TUNING A SIX PACK

[RM23M9A]

My BOTTOM line here, anyone just buy 3 NEW Holley 2 bbl MoPar Six Pack carbs, "Slap em On" and have any luck?

I feel my 51 yr old units are just probably WARPED, gaskets, O rings shot, Start all from NEW?

 

[RM23M9A]

Great posts guys.
Even when I install the 541 aluminum stroker, I'm committed, FULLY, FIRMLY committed to running a 3x2 setup, so all options and tricks are welcome.
As far as "do it yourself" jetable outboard plates, I’ll stick to medical equipment repair and service and just buy the stuff from Promax. They did parts and labor for me, and ran them and "pretuned" them on their dyno mule, which has the same cam my 440 has, and they run good. I need the professional help (possibly in more way than one )

Looks as if their site is out of commission for such "Services" that sucks...
3 NEW carbs? = $1,800 plus!

 

[OH71RRunner]

I have always struggled to understand carburetors. When I first got my hands on my car, it didn't run right. There was nothing like it should: no amazing seat of the pants WOW, or anything that screamed big cam, six barrel setup like I've always heard.

I tried to rebuild. Tune. Retune. Rebuild AGAIN. Tune some more. I read SO MUCH information that I was confused. I did manage to learn quickly of how to disassemble and assemble these carbs almost blindfolded. I had done so many things wrong while trying to set these carbs up, that I still had it better than when I got my hands on it.
I asked supposed car people local to help me. They were scared of 3 carbs. No matter if they said they knew 4 barrel carbs or not. I tried to explain this setup is like a 4 barrel except it has 2 sets of secondaries. Still no luck. I was on my own with the help of this forum. That was difficult as I learn better being SHOWN than reading.
The more I did, the more I was learning. I had the wrong gaskets, (thanks Jegs, lol), tried different jets over and over. I ended up having a vacuum leak in the baseplates where the throttle shaft goes through. I finally had some money to send to ProMax. But I never got the chance to send off because, wouldn't you know, life screwed things up again. So, I did more research digging and figured I can just start from scratch and fix it myself. If I screw up, I'm only out a few dollars and still have to send them off.

Now it idles better, and a couple quick trips around the block, it runs much better. No real driving to see if I really fixed things or not.

Bottom line is this: do not be scared of these carbs or this setup. It looks intimidating. It's really not. Sometimes, you just need to start all over and put everything to stock and tune from there. If it won't run right setup as stock, then there is something else wrong.

 

[Bill Monk]

Well! I'll remember that!

Christ, I used to cuss and throw Sh"t about 4 barrels at one time...LOL
Oh boy, well? I inherited what I never DARED to "Go Near" or could only SHOW my teenaged friends in the 1980's... When I had to sell his house, help my Asshole brother take care of his "Final Wishes" etc, I finally got it into MY garage after finally getting out of the Army in 2008. I knew one day I'd own it. Hating or just disliking a man's Father goes away pretty fast when the inevitable happens..
When I first began to actually take it out & drive this "A12" it ran FANTASTIC. It's a ROCKET, when it runs as it should. Anyway, 3 weeks ago, I ran into long time friend who owns a 68 SS 396 Camaro, (hehe), well? Yeah we know what happens, at even 50 yrs old I was not letting a P.O.S. Bowtie pass this car I've NEVER seen passed by another '60s/'70s Big Block car.. Was always the ol man driving and I usually scared shitless... 10 yrs old? 140 mph? NO SEATBELT.. What the hell was a seatbelt? We all learn that eventually.
After 7-10 short drag races vs this weak-*** 396 (He never has passed this 440 Six Pack since Ive had it).
It falls FLAT ON ITS FACE, when literally "Putting Around", carbs are 51 years old. Todays gas is crap. I've replaced:
DASH WIRING-ENGINE WIRING (Year One), ECU-COIL- BALLAST RESISTOR-WIRES-CAP-ROTOR-Volage Regulator, rebuilt the damn guage cluster! **** works now that hasnt in 35+ years. (Except fuel Guage)... (There IS this, it seems to work) "Hi Rev7500"?View attachment 981662
If I stomp into it, past the cruising RPM? It's a Bat Out Of Hell again..In between? Runs like a 300,000 mile Honda Accord with an automatic.
View attachment 981660
My thoughts are to just BUY ALL NEW Carburetors. A/F screws are stripped on #1 outboard, Ive rebuilt Thermoquads, QuadraJunks, Holley 750s, but this is my FIRST "Six Pack" car. Pain in the ***. I'm not rebuilding just one, and then have to REMOVE it, to service the other 2 within a few days. This my luck. Lets call it "History". Should have STAYED in the damnned Army.
View attachment 981666
Advice? IF I can afford to buy at least the Center 4144 and ONE Outboard carb? (For right NOW) Anyway. Im sick of "Throwing Parts" at it. Not looking to sell it...(Yet) but getting there.
[Sorry for long *** post, but with other guys quitting L&R,17 hr shifts are murder]... Yeah I just typed that..lolView attachment 981660 View attachment 981661 View attachment 981662 View attachment 981663 View attachment 981665 View attachment 981666

