I may be looking for a new 4bbl (square bore) carb for my 499 stoker. This is a street car so I am looking for a unit with an electric choke. I could go mechanical or vacuum for the secondaries but prefer the vacuum ones myself. I'm thinking something in the 800-870 cfm range...

Motor is a 10.4:1 499 stroker, 2400 stall 727 auto, mild-ish cam, 3.55 sure-grip

I want a Holley derived carburetor as I don't want to deal with the duel fuel inlet fittings not working and having to redo all my linkages and lines.

Here is what I have on there now. I was never super impressed with this particular carburetor:
Current Carburetor

I was looking at this one:
One Idea

Are these street avengers any good? Should I consider any other lines/brands like Demon or the Summit knock-offs?
What about this one?

I don't mind spending a little extra for a good carb but I am not looking to sacrifice choke and drivability on some racing carb.

If it was me I'd upgrade your existing 850 carb with a set of billet metering blocks. Then spend some money on a dyno tune session or on a wide band setup. That 850 carb that you have today should work just fine once it is tuned correctly.

I just run a basic 850 DP on my 493 and it works good. Has great driveability and the car will run in the 10's with it. I dont use a choke as it will start and I can keep it running even in 35 degree weather without the choke valve in it but I usually dont take it out when it gets colder then the 50's out. Ron

What will billet mitering blocks get me over the ones I have now?

I did have it dyno'ed but since then I have done so many fixes and tweaks, its off a bit now. When I had it dyno'ed I had a bad fuel pump and a weak ignition. I didn't know it at the time but found that out later as I worked through the car. I also changed the timing a bit to get it from pinging by shortening the mech advance.

I am a bit frustrated as I stripped the accel pump nozzle screw threads and I am skeptical if I can make this repair properly. OF course you can't find any aftermarket main bodies that are setup for choke and its big $$$ to buy a replacement...might as well buy a new carb....

If you guys don't think there is much to be gained by going to a new carb, then I will try and stick with what I have and helicoil the threads. I just figured maybe it was time for an upgrade if I was going to have to drop big $$$ on this.

What is the difference between the Avenger and what I have??

I agree with Andy and Ron about keeping your current carburetor but a 4 corner conversion with billet metering blocks would make it much more responsive and easier to tune.
I have a Quickfuel on mine and it runs perfect.
Gus

Will the metering blocks alone do the 4 corner conversion or do I need an aftermarket main body as well?

Andy is guiding you in the right direction. It is not so much the particular carb that you have on a car as much as it is the tune in the carb. Rather than spend the money on another OOTB generic carb, spend the money on a good professional tune.

And if you do choose to have your carb tuned, don't forget to have them dial in the ignition, too.

I already had this carb tuned about two years ago. I just had other stuff changed which has thrown the tune off.

I feel confident I can tune the squirter. The dyno had a wideband 02 sensor and they did the jetting and PV selection so that should be all set.

I did just change the ignition to get rid of the pinging at WOT so that has changed things slightly as well.

I fought one of those Demon carbs for two years before I went with a Quick fuel. They suggested an 850 double pumper with no choke. I have been very happy with it. Why don't you give Quick fuel a call and tell them what you want out of a carb. They seem to be a good bunch.

One thing you need to keep in mind whne tuning a motor on a engine dyno, there is no under hood heat or any oil sloshing around in the motor from acceleration or deacceleration on the dyno, same thing if your tuning on a chassis dyno with the hood open If it was pinging at WQOT throttle I would figure out why and fix that right away I would bet it is either spark plug heat range or fuel supply at WOT or a combination of both As far as your current carb. I like at least 850 CFM on any Mopar B or RB motor for best performance at the track or on the street, I do tune my carbs. with a LM1 wideban on the car that way I can tune the idle first, I like and use 14.5 or leaner, same thing on the transition and part throttle cruise, 14.3 to 15.3 with a very quick advance curve setting the total timing with no vacume advance at 34 to 36 degrees BTDC from 1500 to 1800 RPM and up I shoot for 12.2 to 13.3 AFR at WOT depending on the motor and fuel, richer is safer than to lean Lots of gremlins out there , whipping them to get the best results is the hard part You can do IT Now, get to work

Here's a thermoquad on my 493" motor. Have it dialed in with a wideband O2, runs great!! 17mpg in a big imperial on long trips. Since you said street car heh

I was going to say keep the 80531 and modify it, as I am conservative about buying new parts, especially with someone else's money.

