Re: Edelbrock AFB blow thru modifications- pics - vid

I havent messed with mine for awhile but its still on the engine.

It honestly doesnt sound like you have enough air going through the secondary venturi.

This will be a very basic question that I dont want you to get offended by but, did you ever make sure the throttle is going wide open using the accel pedal?

 

Re: Edelbrock AFB blow thru modifications- pics - vid

It's been a little while since I've done it, but yes. When I put it on it was WOT at about 1/2 pedal, so I adjusted it.

 

Re: Edelbrock AFB blow thru modifications- pics - vid

As far as having enough air on the secondaries, I agree, kinda. I just cant wrap my head around it. Even without the air cleaner, you can see it drop from 14afr at 2500 to 10.6 at 5k and never tries to stabilize. It just doesn't seem right that it's always the same afr at 2500, though maybe the flap is closed there. It just doesn't make sense to me that even with stupid huge jets and no air cleaner, it doesn't get to 13.0afr even until 3k.

 

Re: Edelbrock AFB blow thru modifications- pics - vid

sounds like you need more signal. I had this problem, I even ran with no jet in the secondaries and it was lean. Vent tube mod was the only thing that helped

 

Re: Edelbrock AFB blow thru modifications- pics - vid

Hmm...

I never tuned my primaries like you have. I left the linkage hooked up and tuned everything by throttle percentage. I stopped my throttle just before it would open the secondaries and made primary fuel adjustments there which is about 50-60% throttle. Then, I adjusted cruise with needle changes. After that, I went wot and only made secondary adjustments. It seemed to work for me.

As just a guess, yours looks like the primary jet might be a little small, and the secondary high speed air bleeds too small also.

 

Re: Edelbrock AFB blow thru modifications- pics - vid

I ran without secondary jets also, before drilling out up to the .125" jet, because I couldn't get it anywhere close on a .098" jet. It finally richened up, but wasn't stupid rich, only 10.8 by 5k.

That's exactly how I tuned the primaries at first, then unhooked the secondaries, just to check and make sure there was no difference.

I have opened the secondary high speed air bleed some already, but I'd have to check and see what it's at. I wish I had screw in bleeds, so I didn't have to worry about going too big, I could just make a big change and see where it makes a difference, if at all, while being able to go back to where I started.

 

Re: Edelbrock AFB blow thru modifications- pics - vid

I think I'm going to add more weight to the door today and see how it does. I don't think it'll be a bad thing and can drill it back out if needed.

 

Re: Edelbrock AFB blow thru modifications- pics - vid

Sounds like its worth a shot. I wouldnt get too worried about getting the secondaries dialed in until you add the turbo. The fuel curve you have right now might be desirable or it could even flip on you and end up going lean at the top end.

 

Re: Edelbrock AFB blow thru modifications- pics - vid

That's true and something I've thought about as well. I might be going through this headache all over again after the turbo is on. I really hope not.

 

Re: Edelbrock AFB blow thru modifications- pics - vid

Adding weight seems to have helped, or its just because there's more load on the road than the dyno...but I logged a 2nd gear pull.#ad


The AFR seems to look much better after it stabilizes. I'm not sure what the swing at the beginning is unless it's from the accell pump. It flattend about 12.2 with 11.8 at the lowest at 3k.

 

Re: Edelbrock AFB blow thru modifications- pics - vid

That doesnt look bad man.

 

Re: Edelbrock AFB blow thru modifications- pics - vid

I didn't think so either, but it still had a bad lean spot on the secondary transition, especially if WOT from a higher RPM, and that's where things took a turn for the worse...

I pulled it apart to work on the secondary early feed circuit. I melted out the solder plugs i had in the air bleeds. I drilled out the early feed main tubes into the venturi from 1/16 to 5/64 and drilled out the first early feed tube into the well without a problem. The second one decided to break into a million pieces and I ended up pulling it out of the cluster completely. I know on Carter big block models they say to remove it for more fuel, but the cluster is made differently and flat with the gasket surface where the tube enters the well, which is not THAT far above the fuel level. The Edelbrock cluster is recessed WAY up in the cluster body where the tube enters and has to be fed a lot of air from the main low speed bleed that's right there next to it...I'm not sure. I may hit up Hobby Lobby today for some brass tubing and redo both clusters if I can.

