Another 318 carb issue!!!

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tsa_035

tsa_035

72 Plymouth Duster
Joined
Feb 11, 2010
Messages
57
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Location
Santa Clarita, CA
Hello friends!!!!

Long story short, 72 Duster 318, Eddy performer cam (.420 lift), Performer intake, Eddy 600 CFM, mechanical choke, headers, and pretty much stock motor. Less than 5K on the rebuilt 904, 8 3/4 with 3.55 gears. Sat for a few years, drained the gas, plugs and wires. Starts up ok, but it is like pulling teeth to go over 60 MPH. She sputters and sounds like she is missing real bad.

What I have done so far - rechecked all the wiring to the plugs, checked timing, air fuel ratio, timing again, air fuel again... When she is running the idle is smooth bt 700-800 RPM. Under any load she lags and sounds crap. Any ideas???

Thank you ahead of time,

Danno
 
I would look close at the carb for issues....

It's probably a little gummed up from sitting...
 
I agree,carb gummed up. May need an overhaul.
 
Ok, now another issue... Back at the carb again... I am leaning towards vacuum. It has the Edelbrock Performer .420 lift @ 204* duration. I cannot get this dang thing to idle!!! A list of check off and what I have done.

Reset the fuel mixture screws to about 1.5 turns. With the idle screw barely touching the plate on the carb (Edelbrock 1405) it idled at about 1800 RPMS. It would fluctuate from 2600 to 1200 RPMS. Plugged the carb for vacuum advance and checked timing (obviously idling way to high to check). Retarded it to bring the RPMS down. Got it to idle about 1200 RPMS (Fluctuate between 600 to 1800). At this point the idle screw is completely not even touching the plate.

Thinking I have a vacuum leak, I sprayed carb cleaner around the base of carb. Could'nt tell if fluctuation was from the spray or the fluctuation of idle. On side of caution I replaced the adapter plate and placed a half inch spacer on the intake. Still have a fluctuation of idle between 900 to 2000. When in any gear it drops to about 400 to 600. Sprayed carb cleaner around carb base and nothing. When it idles about 900 and give any throttle, the motor reaches about 2200 to 2500 and stays there for about five to ten seconds. Shaking my head.

I am leaning towards a meter. Not 100% if it is vacuum related or not.

On a humor side, My neighbor came over when I was working on it and said oh man sounds good. Sounds like you got a big cam in there. All I could do was laugh and think to myself she is supposed to idle smooth.
 
tsa_035 said:
Ok, now another issue... Back at the carb again... I am leaning towards vacuum. It has the Edelbrock Performer .420 lift @ 204* duration. I cannot get this dang thing to idle!!! A list of check off and what I have done.

Reset the fuel mixture screws to about 1.5 turns. With the idle screw barely touching the plate on the carb (Edelbrock 1405) it idled at about 1800 RPMS. It would fluctuate from 2600 to 1200 RPMS. Plugged the carb for vacuum advance and checked timing (obviously idling way to high to check). Retarded it to bring the RPMS down. Got it to idle about 1200 RPMS (Fluctuate between 600 to 1800). At this point the idle screw is completely not even touching the plate.

Thinking I have a vacuum leak, I sprayed carb cleaner around the base of carb. Could'nt tell if fluctuation was from the spray or the fluctuation of idle. On side of caution I replaced the adapter plate and placed a half inch spacer on the intake. Still have a fluctuation of idle between 900 to 2000. When in any gear it drops to about 400 to 600. Sprayed carb cleaner around carb base and nothing. When it idles about 900 and give any throttle, the motor reaches about 2200 to 2500 and stays there for about five to ten seconds. Shaking my head.

I am leaning towards a meter. Not 100% if it is vacuum related or not.

On a humor side, My neighbor came over when I was working on it and said oh man sounds good. Sounds like you got a big cam in there. All I could do was laugh and think to myself she is supposed to idle smooth.
Click to expand...


I like to use this carb base gasket:

Edelbrock Heat Insulator Gasket

First get the timing dialed in... Start around 10° - 15° advance and see how it runs...

then dial in the carb next...

That cam should idle at 700 - 800 RPM ... Something is not right...

Also check to make sure that you haven't mixed the #5 and #7 wires on the distributor...
 
krazykuda said:
I like to use this carb base gasket:

Edelbrock Heat Insulator Gasket

First get the timing dialed in... Start around 10° - 15° advance and see how it runs...

then dial in the carb next...

That cam should idle at 700 - 800 RPM ... Something is not right...

Also check to make sure that you haven't mixed the #5 and #7 wires on the distributor...
Click to expand...


Totally forgot to tell y'all. I triple checked the wires to ensure that. My issue is I can't set the timing with the rough idle. When I retard the timing it dies out on me. The timing then bounce around when the RPM's start fluctuating (Even with the vacuum line is disconnected from distributor and plugged on carb).
 
What kind of gas are you using? Sounds like common and reoccurring issues that I have had due to ethanol in the gas especially for a car that sits for days or weeks unused. I have had great results with a product called Carb Defender by a company called Driven. I was introduced to it in a clinic at Carlisle by Herb McCandlas (not right spelling).
 
str12-340 said:
What kind of gas are you using? Sounds like common and reoccurring issues that I have had due to ethanol in the gas especially for a car that sits for days or weeks unused. I have had great results with a product called Carb Defender by a company called Driven. I was introduced to it in a clinic at Carlisle by Herb McCandlas (not right spelling).
Click to expand...

Thank you for the info... As for an update, I placed a spacer on it. I changed out my throttle cable and kickdown linkage to a cable as well. All of my problems magically disapeared. :thumbsup:
 
For the vacuum leak, take a large rag, make it thick and cover the carb when its running. If there is a leak the motor will speed up. Full strength strength Techron in a 1/2 tank of new gas. Save some Techron, about 4 oz. Run the new treated gas for 30 minutes. Shut it off and add the 4 oz in the vent tubes. Let it sit for a few days. Change the gas filter before restarting. Run the tank to 1/4 full and then change the gas filter again. Most of the gas has toluene and xylene as major components of the gasoline. If you have old or marginal rubber hoses, those additives will swell and narrow your fuel supply. Check your rubber lines from the tank to the carb. Always add a fuel stabilizer to each tankful. It resolves many of the gas issues.
 
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