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Author
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Topic: Autolite 4100 vs. Holley 650 Double Pumper
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rockafellz
Gearhead Posts: 160
From: San Lorenzo, CA, USA
Registered: Aug 2001
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posted 04-15-2002 10:54 AM
   
Hey Fellas,Ok, first off, I know very little about carburetors but I'm VERY willing to learn!! I was researching the Holley 650cfm Double Pumper last night an from what I found out is that it's called a double pumper because it has two (2) accelerator pumps. The primary pump is connected to the accelerator linkage while the secondary pump is connected to the linkage that opens the secondary throttle plates. With a double pumper, you can adjust when the secondary throttle plates will open thus activating the secondary accelerator pump?!? Is my research above correct? Now with regards to the Autolite 4100 (1.12 - 600CFM), am I correct that is also has two (2) accelerator pumps? Thus making it a "double pumper"? Which carb would be better mounted on a STOUT 306 street motor?? The motor is a low-end based motor and will never see passed 6000rpm. I guess what i'm basically looking for is responsiveness and enough fuel throughout the RPM range!! Regards, Erik ------------------
1966 Ford Mustang / 289 / C4 [This message has been edited by rockafellz (edited 04-15-2002).]
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Hemikiller
Gearhead Posts: 124
From: Clinton, CT
Registered: Feb 2002
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posted 04-15-2002 12:36 PM
I'd have to say that the Holley would be a better carb for you setup. THe Autolite carb is notorious for flat response, poor idle, and other odd behavior. The Holley is also much easier to get parts for, and much simpler to tune, as you can change power valves, jets, acc pump timing, airbleeds, and like you said, the timing of the secondaries.
Also, you can generally get a 650 or 700 DP from a swap for dirt cheap if you shop around. I picked of a "box 'o Holley" at the swap meet yesterday for $10. It had a disassembled 750 DP and a 750 VS in it, plus a ton of parts and other stuff. Adding it to my collection, which is now over 30 Holley carbs. Guess carbs are a sickness for me, as I always come home with one.
90% of problems with a Holley is related to bad gaskets, a blown power valve, or just plain 'ol dirt.
Get one of the Holley tech books available at any major bookstore, and it'll dispense with a lot of the mystery of the carb. All of the popular performance holleys are built from a common "platform", with a baseplate, main body, metering blocks and float bowls.
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rockafellz
Gearhead Posts: 160
From: San Lorenzo, CA, USA
Registered: Aug 2001
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posted 04-15-2002 01:04 PM
Hemi,Really? The autolite really has all those bad features? I don't mean to disagree in any way, but based on the past threads on this board, some people swear by the autolite 4100. Maybe we'll here from someone regarding autolites.  I also just learned that the autolite 4100 is a vaccuum secondary carb rather than a mechanical. So does that mean the secondaries won't open until there is a strong enough vaccuum? What are your thoughts about the "newer" Holley Street Avenger 670cfm? I'm basically trying to spec out the carbs that will give me the best performance without all the constant tuning hassles. I guess it's because my knowledge in carbs/engines are still in the novice area. I'll probably stop by the bookstore later and pickup that holley book. I have a Holley 4150 that i got for free sitting at home that could be rebuilt. Erik
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Hemikiller
Gearhead Posts: 124
From: Clinton, CT
Registered: Feb 2002
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posted 04-15-2002 09:59 PM
I agree that some people have good luck with the 4100. Problem is, last time they were used was back in 67 I believe. So you've got at least 35 years of wear on all of them. Besides, most of the time Ford put a Holley on any performance car it built! Unless you have a 4100 on the shelf, I'd go with the Holley especially since you do have one in stock. What is the list # on the airhorn? I can ID it for you if you'd like.I have a couple friends that had 4100's on their cars, and had a lot of problems that I stated. Their carbs were probably well worn, and in need of a trip to Pony carbs. However, for the money spent on remaning a 35 year old carb that might work for you, you could get a carb that WILL work in your application.
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steve'66
Gearhead Posts: 4182
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 04-15-2002 10:32 PM
The main supporter of the 4100 is Alex. He has that carb mastered because he has to run it on his Super Stock Mustang. He's getting 500 or so horse power out of a modified version on a highly modified 289. But for us mortals, stick with the Holleys.  SteveW
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