BSeery

As some of you know I installed the ZZ4 in my 1980 some time back. Since then I have been running a very balky and out of tune Q-Jet. I have a TBI fuel injection system that I want to install, but not until this winter when I can do a full tear down of the interior and install the computer and wiring behind the dash.

In the mean time I want to race. I am thinking of the following options:

1. Pull the 625 CFM Carter (Edelbrock) off my truck, put the QJet on the truck and race with the Carter. My only worry -- is it enough of a carb for that motor.

2. (when I get a job) Purchase the new Edelbrock American Thunder series carb that is a 650 or 800 CFM unit. Or may purchase a regular 750 CFM Edelbrock. Problem is the price for a temp part that I will then either keep for a rainy day or E-Bay it.

3. Live with this POS QJet, send it to Lars to fix and race it. The main reason I don't like it is that it's a pain to pull apart for jet changes.

What do you guys think, and what are you running on your engines for carburetor ? Is 625 CFM too small? Is 750 too much ? I am hoping for a solution for under $350.

Corey_68

Check out the Demon Carbs, Barry Grant makes a carb set up for the ZZ4. There is no need for adjustments just put it on and go.

:cheers:

BSeery

Don't those come with no chokes ?

Also, a Holley or a Holley clone will not work with my stock air filter base. I want to keep that as it is one of the best cold air intake systems ever designed.

Mystery Machine

I am running the Demon carb that is supposedly designed for the ZZ$ motor. Although I did not need to rejet it or anything I did have to make a few adjustments (floats, idle, etc.) but nothing major. It runs GREAT! It has elec. choke, vac secondaries and now my TH400 can grab rubber going into second...pretty cool! It's a 650 and for all intents and purposes it's basically a Speed Demon. The claims are that it flows as much or more than a Holley 750. I dunno 'bout that though.

:thumbs:

The_Dude

If you want to keep the stock air cleaner assembly, I'd send your qjet to Lars. After he's done with it, you should be able to bolt it on and run it without further adjustment. You could also try one of the forum loaners first to see if it makes any difference. :cheers:

Alwyn678

Speed demon 650 with electric choke :cheers:

Black Snowman

625 Carter from your truck should be enough for the ZZ4 unless you've done a lot of upgrades. 625 CFM should be enough for a 350 up to about 6200 RPM. Since it's a temporary solution until you're TBI is in I'd go that route. No sense in spending money if you don't have to and the Carter was a good enough carb for Edelbrock to copy ;)

DaveL82

I purchased a new version of the rochester for my 80 from Edelbrock. No issues at all and has all the emission hookups since it's the one for an 80 vette with electric choke. Runs great with the ZZ4.

Cheapest would be to rebuild the original though. Rochesters are not a problem

jamiejamison

Here is my experience. I drag race at least every week-end and test & tune every wedensday. I have a 1980, zz4, 700r4, 3.73 dana 44, 2800 stall lockup converter, hooker headers, dynaflow mufflers, micky thompson 26x10x15 slicks. I run (best) 12.82 at the 1/4 @ 105.50 mph. 1.68 60 foot times, as you see I run out of hp at the top end. I go thru the traps at 5450 rpm which is just right for the zz4. Now for my carbs: First ran a race demon 650 vac secondary. can't get it to not bog at the tranisition point between the squirters and after the idle. I even stage at 2000 rpm. Had it back to the factory twice, put 50 cc pump on it , different pump cams, even had it on another car with about the same results. This is the smoothest best milage carb on the road, sometimes I put it on to drive to GA, or AL and switch at the track. Great carb until its on a track that sticks at the line. I asls run a demon race 750 mech, works good staging at 2000 rpm but the 60 foot drops to about 1.78, about the same as 750 holley mech. My best times, and most consistant is a holley vacumn 750. Also the cheapest. I put a proform main body on it, it has no air horn, but it sill runs the same. Anyways, with my gear, and stall, thats what works for me. By the way, I'll sell my 650 demon almost new, pretty cheap. Let me know how you run at the drags.
JamieJ

BSeery

Damn -- our cars are almost twins.
I am also running the ZZ4, 700R4, Dana 44 3.73's. My tires are 285 wide (9.5) and 26" diameter. I have the 1800 RPM stall converter, headman headers, no mufflers, dual exhaust with dual cats.

