live2shred303

im trying to pick out a carburettor from summit racing.
all of them are either electric or manual choke.
i need a vacuum choke.
it says secondary type: vacuum.
does that mean you can do either or?

musnicki

Vacuum secondary is good. It causes the secondaries to open slowly depending on the amount of vacuum cased by the car or it's increase for the need for air in turn will cause the spring in the secondaries to open for more air as well as more gas. You'll have a choice between different tensions for springs, a stiffer spring will cause the secondaries to open late ~4-5k rpm saving you gas milage whereas a softer spring will let the secondaries open sooner for more power but at the cost of gas milage. Either way, in a well tuned carb, you shouldn't feel a huge jump in power when the secondaries open because they open gradually.

The other type is a mechanical operated secondaries. Those are good for racing or if you're running a turbo or supercharger where you'll want to know constants like gas usage and what not.

The choke, you can run an eletrical choke, just run a line from your ingnition, one that has power when the ignition is on. And then plug the vacuum line that normally goes to the carb.

James

live2shred303

hm. id rather have stock vacuum choke.

question about your wiring?

wouldnt that have the same voltage/amperage at all times. isnt something supposed to vary so the choke opens or closes more?

rbowmar

Before I answer your question about choke and secondaries, there are much more important considerations for selecting a carb. The cubic inches of the engine, the intended use of the engine, performance modifications installed or planned, how hard you are willing to work to get the carb dialed in, are only some of the considerations. If I can give you one piece of advice, if in doubt, go with a smaller size carb. An oversize carb will not make your engine more powerful and will make it much harder to adjust.

Check these threads: Gun Jam just went through the selection process and dialing-in process.

https://mustangforums.com/forum/clas...questions.html

https://mustangforums.com/forum/clas...ot-dialed.html



For the choke, I recommend electric as they mostly adjust themselves. If you are used to driving a manual choke and like it, then go manual. Some carbs, like the Holley Street Avengers only come one way.

Vacuum secondaries refer to how the secondary throttle is actuated. 4bbl carbs run on two of four barrels at low RPM called primaries, then add the second set of two at higher rpm for maximum performance, called secondaries. How the secondaries are controlled is either manual or vacuum. Manual secondaries are primarily reserved for racing engines, while vacuum secondaries are much more controllable for street engines.

Good Luck!

live2shred303

i just read up on electric chokes. i guess the voltage stays constant at all times and heat is the variable. so that answers my question on that. but could someone be more specific about how to wire it?

musnicki

"rbowmar" was correct about first making your choice based on engine size and what you'll be doing with it.

As for the wire, you'll want a wire thats hot while the key is in the ingnition on.

Gun Jam

you simply connect the red wire from the choke to a 12v source that is hot only when the key is on. One option of doing this is locate a fuse on the fuse block using a multi meter or test light. Find A fuse that has no power with the key off (accessory fuse should work) then turn the key on and it should be close to 12v.

Once you locate this fuse they make taps that fit to the contour of the fuse and install with the fuse the tap allows you to use a spade connector on the end of the tap and draw power from that fuse simply run the wire to the red wire on the choke.

I went with the holley street avenger with a manual choke. I actually found the carb to be only slightly more difficult to tune than the edelbrock series.

If you are looking for a 4 barrel carb the edelbrock performer is a good carb for most stock to mild street applications for stock a 500 cfm would do you well.
http://www.edelbrock.com/automotive_...erformer.shtml

The performer is a double pumper and uses mechanical secondaries which in your application has the ability, when tuned, to provide excellent MPG and optimum HP. Using a 600 carter AFB (same as performer) trick flow heads, fairly mild roller cam, and edelbrock performer 289 intake I was getting about 20 to 24 mpg.

Although after typing all this something tell me you are looking for a 2 barrel carb.

-Gun

rbowmar

+1 on Gun's recomendations. Hooking up an electric choke is not as complex as it sounds. Gun is giving you the step-by-step that will allow you to do it easily. Basically it boils down to: 1:Run a hot wire to the choke and hook it up. 2:If needed, grab a screwdriver and tweak the setting.

+1 Edelbrock Performer Carb. This is the favorite carb in our shop because my son believes they can be fine tuned easier than the Holley Street Avenger series that come pre-tuned. The Holleys can be tuned to perfection, but the jetting procedure is more difficult than the Edelbrock's.

The Holleys' tuning is their best guess. On the stock 302 in my 72 Mach1, I put a new Holley 570 Street Avenger and was able drive it right away. I got the car smogged with a little idle screw tweaking. However, because it was Holley's best guess, it wasn't totally smooth from idle to redline. I was satisfied because I could go straight from a dead car to something I could drive and enjoy. I had so much restoration to do that I chose not to worry about lack of perfect smoothness. Not everyone enjoys such a hassle-free set-up.

Now, with a built 351, the 670 Edelbrock Performer runs smooth through out the powerband. It took quite a bit of tuning to get it right.


Edelbrock performer intake manifolds work well if you need a manifold.

I hope this is useful.