I gotta say I love the look of the carb. It looks really sharp. And the way it responds to your engine, or the other way around, makes me think you are on to something. Too bad you have to put an air cleaner on it, I mean I'd want to show it off for a while.

 

I looked at the packaging and the adapter plate says it's for Holley carbs. And as you can see in the pic, the standard 4 hole gasket fits my intake perfectly (which came with the adapter plate). So, I didn't even notice, but the adapter plate doesn't match up properly to even the gasket they sent with it. Close, but not exactly. As for the Quadrajet side, that's understandable since, well, I don't have a Quadrajet. I may contact them about it although I have a feeling that a replacement will match up just the same.

Did some more tweaking with the throttle and got it to where I could drive it normally. I have plans to fix it properly, but for now, it's working well enough to drive it with ease.

As for driving around... This is by far the best my Bronco has ever driven in the eight years I've owned it. Better than it did with the stock 1bbl, with the Holley 390, the Holley 4011(?) Harte loaned me, either of the Holley 600s, etc. Throttle response is instant! As soon as I let out the clutch, it's moving. Tap the gas, and I'm flying forward. This is especially great since it has a 3.00 rear with 31" tires. Snappy gearing hasn't exactly ever been one of its strengths, so having a carb that bogs and lags is very noticeable.

It takes very little pedal to get it moving, and the harder I press the pedal, the more it pulls, and pulls, and pulls. It went from 0 to 80mph effortlessly and cruised down the interstate like it was nothing. And the baritone of those secondaries is just delightful. . The little whistle of the primaries will take a little getting used to though. Strange to be able to hear them from the cab.


A few things I've noticed that I'll have to figure out are: first, it seems hard to start. Both when it's cold and warmed up. Not sure why. The second is that when I'm letting off or speeding up, when the vacuum needle is between 5 and 10hg, the needle shudders like I have a sticking valve. I can't feel it in the engine, but I can see it in the gauge. I'll contact Holley and ask them about it.

And I agree about the jetting. With the way it's driving, there's no point in changing it. I checked the plugs and they had a nice spot of tan on them. I may try a smaller accel squirter since take-off isn't exactly "crisp", but if it doesn't work, I at least know exactly how to get back to where I started. A 40 just seems really big. I also thought it was strange that it came with the cam screw in the #2 position. On every other carb I've had, if it's in the #2, it doesn't start squirting fuel until around 1200 - 1500 RPMs (which is what it's designed to do), but on this one, it's instantaneous the moment I touch the throttle at 700 RPMs. Oh well, if it works, it works!

I'm curious about gas mileage next. And if it's not stellar (which I'm really hoping it is), that's when I'll try dialing it back a jet size or two.

 

I agree, I really like the way it looks. It's a very different, and cool looking carb. I'm curious why they put everything on at a slant, but I like it. I don't imagine the 4175s are super popular in the general carb populace so anyone who saw under the hood would know it's a Holley right away, but on second glance would be able to tell something's different.

 

I dug through one of my boxes of QJ stuff and found the adapter I mentioned. I set a QJ gasket on it to check. The secondaries are smaller than a QJ's, and the primaries are slightly off set, just like your photos.

The only problem is it is not a square bore to spread bore adapter. It is simply a 1" phenolic spacer. But it is certainly for your carb. You can have it if you like.

 

Hrmm... I'm not sure if there's anything I could do with it. I'd still need something to go from spreadbore to squarebore. Although, I wonder if something like that would help with my throttle. Raise the carb up another inch and it would be able to work it a lot easier without me having to redo the entire throttle cable setup. Is 2" of spacer too much?

Speaking of throttle cable, for those of you that come around from the passenger side to connect to the carb, how long of throttle cables do you use? I see them from 24" to 72" and am not sure what length would be the best choice. I suppose I could just get out a tape measure...

 

I used a 4' Lokar and a little extra length was cut off for a bit better fit.

 

Well, I topped off for the first time since I got the carb, so now begins a gas mileage test. Going to drive "normally" for the next while until I fill it back up. No more fun driving until then.
I'll post results in a week or two.

 

How is your carb project progressing? I hope to hear good results soon. I'm hoping for the best for ya.

While browsing for parts for my Summit carb I couldn't help but notice the vast array of Holley parts. MY goodness, I never really took notice. I must admit I was envious when I saw the unbelievable selection just for pump squirters. It certainly cast Holley in a positive light for me. k

 

Haven't had any results yet, but I'm going to fill up tomorrow. Unfortunately, I just haven't been driving it much since I've been riding my bike to school due to not being able to park on the campus without paying a hefty multi-hundred dollar fee for a parking permit. No thanks. Since I topped it off 10 days ago, I've only driven about 70 miles.

But, I spoke with Holley yesterday and it turns out that the size 64 jets that came in it were a fluke. It's supposed to have have size 62 jets stock. Someone on the assembly line needs their glasses checked. I'll be curious after I top it off how much my gas mileage will increase with 2 drops in jet sizes down to the proper size. Hopefully I won't notice any detriment to performance. I'm sick and tired of bogs off the line and I finally don't have them anymore.

