Help with Holley Street Avenger

-
dartman59

dartman59

Well-Known Member
Joined
Aug 10, 2008
Messages
146
Reaction score
27
Location
Florence, Massachusetts
Good afternoon fellow A-Body fans,
I'm having a devil of a time dialing in my new Holley Street Avenger 4160 770 cfm carb. It's on a '71 Dart; 408 (360 stroker, LA), 0.480", 274 deg, hyd flat tap, headers, 3" X-pipes, O2 in each collector; 4 speed, 3.55 gears. It pulls 17.0" vac at idle (900 rpm) and cruises at 21.5". PV is an 8.5. My A/F at idle is about 12.0. Ive been trying to lean out the cruise curcuit, but I've already jetted down to the lowest jets I have (64s--it came with 72s) and I'm still at about 13.5 When cruising on the level highway at 3,000 rpm. In that scenario, when I give it mild acceleration the AF goes lean (15.5-16.5) and stays there until the car reaches the higher speed, but it drops to 11.5-12.0 if I fully open the throttle so that the secondaries open. Cruising around town, rowing through the gears, I'm at AF of 11.5-12.0. Sitting still in neutral, here are my AFs:
RPM. A/F
900. 12.0
1200. 12.0
1500. 12.0
1800. 11.8
2200. 12.0
2500. 12.2
2800. 12.3
3000. 12.5

Why so rich? When I first bolted it on, and it had the 72 main jets, it would hwy cruise at about 11.8-12.0.

My transfer slot is a perfect square and I tweak my idle with the secondary screw. My float level is right at the center of the sight glass, front and back.

Am I missing something simple? I have noticed that my fuel pressure is normally about 6.5 but sometimes when I check it the pressure is high--9.5ish. Why would it vary and could that explain things?? It's a new Holley mechanical fuel pump.

Thanks for your thoughts and input.
 
I would start with getting fuel level to the bottom of the sight glass, should just seep out the hole, if removed. Idle is adjusted with the idle screws, never heard of adjusting idle with secondary screw. I make no claims to be a tuner. I`d try to regulate that pressure to 6.5-7 I believe is the most you want. Secondary adjustment is done with springs, you should have 2 extra different rate springs if you bought from a store.
The manual gives all this info.
You`ll getter, and others on this site will be better to help if patient.
good luck


Your good if you have the sight glass, evidently they are supposed to be in center
 
Last edited:
Not an expert either , but 2x on high float level. It can pull over additional fuel. 64 jet is a long way from base settings so I'm thinking something is outta wack. The secondary's are only supposed to drip a tiny bit of fuel just so the fuel doesn't stagnate. Sometimes it's better to go back to the base setting and start over. 17hg thinking you need a higher # power valve so it opens earlier, and a lighter spring in the pod also. Like said above tons of info in the destructions if you have them, if not pick up a copy of Holley's tuning book. Tons of info in there. Not uncommon to have to get into the ifr's to clean up idle. Start with the timing, you might need more initial.
 
Notes from my 770 Avenger on my 5.9 Magnum, mild cam, RPM Air Gap. 38 degrees total timing. Tuned with Wideband also. I was getting really good AFR at cruise with the below;

Power valve 6.5
68 Front jets
73 Rear jets
 
I'm no expert, in fact I'm just learning myself. Have the same issues.

You know your psi, but do you have a fuel pressure regulator?
How far out are your idle mixture screws?
Are they equal?
Did you set your idle mixture screws with the highest vacuum?
That's your mistake.
Idle mixture is everything.
 
No, I don't have a regulator, but I'm thinking I'm going to get me one.

Idle screws: all four are approximately equal, and out about 3/4 of a turn. They're very sensitive! Or, at least, some of them are. The front drivers side screw seems to not have much effect. Is that a clue??

What I've done is ease them all in the same amount, turning them in as little as 1/16 of a turn at a time. When it gets in towards the lean limit, that 1/16 of a turn can make a MAJOR difference. From there, I start to open them, 1/16 of a turn at a time (all four corners), and I see the vacuum increase right of the bat, an inch or two, but it only takes 1/16-1/8 turn out to get the max vacuum. In other words, from being at "so lean it almost wants to die" to maximum vacuum, it only takes 1/16-1/8 of a turn on all four screws, and some of the screws seem to have a larger effect than others.

I'm running 16 degrees advance at idle. It would like more than that, but I have an MSD ready-to-run distributor and I'm limited to a minimum of 18 degrees centrifugal (I can't dial it down any less than that). Thus, 34 degrees all-in.
 
check idle bleeds for gunk or old carb cleaner. A/F at idle should be like 15+. Widebands rock!
 
Pishta--thanks. This baby is brand new! (Not that it could have gunk, though ...). Yeah, I love my widebands. I have that cool dual gauge with a sensor in each header collector.

image.jpeg
 
Get your timing curve fixed. You need more initial timing with the cam you have.
Fuel pressure reg is needed to stabilize fuel bowl level.
When normally driving a street car you run on the idle fuel circuit up to around 2500 rpm and then the primary circuit comes in. You will see this on the wideband.
The idle circuit is tuned by changing the IAB and IFR size. A larger IAB will mix more air in the idle circuit and lean the AFR. A smaller IFR will do the same by allowing less fuel to enter the idle circuit.

Read this and tune step by step and your carb will feel like fuel injection. It is time consuming but worth it.
Carb Tunning
 
pishta said:
check idle bleeds for gunk or old carb cleaner. A/F at idle should be like 15+. Widebands rock!
Click to expand...


X2
Sounds like you could have something loose behind your needle, such as gasket material or a sliver of metal from the manufacturing process.
I'd take it apart and spray it like pishta said.
I changed my gaskets, and the next time that I took it apart, I found blue specs in my fuel bowels. I should have sprayed them clean.
I run 230/232* at 50 and have a 360 stroked to 402 ci. 4" X 4".
16 initial, 18 mechanical, 14 additional off my vacuum can always running off the intake vacuum, and 34 total. Mopar Dist. adjustable mechanical w/ vac. can
I'm just learning, have a AFR wideband meter, AEM brand, and am listening to the guys that know. That has helped me a lot. X2 whatever mderoy340 says. There are some great guys on here.
 
Last edited:
The IFR is the idle screw right? Or are they the vertical holes in the metering block? I have edelbrock efi on my 402 buy I also have an 850 DP that I may fall back on or break in with.
 
pishta said:
The IFR is the idle screw right? Or are they the vertical holes in the metering block? I have edelbrock efi on my 402 buy I also have an 850 DP that I may fall back on or break in with.
Click to expand...
IFR = Idle Fuel Restrictor. Best to change this diameter in .001 steps when tuning.
In the pic they call it the Idle jet.

MeteringBlock.jpg
 
Ooh, good to know! I suppose we can drill them to accept the screw in IFR jets? Or just get the QF blocks that have them already. Wideband, here I come.....I don't think my narrowband is worth a flip when it comes to this, it's all in or its all out. Very little resolution out of stoich.
 
pishta said:
Ooh, good to know! I suppose we can drill them to accept the screw in IFR jets? Or just get the QF blocks that have them already. Wideband, here I come.....I don't think my narrowband is worth a flip when it comes to this, it's all in or its all out. Very little resolution out of stoich.
Click to expand...
Best tool I ever bought was the wideband. Those billet metering blocks are pricey. I drilled and tapped my Demon blocks and bought the brass set screws to drill bleeds as I needed them.
 
You must log in or register to reply here.
-

Back
Top