So I spent the entire day trying to fine tune this Holley carb. So I fired it up and as it was warming up it kept eventually dying. It would run good for a little bit and then suddenly it would start running erratically and the idle would slowly drop until it would stall out. Once I got it fully warmed up so the choke wasn't on (after having to baby the throttle to keep it from dying), the idle was so low it wouldn't idle (I had the transfer slots in the shape of a square like it's been suggested). So I continued to adjust secondary butterflies open to try to get it to idle and it still wouldn't idle without stalling. At one point, I adjusted the secondary butterflies open to the point that it started spitting and popping out the exhaust really bad. So I backed off the secondary butterflies and was forced to adjust the primary butterflies open more just to get it to idle. But even when I got the rpms high enough to idle (no less than 1200+ rpm), it would eventually stall out. Every time it stalled out, I checked the float level and kept making adjustments until the floats were perfect; fuel at the bottom of the sight port. So I was able to get the floats set perfect. The fuel pressure kept jumping between 6 & 7 psi really really fast.

The entire time it was running the vacuum gauge needle kept moving around like it had a vacuum leak. So again I disconnected everything that uses vacuum and plugged the ports. It made no difference. I then took some starting fluid and sprayed around the base of the carb and the vacuum tree that screws into the intake manifold (where everything that uses vacuum plugs into) and the idle did not change, so I know I don't have a vacuum leak.

When I disconnected the vacuum advance from the carb, the motor stalled out and would not stay running; therefore I was not able to put a timing light on it.

I tried adjusting the idle mixture screws (starting with 2 turns out) and the vacuum gauge kept jumping around so I couldn't tell if what I was doing was helping or not.

So after getting thoroughly frustrated, fed up, and pissed off, I decided to take the Edelbrock 600 cfm carb off my 67 Cougar and put it on the Bronco and guess what.....it fired up and run freaking perfect!!!!!!! It idled like a dream with no issues whatsoever. The vacuum gauge held steady at 19.5 hg and didn't move around. When I disconnected the vacuum advance from the carb so I could set the timing, the engine did not die like it did with the Holley. It kept running and I was able to put the timing light on it and the timing is at 10* btdc.

I took it for a drive and it run really good. However, I noticed that when I go to accelerate (nothing drastic or aggressive) it seems like it needs richened up a little bit, or something. It seems like it's not accelerating crisp; seems like it's laboring (for lack of a better term) or is slightly lean....not sure exactly how to explain it. During the drive, one time I went to accelerate and it spit through the carb once. It only did it once out of all the different times I accelerated trying to test out the carb. I think this is just a minor fine tuning issue, but it's running 100% better than the Holley ever dreamed of and it's not stumbling or hesitating when I'm cruising down the road holding speed like the Holley was doing.

Something to note...prior to firing up the Holley, I went to Autozone and bought a 4 hole carb gasket to put on the 4-hole 2" spacer I put on in place of the 2" open plenum spacer. After tinkering with the Holley for a few hours, when I pulled it off to put the Edelbrock on, I notice that every square inch of the gasket was soaking wet with gas. That does not seem normal to me and I don't know if that's an indication of what the problem could be with this Holley. Maybe one of you guys can advise on this.

So after what I experienced today, I have decided I will never own another Holley carb...EVER!!!! IMO, they're a piece of S***!!! So I'm going to run the Edelbrock carb and work on fine tuning it. In the mean time, it looks like I need to buy the FiTech efi for my Cougar sooner rather than later since I had to use the Edelbrock carb on the Bronco.

Anyway, if anyone has any words of wisdom, fire away. If anyone wants a Holley Street Avenger 570 and 670 carb, let me know. I'm gonna sell them. I'm sure someone out there can get them working properly, but it's not me and I'm sick and tired of messing with them. It's the middle of winter here and we have snow on the ground and I need my Bronco for the 4wd. So I'm done messing with these Holley carbs.....

 

I have an update and some good news!!!! I've been dealing with both my Holley carbs (570 & 670) refusing to idle and I've also been experiencing a stumbling/hesitation/missing issue while driving down the road. I discovered that both my Holleys have warped base plates, so thinking this was the cause of all my problems I installed an Edelbrock carb on my Bronco that I knew had no problems. It fired right up and idled really well, but after taking it for a drive I still noticed a stumbling/hesitation/missing issue.

Long story short....After analyzing all the symptoms and issues vs what I've done to resolve the issues, it dawned on me that the stumbling/hesitation issue may not have anything to do with the carb since it's done the same thing with 3 different carbs.

Although I've replaced the plugs before I even started this project back in early November, I hadn't replaced the cap, rotor, or wires yet. So I decided to do just that and see if that would resolve my problems. I had a brand new cap and rotor hanging around in the garage that I've had for years and have never used yet, so last night I installed the cap and rotor. Didn't make a difference at all. So tonight I went and bought some new wires and installed them. As I was removing the old wires I just so happened to notice on the #1 wire on the end that plugs into the cap that the metal contact had a thick layer of green corrosion on it. I got really excited and hopeful that I just may have found my problem. So I finished installing the rest of the wires and took the Bronco for a drive and guess what!! No more stumbling or hesitation!!!!!!!!!!! The Bronco is running perfect!!! Fires right up without any issue, idles like a dream and runs really well cruising down the road!!! I'm extremely relieved and excited that after 2 months I've finally got this resolved......well at least one of the issues. I still have to figure out why my Holley carbs won't idle.

I ordered a base plate for the 670 Holley and it just arrived yesterday, but I haven't had a chance to install it yet. I'm thinking that after I replace the base plate that my idling issues will be resolved....I hope. And now that I have the stumbling issued resolved, I'm thinking/hoping that I'll be able to take back what I said about Holley's being a piece of crap. If the base plate resolves my idling issues on the 670, I'm going to contact Holley and see if they will make me a base plate for my 570 since they don't sell one separately, but they still sell a 570 carb. My plan this entire time was to use the 570 on my green Bronco (the one I've been trying to get to run; has a 351m) and the 670 on my red Bronco that has a 400. Then I can put the Edelbrock back on my 67 Cougar and life will be ok again...LOL.

Once I get the base plate on the 670 and installed and running, I'll let you guys know the results. I'm starting to breath a little easier now I would like to thank everyone for their help. It's much appreciated..