edelbrock 1405 problems

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coronet69swede

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Hi Guys and Gals.
340. Flattop. Aluheads. 2 plane intake. 10,5:1 comp. street cam hydraulic very moderat. Carb set at nr 3 in the chart.
Goes perfect at idle, light throttle, transition @ ca 0,95 to 0,97 at lambda. But light stumble to WOT. Not tested next hole on acceleratorpump yet. Then lean about 0,99 lambda at WOT all the way to 6000 rpm. Second main +16% according to the chart in the book.
Tested a 800 cfm edel and that pulled strong all the way. Same setting as the 500cubic motor it came from. Tested fuelpressure and all good from 800-6000 rpm
What am i missing?
 
That's above my pay grade, but I get this part;

But light stumble to WOT.

My question is what are the circumstances surrounding this stumble?
And what is the rest of your combo?
Such as car weight, rear gears, TC stall, and in what transmission.
Then;
at what rpm is this starting from?
and in what gear?
And from what throttle position?
And what is the power-timing during the stumble?
and I suppose it would help to know how soon after the carb goes WOT does the stumble occur, or is it during, or before?
For the most part;
a light stumble is a momentary loss of airspeed or fuel.
As always; first things first; make sure the float level is correct and that the bowl-vent is clear.
If the pumpshot is all used up when the stumble occurs, you might have to pop the M-rods up sooner,faster.
When all else fails remove the rear boosters and prove the rear fuel circuit is open.
 
You've answered your own question.
"Tested a 800 cfm edel and that pulled strong all the way"

Edelbrock 1405 is good for a stock or slightly warmed 318. Way to small for your engine.
 
I disagree; OP said

His engine is just a
and stroked AND BORED 318.

Fixed it for you.

The Carter style carburetors are not measured in the same way as a Holley. A lot of times it will take a bigger Carter (Edelbrock) to achieve the same results as a smaller size Holley. This is probably why his engine ran better with the bigger carburetor. Generally speaking, the Carter style carburetors are leaner than their Holley same size counterparts.
 
Fixed it for you.

The Carter style carburetors are not measured in the same way as a Holley. A lot of times it will take a bigger Carter (Edelbrock) to achieve the same results as a smaller size Holley. This is probably why his engine ran better with the bigger carburetor. Generally speaking, the Carter style carburetors are leaner than their Holley same size counterparts.


Definitely true. Every Holley and Holley clone I’ve seen is pretty fat out of the box. The fix is pretty easy, but it needs to be done. That’s why I posted those pictures in the race forum of the two plugs. The one on the right was the OOTB tune on the carb. The one on the left was my base line tune up. That particular tune was a bit rich at WOT but the rest was about nailed.
 
Hi.
Tested the 1405 with 113 second main and still lean at wot.
Put the 1813 on again with rod for 12% lean at cruise and 4% lean at wot. 4% lean on second main.Still much much better. Not perfect but pulls strong all the way.
 
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