TUNING A SIX PACK

[RJRENTON]

Oh good gravy it’s so simple!

RF,
I realize the simplicity, as I've totally disassembled many carbs B4. I just do not want to loose the originality of a numbers matching carb by mods to its base. I'd rather just remove and install the new base assy. Just my preference.
BOB RENTON

 

[biomedtechguy]

RF,
I realize the simplicity, as I've totally disassembled many carbs B4. I just do not want to loose the originality of a numbers matching carb by mods to its base. I'd rather just remove and install the new base assy. Just my preference.
BOB RENTON

I sent all 3 of my Holley 2bbl carbs to Promax since I bought everything they offer (except the fuel bowls) and I needed them to fix a couple of things, I had them install all of their parts and pre-tune them on their similar to my engine dyno mule.
I had to install the upper and lower stainless steel braided fuel lines of course.
Naturally the ONE problem (and boy was it a BITCH) I had after I put the carbs back on was shards of braid that was in the new fuel lines! I made the mistake of not flushing them out, and got quite a few shavings of braid in my metering block. Went through the whole week of Cruisin the Coast grinding my teeth and cursing Promax.
I finally made the time to take all 3 carbs apart and VIOLA! tiny stainless shards in the vertical ports of the center carb metering block. Flushed all 3 carbs out every way possible, put them back together and the 440 is pounding out the power, and idles like a champ (with a choppy cam)...

 

[440+6]

There was a guy selling kits on this site years back, consisted of 4 hex head idle screws for the outboards and a tool with flexible shaft with ball type driver to adjust them.
They where inexpensive and worked great for me, and you keep your original base plates.
I looked but dang find his info anywhere, maybe someone here remembers.

 

[RJRENTON]

There was a guy selling kits on this site years back, consisted of 4 hex head idle screws for the outboards and a tool with flexible shaft with ball type driver to adjust them.
They where inexpensive and worked great for me, and you keep your original base plates.
I looked but dang find his info anywhere, maybe someone here remembers.

Thanks for your comments....I do remember the item....they were slightly longer than the original scdews, but had a hex on the end and used a hex ball driver tool to be able to reach and turn the mixture screws on the rear carb. Like a dummy, I did not buy the offering....it was relatively inexpensive. Perhaps someone will remember the person and he is still in business.
BOB RENTON

 

[biomedtechguy]

I am certain it was a forum member.

 

[440+6]

Thanks for your comments....I do remember the item....they were slightly longer than the original scdews, but had a hex on the end and used a hex ball driver tool to be able to reach and turn the mixture screws on the rear carb. Like a dummy, I did not buy the offering....it was relatively inexpensive. Perhaps someone will remember the person and he is still in business.
BOB RENTON

yeah they work perfectly for me. best possible solution

 

[Frustration]

This is a very good post, with lots of good advice. I run a 500 CFM center carb on my 6bbl setup. In doing so, I run a much richer center jet than recomended. I am running 73's in the center and 86/87 in the outboard carbs. This on an engine that's 496 inch and has a .575 lift, .262 duration solid roller cam. I have an automatic with a good, 9.5" Dynamic Converter. Before you tell me I'm all wet, this combo is pretty sorted out. It's run 11.0's at over 121 MPH in street trim, and has over 4000 miles of street use. I'm curious if anyone that runs the bigger center carb has found this same situation? I have not had an air-fuel meter on it, but it doesn't foul plugs. I'm thinking about some dyno time to get it to run even better. 68 HEMI GTS???

 

[biomedtechguy]

I have not had an air-fuel meter on it, but it doesn't foul plugs.

I'm amazed at the information that my Innovate Motorsports dual wideband O2 system gives me.
I still have to make use of the data, but it's available.

 

[Bill Monk]

This is a very good post, with lots of good advice. I run a 500 CFM center carb on my 6bbl setup. In doing so, I run a much richer center jet than recomended. I am running 73's in the center and 86/87 in the outboard carbs. This on an engine that's 496 inch and has a .575 lift, .262 duration solid roller cam. I have an automatic with a good, 9.5" Dynamic Converter. Before you tell me I'm all wet, this combo is pretty sorted out. It's run 11.0's at over 121 MPH in street trim, and has over 4000 miles of street use. I'm curious if anyone that runs the bigger center carb has found this same situation? I have not had an air-fuel meter on it, but it doesn't foul plugs. I'm thinking about some dyno time to get it to run even better. 68 HEMI GTS??? View attachment 934010

If it works, go with it! Every engine is different and these rules of thumb are great but real life tuning is always different depending on the build. Congrats on the 11!

