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Engine running rich
#1
So I am having an issue with the car. Since I got the car it seems the exhaust is very rich. I currently have a 351C with Edelbrock Performer intake, Crower Baja Beast Cam, and most importantly (i think) an Edelbrock 1406, which I had previously thought was 650 CFM but apparently is only 600. The idle is set at about 900, which was where the carb manual said to put it. I currently have the choke adjustment at about 1 notch lean. Looking for some thoughts on adjustments and/or getting a bigger carb. I know a bigger carb will get more air, but will it also try to get more fuel. That would basically give me the same problem on a bigger scale. I did adjust the idle mixture screws to what i felt was the best vacuum/idle. Maybe this is where I went wrong however. I did have to run my own power for the electric choke because previous owner had it connected to ground side of alternator (?). It seems the choke is not coming all the way open when warmed up, but only just barely. I am not sure if that means that one of the linkages is off, or if the heater is not functioning properly. Thanks in advance for the inputs.
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#2
Firstly, 900 R's sounds way way too much.
If an automatic, it probably strains against the brakes when in gear at a stop.
I'd imagine somewhere around 600 RPM for that cam should suffice.
Generally, it is the cam's determination, not the carb, as to where the idle should be.

Personally, I don't set a choke by recommendation. I initially adjust the spring housing just so the flapper barely touches the carb body when ice cold. If it "snaps" shut, it's too tight. Adjusted this way it will open fully, and early. If jetted properly, throttle stumble should be at a minimum when cold or the first few minutes of operation.
If it's too cold blooded, go a tad tighter on the spring (towards "rich"). I'd rather have my cold engine a bit lean than (choking-the-plugs-out/washing the cylinders with fuel) rich.
The flapper should be vertical as possible when warm (spring should be holding it hard open). You should literally be able to watch the flapper open slowly as the spring heats up over the course of a few minutes from cold startup.

That carb should be a perfect match for your cam and intake. Throttle response should be real nice. No need for anything bigger in your application.

Is the engine rich only at idle, or all over the rev/temperature range? Have you checked the color of the plugs after a good run? Although it sounds like your problem is choke related, **DO NOT** perform any other adjustments in jetting, spring or metering rod changes until you are satisfied that the choke is functioning properly. You'll need to isolate the real problem first...

Pete - MotoArts Decals and Signs
'71 Sportsroof 351C-4V/4-speed - FINALLY under construction - no, wait, on hold again...
'90 Mustang 7-Up 5.0 ragtop, rolling beater
'66 Sunbeam Tiger Mk.IA, survivor
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#3
Verify one before moving on to the next. Good advice!

[Image: 2rr7aiv.png]

Just cruising along minding our own business when BAM!!! The LAWS show up.
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#4
OK, so your suggestion is to first check that choke housing? As I said i have it one notch to the lean. I will get out there again soon and check the choke position when 'ice cold' as you said. I think it may be too tight. Would that be in the choke housing or in a linkage, which is what I am concerned about. Still trying to figure out how to make those little adjustments. I had an autolite 2100 on my 72 f250 that I had finally dialed in...then I sold the truck. Thanks for the help, I will get to this check as soon as I can.
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#5
The owner's manual:
http://www.edelbrock.com/automotive_new/...manual.pdf
And the rebuild instructions should help:
http://www.edelbrock.com/automotive_new/...0/1477.pdf



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#6
Yes, basically.
Inside the black choke spring housing (what Edelbrock is calling the "choke cap") is simply a flat coiled spring. As it gets heated, and expands and opens the flapper (they call it choke valve).
They list setting it kinda bass ackwards than how I explained it, but achieves the same thing.

Between pages 14 and 16 in the owners manual, they get pretty detailed on the adjustment.
Again, I'd simply start with the spring adjustment and see how it works for you. I'll also venture a guess that all those other settings are close and rod bending and such probably (hopefully) will not be needed, unless someone else has fiddled there before.

Key is to get it off of "closed choke" asap... Find the balance to keep it from gagging on raw fuel, yet still be drivable within a reasonable amount of time from startup.

Pete - MotoArts Decals and Signs
'71 Sportsroof 351C-4V/4-speed - FINALLY under construction - no, wait, on hold again...
'90 Mustang 7-Up 5.0 ragtop, rolling beater
'66 Sunbeam Tiger Mk.IA, survivor
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#7
Another thing for richness is to make sure the butterflies aren't open enough to be into the transition circuit on the carb. Being that the engine is idling at 900 RPM at idle instead of 600 RPM you may have them set too far open. The tell for this is the car will diesel or backfire when you turn it off.
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#8
You may need to change the metering rods. Have you determined from exhaust gas how rich it is after it warms up or when it is under load? Have you done a good hard run, shut it down and pulled the plugs?

[Image: 1_01_07_15_8_53_18.png]

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!
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#9
I didn't get around to visiting the car yesterday like I had hoped, but hopefully tomorrow morning.

1. Pull the plugs and inspect,
2. Adjust the choke housing

Not going to be able to run the car too much on the road this is North Idaho in December. Can I just get the engine revved for a few minutes or will it not give me the same indications?
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#10
No.
Not even close.

As long as it's running on all 8 cylinders, pass on the plug check for now.
To do it properly requires a good, solid hot run.

Do the choke adjustment and get back to us. I think you'll be seeing a good result Wink

Pete - MotoArts Decals and Signs
'71 Sportsroof 351C-4V/4-speed - FINALLY under construction - no, wait, on hold again...
'90 Mustang 7-Up 5.0 ragtop, rolling beater
'66 Sunbeam Tiger Mk.IA, survivor
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