360 running rich

[philcollins]

i have a .030 over 360, 9.75 to 1, ported X heads, P4452992AE Mopar purpe grindcam, .477 lift, headers, stock 1972 intake manifold and an 600 cfm Edelbrock carb. Mopar electronic ignition,20 initial, 35 total.
Engine pull hard, idle is fine at around 900 rpm. But, it smell gas and tailpipes are black from soot. Carb is new, i tried a good 1972 Thermoquad, still running rich.
Any suggestion?

 

[Lionized]

i have a .030 over 360, 9.75 to 1, ported X heads, P4452992AE Mopar purpe grindcam, .477 lift, headers, stock 1972 intake manifold and an 600 cfm Edelbrock carb. Mopar electronic ignition,20 initial, 35 total.
Engine pull hard, idle is fine at around 900 rpm. But, it smell gas and tailpipes are black from soot. Carb is new, i tried a good 1972 Thermoquad, still running rich.
Any suggestion?
View attachment 764211

How do the plugs read?
You'd have to richen that carb up in order for it to run rich. They're quite lean out of the box. I run the 600 Edelbrock on my 383 and it took a bunch of tuning to get it where it's at now.

 

[PurpleBeeper]

???? So is it maybe just your idle mixture too rich ???

 

[philcollins]

will try adjusting idle mixture.

 

[Crackedback]

Not enough initial timing is my guess. If the timing at idle is less than 16 on that cam, it's not enough. If you set it per a book spec, forget it. Factory settings stink when you start putting performance cams in the engines. Smog era timing settings don't work here.

Bump the idle timing to 16-18, reset idle speed/mixture screws and see how it cleans up. You will likely have to limit mechanical advance in the distributor to keep your total number from going out of bounds in the 34-38 range.

It takes work to get the timing profile correct. When done right, the engines run so much better.

 

[philcollins]

I'm running 20 at idle, with about 35 max at 2200 rpm. Will check advance, just to be sure.

Thanks

 

[Crackedback]

Check fuel pressure too. Ede carbs have issues when pressure gets in the 5.5 range. I run them at 5psi max.

When running look down the venturies to see if any fuel is dripping from boosters or squirters.

 

[philcollins]

New spark plug with about 5 minites of idle.

Did check the carburator, no leak from the boosters. Will try tomorrow to adjust idle screws, will check carb jet size also.

 

[Don Frelier]

Yikes. You've got to get that fixed, you will destroy the cylinder walls running it like that.

 

[Crackedback]

Vacuum is probably very low. May need the weaker step up springs on metering rods. The rods need to stay seated or it will fatten it up. I've had to remove the covers and lightly hold the plungers/rods down. That helped me get an idea whether I was on the right track.

It's dragging fuel in from somewhere. I'd put as much initial timing on it that the starter can handle and tune it from there.

If the idle mix screws don't shut it down, it's getting fuel from a different location other than the idle circuit.

 

[Don Frelier]

You could try it with no springs on the metering rods just as a test.

 

[philcollins]

Going in the right direction. Did set idle speed, found the idle mixture screws were open about 3 turn each. Closed them and the engine stalled. Idle is nice at about 1 1/2 turn, vaccumn is about 11 lbs, timing is at 22 degrees. Still runnibg a bit rich but much better.
Did not open the carb to check jet size, but the metering rod are the stock one for that carb. Will check tonight, want the engine to cool down.

 

[Don Frelier]

11" vacuum might be too low to pull down the metering rods with a stock spring

 

[Crackedback]

You could try it with no springs on the metering rods just as a test.

Good idea there... probably better than a pair of fingers holding them down!

Look up the edelbrock step up spring kit. Usually about $10-15. Check out the instructions online and see what spring they recommend with each vacuum reading. 11-12 inches is about where a 238at .050 is going to come in.

Watch out for your total timing number after twisting in more initial.

 

[philcollins]

Did plug vacuum advance hose to direct manifold vacuum. Engine run better with less throttle opening. Almost no black smoke coming from the exaust. Also now, getting 14 in of vacuum. I ordered Eldebrock 1464 spring kit, i'll try lighter one.

Total timing is 34 degrees so it should be ok. Will install engine in car tomorrow and i should be able to do a complete road test next week.

Thank you all for your help.