I've rebuilt these carbs several times and they are not that bad. Like all rebuilds, getting them clean is half the battle. I take em apart and soak them in carb cleaner overnight. You can get kits easy, ebay has a bunch of them, like here:
https://www.ebay.com/itm/Holley-Mopar-Carb-Rebuild-Kit-For-Six-Pack-Three-Kits-Plus-Diaphragms/303187981101?
hash=item469769732d:g:2QMAAOSwi5xd8H1f
Cheaper if you don't need the diaphrams. You shouldn't have a problem finding an outboard base plate either if yours is stripped out

 

[70sixpkrt]

As far as I know, Indy Cylinder heads has the best deal on 3 carbs or try Summitt Racing. I would buy new carbs and try them but save your carbs esp. if they are the original ones. You would probably have to adjust rear mixture screws on the new ones to 1/4-1/2 out. Once you get them dialed in, they will throw you back in your seat. DON'T put a 4 barrel on it. Rebuilding your set is pretty easy. Soak them in carb cleaner and lightly blast them with your air compressor.
https://www.holley.com/products/fue...omponents/rebuild_kits/renew_kit/parts/37-396
https://www.holley.com/products/fue...omponents/rebuild_kits/trick_kit/parts/37-933

 

[70sixpkrt]

You could also send the carbs to Harms Auto for a complete rebuild. He does excellent work.
http://www.harmsauto.com/services.html

 

[biomedtechguy]

There's NOTHING I've experienced in acceleration, other than a turbo, that compares to the RUSH of power when my 6bbl opens.
I will always have a 3x2 on my V-code Roadrunner, and likely the Promax modded Holley 2bbl carbs the factory used.

 

[biomedtechguy]

I don't know if I posted this yet, but this, THIS was truly THE turning point in my struggle to get my 6bbl to idle properly, and THAT is the strong foundation that is required to make them run right at every other throttle position.
I first knew I had a problem when I turned the center carb idle mixture screws all the way in, as in no fuel, and the engine ran better! The outboard carbs needed tuning, badly!
Get to those outboard idle mixture screws, follow these instructions, and get going on the path to 6bbl bliss!

 

[OH71RRunner]

I don't know if I posted this yet, but this, THIS was truly THE turning point in my struggle to get my 6bbl to idle properly, and THAT is the strong foundation that is required to make them run right at every other throttle position.
I first knew I had a problem when I turned the center carb idle mixture screws all the way in, as in no fuel, and the engine ran better! The outboard carbs needed tuning, badly!
Get to those outboard idle mixture screws, follow these instructions, and get going on the path to 6bbl bliss!
View attachment 981784 View attachment 981785

This was a HUGE help in getting mine setup. I've got that saved on my phone and computer. Lol

 

[RM23M9A]

I don't know if I posted this yet, but this, THIS was truly THE turning point in my struggle to get my 6bbl to idle properly, and THAT is the strong foundation that is required to make them run right at every other throttle position.
I first knew I had a problem when I turned the center carb idle mixture screws all the way in, as in no fuel, and the engine ran better! The outboard carbs needed tuning, badly!
Get to those outboard idle mixture screws, follow these instructions, and get going on the path to 6bbl bliss!
View attachment 981784 View attachment 981785

Thank you for that link to Promax! Ordered the rear "Angled Screw Baseplate". $190 Im sure will be well spent! Also went ahead and ordered new Center 4144 carb from Holley, since theyre WetFlow tested for 390 HP stock 440, no need to deal with that one for a few years I hope. Liked that Black metering block too..But I don't or wont be racing much more on streets..(LoL yeah right) so just stick with Holley's block for now. Figured I'd swap out rear baseplate with Promax one, when the 350 cfm gets here. Front carb? Is still off of car, may be better to just replace it or have it Professionally rebuilt also.
I never knew it was THAT IMPORTANT that these "M Code" or "V Code" or any 6 pack motor RUN AT 195° either...

