6 pak run bad cold

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redlightrich1

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Hi All, I have just started my 440-6 for the first time after a complete rebuild. It was an original 440-6, and I assembled it mostly to stock 70 specs. I removed the exhaust heat riser and used the block off valley pan. It will not idle until quite warm, I mean about 15 minutes of working the throttle until it will idle near 850-900 which is factory spec. I have 12 degrees of initial advance, I have the stock 6 pac resto cam, it pulls around 13 inches, I do not think there is a vaccum leak.
I have a mopar performance electronic distributor. The carbs are the new holly 2300s for the 6 pac set up. I installed them out of the box. I did check the float level, and adjusted the idle circuit. Anyone have any ideas? If I advance it to danger levels, it will hold an idle, but then I will have other problems.

Thank you for any input you can give


Rich

Rich
 
advancing the timing is not a bad idea but you need to limit the total advance in the dist. do a re-curve. when you block the heat riser you need to set your idle circuit a little rich when hot to get it to idle when cold. or wait for it to worm. if this is something new i would say you have a vacuum leak or cam timing is some how off or blockage in thee idle circuit in the carb.
 
You can also fatten up the center carb a jet or two since cars run leaner in dense cold winter air. I did this with my 6bbl GTX and she liked a little more enrichment in the cool weather. If you are at higher elevation you have to be more observant since the airs effects would be altered.:happy9:
 
A stock 440-6 should pull a hell of a lot more idle vacuum than that.

Did you actually adjust the idle mixure on the center carbs? IF so, "how did it act?" That is do the mixture screws seem to have normal effect? Are they "all out" or "all in?"

Could be a LOT of things. If you can't run it down, one thing I'd try is pull all the carbs and carefully inspect the gaskets and mating surfaces. Then figure a way to make block off's for the outer carbs. You could even cut some out of soda/ beer cans. Cut out a metal gasket from a soda can, but do NOT cut the throttle bore holes. If possible use an extra gasket, so manifold, gasket, block off, gasket, carb, on both outer carbs If you don't have, can't get extra base gaskets, just go manifold--base gasket--block off--carb.

This will at least allow you to twiddle the center carb and see if you can get it close.

I'd be lookin for leaks---vacuum leaks.

You have a shop manual? The sixpack setup is right in the service manual
 
The vacuum at 13 is; Steady?, moving 2 each way? Gauge, adjust initial timing for highest. then time to play with those aggravating things. Leaks, linkage, jetting. never again.
 
Thanks for the ideas, the vacuum is rock steady. The carbs are brand new. I did not even open them to check jet size. when I adjust the left mixture screw, it responds, and at 3 turns out, it hits max rpm the right one is almost innefective. It is indoors, at approx 60 degrees. I am using NJ winter gas ( oxygenated I guess with alchohol) premium grade. I thought the vac reading was a little low, but I am reading it at the vac advance fitting, which I spliced into. I am not sure if that is full manifold, or partially ported. I was looking more for needle movement than inches of merc. I have used these 2300 holly's before without issue, but that does not mean I am not lean. After double checking, I do not have the valley pan cross over blocked off, so it does get heat. I have the choke properly hooked up and it functions well. I checked for a vac leak, and so far nothing. It does seem to want more initial timing, but how far is too much. I do not want to fool with the springs and centrifcal adv until I get it idleing right. I took it out, and it runs strong. It is just the eratic idle. If I let it idle for a while, I can get it to settle down at 900 rpm ( calls for 900+-50, and it will stay there until I blip the throttle then it wants to stay at 12-1300 for a while and no, the linkage is not sticking.. I am starting to think either center carb is lean or idle circuit problem, or vac leak that is not readily detectable. The motor was completely done, all mating surfaces machined. It has a cast iron intake. I have built my share of motors, and usually can get them set up less than 2 hours. This is making me scratch my head. Please keep the ideas coming. You all are a big help. I appreciate it!

Thank you

Rich
 
The one idle screw not responding, and the erratic idle speed = problem.

I would tear down the center carb, go down and get some spray carb cleaner with a "snorkel" tube. Pull any plastic/ rubber out of the carb--needle and seat, o rings, etc, and blow through ALL passages you can see and get to. Unscrew the idle screws and blow through them from the screw side, from the transfer slots, and the air bleeds.

I still think you have a vacuum leak
 
Yeah, center carb first. Timing; hook vac gauge, advance to best, lower idle back down. Check initial, then the dist to limit.
 
There are idle mixture screws for the outboard carbs as well, originals under lead seals. I ended up replacing the throttle plates on my outboard carbs because the mixture screws were frozen in place and broke when I tried to adjust them. Once I got the outboard carbs a little richer at idle, the center carb responded better and mine idles nicely even when cold.
Rod
 
hello and thanks again for the input and ideas. Mistake number one was putting on the carbs without even peeking inside. In NJ, we get blessed with oxygenated fuel from Oct to Apr. It has a 10% alcohol blend. That can cause further lean conditions. The carb came with 62 jets in it. The factory recommends 64, I put in 66. Then I set the timing using a vacuum gauge. Got it to 16.5 and backed it to 15 inches. The final tweaks were making the outboards richer. This required setting the front with engine running then removing the center to duplicate the same setting to the rear with engine off. It resulted it a very nice idle. I have done a fair amount of 6 pack work, and this was the most difficult to set up.

Well, thanks again for the help!!! You are all the best!!

Rich
 
redlightrich1 said:
The carb came with 62 jets in it. The factory recommends 64, I put in 66. Then I set the timing using a vacuum gauge. Got it to 16.5 and backed it to 15 inches.
Rich
Click to expand...

So in a nutshell, this was a "get rich quick" fix... Including your name... LOL! :sunny:
 
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