350 running rich

[nascarmikeb]

I have a mildly built 350 w/ a 1407 Edelbrock carb. 0.30 over silvolite pistons, 292-501 lift comp cam & lifters, stock valves in 194 heads.

Initial timing w/out vacuum advance set to 12 deg BTDC, total timing @ 2500RPM is 30 deg. once engine is warm, the idle is 1000rpm, i'd like to get it lower to 800, seems like when I do, it becomes real rich and wants to stumble, if I don't rev the engine it will stall out. When I try to restart, it as if it is flooded, where you have to hold the throttle wide open to get it to fire. Even though I move the distributor to get the correct degree, I can also decrease/increase the idle speed with the idle speed adjustment screw. So I am slightly confused with getting the corrrect timing and lowering/increasing the idle to get me around 800rpm. I'm not sure if I don't have the correct timing if this will rsult in a rich fuel mixture.

I have never adjusted/touched the fuel/air mixture screwes. It used to idle fine. I just replaced stock HEI w/ aftermarket 65k HEI and 8mm wires, plugs gapped to .045.

Engine did sit on engine stand covered for approx. 2 years until I finally got the 700R4 beefed up to handle the torque. Although there was no fuel in the carb, and at times, I had the engine upside down to change oil pump and inspect bottom end of engine. So any fuel in carb, would have likely drained out. So, I don't believe the carb got gummed up.

I guess what I need help wuth is making sure I have the timing set correctly in conjuction with lowering my idle without the engine stumbling, and trying to determine if the timing/idle issue will result in a rich condition.

I hope I have provided enough info here.

Mike

[Getter-Done]

If you still have the stock HEI I would put it back in to try a process of elimination.

[andyh1956]

I'll try to help here.
1st- be SURE the mechanical advance in the distributor is working.
2nd- look into the carb while idling & see if you have fuel dribbling from the boosters. If so the carb is in "Main Metering" & we have to find out why.
3rd- install a vacuum gauge to manifold vacuum & see what it reads.
Do not try to adjust the carb yet. If the mechanical advance is working & carb is idling in the idle slots then I would bet the power enrichment valve is stuck "Up" & letting fuel bypass the jets at idle & this needs checking before you go further.

[Pontiac1976]

Quote:3rd- install a vacuum gauge to manifold vacuum & see what it reads.

The best tool for carb, find out Vacuum, fuel pump pressure. ((one of the two of most used reading))
You want try to get the highest Vacuum reading you can @ the idle your trying to reach
when you do try to a just the carb..

[nascarmikeb]

Originally Posted by Getter-Done

If you still have the stock HEI I would put it back in to try a process of elimination.

This was going on before replacing the dizzy. Replacement was my 1st step, besides I wanted to replace the stock as it had 2 loose plug wire terminals.

I also just installed a fuel pressure guage, at idle, it is between 5-6psi

[Dead Parrot]

Vacuum advance on ported or manifold?
What is idle timing with vacuum advance connected?
If on ported, for testing move to manifold to get more idle timing. Should help in getting the carb off the main ports and working only on the idle circuit.

The idle mix screws are just that, IDLE mix screws. They have minimal impact on driving mixture, that is the job of the jets, rods and springs. If it seems rich at idle, turn them in until idle improves or they lightly bottom. If the idle mix screws bottom before the idle improves, possible the float levels are set too high. Not uncommon on an out of box Eddy.

Wouldn't hurt to pull the power piston covers and check the pistons and metering rods for gum. Easy to do with the carb still on the motor. While they are out, clean with carb cleaner, just to be sure. Spray some down the holes as well.

[nascarmikeb]

Originally Posted by Dead Parrot

Vacuum advance on ported or manifold?

Vacuum advance is on ported.

[quote=What is idle timing with vacuum advance connected?[/QUOTE]
Idle timing on ported is approx. 12-13 degrees BTDC.

[QUOTE= Wouldn't hurt to pull the power piston covers and check the pistons and metering rods for gum. Easy to do with the carb still on the motor. While they are out, clean with carb cleaner, just to be sure. Spray some down the holes as well.[/quote] I purchased EDDY rebuild kit 1477, I haven't touched it yet, but I do have the kit in the event I need to use it. I do plan to remove the top of the carb, look at the floats, check adjustment and inspect for signs of dirt/gum.


Thanks for all of the input/ideas.

Mike

[Desert1957]

IMO way too much carb for the street and your combination.
Here is a description of this 1407 carb straight from "Edelbrock"
FYI Edelbrock carbs HATE high fuel pressure, limit to 5lbs and maybe some of your problems will clear up.


