I got a 1975 Ford F-100 with 1971 Ford 460. It has a edelbrock torker II manifold and a Holley 3310 780 cfm carburetor,headers, C6 auto and a electonic ignition and is converted to unlead fuel, 2wd. The gas mileage is horrible. I want to change out the holley with something else. I have seen that this Holley can be upgraded by installing a ProForm carburetor main body, the Proform 67101C. Is this the way to go or do you have any better suggestions

 

the fuel mileage is always going to be horrible.

that being said, i would change out the manifold to a good dual plane like the Weiend Stealth or even Edlebrock Performer RPM or air gap. the Torker II is a single plane intake more suited to high rpm usage. the dual plane intakes sacrifice top end for more usuable low and mid range performance, the rpm range most people drive in.

as far as the carb, the Holley is a good carb, probably just needs to be tuned and dialed in. either do some research on the net about tuning the holleys or take it in to a good performance shop to dial it in for you. they are not that hard to dial in properly. the Proforms are also a good choice along with the Edlebrock/Carter carbs. the Edelbrocks sacrifice some hp but get better mileage and driveability(maybe .5 mpg give or take, we still are talking a 460 here) and seem to keep thier tune for longer than a holley.

that would be my suggestion to make the truck a little more friendly on the street.

Rgds
Mike

 

The typical 3310 is a vacuum secondary carb that is rated at 750 CFM. This is probably one of the most common carbs around.
If you are looking at mileage. this may not be the carb for you, and adding the Proform kit, will not make it any more economical. I mean the Proform center section is more of a performance oriented piece that provides a greater amount of tunability due to its adjustable or replaceable high speeds and low speed air bleeds.
Much of this kit also requires a metering plate for the secondary side, so you add yet another level of adjustment. This being said, the chike horn also goes away, as there are zero provisions for a choke of any kind.
The center section os of a superior design, and will out flow the original unit, but higher CFM means a greater demand for fuel and this greater demand for fuel is not going to provide any better mileage.
I dont see why you F100 cant get reasonable mileage, but the key word here is reasonable. What is poor mileage to you now? What are you hoping to expect?
Low double digits are not unreasonable, but much of this has to do with the ccomplete packeage and driving style. Even a Honda can consume fuel if you have a heavy right foot.
maybe a driving style change would lead to a change in mileage.

 

After playing around with a 76 460 (4350 carb) and various Q-jets on boats, I found that unless you are after acceleration, you can ty-wrap the secondaries shut and get lots better mileage. On a heavy vehicle, even a fairly normal take-off can pull in the secondaries slightly, which dont mix all that well. The 4350 autolite carb had primaries way too small to run very much, but the hollys are ~300-350 cfm on primaries, which on a 460 will surprise you. Why dont you try ty-wraping (or some other method to totally disable) the secondaries and drive around for a while----its free, and you can tell just how much the secondaries are costing you. It will definately be slower, but at least you can try it. If you like it, then you might put a really stiff spring in the vacuum pull-up on the carb and keep the 4 bbl.

 

The Stealth intake, as I understand it is way to big in the plenum area for stock and mild engines. The Performer is pretty good for stock levels. If the motor is all stock, a 600cfm would prolly work best, but, as stated, don;t expect much out of the 460 in mileage. The 3 speed c6 isn't helping either. What gears are in the truck? What do you intend to do with and get our of your truck.

 

The gears are 3.73 . The highway milage isn't that bad but the city milage is. I was hoping to use the truck for daily driving but it's to expencive to use. The gas price in Norway are about $8.50 for a gallon

 

Here is some spec on the engine: the cam is a Edelbrock Performer. The duration of it is 272 (intake) and 282 (exhaust), and the valve lift is .460 (intake) .480 (exhaust) and the part # is 2167. That part is out of a PAW catalog

 

my 75 4x4 gets 8 mpg with a 360 c6 combo.

 

I think that about the only way to significantly improve mpg on most old carbed engines, aside from plugs, wires, sparks and timing is to use a Wideband O2 sensor. My .02, after playing around with various Ford and Holly carbs is that the mixture needs a lot of very careful tuning. Jetting (main jets/rods is only a small part of that) needs to be really tuned and that includes power valves and even secondary operation. You cannot get mileage using the old standards from years ago when gas was cheep.

Heavy vehicles (I had a 460 E250 club wagon van, 5200#) get into the power circuit a lot and that kills mileage. I put a 4010 holly on it and it went from bad to worse. Just before I sold the van I discovered that the Power valve jets (pressed in) were WAY too big. I called Holly and they sent me a little bag of smaller ones, seems they were aware of the problem---! Most power jets are ~ .060 (best memory), the jets in the 4010 were ~.093. Obviously, everytime the vacuum dropped enough to let the pwr valve fall open, WALLA---- terrible rich mixture.

My point is that on a heavy SUV, short of spending a bunch of $$$$ on a chassis dyno, about the only way to watch the mix in real time is a Wideband. Sure, you can read plugs, but what a PIA---besides, hard to do at 70 MPH . The processor looks at and optimizes all these things on FI, and you cannot match that speed. As I am learning on my 07 Expy EL, driving habits play a very large part. I am about to get used to the "Soccer Mom" in a mini running away from me at the lights. With these low gears in the 6 speed and a 3.73, I have no doubt I could blow that thing away

The bottom line, is either change something, get used to it or sell the damn things. I am not trying to pizz anyone off, nothing personal, but my .02 is----thats the reality. If I wind up with another carbed vehicle (My 70 Mach I, 4bbl C) I will get a Wideband, they are not that expensive.

 

For increased mileage purposes a 600 CFM carb will improve things. Besides that if you still have the stock cam, anything past 4500 rpm is just beating your motor up for no good purpose. My 1984 F250 Supercab came with the junk 4180 600 CFM Holley emissions carb. I replaced it with a 4150 600 CFM List #1850 Holley and gained low end performance and almost 2 mpg. Along with a dist. recurve and a 3" single exhaust it now gets almost 10 mpg and that is with 4.10 gears in the rearend.

 

I should have gone with the Holly 650 (spreadbore) in that series, but somehow wound up with a spreadbore intake and didnt want the squarebowl design holly---dont know why now. I used the 600's as a Q-jet replacement (along with an intake) on marine engines. If you really want MPG out of a carb setup on a heavy vehicle you will have to be aware of the power circuit in addition to dist and other tuning. Anyway, thats my .02. One of these days, I may have to get back into carb tuning, then I sure would like to have a wideband sensor to play with---