Edelbrock 1407 lean at WOT

[ohitsjustbrian]

Been banging my head on this for awhile now, I have a mild 440 with secondary metering jets 3 stages rich (.116" jet) and still reading high 14s AFR at WOT. Cruise reads around 13.7 and Power Mode is upper 12's, the calibration is below. I'm not sure where to go from here as there is no Richer setting I can even use for either the primaries or secondaries. I guess I could have a massive vacuum leak but I'm getting about 10 hg vacuum at idle so I don't think that's it. Any input would be appreciated.

Note: I did order the high-flow carb needle and seat. It arrives later today and ill update this after I install and test it.

Calibration:
Primary Jet .116" Rod 0.065" x 0.037"
Secondary Jet .116"

 

[RemCharger]

Make extra sure there's no leaks in the exhaust before the 02 sensor

 

[GTX JOHN]

There is something out of sorts. Maybe a undetected vac. leak or pressure
issue.

That is richer than I run (.113) in my 440 race car.

 

[lewtot184]

Check fuel pressure and try a volume test. Hooking up a fuel pressure gauge and doing a WOT test would help. Probably not a carb problem.

 

[ohitsjustbrian]

Make extra sure there's no leaks in the exhaust before the 02 sensor

O2 sensor just behind collector and it looks good. Just pulled a spark plug to sanity check as well. I'm not great at reading these but this doesn't look super rich to me

 

[Darter6]

doesn't look super rich to me

I agree

 

[BSB67]

Check fuel pressure and try a volume test. Hooking up a fuel pressure gauge and doing a WOT test would help. Probably not a carb problem.

This. You need to start here. Your lean WOT might be fuel delivery and not jetting. Get a WOT fuel pressure reading and report back.

 

[lewtot184]

This. You need to start here. Your lean WOT might be fuel delivery and not jetting. Get a WOT fuel pressure reading and report back.

You got me doing this. It's truly an eye opener..

 

[Geoff 2]

Do the basic checks first:
- float level correct [ 7/16"]
- are the sec blades opening fully
- fuel delivery. A 300 hp engine will consume about 25 gal/hr. Estimate the hp & measure the fuel delivery.

Further comments:
- while it could be the n/seats restricting flow, I doubt it; if the fuel pressure is very low, it could be the cause. Get some Carter AFB/AVS 0.101 or 0.110" n/seats to eliminate the possibilty. Set the new float level to 15/32" or 1/2" respectively.
- the most likely cause. I have seen pics of some Edel 750 AFB carbs that had a bullet nose end to the sec booster emulsion tubes. These had a small hole in the end which was smaller than the sec jet & in effect became the sec met jet. Simply enlarge this hole so that it is larger than any sec jet that is likely to be used; this ensures the jet does the fuel metering, not the emul tube entrsnce hole.

 

[ohitsjustbrian]

Do the basic checks first:
- float level correct [ 7/16"]
- are the sec blades opening fully
- fuel delivery. A 300 hp engine will consume about 25 gal/hr. Estimate the hp & measure the fuel delivery.

Further comments:
- while it could be the n/seats restricting flow, I doubt it; if the fuel pressure is very low, it could be the cause. Get some Carter AFB/AVS 0.101 or 0.110" n/seats to eliminate the possibilty. Set the new float level to 15/32" or 1/2" respectively.
- the most likely cause. I have seen pics of some Edel 750 AFB carbs that had a bullet nose end to the sec booster emulsion tubes. These had a small hole in the end which was smaller than the sec jet & in effect became the sec met jet. Simply enlarge this hole so that it is larger than any sec jet that is likely to be used; this ensures the jet does the fuel metering, not the emul tube entrsnce hole.

Update:
I finally got the fuel pressure sensor in and did some WOT testing, seems like the pump is keeping up but i still see the A/F ratio creeping up toward 15 near 5k RPM. I'm thinking its in the carb now

Is this the bullet nose booster your talking about? How do I enlarge? I want to be sure this is it before I make a permanent change. Also is there anything I have to do with the air bleeds if I'm enlarging the booster nozzle size?

 

[Geoff 2]

Yes, those are the 'bullets'. Drill them out with a 1/8" drill bit. That is 0.125" & is bigger than any jet that would be used with a NA engine. The jets will control flow rate, not that hole. I have never seen an original Carter AFB with those bullet ends, do not know what Edel was thinking....

There was some more info on those holes on speedtalk.com.

 

[Bee1971]

These pinched holes where only on early build 1407/1411 Edelbrock 750 ? They have since fixed the issue ? Bet they made a lot of money on jets and metering rod kits back in the day , me included - Man I hated these carbs compared to other Edelbrock

How about the Carter Competition Series carbs ?

 

[ohitsjustbrian]

These pinched holes where only on early build 1407/1411 Edelbrock 750 ? They have since fixed the issue ? Bet they made a lot of money on jets and metering rod kits back in the day , me included - Man I hated these carbs compared to other Edelbrock

How about the Carter Competition Series carbs ?

I wish I had valued my time and spent more money but when I was buying parts this seemed like a deal, spent $125 for the carb and got this jet/metering rod kit for $15, has worked well so far - the kit not the carb. What other Eddy have you had better experience with?

 

[Geoff 2]

The original Carter Comp Series AFB came out in the late 60s. There were five models# 4758 to 4762, 500 to 750 cfm. All exc carbs. Modyfying the Edel carb as per post #11 will make the sec performance as good as the Comp Series. The same booster design is used.
In post #10, you can see the clever low speed start up cct that Carter used to initate sec fuel flow. It is the small brass tube in the venturi ring next to the booster leg.

 

[Orig69]

The original Carter Comp Series AFB came out in the late 60s. There were five models# 4758 to 4762, 500 to 750 cfm. All exc carbs. Modyfying the Edel carb as per post #11 will make the sec performance as good as the Comp Series. The same booster design is used.
In post #10, you can see the clever low speed start up cct that Carter used to initate sec fuel flow. It is the small brass tube in the venturi ring next to the booster leg.

Yes I agree the late 60s.

I have this list of Carter Competition series carbs that came out in the late 60s

4758s - AFB 500 CFM manual choke
4759s - AFB 625 CFM manual choke
4760s - AFB 750 CFM manual choke
4761s - AFB 500 CFM chokeless
4762s - AFB 750 CFM chokeless
4846s - TQ 850 CFM manual choke, press-in jets
4846sa - TQ 850 CFM manual choke, screw-in jets
4847s - TQ 1000 CFM manual choke, press-in jets
4847sa - TQ 1000 CFM manual choke, screw-in jets


Left booster is from a Carter 9000 series carb produced in the late 70s


The booster on the right is from a Weber(USA) carb

 

[Geoff 2]

Looks like the Weber AFB started
the problem....