so ive ben fighting carb issues in my duster for a while. its bad enough to where ive all but stopped driving it.
idle mixture is set properly with a vacuum gauge, with the ac compressor on, fully warmed up.
electric fuel pump, regulated to 5.5 psi.
floats set to 1/2 from the carb gasket to the top of the float with the cover inverted.
stock jets, rods, and springs.
3/8 thick insulating carb gasket.
air gap intake
so my issues are a few fold.
1. will not restart hot. seems to be vapor locking.
2. doesn't pull nearly as hard as with the 850 double pumper I had.
3. erratic idle with ac compressor on.
4. diesels on cutoff.
while adjusting float level tonight in a vain attempt to solve the hot start issue, I forgot to put the metering rods and springs back in. no covers either. the car ran significantly better when I got on it. almost like the old double pumper. I was excited. when I put the rods back in, it was back to its same old tricks. I don't know if it was all in my head, but with no rods or covers the hot start issue seemed all but gone, but I didn't really validate that well. also didn't seem to even think about dieseling.
so what am I missing? im thinking that the rod and jet combo is way too lean, causing most my troubles, and the springs too stiff. does this sound right?
please, help me out here. I just want to finish out until my leg surgery driving this car.
Michael
Michael,
Which Ed carb are you working with?
What's the cam specs?
Float level should be 7/16"
You shouldn't be pulling fuel from anywhere but the idle circuit at idle. If the transfer slot is fully exposed you have the idle screw in too far. Since it ran better with the rods out I suspect the transfer slots are fully exposed. Same for the dieseling on shutoff.
I'll try and check in on the post during the day on Wed.
What is the timing set at, and where is the vacuum advance hooked up?
Running a 750 cfm afb. Electric choke. Udle at 850 unsteady with ac on. Dont remember initial timing. 36 degrees total at 3200.
360, indy heads, dual plane intake, 3.55 gears, 5 speed, 3400lbs or so. Vacuum advance hooked to left port. Solid roller 236/242@.50 110lobe seperaton.
Don't think idle slots exposed as idle mixture screws still have an effect, but can check.
Holley blue pump regulated to 5.5
Oh: power btakes, power steering, ac.
Get it working with the A/C off first then go back and work on the A/C idle speed. You might need an 8059 idle compensator kit (bracket and solenoid to bump up the idle speed with the A/C on).
By the left vacuum port on the carb, are you referring to it as you face the carb? If so, that's the one on the passenger side and should be fine. It's the ported fitting. I'd still pull the hose and cap it until the rest is dialed in.
Sounds like you have the solid roller version of my cam. My 360 likes 18 degrees initial. That cam has a pretty choppy idle. It needs more air getting in at idle than the idle speed setting on the carb can give. Might need to drill the primary butterflies to allow the air to pass through. Before grabbing the drill, try cracking the secondaries open a hair. Not enough to have them start drawing fuel from the boosters, just enough for a controlled vacuum leak.
Will do. Should that have an effect on the idle quality as well as desiling?
Ill try that tonight after work. Hopefully it help. Any idea on the metering rod snafu?
With it dieseling it sounds like your timing might be off and lack of power, give the dizzy a twist and re-try your throttle response.
While readjusting the floats, I found that this carb had had the metering rod changed to leaner. Back to stock calibration now. Got it warmed up and checed for leaks.
Next step is checking timing. With it desiling, would y'all bet that its too advanced or too retarded?
Also, I have found no way to crack the secondaries open at idle without bending stuff. Am I missing something?
Hoping to get it somewhat sorted this weekend, as I get cut open the25th.
the few people that i've known that were running Edelbrock carbs always seemed to have vapor lock/hard start issues that wouldn't go away. you could hear the fuel boiling out of them once they get up to temp.
the reason i asked about the timing before was because in general, older American V8 engines with bigger than stock cams like a lot of initial timing with a lot of vacuum advance hooked up to the port that gives them full manifold vacuum at idle. this is especially true if a high rise intake manifold is used that gives a weaker vacuum signal to the carb. it diesels when you shut it off because you have the throttle blades open farther than the engine wants due to not running enough advance at idle..
the lumpy cam equipped 355 in my Camaro currently reads 45 degrees at idle due to the vacuum advance, and it loves it. i don't have AC to worry about, but it idles fine in gear with the stock torque converter at 600rpm.
Dusterbd13 wrote:
While readjusting the floats, I found that this carb had had the metering rod changed to leaner. Back to stock calibration now. Got it warmed up and checed for leaks.
Next step is checking timing. With it desiling, would y'all bet that its too advanced or too retarded?
Also, I have found no way to crack the secondaries open at idle without bending stuff. Am I missing something?
Hoping to get it somewhat sorted this weekend, as I get cut open the25th.
I'll take a look tomorrow at one of the used Ed's on the shelf to see if there's an easy way to crack the secondaries open a little. On mine I cheated and put a fitting off the vacuum port in the back then drilled (I think) an 1/8" hole in the cap to see if it would idle better. It did. It runs to a vacuum hose to the air filter housing now.
The 3/8" insulating gasket should help with the heat soak.
For the dieseling try advancing it some.
Recently saw a Pontiac motor with a Demon carb get a chunk of rubber stuck in the exposed secondary accelerator pump linkage which held the secondary flaps open a bit, it was stuck at ~3500 RPM. Carbs are designed so the secondary throttle flaps can't get sucked open by vacuum, that would be A Bad Thing. It might be possible to temporarily disable the interlocking linkage for test purposes but I would not leave it that way.
I'm not very familiar with setting up AFB's so can't offer any blatherings about the hot start issue.
So im finally getting back to this. Surgery was not as successful as hoped. But I can't stand to see it sit, so I'll deal with the pain.
Drilling the primary plates an checking initial timing are in order for Saturday morning. Im thinking i set it to 18 initial during the manifold swap, but im not entirely sure.
i've always found dieseling related to throttle blades being open, i've never fixed it with timing. however, dieseling uses heat to ignite the mixture, and if all else is working right the heat in the heads is probably due to the timing being late. so yeah, some initial advance might help, if just closing the throttle blades all the way doesn't do it.
Well, back to the car sitting. Apparently a mouse got into the dash. Had a small fire on the way to the cruise night. Im about an inch away from blowing the whole car apart and redo it.
360 with a solid roller and indy heads.
I also discovered today that the mechanical advance has come apart, and I now have up to 35 degrees of timing at idle.
So frustrated with this thing right now.
In reply to Dusterbd13:
Yea time to walk away for a bit.
Dusterbd13 wrote:
Well, back to the car sitting. Apparently a mouse got into the dash. Had a small fire on the way to the cruise night. Im about an inch away from blowing the whole car apart and redo it.
that's just normal Dodge wiring.. it's supposed to do that.
