who is the Edelbrock carb guru on FABO

-
I know my son had messed with the springs in the dist. when we put the 440 together. I know he changed them and put lighter ones in. I will have to talk to him about that. I have a little bit of a bog when coming off of an idle. I don't have much of a rap on the throttle like I did on my Chevelle. I will look at the needle and seat. very possible a piece of rubber got through.
 
[ame]http://www.corvette-restoration.com/resources/technical_papers/Q-Jet_Troubleshooting.pdf[/ame] Yeah, I know, for q-jet, but they are very similar in operation and troubleshooting. Should give you some ideas on what to check.
 
I tore this carb apart this morning. There was dirt in it under the floats. One of the floats was hanging too much. 1 1/4". so I adjusted the floats. pulled the needle and seats out and cleaned them. pulled the A/F screws out and cleaned them and blew them out with air nozzle. put it all back together. BUT..........last year towards the end of the year when I was having some trouble with Tylers carb and we were switching carbs around, I put a new fuel pump on and we had a car show the next day and in the hurry up process, the parts house didn't have the fuel line filter I wanted and I put the new line back on without the fuel filter thinking I would do it when we got back home. That didn't happen so that is why the dirt was in the carb. I put new fuel lines on and a new filter today. It runs better. starts better. I now have the rap back in the throttle response. but when I took it up the road and slowed down to turn in the church parking lot, it did the same thing. Turned around and came back home and slowed down to turn in the driveway and it did it again. Seems like the RPM's dropped a little too much. Idle is set fine. It doesn't do it going around a curve in the road. I live on a curvy road out in the country. just making a sharp turn into a driveway or such.
 
You also might want to try this trick out of the q-jet manual:

When set up with the correct metering rod for cruise & idle, will produce a slight hesitation upon acceleration if the
accelerator pump is disconnected. I do this with the engine running so I don’t have any trouble starting the engine without the
accelerator pump. With the pump disconnected and with the engine running in neutral, “flick” the throttle just a little. If the engine
actually feels more responsive with the pump disconnected, your cruise metering area is too rich, and you need to install a fatter set of
rods. If you get a severe stumble, or if the engine dies, you’re on the lean side and need smaller rods. When the rods are correct for
the jets in use, you will get a slight hesitation when the pump is disconnected.


After your done verifying the jets and rods are good, watch this:

[ame="https://www.youtube.com/watch?v=Kw-8lv4QIfQ"]Edelbrock Carburetors - Troubleshooting - Hesitation and Stumbling - YouTube[/ame]


Once you have set the rod size up like this, using the disconnected accelerator pump, a road test is in order. If the car is a little “flat” on light acceleration, or if it has a slight “surge” at steady cruise, you need to richen up the metering area slightly. If it is smooth and responsive on light acceleration, and feels smooth at cruise, you have the rod size nailed down.

Again, use the charts to keep all changes limited to 10% at a time. This will prevent you from “over-shooting.” Remember, with the
main jet size determined, your rod sizing is affecting idle, off-idle, light acceleration, and cruise. In most cases, when there are
problems with stumbles, poor idle, idle speed that starts out high and then degrades, and surging at cruise, the rods are too big and are
causing a lean condition. On the other hand, if the rods are too small, causing a rich condition, the throttle will feel “lazy” or “slow”
when you rev the engine, and you may get a puff of black smoke with a hesitation when you “flick” the throttle. Correct rods will
produce crisp, clean and instant throttle response.
 
I don't think anyone has mentioned it yet but the engine wanting to stall while doing a tight turn can be a symptom of improper fuel pressure but since you mentioned it ran fine before, it probably has to do with the changes you made recently.

I'd start with getting some numbers first. Find out what your timing is set to at idle and what it is set to when fully advanced. Once you know the timing is set up properly you can start making changes to the carb, otherwise you're just shooting in the dark :)
 
You must log in or register to reply here.
-

Back
Top