The 80531 is the stock carb on the bigblock chevy ZZ502. I'd expect it to need quite a bit of tuning due to to the different R/S and cam configuration of your 499. It is also supposedly a version of the 870 Street Avenger.

I remembered some Internet trash about this carb as being difficult to tune, so I did a search and found a few reviews. EVERY complaint included the throttle tip-in lag and going lean at high rpm. This is hearsay, though.

So I cast around some more and ran into a David Vizard article in which he claimed the Holley UltraHP 950, 80805 carb was almost unbeatable and worked well right out of the box. I have also read other good reviews. I think it's the real choice for your engine. Bad news is, it's $750 or so. You should be able to get at least $200 for your old carb to help the cost.

Your other alternative is to send your carb to a reputable shop and have them go through it. It should come back much better than it is now.

R.

Yeah it did have weird oddities with it originally. It had an extremely soft secondary spring (like off the charts soft), I had to go up 2 sizes on the jets, 3.5" PV's (went to 8.5's), and a 32 squirter which was lean. All this has been changed and gone through.

Yeah it's been a bear to tune. I am going to see if I can fix what I got for now. I just hate how this stuff happens ALL the time....haha.

In my area, we have two dyno's that I know of. Both specialize in newer cars (mostly Chevy LSx). Unfortunately it is hard to find anybody who really knows these carb's and wants to take the time to truly tune one.

Which chassis dyno shop did you use? What is the other one you refer to?

I used Mayhem. There was another in Garner I think but I forget the name.

The guy at Mayhem seemed knowledgeable but my complaint is they didn't have any other parts to swap in besides the jets. I had to go buy the 8.5PV, nozzle, and springs after the fact and do some testing.

OK, I used Mayhem as well. I brought all my parts though, and tuned myself. I was just focused on power during that session. They ran the dyno.

I run a Holley 950HP vacuum secondary on mine.I was just as happy with the 750HP double pumper other than I like the vacuum secondaries on the heavy pig.
Mayhem or RPM in Garner can tune on the dyno.Mayhem did my corvette years ago.You have to remember that these places don't see many carburated engines these days.99.9% is fuel injected so I don't blame them for not tying up inventory in something they rarely use.
Fastlane inbetween Garner and Benson though mustang oriented does dyno tuning as well.They likely see more carbs with a lot of the 80's early 90's mustangs either running carbs or switched to them .

Thanks for the information, guys!

I think I have gotten to the point where I have slightly more money than time (which isn't saying much) so I bit the bullet and ordered the aluminum Holley 870 CFM Avenger.

I am not quite ready to ditch the choke entirely so I steered away from the HP carbs even though I'm sure they'd give me a little more top end. I'd still like to be able to fire it up on a cold day...

Since this carb is a close cousin to the one I have now, would it be a good idea to go ahead and move the jets over from the other carb and PV it the same way? Mayhem settled on 82 front/88 rear jets for my carb...so safe to just jet the new one the same way?

Eventually I want to take it back and dyno again but won't be till at least fall. I am swamped at work and really don't have the time to take a day off right now.

No. Holley carbs are pretty close right out of the box, for their intended purpose. Start from there. Here's a quote from a Holley installation manual for a middle of the line carb.

"Your Holley® carburetor has been factory wet flowed and calibrated. The “out of the box” settings should be very close for all adjustments. The following tuning section is included ONLY to aid you in fine tuning adjustments."

Many little things can change on a Holley from list number to list number, even from one version or dash number to another. Things like idle air bleed, high speed air bleed, power valve channel restriction and idle feed restriction. Unless you have a set of pin gauges you'll never be able to see the difference.

Drive the new carb for a while. Then you do the regular tuning stuff.

A wide-band A/F meter would really be a help in doing more adjustments to the carb.

R.

Some how I doubt this will be pretty close with nothing else done to it. I am not naïve enough to think I will just slap it on and have it work well. Every Holley carb has that statement (including my current carb) and it was pretty lean more my motor out of the box. In fact just upping the PV/jets and adding some timing added ~4 5rwhp from the first pull to the last.

I may just up the PV to 8.5 front/6.5 rear then as my engine makes plenty of vacuum. The low PV's that come in that thing may be a bit lean for my motor....

I will hopefully get the carb installed this weekend and report back...