Six Pack idling rich

[fasjac]

I have 500 stroker six pack that idles a bit too rich. In the past I’ve read some post from very knowledgeable folks. Car idles at 950-1000 rpm’s just fine. She runs at WOT very strong, no stumbling or pinging. I’m using 93 non ethanol fuel. I’ll include the cam specs too. Yesterday I pulled the manifold vacuum from the big port on the back of the manifold.

I also installed a promax baseplate on the rear outboard carb on initial build 7 years ago. I can’t get in touch with promax but, I think the air screws are 1/8 -1/4 out. If anyone has any advice I would sure appreciate it.
Thanks,
fasjac

 

[Adam]

Put a gauge on the fuel line and see how much pressure the pump is putting out. Also check needle and seat settings and condition.

 

[fasjac]

Put a gauge on the fuel line and see how much pressure the pump is putting out. Also check needle and seat settings and condition.

Thanks Adam, will definitely get this done. Just realized I probably should of had this information after reading online. I will let you know the results.
Thank you

 

[Adam]

Anytime... I have had fuel pumps the overpower the needle & seat, what a headache.. good luck.

 

[fasjac]

Anytime... I have had fuel pumps the overpower the needle & seat, what a headache.. good luck.

I am running the carter mechanical pump. The car just runs soooo good. And I’m not a carb guru but have the basic knowledge. I know, that’s scary

 

[Adam]

I had a Carter mechanical pump that put out about 11 psi, but I didn’t know. After trying every adjustment, rebuilds and another carb, I finally put a pressure gauge on it and immediately knew the problem; I put a regulator on it and problem solved.

 

[fasjac]

I had a Carter mechanical pump that put out about 11 psi. After trying every adjustment, rebuilds and another carb, I finally had to put a regulator on it.

Good info my man!
I didn’t think that would ever happen. Gets me thinking now about fuel lines from the tank. Is the diameter different on the 73 cuda than say a 70 six pack car and how that could effect things. As I used all six pack lines from pump to carbs. Just a thought. I’m about to get a full pressure reading.

 

[rklein71]

A 73 used 5/16 fuel lines from the tank, a real six pack car would have 3/8 fuel lines. The smaller line would not affect idle quality though.

 

[rklein71]

Excess fuel pressure is a good tip, make sure your float levels are right as well. Verify no vacuum leaks.

A weak spark can also mimic carb problems. If you have electronic ignition, verify you have a good ground from the block to the body and the ECU is grounded good as well.

 

[fasjac]

Excess fuel pressure is a good tip, make sure your float levels are right as well. Verify no vacuum leaks.

A weak spark can also mimic carb problems. If you have electronic ignition, verify you have a good ground from the block to the body and the ECU is grounded good as well.

Absolutely!
When I built the car probably went overkill on grounds because I’ve been down that road for sure. It was a long road too. I’m running the MSD 6AL
Will definitely check those grounds as it’s been together for several years now.
Thank you for the advice!

 

[fasjac]

A 73 used 5/16 fuel lines from the tank, a real six pack car would have 3/8 fuel lines. The smaller line would not affect idle quality though.

A 73 used 5/16 fuel lines from the tank, a real six pack car would have 3/8 fuel lines. The smaller line would not affect idle quality though.

Thanks for the verification. Had to run to parts store fore some fittings. Should have the fuel pressure test shortly.

 

[rklein71]

Thanks for the verification. Had to run to parts store fore some fittings. Should have the fuel pressure test shortly.

Thought you might like a pic of my 69 383-s that I had a 440+6 in for over 25 years. The bad ground sure messed me up the first couple of years.

 

[fasjac]

Very nice!! I bet that’s a screamer!
All grounds are clean on mine but, I’m getting 10psi out of the mechanical pump. Never would have thought it.
Runs great just a tad rich at idle.
Thanks for the pics rklein71

 

[fasjac]

I can’t believe this much pressure from the mechanical pump???
I’m going to have to back it up with guages I have at work. But, I have the first reading.... thank you for the help guys. I’ll let you know if this is accurate.

 

[74 challenger]

I would say-Houston we have a problem

 

[fasjac]

yep, now that I’m re-entering the atmosphere! That’s my luck cuz, this motor rocks just like it is. Just wanted a little leaner idle. We’ll get her fixed up.

 

[Chryco Psycho]

I assume the carbs are basically unmodified , you are running low vacuum with the cam in there & it looks like you have a 4 spd which is a big + , but the 6 pack carbs are not set to run vacuum that low & the idle bleeds are generally too big & can't be changed , I have often dropped a piece of .035 mig welding wire into the idle bleeds & it helps the idle & whole bunch with low vacuum , , you can build a horseshoe with the wire & trap it behind the squirter on the center carbs , the outboards should respond a lot better with the same mod as they also have idle circuits

 

[fasjac]

Thanks for looking. I didn’t think it would pull the vacuum that it does.
Most all of other BB Mopars would only pull about 6. This one seems to be about 12 inches. Is that low? Because I don’t know. I can tell you with this set up, I can go WOT and get on the power brakes and they work perfectly. The engines before....WOT, be ready to push on the brakes a lot harder when you let off. I’m still learning.
Thanks for all your input. Much appreciated!

 

[rklein71]

I was thinking 12" of vacuum was pretty good....

 

[Chryco Psycho]

The factory cams used a 114 cl , so the vacuum was usually 15 or higher , you are doing well to get 12" & a lot of that has to do with the larger CI still I bet there is more in your set up by tuning it further