However, my best run is a 14.5 (:U) at 96 MPH. I have a 2.0 60 foot time with some tire slip if I launch too hard. My TV cable is not set correctly for racing. I need more length to allow full open throttle. When I allow more length, then it is shifting wrong and maybe slipping (a lot). I am working on getting that fixed, but need to pick a carb. first.

Send me an e-mail to BSeery@***.net and let me know what you want for the carb.

I may put the Carter on first and see if I pick up any time at the track.

VetteNut72

Bryan,

When I first got my ZZ4 I had a 750 DP on it which was way too much carb for the motor. I had much better luck with a 650 vac sec. After the head, cam and rocker change the 750 DP might have been a good choice but I went with EFI instead.

I haven't met any of you ACE guys yet because life was very busy as a caregiver to my Wife and taking care of my children. Things are still a little crazy but my sons and I will make it through this.

You all have an open invitation to come down this way any time. Right now my body is on a dolly on one side of the garage and the rolling chassis on the other. It's really neat to see it that way and gives you access to everything. I have to run another 3/8" fuel line to satisfy the EFI requirements and it makes it easy with the body off. Will you also need to run another line for your EFI setup?

I think that if the Qjet was set up right for your motor it would be a good interim choice until you go EFI. I would bet that someone out there has the proper setup requirements for a Qjet on a stock ZZ4 (Lars?).

Craig

BSeery

Craig, thanks for the invite to Tucson.
Maybe the wife and I will blast down there for a weekend day when we've got nothing to do.
I would love to check out your EFI setup and the fuel line as I will have to do the very same thing.

I will give you a heads up before we decide to come down.

vette_c5c6

Biggest mistake people make is buying a very large carb. Always follow the following formula ( cu.in x RPM / 3456 = CFM) 350 cu. in X 5,500 rpm= 1,925,000 / 3456=557 cfm or 600 cfm.

hauk

I'm running the new edelbrock 800 with electric choke on my new 375 HP 350 and I love it.It does everything I expect it to do.

Krystal

For what it's worth.......650 cfm Holley double pump.......other than 1 5/8" inch headers it's all stock ZZ4. Runs VERY well, in my '79, and knocks out high 13s in the 1/4 mile too. :D

Kris

BSeery

What made you decide to step up to the 800 CFM unit over their 650 CFM unit?

Jason Staley

I'm running a BG Speed Demon 650 Mechanical Secondary w/ Electric Choke ZZ4 crate motor carb on my ZZ4. I just installed it and it does need a little tuning (idle, choke, etc.), but it runs great. I've tried a 600 & 750 Edelebrock, and a 750 Holley Double Pumper but was unhappy with how any of them ran. I love the BG carb!!! Starts up and runs great. My best time with my ZZ4 (w/ GM's hot cam) was 13.2 @ 100 last year using the 750 Holley. It made power, but was terrible around town. I'm going out to the track tonight so I should have some new times to post using the 650 Speed Demon.

Sigforty

I bought the Crate Demon for the ZZ4. I got the mechanical secondaries and it runs great. Out of the box I just had to set the idle speed and mixture. The mechanical secondaries are great and it definately opened the car up over the Road Demon I had and the Qjet.

Sleestak

I bought my motor with an Edelbrock QJ but it had to be setup for the motor which was done by the vendor. It runs great. From my understanding the Edelbrock QJ's come with the wrong jets and metering rods out of the box.

adamdinat

I have a holly 750 cfm. I have been told it is too big which seems to be right. I have not got the secondaries to open up yet. I will be looking to do a swap once the car is back on the road.