Topic: Autolite 4300 -- Do they deserve their bad reputation?

[drummingrocks]

Hi guys, some of you might have seen or participated in my earlier thread about Concours Driven and my '69 Mach 1.  It's an M-code, so it would've come with an Autolite 4300 originally.  Since the original carb was long gone when I got the car, I replaced it first with a 600cfm Edelbrock, and later with a 600cfm Holley.  The Holley is on the car now, and while it runs light years better than it did with the Edelbrock, I'm still not 100% happy with it.  No matter what I do, I end up with a slight binding feel in the gas pedal.  I've tried two of the best quality throttle cables from NPD, have removed and greased both the cable and the gas pedal assembly inside the car, and have modified an extra throttle bracket to ensure the cable is traveling straight.  All of this, and I'm still not happy.

I thought about trying to track down the correct 4300 for this car, but from everything I've heard and read, the 4300 is not the greatest design in the world, and is nowhere near as well thought of as the 4100 (which is on my '66 fastback, and is great).  I generally use a local, well-known carburetor guy for my carburetor rebuilds, and he told me to stay away from the 4300.  He was a Ford/dealership mechanic back in the late 60s and early 70s, and he said that those carburetors were junk when they were new.  He said it go to be so bad that when the dealership called Ford about a warranty issue with a defective carburetor, Ford gave up trying to troubleshoot the issue or walk the tech through fixing the carburetor and instead began sending out entirely new 4300's.  Apparently some of these carburetors ran "ok," and some just absolutely refused to run well, and Ford's recommendation was to try another when the original failed.  Are these carburetors really THAT bad?

With that being said, I've read online that Pony Carbs claimed to have fixed most of the well-known issues associated with the 4300.  Can anyone comment on that?  I'd hate to drop $400-500 on a show-ready carburetor, only to have it be an expensive paperweight.  However, I know that the throttle linkage was designed for the 4300, so presumably it will work well with it, AND I'd get some points back if I show in Concours Driven.  Anyone care to offer any advice about what to do?

Thanks! 

[67gtasanjose]

Google KP Carbs and email Kurt, he used to work for Jon @ Pony Carbs which is now out of business (Jon has passed on)
If anybody can help, Kurt's your man. I placed a special order without a core and he delvered in less than 2 weeks.
Looks great, works great, no complaints here.
Here's an image of his work: btw, I just uploaded this to another thread a few minutes ago

[67gtasanjose]

   However, I know that the throttle linkage was designed for the 4300, so presumably it will work well with it, AND I'd get some points back if I show in Concours Driven.  Anyone care to offer any advice about what to do?

Thanks! 

It sounds for sure like it's linkage alignment. You would need to match the exact radius location of the 4300 to overcome this issue using the Holley you have now. Picture it like the throttle shaft as the center of the radius. The distance away from the center of the throttle shaft has to be matched AND the "clock position" for the begining of the sweep backwards or "idle position". Usually the ide position is around 10 o'clock. Look at the image I just posted above, it can give you an idea where your cable should be connected on your Mach 1. I cannot tell you what that carb is off of, but it is a throttle cable variety, auto trans. The auto trans portion doesnt apply to the throttle clip location

[jwc66k]

It sounds for sure like it's linkage alignment. You would need to match the exact radius location of the 4300 to overcome this issue using the Holley you have now. Picture it like the throttle shaft as the center of the radius. The distance away from the center of the throttle shaft has to be matched AND the "clock position" for the begining of the sweep backwards or "idle position". Usually the ide position is around 10 o'clock. Look at the image I just posted above, it can give you an idea where your cable should be connected on your Mach 1. I cannot tell you what that carb is off of, but it is a throttle cable variety, auto trans. The auto trans portion doesnt apply to the throttle clip location

You nailed it. A friend put a 1.12 4100 from a 390 Galaxy on his 66 daily driver and couldn't figure out why he couldn't get full throttle. It's back to high school plane geometry.
Jim

[drummingrocks]

Guys, thanks for the suggestions on the throttle linkage.  The easiest way to solve it would probably be to move away from the factory throttle cable bracket and go with something like one of those aftermarket cable holders that bolts to the intake.  That would probably help a lot, but again, it seems like this would get points knocked off in Concours Driven.  Right now, I know I'll lose points from the Holley carb, but it's something that's at least sort of hidden under the air cleaner.  If I were to go with one of those aftermarket brackets, I'm afraid it would be a giant red flag at shows.

How are the 4300 carbs as far as driveability, idling, gas mileage, etc?  What should I expect with running one of these? 