 

[68 HEMI GTS]

This is a very good post, with lots of good advice. I run a 500 CFM center carb on my 6bbl setup. In doing so, I run a much richer center jet than recomended. I am running 73's in the center and 86/87 in the outboard carbs. This on an engine that's 496 inch and has a .575 lift, .262 duration solid roller cam. I have an automatic with a good, 9.5" Dynamic Converter. Before you tell me I'm all wet, this combo is pretty sorted out. It's run 11.0's at over 121 MPH in street trim, and has over 4000 miles of street use. I'm curious if anyone that runs the bigger center carb has found this same situation? I have not had an air-fuel meter on it, but it doesn't foul plugs. I'm thinking about some dyno time to get it to run even better. 68 HEMI GTS??? View attachment 934010

I tune mine with a wideband. I’d have to check but I either have 72s or 73s in the center carb (500) also. I did end up shrinking the IFR’s a touch as well as the IAB’s. Mine had weep holes above the butterfly’s I plugged that were adding fuel. I also played with a transfer slot restriction although it seemed to lean it out to much.

Vacuum outboards currently just have drilled out metering plates. I’m around 91/92 on those.
My mechanical carbs are high 80’s as it pulls fuel from the squirters under WOT. Both set ups run the same center carb. Seems to put me in the low 12’s A/F wise at WOT which is where it seems to run the best.

 

[Frustration]

I'm amazed at the information that my Innovate Motorsports dual wideband O2 system gives me.
I still have to make use of the data, but it's available.

Thank you for the feedback. To use a wideband, do I simply need the bungs that are welded into the headers for a dyno session? I have a buddy with a meter that has offered to loan it to me on numerous occasions. I have yet to take him up on it since I do not have the bungs welded in. My headers are coated.

 

[68 HEMI GTS]

Thank you for the feedback. To use a wideband, do I simply need the bungs that are welded into the headers for a dyno session? I have a buddy with a meter that has offered to loan it to me on numerous occasions. I have yet to take him up on it since I do not have the bungs welded in. My headers are coated.

mine are in my exhaust pipes about 14in after the collector. I do all my adjustments from driving the car on the road. Then I may make small tweaks at the track for ET.

 

[Frustration]

mine are in my exhaust pipes about 14in after the collector. I do all my adjustments from driving the car on the road. Then I may make small tweaks at the track for ET.

Much appreciated. I have a track rental scheduled at Cecil Co. on May 24th. I was hoping to do some testing, but I can't imagine it will go off with this virus.

 

[biomedtechguy]

Thank you for the feedback. To use a wideband, do I simply need the bungs that are welded into the headers for a dyno session? I have a buddy with a meter that has offered to loan it to me on numerous occasions. I have yet to take him up on it since I do not have the bungs welded in. My headers are coated.

My TTi headers are ceramic coated. I think the bungs are welded in the collectors. Bosch and came w/the system. The voltage output and plug has to be compatible with the gauge.
The lean spike upon the tip in of the vacuum operated (no outboard accelerator pump) outboard carbs is dramatic, and lasts about 1 second. Goes from 12.X or 13.X to a very lean 19.X
If I were to do Nitrous Oxide, I would definitely have a WOT plus 1.5 seconds delay, or I'd turn my combustion chambers into welders.

 

[Frustration]

When I first started running the 6bbl, a buddy of mine welded/soldered/brased piano springs to the rear air/fuel metering screws. You could turn them by hand without removing the center or front carb. It worked great, but I didn't like the looks of the long spring hanging on the manifold. Now they're set and forgotten. This was done on my old Weiand tunnel ram manifold. I run a stocker now.

