: Chargerfan68] #2827290
10/01/20 10:53 AM
10/01/20 10:53 AM
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central texas
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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.

Re: Going to dyno - 6 pack jetting starting point? [Re: krautrock] #2827311
10/01/20 11:32 AM
10/01/20 11:32 AM
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Originally Posted by krautrock
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


1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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