And yeah, Holley makes a LOT of tuning parts for their carbs. Like the saying goes. The great thing is, they're infinitely tuneable. The downside is....they're infinitely tuneable.
But, it makes it fun whenever a new little packet of tuning parts shows up in the mail. It's like big kid toys.



About the only real negative I've noticed is when I start it up after sitting for any length of time, it bucks and sputters for a few moments (a minute or two if left at idle). The vacuum will dance around 9 - 11hg and it'll cough and sputter like it's chugging the cobwebs out of its system. Once it finally does, it'll slowly smooth out, idle nice, and my vacuum will climb back up. I don't know what would cause that. The squarebore I pulled off would snap to life with half a turn of a key. Even if I rev this one a couple times, it'll still cough and sputter when the RPMs come back to idle.
Anyone know what causes this kind of behavior?

 

I wouldn't be in too much of a hurry to dial back on the jet size just yet. Give it some time with a few tanks of fuel run through it to well establish the starting point and go from there. I'm going to have to break down and actually go up in size on my carb...it's had a hard lean condition at low to moderate cruise speeds (indicated on narrow band AFR gauge). This lean condition is reduced when I run non-ethanol fuel but that stuff is too spendy to run exclusively so I'm thinking the jet change upward may be the cure.

As far as the spitting and sputtering at start-up goes, it IS a Ford ya know...LOL I don't think I've ever had one that wasn't a bit cold blooded.

 

Well, I did my first fillup. I'm not super thrilled, but not massively disappointed either. 84.2 miles and 7.79 gallons. So, about 10.8mpg. I, of course, was hoping for better. Especially since I've been really gentle on it and have driven very modestly.

I contacted Holley about the jets and they told me it was a fluke, so they're sending me another set of 62s to replace the 64s. Hopefully the richer jets explain the not so stellar results. Since I didn't have the 62s on hand, I put in some 61s. I know it's 3 jet size jump, but it's only one leaner than stock, which is what I would expect to put in anyway due to my elevation per Holley's instructions. I guess we'll see what that does.
I went for a spin and I really couldn't tell the difference between the 64s and the 61s, except that the 61s didn't feel so "thick" in the acceleration. At least that's off to a good start.

I know what you mean about the ethanol fuel. I haven't tried non-ethanol in quite a while. There's a non-ethanol pump nearby that has a membership only thing, but I haven't looked into it. Maybe I should. It is expensive though. Kinda like buying organic vegetables.

Heh, I'd agree with you on the cold-blooded thing except this had always fired right to life at the first tap of the key. More often than not, I only snap the starter for 1/4 of a second and it's idling smoothly. This definitely came with the carb, so maybe an internal leak of some kind?

 

10.8 isn't bad! That's what you call "amazing fuel economy" for us V8 guys. 10.01 is standard.

Changing jets should make a noticeable difference, just keep an eye on the plugs and tailpipe color, it should be a light to medium brown. Also keep an eye on oil pressure, if the pressure gets lower than usual its running too hot from being lean. Water temp isn't affected nearly as much by a lean condition as the oil temperature and higher oil temp = lower oil pressure.

For the hard starting I'll bet the choke just isn't adjusted right. It makes a big difference, try this: Pump the petal more than usual before starting, if it's even harder to start, then it's too rich, if it starts easier, it's too lean. It'll also backfire out the carb if it's lean.

Good luck!

Sam

 

Thanks Sam, and heh, no, 10.8 is what my brother's Bronco gets on the freeway with his 351.

But, compared to what I was getting with the squarebore before, it's not good enough for me. Hopefully these leaner jets make a big difference, especially since it wasn't supposed to have 64s in it. That was just a fluke. Right now, I have them one step down from stock. Guess well see what it does.

For the hard starting, I should probably explain that better. It's not really that it's difficult to get it to fire up, it's that once it starts, it chugs and sputters for a minute or so until it "clears the cobwebs out". The vacuum is a few pounds lower than it should be too. Then, slowly, it clears out, the idle smooths, and the vacuum goes back up. Takes about a minute or so.

 

Sounds like the choke is set too rich and the motor is fighting for air until it starts opening a bit. The last electric choke Holley I had did the same thing.

Fire up the motor (when it's cold) and just open the choke butteryfly by hand, I'll betcha it'll smooth out and run better.

Sam

 

Is the fast idle set where it should be? I would pull the a/cleaner in the morning b/f start, then, hit the throttle once by hand, and see what the choke does, then work it by hand to see if leaner or richer makes it improve that cold chug. (I know you probably know that). It usually takes me three mornings to get it set right.

I'm sorry about the mileage. I've read where guys, using a w/band, have been able to go from (iirc) 8 to 14 mpg. I hope it works well for you. k