[67gtasanjose]

I think the 4300 is the best way to go overall. I wouldn't continue changing away from the stock parts especially if you are showing the car in any Concours class. They were engineered to work on your engine with the original distributor and other emission control parts originally installed on your car. Working out the bugs might take some doing, but when you get it dialed in or if you need to hire somebody who understands how all of the tuneup related parts work together, you would be amazed how well it will run with the 4300. All of the hype about them being junk was no doubt started by people who were not properly trained on how to work on these newer emission controlled carburetor systems of the day. The "canned answer" was to "Pull it all off and throw it away, just put a Holley on it"
The Holleys were simpler for the old-school way of thinking. But as you see, there are problems even getting that absolutely perfect too.
Hunt the right 4300 down, get it restored by somebody who knows them inside and out, getting the parts right on the inside too, work on the rest of anything else that has also been altered. Take your best shot at dialing it in, then take it to an experienced professional tuner with a dyno and get it really adjusted right. It might cost more, but your overall satisfaction on how it will run strong and economically will make it worth it in the end. Realize this also, that gasoline isn't the same as it was back in the day. These people who "know" them inside and out can help getting them right in that area of need too.
Well, that's my nickels worth of thought.
Richard

[drummingrocks]

Thanks, Richard, that's what I'll do.  I wish I had done this in the beginning instead of wasting money on the Edelbrock and Holley carburetors, but oh well, live and learn!   

[67gtasanjose]

They were engineered to work on your engine with the original distributor and other emission control parts originally installed on your car. Working out the bugs might take some doing, but when you get it dialed in or if you need to hire somebody who understands how all of the tuneup related parts work together, you would be amazed how well it will run

get it restored by somebody who knows them inside and out, getting the parts right on the inside too, work on the rest of anything else that has also been altered. Take your best shot at dialing it in, then take it to an experienced professional tuner with a dyno and get it really adjusted right. It might cost more, but your overall satisfaction on how it will run strong and economically will make it worth it in the end. Realize this also, that gasoline isn't the same as it was back in the day. These people who "know" them inside and out can help getting them right in that area of need too.

I am a professional mechanic and own my own Auto Repair shop. Usually, the cars that don't run right after the owner has tuned them up to the best of THEIR own ability always seems to stem back to the owner or previous owner's attempt to tune it themselves. This has been my experience with nearly ANYTHING tuneup related along these lines. I mean ANYTHING whether it's a concours Mustang, another Ford as well as any other car on the road. Recently I had to get the right original, numbers matching carb for an 88 Dodge I was working on. It too had an EDELBROCK on it that ran really good after it warmed up but was the most miserable POS warming up until it ran for over 5 minutes. I couldn't tune the choke settings to work with the aftermarket choke heater the carb had on it. The choke simply opened up too fast. It either had too much choke, or not enough when making attempts to adjust it. I ended up finding an unmolested, untouched NEW TAKE-OFF for $75 on eBay with the right numbers and all. I didn't even have to put a kit in the carb! The original carb fixed all the main issues, I also found a few vacuum leaks in a vacuum valve and the EGR valve that helped with the finer details after getting the choke right. I did NOT need to send it out to be DYNO'd, but if it did need to go for the finer settings, I sure wouldn't have hesitated. I do not own a Dyno (wish I did) I was trained in tuneup related work to be certified as SMOG INSPECTOR for the state of California, and I think we all know how strict the state requirements are there so I feel this advise is valid across the board on anything tuneup related.  Whether it is a newer car going in for it's first tuneup or it is a Model-A Ford. Using OEM parts, not "parts store equivalencies" (for any make or model vehicle) will ALWAYS yield a much more happier drive.

[krelboyne]

One other thing worth mentioning regarding carburetors. Today's gasoline with Ethanol is not good for them if they aren't regularly driven. Anyone know of an additive that specifically works with ethanol blended gasoline during storage?

[J_Speegle]

One other thing worth mentioning regarding carburetors. Today's gasoline with Ethanol is not good for them if they aren't regularly driven. Anyone know of an additive that specifically works with ethanol blended gasoline during storage?

No personal experience with it yet. There are others you'll find for boats since they often set for a long time



http://www.sta-bil360.com/?utm_campaign=Auto%3A%20Ethanol%20Additives&utm_source=msn&utm_medium=cpc&utm_term=stabilize%20gas%20additive%20ethanol%20fuels&utm_content=4583518103

[midlife]

One other thing worth mentioning regarding carburetors. Today's gasoline with Ethanol is not good for them if they aren't regularly driven. Anyone know of an additive that specifically works with ethanol blended gasoline during storage?

Find a local marina and ask around where boat owners get their gas (almost always ethanol-free).  Fortunately here along the Gulf Coast, there's a half-dozen stations that carry ethanol-free gas.  I've switched to it a few years ago and haven't had any problems, particularly with house-hold small engines. 

Hmmm...wait a sec!  If the lawnmower won't run on normal gas, doesn't that mean I don't have to mow the lawn?  What was I thinking???

[priceless]

I own a small lawn care business. I use the Sta-bil marine ethanol treatment. I have used this treatment for 6 years now with no issues. I haven't replaced any hoses or the like, haven't had any carburetor issue neither. My rider is a Kawasaki 23HP and my other mowing equipment is a mix of Briggs & Stratton and Tecumseh. My mix engines are stihl equipment. I use the Sta-bil marine in ALL my gas,everytime at fill up and use Stihl HP synthetic mix oil with great results.

Hope this helps.