460 issue

[Scotthw]

I have a 1970 f100 with a stock 460 with an 600 cfm edelbrock that is brand new in it from a 76 f100 paired to a C6 out of a bronco and when you hammer the throttle it will cough/hesitate then take off or even some times stall but i can accelerate pretty hard and it doesnt do it do you guys have any idea what it could be it runs awesome other then that
Thanks

[markguiver]

A couple of things to check for right off the get go are;
1) Is the vacuum advance can still working properly. You can check by pulling the distributor cap and watching the lever while sucking on the vacuum hose with a hand pump (Mighty Vac, etc...) or by mouth. If you can't get it to hold vacuum then it needs to be replaced, it's now just a vacuum leak.
2) The carb may need more of a pump shot from idle, Which you can change by moving the accelerator pump linkage down to the second or third hole. If you have the Edelbrock manual or CD for the carburetor it explains how to do this.
If you live at sea level the jetting should work but, there are still adjustments that need to be made to optimally suit your engine. I would suggest reading the manual/CD to get a thorough knowledge of the setup and function of the carburetor. There is also a troubleshooting section at the end of the instructions.
Mark.

[Scotthw]

I forgot to mention it has a new HEI distributor but ill watch the cd

[rollercam1]

I agree with mark, make sure the engine is sound on the vacumn. Then, more than likely it is the pump shot. I usually always have to increase that for the 460's regardless of carb size

[RottenAppleRed]

I’ve made this post several times here and around the web regarding AFB style carburetors. Whether this be your issue or not, it is something worth addressing in your case as well as anyone else that happens upon this thread. It is my opinion that these carbs are superior to any other carb for street use and I wouldn’t hesitate to use them in performance applications.

The layout of these carburetors has the jets on the floor of the fuel bowls. This makes them very susceptible to dirt and debris clogging them up. It is very important to use a paper element fuel filter in line with the AFB style carb. There are see-through and metal can filters available, but do not, I repeat...DO NOT use the reusable glass filters with the mesh screen. They will allow all sorts of tank sediment past them, thus clogging the jets and cause the exact issue you describe. Double check the location of the accelerator pump arm as well. Start with it in the middle, then move to the lower position to note a change, then the upper. Leave it where it responds best.

It’s also a good idea to get a tune kit with rods, jets and accessories to get optimal performance out of your carb. There are tune guides all over the net for these things, but there are also books for those of us that like having them. I do think you may be a bit under sized at 600cfm for a 460, but it should still run strong. With a 500cfm, just not at higher rpm.