I changed the secondary jets to .104 because a friend lent them and the next smaller I have is back to .098" and these aren't drilled like mine.

I took it on a test drive and it did well from 1000rpm WOT, but still lean transition, even worse than before. A horrible stumble when opening the secondaries quickly at 2500 or above. The AFR seemed to settle around 13.0 though, so I was kinda happy about that. It never seemed to stay the same from one pull to the next though, or as good as it used to.

Then, while lying in bed last night I realized I forgot to put the secondary main feed Welch plug back into one of the clusters. It fell out as I was melting one of the air bleed solder plugs out because the cluster body got so hot. How in the hell it had any semblance of a sane AFR at WOT is beyond me. I'll put it back in today when I get the early feed tube I guess...

 

Re: Edelbrock AFB blow thru modifications- pics - vid

Also, FWIW, I measured the secondary main emulsion tubes at .250"OD and the early feed at .100" if anyone needs those measurements. The wall thickness on the .250" measured around .020". The big recess hole around the early feed tubes I measured somewhere around .200", but it was hard to get accurate with dial calipers.

 

Re: Edelbrock AFB blow thru modifications- pics - vid

So, I fixed the secondary early feed tubes with new 1/8" OD tubes from Hobby Lobby and it was still lean on transition but decent once it settled around mid 13s.

I plugged the early feed air bleeds again and changed the Jets back to the drilled 7/64" I had in originally. It still had a leanish secondary transition but sabilized real rich at about 10.8-11.0.

I then changed back to the .104" jets again and it's back to 12ish with a lean transition, which mimics right about where I started. The tip in when I stomp it from 3k isn't bad and doesn't bog much, BUT...

I found that if I hold it at one RPM for a while, under high load and WOT, it just gets richer and richer until it misses, even if I'm down around 1500rpm.

I'm so confused now, I don't know where to go.

 

Re: Edelbrock AFB blow thru modifications- pics - vid

I decided to try putting the float levels back where they're supposed to be....now it's rich as hell on the primaries and the secondaries only make it worse. 13.0 cruising, 11s on the power step and 10s with the secondaries. WTF. I guess I messed something up? It was flooding over after shut off with the float level so high before, so I figured I could fix that and lean it out some. Who knows...

 

Re: Edelbrock AFB blow thru modifications- pics - vid

what is your fuel pressure?

 

Re: Edelbrock AFB blow thru modifications- pics - vid

About 7psi, stock mechanical Ford pump without regulator.

I killed the wideband and got a new sensor. Did a whole bunch of changes on the secondaries and pulled the floats, needles and seats, inspected and reset the height. Now it's as close as I'm gonna care to get. Cruise is nice and lean where I like and it drives well, with only a small lean bog if I open the secondaries real quick. I give up and it's probably gonna stay how it is.

 

Re: Edelbrock AFB blow thru modifications- pics - vid

is the pump boost referenced at all? and have you tried messing with the pump shot yet? those squirters can be changed out for bigger ones

 

Re: Edelbrock AFB blow thru modifications- pics - vid

It's still N/A, so no boost reference. I don't want to try and run boosted if I can't tune it N/A.

I have tried every hole available on the pump arm without change. It runs the best on the lowest setting and loads up on any higher when normal driving on just primaries.

The latest changes are a bunch of wire plugging the high speed and low speed bleeds some, as well as the emulsion tube holes. I didn't care to measure the sizes. I also drilled the early feed bleed again to something like .039". I also took some weight back out of the door.

I did all that after deciding the secondary main wasn't pulling enough fuel and the early feed was supplying most of it. Just revving it and looking down the carb, you could tell the early feed was flowing a ton and the mains hardly at all.

Suprisingly, the AFR is nice and flat and right at 13.0 at and after 3k, just before that it doesn't want to richen up no matter what. And same with the initial secondary tip in, no matter what rpm.

I'm just burnt out, with probably over 50 times inside the carb and still no solution.

 

Re: Edelbrock AFB blow thru modifications- pics - vid

Might wanna start over from the original calibration. Looks like it worked well in your 1st post. Look at your changes along the way and try and figure out where it went wrong.