trying to set up timing/carb

Anonymous · Post by **Anonymous** » Tue Jan 25, 05 8:23 pm

i am trying to set up my carb and ignition timing (440 68 charger r/t) as described by dave in a post two weeks ago.
anyway, set timing using good quality dial in light and after market tach-
iv`e got 30 deg btdc @ 3000 rpm and 12deg btdc at idle -800 rpm, vac disconected. connect the vacuum line and i only get 5 deg increase at 3000 rpm 35 not 50 to 55 deg-- any ideas???? the allen screw in the canister is screwed all the way in. i have no vacuum at idle and 20 inches at 3000 rpm, below the throttle plates i have 20 inches all the time.
what/how, measurement is needed so as to get the right powevalve?(holley 750 vac sec 3310) and what else do i need to look out for?
the mixture screws are working because the engine dies/stalls if i screw thm right in,and there is only 0.5 inches of vacuumat idle. i have found them best one turn out- best vac and rpm.
before i did this i found the timing was 10 deg atdc would that make much difference as i have not road tested the car
thanks for the help

Dave-R · Post by **Dave-R** » Tue Jan 25, 05 9:20 pm

Power valve first. You have good vacuum. Very good. Most of my instructions really refer to performance engines with longer duration cams where you need to worry about how low vacuum can drop in normal operation. In your case I would use a 10.5" power valve.

The advance in the dizzy now. If it goes from 12-30 without the vacuum there are two possible answers.

First of all it could be that you need to lengthen the slots in the weights so that you can go from 12-35 degrees. You must try to get 35 degrees @ 3000rpm if you can.
On the other hand there is a small chance that you either have a spring missing from the weights or very light springs indeed. This will give you some advance to start with at idle so your advance total will end up short as it seems to be now. Check what rpm the 30 degrees comes in at. You only want about half your centrifugal advance in by 2200-2300 rpm. If it is more that is a sign of weak springs.

Now to the vacuum advance.
Dunno. Try sucking on the thing and see if you can get it to move. It must be stuck or something.

Anonymous · Post by **Anonymous** » Tue Jan 25, 05 10:00 pm

I set the timing - 30 deg btdc @ 3000 rpm. this is what i thought it said to do in your post, dave
i would be able to set it at 35 deg btdc@ 3500 and will probably get about 15 deg btdc at idle.
the dizzy is advancing fine mechanicaly.
if i suck on the canister it pulls the plate o.k.

Kev · Post by **Kev** » Tue Jan 25, 05 10:08 pm

sean, what dave is saying about the mechanical is that the springs might be really light and therefore giving advance at idle.... therefore your advance has already begun giving LESS idle-full advance movement. If you know intimately and have had physical contact with your springs you have installed then sorry for posting

Dave-R · Post by **Dave-R** » Wed Jan 26, 05 9:17 am

15 degrees is a bit much for idle. You could probably live with it though. 14 MAX I would say. 12 is better.

I am pretty sure I said 35 degrees total in my post on the subject?

If the plate moves fine when you suck on it then it should move ok when the engine sucks on it. That only happens when the throttle is open of course. In fact I think you said you had vacuum on the dizzy port when you opened the throttle didn't you? I can't understand why it does not move the plate in the dixxy then.

Guy · Post by **Guy** » Wed Jan 26, 05 2:58 pm

One thing to check is that the vacuum pipe is not collasping between the carb and dizzy it happens and can give you all sorts of wierd readings one minute no advance next full/partial advance at idle .