Need help tuning AED carb

-
mderoy340 said:
At 55 mph you are cruising on the primary jet. You will need to go back to 66 to get rid of the surge. Read the plugs after you go for an extended cruise as YR said and see where you are at. The AFR is a tool not gospel. Installing smaller main air bleeds will delay primary fuel flow but the MAB holes will need to be tapped for that to happen.

I also noticed that when I gave it heavy throttle that it would go full lean just for a second and then drop back in the 13 range. Make sure you have instant pump shot when moving the throttle. You went lean getting into the throttle and recovered to 13 so I'll bet pump shot adjustment is off.
Hopefully AED will let you know the other specs.
Click to expand...

I will check the pump shot arms.
 
yellow rose said:
How much vacuum do you have at a cruise? That's what you need to know to pick your power valve opening. Idle vacuum doesn't mean anything when selecting PV opening.

That will probably clean up the lean surge. Also, don't fall in love with an AF number. Make the car run the best and check your plugs. Then you can use the AF gauge.[/QUOTE
I will hook a vacuum gauge up and check cruise vacuum.
Click to expand...
 
Just some random info to post, but the T-slots are almost square on the primaries and the secondaries are closed at idle.
 
duster360 said:
Just some random info to post, but the T-slots are almost square on the primaries and the secondaries are closed at idle.
Click to expand...
Nothing wrong with that. Square up the front and use the secondary to fine tune the idle rpm.
 
If it's still cruising rich, it may be the IFR's.

How many turns out are the idle mixture screws. If less than 1.5, it may need smaller IFR's.

Jets do not always control cruise speed fuel in the system. With the AFR, you can figure out when the jets start to feed the engine. Watch it on a flat road and run 2K and up 250 rpm steps and note any change to the AFR. Once it starts to go richer, that's where the jets are likely activating.

This way you can tune the appropriate circuit.
 
crackedback said:
If it's still cruising rich, it may be the IFR's.

How many turns out are the idle mixture screws. If less than 1.5, it may need smaller IFR's.

Jets do not always control cruise speed fuel in the system. With the AFR, you can figure out when the jets start to feed the engine. Watch it on a flat road and run 2K and up 250 rpm steps and note any change to the AFR. Once it starts to go richer, that's where the jets are likely activating.

This way you can tune the appropriate circuit.
Click to expand...

It is a 4 corner idle circuit. I have them all turned out just a little over 1/2 a turn.
 
duster360 said:
It is a 4 corner idle circuit. I have them all turned out just a little over 1/2 a turn.
Click to expand...
As crackedback stated you are going to need smaller IFRs to lean the idle and cruise. You can wait for AED and maybe they will send you some.
Here's a good read that explains step by step tuning:
Carb Tunning
 
mderoy340 said:
As crackedback stated you are going to need smaller IFRs to lean the idle and cruise. You can wait for AED and maybe they will send you some.
Here's a good read that explains step by step tuning:
Carb Tunning
Click to expand...

Thanks for the link. I will be calling them Monday first thing. One thing crackedback mentioned was to check the afr with increasing the rpm. I did notice yesterday when I hit the interstate to get some speed up for 3 miles or so that at 70 mph the afr got better. Then I push the pedal on down a good ways til it hit 90 or so then let off. I noticed that at that speed the afr was in the 14's. But the secondaries were being used at this point.
 
duster360 said:
Thanks for the link. I will be calling them Monday first thing. One thing crackedback mentioned was to check the afr with increasing the rpm. I did notice yesterday when I hit the interstate to get some speed up for 3 miles or so that at 70 mph the afr got better. Then I push the pedal on down a good ways til it hit 90 or so then let off. I noticed that at that speed the afr was in the 14's. But the secondaries were being used at this point.
Click to expand...

You are going to have to make a few changes to that carb to get it right for street/strip performance.
Smaller IFRs to get the idle/cruise leaner. You probably have .033 IFRs it it now and need .031 or smaller.
Larger PVCR to get 12.5 WOT with 66/80 jets.
The 5 emulsion hole metering blocks IMO are over kill. Look at the old holley metering blocks and they used 2 .026 or .028 holes and work great. I've set up all the 650 and 750 carbs I've run with that set up using a .029 - .030 MAB and they cruise at high 13 to low 14 on the highway and mid 12 WOT. The WOT curve is very flat and stable.
 
I talked to AED today. They said my IABs are .070" and that I should get some blanks and drill them .078"-.082". I will start with the .078". He said that will help my AFR at idle, get the cruise AFR up and get the wide open throttle mixture down closer to where it needs to be. I ordered some blanks from Fastenal and they should come in friday. Will be couple days after that I should be able to report here what the results were.
 
You must log in or register to reply here.
-

Back
Top