Holley Street Avenger 670

[420ponies]

Anyone have this on a mild 350? I just threw this on to see the difference from a 750cfm I had been running forever on it.Seems a little better as to throttle response.Have not torn it down to see what jets are in it or power valve yet. Any tricks I need to follow? Edlebrock RPM Air-Gap intake,68cc heads,10:2CR,.490 lift/292deg. hydraulic cam,headers,High output HEI ignition.

[Daryl]

Here is a formula for sizing a carburator. Easy to remember thats why I use it as a staring point. I would however drop the results down to the next lower carb size for stock to a medium modified engine. Its not an absolute but close for a street engine. I think that 750 was a little big unless your engine lives in the red zone. If you go to Holley's site they have a sizing calculator that may help. Do you own a vaccum gauge? Manifold vaccum can tell you a lot.

 

(cid x 2) - 15% = CFM

 

 

 

 

[420ponies]

Daryl, My vacunm gauge reads about 18-20 at the full vac.port under front fuel bowel. I also have a 1/2" spacer plate under carb. to run my accummulator tank (brakes). I really do not think I have this much vacumn at idle in park. Cam has alot more lift than advertised. I have angle milled and flat milled these heads to get the 67cc chambers w/2.02in. 1.6exh. stainless valves, 1.6 roller tip rockers and special length pushrods to center the rocker on valves. Should I be checking vacumn in drive? motor seems to like 750rpm in drive,1000 rpm in park. Oh, this is a 355sbc.

[Malyc]

Thanks for that post, Daryl... I didn't know that was how you picked a Carb.

[bdk70monte]

I was running a Holley Street Avenger 670cfm on my ZZ4 crate motor until I did a big block swap this winter. The ZZ4 is rated at 355hp and I thought the Street Avenger was a great carb on it. It was almost plug and play out of the box like they advertise. We bolted it on and hooked everything up and it started right up. Just had to do some minor tweaks to get it the way I wanted. I'll use it again on something in the future. I went stock with the big block so I'm running a quadrajet now.

[Sam (Bones)]

you should check what vacuum you have at wide open throttle while driving

[72MC]

you should check what vacuum you have at wide open throttle while driving

 

At WOT, I believe that should be 0 (zero). - Dave

[Sam (Bones)]

I like to see some vacuum (say around 1")for a street engine, otherwise you don't know if the carb is to much, if it's over 1" you need to go next step larger

 

I run a 750 on my .030 over 454 and it pulls great to 6000

[72MC]

I hear what your saying Sam. I have the Holley 750 HP Series (p/n 0-82750) on my 383 and it pegs at zero but if you let off even just a hair you can see a blip in the vacuum gauge. Figure I am dead on with carb size.

 

My fuel injected LT1 in my Impala SS did the same thing and that thing kept pullin well past 100 mph. Granted, that was not naturally aspirated. - Dave

[Sam (Bones)]

I'd say so too!

 

I can't see my vacuum gauge when I peg it, I know this engine wants a little more, a 830 would be perfect

[420ponies]

Well, I thought it was good-to-go in the garage.I took to work (20 min. thru town 30mph,70mph,45mph).awfull stumble just off idle,had to feather throttle at stop lights to take off. so bad it popped thru the carb. and died in the lane. get to work adjusted mixture screws again(2 full turns out),same thing again. changed vacumn advance to full vacumn port, same results. changed back, re-adjusted mixture screws (1 3/4 turns out). acted a little better. I could take off and no stumble. So,took it down the road full throttle,1st, 2nd,part of 3rd (over 80mph)pulled good thru the gears, slowed it down, got off interstate rolled into gas staton went to leave,popped thru carb.,died. I'm going to put my 750cfm back on and see what that does for it. I thinking power valve not opening quick enough off idle? I'd really like to try and keep this 670 cfm avenger on the motor.

[Daryl]

I just went through the same process you're currently are with my 489. Holley's I have learned you gotta start with the basics and work your way from there. The very first thing you need to check to make sure the float levels are set correctly. What size of jets and power valves are you running? Have you pulled your plugs to read them? It sounds like you're starving for fuel.

[Sam (Bones)]

you need a larger squirter (accellerator pump nozzles) I would go up 4-5 numbers or a different pump cam

[72MC]

Is this carb brand new or just new to you? I think you have a mixture problem and maybe the need to adjust the accelerator pump arm. Be careful that this arm is not stiff against the pump. That will cause fuel to constantly want to dribble out causing a bog. The acc pump arm needs a slight bit of play. And always remember, your idle screw is just a fine tune instrument. It's not meant to fix a mixture problem. If your rpms are dropping 400 rpms or more going from park to drive, you have a setup/mixture problem. Your optimal mixture will produce the highest vacuum in drive. That's when you know you have the right mix.

 

That being said, Holley's are one of the easiest carbs to work with. Still misunderstood from the 70's but I digress. If it were me, I would start over. Check out the link for Holley's method to set these carbs up properly. It will take two(2) people but it is easy. I bought their instructional CD years ago and it was well worth the 15 bucks. Here is the link:

 

http://forums.holley.com/entry.php?429-How-To-Adjust-The-Idle-Mixture-On-Holley-Carbs

 

The link has an easy write up and a video as well. Hope this helps you out. - Dave

[420ponies]

Well, I have not given up yet on this carb. I did find that a plug for the PVC on the front of the carb was leaking vacumn. I noticed that when I was trying to install my vacumn gauge next to it and heard a whistling sound from it (dryrotted). replaced that and reset mixture screws. 22 inches of vacumn at the full vacumn port on front of carb. Now it still has a slight hesitation just off idle, but not to where it pops back thru carb. I think I will go bigger on the squirter size for the accelerator pump. Holley recommends up 3 sizes to start.

[420ponies]

Well,I have disassembled this carb. and am very disappointed . 65 jets in front, 68'S in rear. 031 squirter,10.5 power valve. no wonder it was running lean. After 3 days of wondering what I should do with this carb,I decided to scour the internet for info. What a wake up call ! this carb has had issues since it was put into production. I have made some changes to it. I have taken out the 68's and put those in front. 72's in the rear.I changed to a 8.5 power valve.the squirter will be a .037 tube style as to get the squirt into the center of the venturi. I have since put my 3310 back on it. I am still looking for a replacement front metering plate for this carb because I cannot adjust the fuel mixture screw on the right side(no difference in idle).I did take this apart to find the problem,nothing is blocking that port. stilll no adjustment. stay tuned for more posts as I am nearing completion on the 670 street avenger (waiting on squirter ).

[Mike 57]

Here is a link to the Holley page that gives all the part numbers and jets for the carb. Holley carbs

[420ponies]

Mike,Thanks for the link.will come in handy.Should have new squirter this morning and get the 670 on my car today.

[420ponies]

Well, I think I got it. put 670 carb on it this afternoon and runs good to my ears. Not alot of adjustments, not popping back thru carb. just off idle as before . 850 rpm idling, 750 rpm in gear. not sluggish coming up rpm range. I do have it at 1" of vacumn at full throttle now, I will be taking it out on the road as soon as the weather breaks here. But it runs very well. The .037 squirter did the trick I think.Very reponsive throttle now. Time on the road will tell the difference.