 

[biomedtechguy]

When I first started running the 6bbl, a buddy of mine welded/soldered/brased piano springs to the rear air/fuel metering screws. You could turn them by hand without removing the center or front carb. It worked great, but I didn't like the looks of the long spring hanging on the manifold. Now they're set and forgotten. This was done on my old Weiand tunnel ram manifold. I run a stocker now. View attachment 936504 View attachment 936505

@Frustration PLEASE PM me or reply to this post with as much information about your experiences with the Weiand P3690982 6bbl intake as possible! I have a very nice example of the Weiand, after torturing my mind and dealing with several people who had them for sale.
I'm trying to learn as much as possible and I have already read just about everything that is out there, exchanged emails, and talked on the phone with several people who run them.
Well, that is the only time I've seen that approach to being able to adjust the idle mixture screws on the rear carb in place, but it's so important to be able to make that adjustment, whatever works.
I had Promax go through all 3 of my Holley 2bbl carbs, because I figured I'd get the most out of the one time I was sending them out to them, it matters what gaskets and rebuild kits are used, and they were modding all 3 carbs anyway, so I wanted the peace of mind that they had been inspected and the right parts used.
I had borderline threads in one of the 4 screw holes that hold the center carb accelerator pump clamshell together, and that was repaired, jetable metering plates in both outboard carbs installed, their fantastic metering block put in the center carb, and the angled idle mixture screw throttle plate base for the rear carb. They used the fuel bowl gaskets that don't stick and are reusable, and that is really great for me right now, because I have some tinkering and adjustments to make.
The Promax metering block works so much better than the factory block when you have a hotter than stock cam.

 

[66Satellite47]

When I first started running the 6bbl, a buddy of mine welded/soldered/brased piano springs to the rear air/fuel metering screws. You could turn them by hand without removing the center or front carb. It worked great, but I didn't like the looks of the long spring hanging on the manifold. Now they're set and forgotten. This was done on my old Weiand tunnel ram manifold. I run a stocker now. View attachment 936504 View attachment 936505

I'm with Bio, telle us more about your experience with the Weiand tunnel. What mods did you do to the manifold? Jet combo? Etc.

 

[biomedtechguy]

@Frustration PLEASE reply to this post with as much information about your experiences with the Weiand P3690982 6bbl intake as possible!

I'm with Bio, telle us more about your experience with the Weiand tunnel. What mods did you do to the manifold? Jet combo? Etc.

@Frustration

 

[Frustration]

Sorry folks...here's the deal. I purchased the tunnel ram in new condition with no modifications. I made, or had made all the modifications that the Mopar Engine Book calls out. I'll show pictures in a bit when I can get to the garage. Ultimately, while I was running this intake, I had very little knowledge of how to tune a 6 bbl set up. Along with that, I had issues with an original gas tank coming apart and clogging my needle and seats...regularly. As you likely know, without good float level control, most everything else you do is useless. I ultimately got a 440 with stock stroke and cast iron max wedge heads to run 11.42 at Numedia Dragway. That was with a .575 lift, .262 @ .050 cam. This intake, with stock carbs and a stock-sized air cleaner, were able to fit under my repro-lift-off hood.

This intake screamed when it was up in RPM's. I had trouble tuning it not to bog off the line. I ultimately traded it to a good friend of mine for work done. He had a more-tame combo, and used his stock carbs with good results. It was much more driveable than when I had it. He did not do the jet mods that The Mopar Engine Book tells you to do. I'll post more photos shortly. One thing for sure...that intake was a great conversation piece at the track or car shows. I may try to borrow it back to try it again now that my set up is pretty sorted out.

 

[Frustration]

The first photo below is of the recommended settings for this set up. Notice the part that says "This is the best package for 440-6bbl Super Stock Racing". Obviously, this was printed quite a while ago. Notice the staggered jet recommendations on this page. PVCR=PVC Restriction...the holes behind the Power Valve on the center carb. I tried drilling stock outboard metering plates, then threading them to use Holley jets. That didn't work too well, so I purchased the plates from "Pro Maxx". They were much better as noted above. The handwritten notes on this page were where I ended up. I'm not saying it's the correct setup, but it was as correct as I could get at the time. One thing that was duly noted...this setup does not like the light, yellow springs. I used one brown and one purple in each outboard carb.

The second photo is what the modifications to the manifold and underside of the lid should look like. The wooden dams recommended were done out of aluminum by a friend, but were done exactly as mentioned below.