Help selecting the right carb

Learning as I go. I've got capable mates that are great with the wrenches but I need to get them the correct parts to work with.

My D8 head is being worked over and converted to 2V by a forum member who knows what he is doing. Full treatment. Everything in the handbook.

I have a '79 DSII that will be swapped in at the same time that the head and carb get swapped in.

Will later have a driver profile, low/mid RPM cam.
Will soon have the speed daddy headers
Will eventually have a T-5 with 3.5 or 3.73 rear end

I live at 6000 feet elevation.

I'm going with the Autolite 2100. I'm thinking 1.08 or 1.14.

Is there a specific year range I should be looking for? Does it matter what vehicle or what engine my donor carb comes from?

Does my altitude effect my ventri choice?

Any thoughts on jetting?

Anything else is need to be considering regarding the carb?

Thanks in advance for your help!

David, CZLN6 can advise you. If you choose a Holley I could help you. If you need distributor help just let me know.

Howdy Shelly:

I sure like the sound of your project engine. Please keep us updated on your progress. First some questions. What car is this engine going into? What is your goal compression ratio?

In general, the Autolite 2100 is a great little carb- but with some limitations. The 1.08 and 1.14 are very close in cfm. Both were used in 302 V8 engines from 1964 to 1973. More specifically, the 1.14 was used in 289 and 302 V8 engines from 1964 to 1967. The 1.08 followed from 1968 to 1973. These carbs were used in a variety of FoMoCo vehicles from Falcons to light trucks with 289s and 302 V8s. In addition these later years were the beginning of FoMoCos quest for improved fleet MPG and more strict EPA requirements. I offer this history as background for you to understand. In general, I prefer the 1.08 from a Mustang or light car, for applications like yours. They run cleaner and leaner. At 6,000 ft elevation that will be important.

For your situation, I'd run the 1.08 as is before changing anything. I'd wait until several plug readings to decide on main jetting changes. I'd also suggest that you drive the car with a vacuum gauge hooked up to assess an appropriate power valve. The Autolite power valves are not rated other than a color code. Fortunately, Holley power valves work in Autolite 2100s and are very specifically rated.

While very similar, the 1.08 is built, internally, to be much leaner and cleaner than the 1.14. Internally, meaning the idle circuit, transition circuit, and power circuit, all of which are built in and are not easily adjusted or modified. The first two are engineered into the K cluster, a piece that is seperate from the main carb body. The last is the power valve channel restriction, which is part of the main body.

Externally, the 2100 has several accelerator pump settings on the two lever arms. This adjustibility is useful in off-idle and part throttle transitions. Again, leaner is better. The other external is the choke. These early years used the Hot Air choke system. In a nut shell, you'd do yourself a favor by switching to an automatic choke from a post 1975 2150 Autolite. The later electric choke is cleaner, more reliable and easier to set. The choke is a factor where four seasons weather is likely.

So, in a nutshell, IIWIYS, I'd go with a 1.08 from '68- '69 Mustang or Falcon. That's my two cents, for what it's worth. Good luck and keep it coming.

Adios, David

Thanks David, your knowledge was appreciated. If you get the main jet size perfect, but are still rich on WOT by testing with a wideband A/F tester then you would have to install screw in orifices in the PVCR-power valve restriction channel.
If you have to go that route you have to VERY carefully drill & tap so a screw in 6-32 drilled orifice-jet can be installed.
Also on the electric choke Ford used power from the stator terminal on the alternator which only supplies 8-10 volts. That was the way it was done on my 1980 302 truck engine. I believe a Holley choke will fit the Autolite & that uses battery voltage.

Thanks guys!

Billy - I'll definitely want to get my DSII curved.

David - the project is my mom's 65 fastback. Dad bought her the car new. Mom passed away years ago and the car has been waiting to be reborn.

My compression goal is about 9.5. At my altitude I see no issues there. And 6000 is "base", it'll spend plenty of time at 7000-8000. It'll probably never see anything under 5000 as long as I own it.

Begs another question I was going to ask later. The D8 has not yet been milled but the plan is .075 per the handbook. I'll be using the common .05 head gaskets. The head will likely be installed on my "as-is" block for a while.

If I mill the head like that, when I get to the bottom end would I mill the block at all? The handbook talks about zero decking but surely you can't do both.

Howdy Back Shelly and Bill:

Good call on the Holley electric choke. I've never tried one but It is a great idea.

"If I mill the head like that, when I get to the bottom end would I mill the block at all? The handbook talks about zero decking but surely you can't do both."

Typically on a '65 200 the pistons are down in the bore about .025". If you were to deck the block on rebuilding you would be adding about another half a point of CR, or about 10:1. With your elevation and plans for a mild performance cam, I'd guess you'd be safe- and you'll love the extra torque. To be on the safe side you might want to mill the head .050" or .060" rather than .075".

Keep it coming.

adios, David

Use a victor head gasket, they are .004" thinner than the felpro & seal better. Advance can get you one.

I have immediate access to a C8AF-L 1.08 carb but I'm told it is for an automatic car with IMCO. Is that compatible with my build (manual transmission, DSII) ? I don't know what that IMCO emissions reference means as far as the actual carb itself.

It may have had a smog pump on the engine??
Get with David on that.
Check your PM's Bill

Howdy Back Shelly:

The '68 1.08 Autolite 2100 should be fine. There is extra levers for the auto trans kick down linkage. I remove that piece of the arm to clean it up and to clear the log. I like to keep the two barrel conversion as low as possible for hood clearance.

I believe IMCO is the rebuilder of carbs. Do you have a photo?

Adios, David

Ask, and you shall receive. Pics.

Howdy Back:

That carb looks fine. Impco is a major carb rebuilder with a pretty good reputation for quality. BUT- (Don't you just love a big but?) I'd be inclined to disassemble to, at least, check the floot level, main jet size, note any marks on the K cluster and color code on the Power Valve. Also check to make sure all parts are there and all screws are tight. Make sure there is no junk left over from the cleaning process. CAUTION- do not overtighten screws on reassembly.

IF this carb is coming directly from IMPCO it will have a warning that any tampering with the carb will void the warrantee. I would be willing to take that risk. How about you?

THe good news is that the 2100 is one of, if not the, easiest carbs to work on ever. In the worst case scenario you might tear a gasket. More good news, a rebuild kit, which includes gaskets, only costs about $30.

Take pictures, take your time, and work in a clean, well lite area.

On the levers, you'll notice a second, free swinging one on the shaft, inside the throttle lever. That is the Auto trans kick down lever. It hangs lower than the throttle lever. That is the one I usually cut off for more base clearance. For you use, it is just in the way.

Keep us posted you your progress.

Adios, David