ok im dieseling again! im at 12 btc and i think i need to go higher but i dont know how much? i hear 18-22 for higher performance 302's...let me know.

 

Hi Vin,

are you dieseling because you advanced the timing, or did you advance the timing because you are dieseling?

What are your overall goals?

 

as far as timing goes, When you accelerate hard, you you hear a rattle type noise come from the engine, is that pinging from too much advance???? If so, i need to lower my timing alittle.

 

Ohhh no i dont have any ping. i am not getting the performance i should be and im dieseling so i need to advance it a little more to correct both. I dont know how far to go with my engine.

 

What kind of advance are you running? You should be 38-40 at full advance.

 

i see in you pic you have msd did you install diode i had to in my truck

 

what is diode? and what is the initail degree is it 34? i hear people running up to 22 btc on mid/high perfmance engine

 

HI, I hope I can help. It sounds to me that the "dieseling" that your encountering is not actually pinging because of bad gas or too much timing advance, but actually what is called run on. What happens is that the engine keeps running in sort of a pinging idle. FIrst thing to check is to reset your idle speed. If your idling too fast (especially with your advanced timing) this will happen. Any time you reset the timing the idle speed is affected. RESET THE IDLE ON THE CARB FIRST! If that doesnt workt he way to fix this without playing with the timing/idle is to get an idle solenoid. your local parts store should be able to help you. If your bucks down you can also pick one up from a vehicle in the junkyard. Look for a car with air conditioning. What this does is set your idle speed instead of the screw on the carb. When you shut power off to the ignition the solenoid basically shuts the carb throttle shafts so the car shuts off. If you buy the solenoid at a parts store look for one with a built in bracket or one that can be mounted easily. The solenoid should be wired to the same 12 volt power source that the ignition is being fed from. The solenoid sets your idle speed ( you actually have to turn down the idle on the carb enough so it will die when the solenoid shuts off.

IF your really serious about performance, you may want to check your timing curve. For this you need a dial back timing light or a timing tape. The initial timing is giving you only a small fraction of what you need to know to tune your motor properly. I will describe the dial back timing light because its easiest and you should have one or access to one if your a serious tuner. I guess I will have to give you a lesson in timing first. There are all kinds of variables to what I am about to say, but this will give you a general understanding. Basically, when you are setting your timing to what your saying is up to 22 degrees, this is just initial timing. from there, your distributor adds timing by centrifrugal or vacuum advance( I am assuming its a distributor because of pic) (dont want to get too technical, but some distributors actually retard timing with vacuum dashpot). By using a dial back timing light what you want to do is not only set initial timing, but more important from a performance standpoint is everything after initial timing. You should have around 36-40 degrees total timing, and you should have this between 2500-3500 rpm depending on how aggressive you want to get with your tuneup (your limited by the octane of the gas you use among other things) With a dial back timing light and a pen and paper you can actually graph your ignition timing. You can also see how much centrifrugal timing you have (the weights in the distributor along with the springs change this) also you can see if the vacuum advance is working. You can also check your vacuum advance by sucking on the vacuum hose and seeing if the plate that the weights are on turns inside the distributor. I could write a book here, but basically ask a lot of questions about total timing and everything between there and initial timing. If you have any questions email me at genecanbefound@hotmail.com
One other thing to consider. You really need to get the big picture on your timing. If you have lets say 20 degrees of centrifrugal advance and ten of vacuum advance you need to add that to your initial advance and that will give you your total timing. Each engine will need a different total timing because of how fast the mixture burns in the combustion chamber and a lot of other variables. If you set your initial lets say to 22 degrees, with the above example you would have 42 degrees of total timing (this would probably be too much and your car would ping)
I am sorry to be so long winded, but there are a lot of things that I have learned over the years the hard way and I wish I had someone I could ask questions to ( I didnt have the luxury of the internet)
A couple of other concerns:
the vacuum hose for the distributor should always be plugged when setting timing. the reason being is there isnt enough vacuum signal while no load is on the motor (just revving it) so the proper way to see what the total timing is is to use a vacuum pump or your mouth and actually check how much the timing is moving off idle when you actually put vacuum on the the vacuum dashpot.
if you have two vacuum diaphrams on the distributor the inner one (closest to cap) goes to manifold vacuum and the outer goes to carb vacuum (ported vacuum-above the throttle blades. )
If you want a lot of initial timing and the car is hard starting (the engine will be very hard to crank with too much initial especially 22 degrees!) What you can do is get a starter button. You wire this button directly to the starter or the solenoid for the starter (the button -or switch it you will is usually rated for very high amperage) anyway, what you do is turn the starter over (which obviously turns the motor over) and then hit the ignition switch.

Again, sorry to be so long winded, but I hope I helped - I know if I were in your shoes it would help, but also stir up a lot of other questions. little stuff like this is what seperates a good tuner/mechanic from a bad one.

One other point- msd makes a distributor that you can set all the advance mechanically, but you need to set up the proper weights and bushings in the distributor. you can change the timing advance by playing with bushings and springs and weights in your (assuming) stock distributor.

Also, you can take your distributor out and have the advance checked on a machine.

 

wow thanks alot. ive been trying to find some good information like that for awhile now. Ill be sure to email you with any further questions. thanks again