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Six pack tuning help needed, please

69 GTX

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Meep & Lew maybe you can help me a little here. Trying to help a friend with his 440+6. First a little history. 440 .060, 10.7 cr, auto trans. comp cam 540 lift 236 @ .050 dur. 110 lsa 10 inches of vaccum @ 800 RPM. Center carb has .118 holes in blades. 12 degrees timing base mech advance distributor. 2 problems we were trying to correct, rich idle & a near stall stumble when lifting off throttle at stop lights. I went through and set the outboard carbs so butterflys were closed. Long story short to get the idle close I had 1.75 turns on the idle screws on the center carb and outboards closed. I'm thinking that the outboards need some holes in the blades so I can use the idle screws on the outboards. We started with one turn out on the out boards but ended up having to screw them in to get the idle closer. I did use the blocking the bleeds on the out boards to determine this. I think we are going to pull them off so I can go through and verify where everything is. Also I'm thinking a power valve of 5 -5.5? I'm helping him so I can learn and then tune mine when it's done. Thanks in advance!
 
I have a six pack and the only carb that is adjustable is the center carb?? I have seen several and none had outboard carbs that were adjustable.

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This is my six pack as you can see the outboard carbs don't even have the metering DSCN8054.jpg block
 
the idle mixture screws on the end carbs will need to be out 3/4 turn as a starting point, the linkage that ties the end carbs to the center carb must not be tight; should be a little wiggle. you don't want the throttle blades on the end carbs cracked open; that will really screw the idle up. check the idle feed restrictions in the end carb metering plates to make sure they're not plugged. opening them up to .038" wouldn't hurt nothing. i don't think you have enough timing at 800rpm. i'd shoot for at least 16; 18 would be better. if it's an automatic check the idle vacuum in gear. i think you need a 4.5 power valve. float levels in the end carbs should be a slight trickle out, or at least up to the sight hole. primary carb jetting will need to be at 64, maybe 65. don't go out and blow a bunch of money on gadgets, and don't try to re-engineer the carbs.
 
OK thanks Lew. I had everything as you mentioned but was really rich at idle. Do we need to do all tuning in gear?
 
OK thanks Lew. I had everything as you mentioned but was really rich at idle. Do we need to do all tuning in gear?
the only time i've done tuning in gear is when i have a noticeable idle problem in gear and i'm trying to tune it out with the centrifugal advance. i haven't found adjusting fuel mix in gear to help but if you want to try it won't hurt. i think the big hydraulic cam an low idle rpm are working against you. try to get some more degrees of timing at idle and work the power valve. fuel pressure may be an issue so monitor that.
 
Thanks Lew! He took it for a drive yesterday. Runs great everywhere but is a little rich at idle & still has the stumble getting off the gas at stops. We'll check the timing first then retune and see what happens. We are carefully recording each change so as not to get to lost. If 20 works on the timing we will have to take some out of the total advance to keep it at 36-38 correct?
 
depends on what distributor you have. if your using a mopar electronic FBO sells an advance limiter plate that may be a good tuning aid. i've also found in my experience that adjusting the kick down rod to eliminate all free play in it can cause trouble when stopping. basically if there's not some slop in it the downshift to first won't occur at the right time and will drag the engine down. i usually adjust the free play out and then back off the adjuster 2 turns.
 
MSD pro Billet mech.
should have some bushings and springs that came with it. put the largest bushing in with one light spring and one medium spring. there should be some details on the box or in the literature. those are just glorified GM-Delco type units. you may have to remove the shaft to change bushings. they are pretty good pieces and aren't difficult to work with.
 
That's exactly what I was thinking looking at the chart. Great to have someone to confirm your thoughts. Thanks again. I'll let you know how it goes. Working on it tonight.
 
Center carb had 62 jets & 6.5 power valve. changing to 65s & 4.5 pv. needed new a accel pump too.
 
Center carb had 62 jets & 6.5 power valve. changing to 65s & 4.5 pv. needed new a accel pump too.
that will help. i always ditch the .031" squirter. the best throttle response and driving for me has been a .025" with tubes and the white 218 cam. those center carbs are very small and don't need a big squirter.
 
Also distributor was correct on springs & bushing but need to see where he has the initial set at. I could also see his blades were open too much revealing to much of the transfer slot. We'll try to get it together tonight for a test drive.
 
i think the large bushing will restrict the distributor degrees to around 9. you may need to use both light springs. those larger hydraulic cams are a pain in the butt. most people will struggle with a good tune-up with them. also, you may be having some issues with winter blend gas.
 
I don't know if I mentioned it but it has power disc brakes, not helping the vaccum situation at all!
 
I don't know if I mentioned it but it has power disc brakes, not helping the vaccum situation at all!
pretty sure it'll need a vacuum can or electric pump. the 284-.528 mech cam would have been a super choice.
 
He did have one on at one time but took it off. Which cam are you speaking of, haven't picked one out yet for myself.
 
Lew made some huge improvements last night! First though these carbs were new in 2009, but had at leat 4-5 people trying to get them tuned. When we started this time the center had .118 holes and outers had .70 holes in blades. 6.5 power valve, and idle screws anywhere from 2 1/2 to shut. Ignition had initial set at 11. 63 jets in center and 82's on outers. First try we closed the holes in the outers and instaled the phenolic spacers. We ended up with 1 1/2 turns on the center carb outers clear in. Still rich and had the stumble at idle.
So last night we instaled the 4.5 power valve, 65 main jets, and opened back up the outer holes to .070. Also set the initial timing to 18. After seting the outer screws at 1/4 turn and the center at 2 1/2 we are very close! Idles good with 10-12 vac loping from 850-950. Shuts off with out the diesel solenoid, starts fine, seems alot crisper! We didn't road test it because it had the red bushing in the distb, full advance at 3k was 44 so we need to get the black one in there. Only question I had was in gear with his foot on the brake it has a pretty good lope and the vacumm was bouncing between 5-9 & 6-10. Should we put the 3.5 power valve in? Thanks for all your help! Has been fun to seen his face light up with each improvement, he is very pleased. I'll try to post a picture of the care next time we work on it. Maybe a week till we get back to it though. Unless it rains. Thanks again!
 
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