Edelbrock 1407 Details
750 cfm

*Calibrated for performance rather than mileage
*Recommended for large cubic inch Performer and most Performer RPM/Torker II applications

[geezer#99]

You don’t have enough initial timing.
Likely close to 2 degrees if you’re checking it at 800 rpm with the vac pot hooked to ported.
Always set your initial with the vac pot plugged off.

[Desert1957]

Here is an interesting read from Hot Rod Magazine about fuel pressure.


Number One: Incorrect Fuel Pressure

Surprisingly, the most common problem with getting a carb working right is not having the correct fuel pressure. Quick Fuel Technology tech expert Zach Baker says: “These carbs are designed to run at 6.5 psi. You might be able to get away with 7, but we’ve had a rash of pumps that do 8 or 9 pounds, which is great from a volume standpoint of getting fuel to the front of the car, but the carburetor’s not going to be happy there so you have to run a fuel pressure regulator and a lot of people just don’t.” The head of Edelbrock’s tech department, Dave Stinson, recommends a regulated pressure of 5 to 5.5 psi on their carbs, with a max of 6.5 psi.

[nascarmikeb]

Originally Posted by Desert1957

Here is an interesting read from Hot Rod Magazine about fuel pressure.


Number One: Incorrect Fuel Pressure

Surprisingly, the most common problem with getting a carb working right is not having the correct fuel pressure. Quick Fuel Technology tech expert Zach Baker says: “These carbs are designed to run at 6.5 psi. You might be able to get away with 7, but we’ve had a rash of pumps that do 8 or 9 pounds, which is great from a volume standpoint of getting fuel to the front of the car, but the carburetor’s not going to be happy there so you have to run a fuel pressure regulator and a lot of people just don’t.” The head of Edelbrock’s tech department, Dave Stinson, recommends a regulated pressure of 5 to 5.5 psi on their carbs, with a max of 6.5 psi.

I have a fuel pressure regulator that I can install directly before the pressure gauge. The pressure is bouncing around a little, but is between 5 -6psi.

[nascarmikeb]

Originally Posted by Desert1957

IMO way too much carb for the street and your combination.
Here is a description of this 1407 carb straight from "Edelbrock"
FYI Edelbrock carbs HATE high fuel pressure, limit to 5lbs and maybe some of your problems will clear up.


Edelbrock 1407 Details
750 cfm

*Calibrated for performance rather than mileage
*Recommended for large cubic inch Performer and most Performer RPM/Torker II applications

forgot to mention that I am using the Performer intake manifold.

[nascarmikeb]

Originally Posted by Desert1957

IMO way too much carb for the street and your combination.
Here is a description of this 1407 carb straight from "Edelbrock"
FYI Edelbrock carbs HATE high fuel pressure, limit to 5lbs and maybe some of your problems will clear up.


Edelbrock 1407 Details
750 cfm

*Calibrated for performance rather than mileage
*Recommended for large cubic inch Performer and most Performer RPM/Torker II applications

My mistake, you are correct, I mistyped. I have the eddy 1406

Mike

[RotaryRocketeer]

Originally Posted by nascarmikeb

My mistake, you are correct, I mistyped. I have the eddy 1406

Mike

1406 carbs are set up lean, for fuel economy, from the factory. Doubtful that it's running rich if you haven't cracked it open and changed jets or rods.

My money is on timing. You need to dial in your tune first, and then see where that leaves you on A/F mix. I just went through this same sort of thing on my truck.

[RotaryRocketeer]

Also, consider checking your mechanical advance setup. The springs could be really light and allowing some advance to come in too low, which would manifest itself in idle setting difficulties. Just a thought.

[nascarmikeb]

Originally Posted by Pontiac1976

Quote:3rd- install a vacuum gauge to manifold vacuum & see what it reads.

The best tool for carb, find out Vacuum, fuel pump pressure. ((one of the two of most used reading))
You want try to get the highest Vacuum reading you can @ the idle your trying to reach
when you do try to a just the carb..

Ok I purchased a vacuum gauge and this is what I got

I set the initial timing w/ advanced disconnected to 14 degrees BTDC
I was able to get to 12-13 inches vacuum at approx 850 idle.
I am running a comp cam 292-501,
Should I have more vacuum at idle?
When I burp the throttle, the vacuum drops to 0 quickly, then jumps all the way to 25, then returns to 13.
Engine is responsive, and doesn't smell rich like it was. When I kill the engine, it fires just with the bump of the key.

Appears to be running good. I just read where normal vacuum is higher than what I am getting. The vacuum needle is not bouncing, or moving significantly. It does hover between 12-13 lbs.

Any thoughts?

Mike

[geezer#99]

14 initial is for your average stock cammed motor.
You need way more. Maybe even up into the 20’s.
Read this.
http://www.badasscars.com/index.cfm/...d=76/prd76.htm