 

[biomedtechguy]

Liked that Black metering block too..But I don't or wont be racing much more on streets..(LoL yeah right) so just stick with Holley's block for now. Figured I'd swap out rear baseplate with Promax one, when the 350 cfm gets here. Front carb?

Ok...the Promax center carb metering block is mainly for hotter than stock cams. It does a much better job, IMO, utilizing the various circuits for idle, part throttle, etc and damn! sure looks cool too.
The front carb does not need the angled idle mixture screws.
I am not convinced about the 195° operating temperature for proper fuel distribution, but I also have an aluminum 6bbl intake, and they warm up (and cool off) faster than cast iron.
Sounds like you are on the right track.
I'VE SEEN DYNO COMPARISONS OF MODERN RACE 4BBL CARBS AND INTAKES COMPARED TO THE FACTORY DUAL PLANE 6BBL and the 6bbl HOLDS ITS OWN!!

 

[70sixpkrt]

I am not using a 195* thermostat. I have been running a regular Stant 180* for years with no problem. I would use the rear base and the jettable plates from Promax. Use the stock metering block for the center carb and see what happens.

 

[RM23M9A]

This was a HUGE help in getting mine setup. I've got that saved on my phone and computer. Lol

Yep! Same here. There's a blue book out there,

about tuning Six Packs as well.. Other than going back to the 1970's and finding that older guy at the shop who knew these inside & out, (who's probably 75-80 yrs old by now), I guess only way to go is getting lucky here!

 

[RM23M9A]

Ok...the Promax center carb metering block is mainly for hotter than stock cams. It does a much better job, IMO, utilizing the various circuits for idle, part throttle, etc and damn! sure looks cool too.
The front carb does not need the angled idle mixture screws.
I am not convinced about the 195° operating temperature for proper fuel distribution, but I also have an aluminum 6bbl intake, and they warm up (and cool off) faster than cast iron.
Sounds like you are on the right track.
I'VE SEEN DYNO COMPARISONS OF MODERN RACE 4BBL CARBS AND INTAKES COMPARED TO THE FACTORY DUAL PLANE 6BBL and the 6bbl HOLDS ITS OWN!!

Yeah I agree... My car still has the factory Aluminun intake, and 180° stat. Apparently someone (probably my father) stripped off the brass A/F screws on front one.. Or it would be already back on car.
Chicago Carburetor has a great selection of goodies too.

 

[68 HEMI GTS]

180 stat works just fine. That’s just someone’s interpretation of how they think tuning a six pack works. It’s kinda like the Internet, just because it says it doesn’t make it accurate

 

[monaco66coupe]

I have been helping a friend get a six pack setup to run right. The units are the new carbs, and ran great until it sat four years, we rebuilt the carbs, which was badly needed, But we still have an intermittent backfire out the passenger side tail pipe. one plug was sooted badly during our last effort. Also, the engine was modified around 2013, with a dyno sheet showing 472 HP at 5,000. After closely checking TDC on #1, it looks like it is 15 BTDC static. we are presently running the mopar electronic system, new out of the box.
any suggestions?

 

[62MAX]

I am not using a 195* thermostat. I have been running a regular Stant 180* for years with no problem. I would use the rear base and the jettable plates from Promax. Use the stock metering block for the center carb and see what happens.

Rear base plate is a no brainer,bought mine 20 + years ago when they were $75.On the metering plate you can get them here for 1/3 the cost of Promax.

https://www.atminnovation.com

 

[biomedtechguy]

Apparently someone (probably my father) stripped off the brass A/F screws on front one..

The outboard carbs idle mixture screws are VERY FRAGILE I've read several times, and require far less turning than the center metering block mixture screws do.

 

[70sixpkrt]

I have been helping a friend get a six pack setup to run right. The units are the new carbs, and ran great until it sat four years, we rebuilt the carbs, which was badly needed, But we still have an intermittent backfire out the passenger side tail pipe. one plug was sooted badly during our last effort. Also, the engine was modified around 2013, with a dyno sheet showing 472 HP at 5,000. After closely checking TDC on #1, it looks like it is 15 BTDC static. we are presently running the mopar electronic system, new out of the box.
any suggestions?

This is what happens when you let gas sit in the carbs for 15 years.

 

[monaco66coupe]

yes, they looked a bit like that. I TOLD him do not wrap that engine up! he did anyway.
We are getting there, but not there yet!