I might try that first and see what happens. I'll take it to a machine shop and see if they will do it. I did talk to a guy at Holley (via email) and he mention that they could probably make on for me but wasn't sure how much they would charge. The base plate I just bought for the 670 cost me $105. So depending on how much they charge to make the 570 base plate with determine which route I go. Need to talk to the machine shop and get their opinion and see how much they will charge.

I think I found the problem on why these carbs are warped. The 1" spacer I had them mounted on has a plastic inset in the center (open plenum spacer) and for some reason it is sticking up a little hightler than the body of the spacer. I have since discarded the spacer but the damage is done. I've had both of these carbs on this spacer at one point.

 

I know what spacer you're talking about. With those, you need to be sure that center piece is fully flush, usually by tapping it down with a rubber mallet. But, that would do it.

Personally, I've had very good luck with this one and would buy it again.

https://www.summitracing.com/parts/sum-g1412/overview/


Good luck with getting the 570 dealt with. If you fully disassemble the baseplate, usually they can just zap it on a belt sander for a few moments and it's good.

 

​​​​​​I have another spacer just like that one and I'll either use that one or the 2" open plenum I just took off my green Bronco and use it in place of the 1" spacer i had on my red Bronco. But before i do anything with the 570 base plate, I'm gonna replace the base plate on the 670 and see if it resolves the problem. If it does then I'll throw Some money at the 570. The base plate should be here tomorrow. Ordered it from Summit.

 

Do you prefer the 570 over the 670? If the 670 works, why not just stick with it?

 

Its not that I prefer one over the other, its the fact that I currently have two vehicles without a carb because these carbs aren't working. I have two 79 Broncos and these carbs were on the Broncos. Well I had to pull he Edelbrock off my 67 Cougar and use it on one of my Broncos because i need a 4wd for the winter.

 

Oh, wow, sorry, I completely missed that. That makes sense.

If you can't get that 570 fixed up, have you looked into QuickFuel's carbs? They're quite reasonably priced, and a solid, well built carb. A 600cfm is around $299.

https://www.quickfueltechnology.com/...uel-bowls.html

 

​​​​​​No I haven't thought that far ahead yet. I'm focused on trying to figure out the problem with these carbs and what it takes to fix them. I guess you could say I haven't given up on the Holleys yet. If the base plate resolves the problem then I'm going to go that route. If it doesn't then I'll be forced to look at other options. My long term goal is to install a FiTech EFI system on all my vehicles that have a carb. But I don't have that kind of money right now. So in the mean time I'm using carbs. I might end up buying another carb if I can't get the 570 going, but I'll cross that bridge when I get to it.

 

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..

 

Good to hear!
Man, finding stuff like that just makes your day. Been there! And props for perseverance!

That would add a crazy amount of resistance for one thing, and the spark is probably intermittent at best.

I imagine if there's a leak in your baseplate, that small amount of air leak was amplified by the poor spark.
Here's to hoping that when you get that baseplate put on, it idles smooth as butter and drives great.

I'd be curious what Holley says about the 570 baseplate. When I asked for one for my 465 (which they still make new) it was a straight up "no, you have to buy the whole carb" which is why I went with the QuickFuel.

Keep us posted!

 

Any updates on this? How goes the battle?

 

Well I ran into a detour in my project. I was driving my green Bronco to work and the oil pump seized up. So I've been spending the last couple weeks in the freezing *** weather replacing the oil pump as time allowed. I should have it back together tomorrow....maybe. Once I get it back on the road, I'll work on the carb again. Should be this week.

I have the 670 installed back on the red bronco after replacing the base plate, but I need to fine tune it, if I can get it fine tuned. I got it started after I initially installed it and had to adjust the idle to 1000+ rpms or more to keep it running when I put it in gear. When I put it in gear, it idle went so low that the motor stalled, which seems abnormal to me. So that's as far as I got with it so far.

 

Ugh, sorry to hear it. Been there. Unfortunately, if something's going to go, it's going to go when it's cold. And the colder it is, the more likely it'll happen and the more it sucks to fix it.

Oil is like tar when it's ice cold out, and I know too many people who've blown seals or their oil pump by going out when it's almost 0°, firing their engine up, throwing it into gear, and driving off.

I'm not very familiar with tuning idle on an automatic, but I do know it's a little different.

Not sure if there's anything new for you here, but this is a good writeup on the idle:

How To Adjust The Idle Mixture On Holley Carbs - Blogs - Holley Performance Products Forums

 

Thanks for the link. I'll definitely read it and see if there's any tips I can use.

Haven't got back to working on the red Bronco yet; still working on getting the green one back together. Worked on it tonight and almost done. Just ran out of daylight. Should have it done in the next day or two and then I'll get back to the red Bronco.

Yeah you're exactly right, when things go back it's usually at the worst time. That seems to be my luck. Hoping this turns out to be a blessing in disguise, which actually it already has been. During the tear down, I found that the timing chain was wore out, so I installed a new one. And during the super cold weather we've had, the water pump started leaking so I installed a new water pump also. So along with the new oil pump, I installed a new water pump, timing chain and distributor (which had a lifetime warranty, so that was free to replace). Should run pretty good once I get it fired up.