OK guys, here goes. . .I have a 1978 F150 4x4 SuperCab with a 351M/C6 in it. The 351M is shot, so I recently bought a non-smog, reman. 460 ci. long-block from S&S Motors in Spokane, WA.

I have almost completed buying the goodies (intake, motor mounts, oil pan, etc.) needed to drop her between the frame rails. Here is my problem. . .

I know nothing about carbs. I purchased an aluminum Edelbrock Performer intake manifold for the new engine. (BTW, the engine is stock except for a Stage 2 cam kit. . .basically an RV cam for more low-end torque). I have been told to buy a carb in the 750 cfm range.(The truck will be a daily driver, occasionally towing my utility trailer or bass boat.)

The carb on the 351M currently in the truck is an Autolite/Ford 2150 with what appears to be a manual choke (no wires). I guess this means I should buy a 4-bbl carb with a manual choke too?

Again, sorry for my ignorance, but carbs are something I just never got into, or understood to any degree. Any help you guys can provide will be appreciated. Thanks.

 

A fantastic chance to get a electric choke!


When you buy the new carb, one with a electric choke, and it'll come with the wire you need. It'll just be a single wire you run to a switched + and your truck will be that much better mannered..

 

Ford didn't offer a manual choke after 1972 on F100/350's.

Where's the choke cable on your truck?

There isn't one, and there's no place for one in the dash.

Your carb was changed, how do I know that?

If the carb says Auto-Lite on it, it's a carb from 1972 or earlier.

Ford was forced to sell Auto-Lite by the US Gov't, who said they had a monoploy on auto parts.

So, in 1973, Ford started a new in-house company: Motorcraft.

Your truck would have had an electric choke originally. Some PO either clipped off the wire, or taped it to the engine gauge feed wiring harness.

 

OK, I mentioned Autolite. I probably should have said Motorcraft. I vaguely remember the NAPA website listing several carbs available for my truck when I had to replace the 2-bbl. . .(overtorqued the fuel filter, cracking the aluminum carb body)

Maybe I am not looking at my current carb correctly, or am simply using the wrong terminology. The choke does not have a cable that enters the cab. Never did as far as I know. The choke is set by stepping on the throttle once, prior to turning the key. The choke "gap" is adjusted by turning this round black thing that houses a coil spring. Is this considered a manual choke? I have also seen these "round black things" with electrical spade terminal connections on them, and I always assumed this was an electric choke. Am I correct here?

 

That round black thing is a electric choke.

 

OK, now I feel silly. I just found out that there are basically three types of chokes. . .manual, electric, and automatic. I currently have what appears to be an automatic choke. In other words, the little black housing with the coil spring inside does not have any electrical connections on it. The choke opens automatically as the engine warms up.

So, with this in mind, I should be shopping for a new 4-bbl with either an electric or automatic choke. Sound right?

 

Your choices are going to be manual or electric. When shopping for a carb for either my truck, Mustang, or Tbird, I never came across a third option from the aftermarket...

 

Your carb should have an electric choke on it.

I'm looking at the Ford parts catalog illustration of the Motorcraft 2V carb used 1975/79, and on that choke cover is a spade connector, for the choke wire to plug on to.

 

http://http://www.partsamerica.com/ProductDetail.aspx?MfrCode=HO2&MfrPartNumber=64625 6

Here is what I bought for my truck a few years back to replace the one I broke. It was identical.
I am starting to see that it won't be a big deal to put a carb with an electric choke on the truck. Someone mentioned a PO (my dad) taping the original wire to the harness. . . .I do have such a wire. . . .always wondered what it was for. Thanks guys.

 

As long as smog inspections are not a problem, get a good aftermarket carb WITH an electric choke, they are easy to hook up and set, just read the instructions a few times and use common sense. I love holley carbs and have used them for years, simple design, easy to install and adjust and plenty of adapter parts for the ford transmission kickdown rod. I recently purchased a new edlebrock carb for my 460, thought I would give them a try and my truck runs great with it. I did have to buy the transmission kickdown lever adapter for it and do some adjusting with my factory throttle cable brackett, but it came out nice.

On the choke end, you can adjust how rich you want your choke by loosening the three screws on the side and twisting the spring in the cap tighter or looser (the black thing on the side of the carb). If you live where it gets really cold you want the choke plate on the top of the carb to close all the way with some LIGHT spring pressure on it when it is real cold outside. If you live in warmer climates you adjust the spring cap to just barely close with almost no spring pressure on it when it's cold outside. You then adjust your high idle rpm with the little screw underneath the black spring cap. I have mine set so that it high idles nice and low when cold (about 1300 rpm), then after a couple of minutes you just touch the throttle and the rpm returns to 700 (idle). Of course, in really cold climates the engine may not run at 1300 rpm when cold and you may have to set the cold idle speed a bit higher. Play with it a few times when it is stone cold and you will get it where it runs best. By the way, I now favor Holley's and Edlebrock carbs, I've used quadrajets and they have been a pain in the *** for me at least.

 

I have the 1969 460 from s&s as well the 670 avg does appear to be to small feels like I need more carb; however I have a multitude of upgrades like hooker super comp headers with 2 1/4" primarys 3.5" collectors, performer intake, pertronic ingnitor, blaster coil, flowmasters. Oh yeah its in a 93 mustang fox body its nuts at 4500 rpm. Would these upgrades constitute more carb than a 670? Ive read all the pros and cons but havent read any real solid replies its like the 460 is a mystery! I had a 1978 460 with spread bore 800cfm quadra bomb with cob webs in it and this mother would snap your neck even with a bad intake valve; in a mustang of course.

