Motorcraft 2100 on 225 tuning help

Yes I am running a Ford carb on a GM engine. Wondering if anyone else is doing the same and any ideas on tuning. I am using a Motorcraft 2100 2 bbl 360 cfm manual choke. Engine has the HEI conversion tuned per forum suggestions and runs pretty good. It has one problem of slight hesitation from crusing speed to slight increase in throttle pedal. Hesistation will not go away unless more pedal to give it a shot from accelarator pump. Idles good and accelarates good. Has 48 jets, tried 45s for better economy but too small. Carb has been pro rebuilt 3 years ago, power valve and accelarator pump good. Using a small (10 inch dia) open face air cleaner, driven daily in town and highway at 9600 feet and cold - below zero to 40 above F. I have accelarator pump linkage in second from top hole, although do not think it is accelarator pump related because it only uccurs on slight throttle increase at slow speeds ( 5mph) and highway speed (50mph). Any ideas appreciated.

Also how does one post pic of there heep on signature?

Thanks

 

Hi - a hesitation is caused when the vacuum drops, causing momentary low air velocity. This leans out the mixture until the engine speeds up.

Usually the accelerator pump compensates for this lag. If the mixture is lean to begin with, the normal AP setting may not be enough to overcome the lag. You can have a lean mixture from small jets, low float level, or a power valve with too low a vacuum set point. It's pretty easy to change the AP shot - the top hole on the throttle arm and the inner hole on the AP arm will give you the largest possible shot.

Don't know what car your 2100 came from, but the later 2100s and 2150s used a 2-stage power valve to allow the primary jet size to be smaller. The objective was lower emissions and better mileage. The power valve richens the mixture by opening when vacuum drops to a set point - ie at low speed and full throttle. The 2-stage power valves simply have 2 orifices that open at different vacuum settings. Holley lists these 2-stage valves, but their availability isn't very good and they are more expensive than the single-stage valve.

The various single-stage power valves are widely availalbe, and could be another solution to your problem. I'd suggest you read the Holley tech page on power valves http://www.holley.com/HiOctn/TechServ/TechInfo/CI-121.html - Holleys and Motorcraft use the same power valve, so you can get the single-stage valves at your local speed shop or from many different online sources.

You could also try larger primary jets - Parker Carburetion in NC has most sizes http://www.holleypartsforsale.com/jets.php

What's your mixture now? Have you looked at your plugs lately?

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