 

You should go find a "volumetric effieciency calculator", you could probably do a search and find one. It will give you the exact amount of CFM needed for your particular set-up. If I remember it goes something like: Displacement X RPM X Vehicle Weight= CFM, or something like that, I forget just how it works, but it will tell you what size carb you should be running.

 

go to this link. http://bigboyzheadporting.com/VeCFMCalc.htm this assuming you arn't wanting to go crazy, and race it. also I figured it at .030 over bore, stock stroke. well you can see my numbers I entered. looks like a 600CFM carb will do what you need. if you need to change any of the numbers please go to the link.

<TABLE style="WIDTH: 321pt; BORDER-COLLAPSE: collapse" cellSpacing=0 cellPadding=0 align=center bg*************** border=0><TBODY><TR style="HEIGHT: 13pt"><TD class=ee103 colSpan=5 rowSpan=3>Volumetric Efficiency and Cubic Feet/Minute Calculator </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee109 colSpan=2> </TD><TD class=ee100> </TD><TD class=ee109> </TD><TD class=ee100 colSpan=2> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee111> </TD><TD class=ee114>Bore </TD><TD class=ee117><INPUT class=ee119 id=p1D6 onblur="this.value=eedisplayFloatND(eeparseFloat(t his.value),3);recalc_onclick('p1D6')" style="WIDTH: 100%" tabIndex=1 value=4.390 name=p1D6> </TD><TD class=ee120> inches </TD><TD class=ee123> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee111> </TD><TD class=ee126> </TD><TD class=ee123> </TD><TD class=ee111> </TD><TD class=ee123> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee111> </TD><TD class=ee114>Stroke </TD><TD class=ee117><INPUT class=ee119 id=p1D8 onblur="this.value=eedisplayFloatND(eeparseFloat(t his.value),3);recalc_onclick('p1D8')" style="WIDTH: 100%" tabIndex=2 value=3.850 name=p1D8> </TD><TD class=ee120> inches </TD><TD class=ee123> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee111> </TD><TD class=ee126> </TD><TD class=ee123> </TD><TD class=ee111> </TD><TD class=ee123> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee114 colSpan=2>Crankshaft Speed </TD><TD class=ee117><INPUT class=ee119 id=p1D10 onblur="this.value=eedisplayFloat(eeparseFloat(thi s.value));recalc_onclick('p1D10')" style="WIDTH: 100%" tabIndex=3 value=5000 name=p1D10> </TD><TD class=ee120> RPM </TD><TD class=ee123> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee111> </TD><TD class=ee126> </TD><TD class=ee123> </TD><TD class=ee111> </TD><TD class=ee123> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee114 colSpan=2>Horse Power </TD><TD class=ee117><INPUT class=ee119 id=p1D12 onblur="this.value=eedisplayFloat(eeparseFloat(thi s.value));recalc_onclick('p1D12')" style="WIDTH: 100%" tabIndex=4 value=300 name=p1D12> </TD><TD class=ee120> HP </TD><TD class=ee123> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee111> </TD><TD class=ee126> </TD><TD class=ee123> </TD><TD class=ee111> </TD><TD class=ee123> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee114 colSpan=2>Compression Ratio </TD><TD class=ee117><INPUT class=ee119 id=p1D14 onblur="this.value=eedisplayFloatND(eeparseFloat(t his.value),2);recalc_onclick('p1D14')" style="WIDTH: 100%" tabIndex=5 value=8.50 name=p1D14> </TD><TD class=ee120>:1 </TD><TD class=ee123> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee111 colSpan=2> </TD><TD class=ee123> </TD><TD class=ee111> </TD><TD class=ee123> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee114 colSpan=2>Atmospheric Pressure </TD><TD class=ee117><INPUT class=ee119 id=p1D16 onblur="this.value=eedisplayFloatND(eeparseFloat(t his.value),1);recalc_onclick('p1D16')" style="WIDTH: 100%" tabIndex=6 value=14.7 name=p1D16> </TD><TD class=ee120> PSI </TD><TD class=ee123> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee111> </TD><TD class=ee126> </TD><TD class=ee123 colSpan=2> </TD><TD class=ee123> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 15pt"><TD class=ee100> </TD><TD class=ee129 colSpan=2>Volumetric Efficiency </TD><TD class=ee132><INPUT class=ee131 id=p1D18 style="BORDER-RIGHT: #000000 0px solid; BORDER-TOP: #000000 0px solid; OVERFLOW: hidden; BORDER-LEFT: #000000 0px solid; WIDTH: 100%; BORDER-BOTTOM: #000000 0px solid" tabIndex=-1 readOnly value=326.3 name=p1D18> </TD><TD class=ee133>% </TD><TD class=ee123> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee123> </TD><TD class=ee136> </TD><TD class=ee123 colSpan=3> </TD><TD class=ee100> </TD></TR><TR style="HEIGHT: 13pt"><TD class=ee100> </TD><TD class=ee129 colSpan=2>Cubic Feet/Minute </TD><TD class=ee132><INPUT class=ee131 id=p1D20 style="BORDER-RIGHT: #000000 0px solid; BORDER-TOP: #000000 0px solid; OVERFLOW: hidden; BORDER-LEFT: #000000 0px solid; WIDTH: 100%; BORDER-BOTTOM: #000000 0px solid" tabIndex=-1 readOnly value=549.0 name=p1D20> </TD><TD class=ee138> CFM </TD></TR></TBODY></TABLE>

 

for JMARKLE carby size of 650/750 cfm is fine , as for choke type it's up to you if you want manual or electric/automatic choke. either one requires only minor alterations depending on year of vehicle

 

hi jason, i do not what cam you have, but with the other parts you have at least run an 850cfm