Factory fresh engines can get away with 6 degrees. That was also done in the early days of EPA mandated emissions requirements. It also guarantees that the engine will turn over in any weather climate anywhere in the country and not leave a new car buyer stranded. Factory settings are so safe they are pathetic. Remember when the fuel injected 5.0 cars first came out? What was the first thing you did when you got it to the track? Pull the spout connector and put the timing at 14 degrees then go run the car. Immediate 1/2 second improvement. With a "seasoned" (ie: used) engine and an unknown camshaft you are simply inviting the engine to lug itself with six degrees of timing. When they lug....they do stupid things. Like backfire or try to die when you tag the throttle. The engine needs the extra timing in order to develop cylinder pressure. I can't tell you how many part throttle tuning issues I have solved by simply adding timing. Throttle response becomes crisp and the engine responds to tuning changes much better. Once you get the engine to act better at ten degrees you can try another two degrees or so. Depends on the engine and what grade of fuel you are using. I have had iron headed engines that tolerated 14-16 degrees and others that didn't like anything over 12 degrees. Bottom line: start tuning with 10 degrees minimum.
When setting the initial timing you have to remember that most of the FSB engines don't like more than 34 degrees TOTAL advance. You can take 34 and subtract the amount of centrifugal advance (the mechanical advance in the distributor) and that leaves you with your maximum initial advance with that advance curve. If you want to be able to have more initial advance then you must limit the centrifugal advance in the distributor. Having the advance curve start sooner and get to the maximum advance sooner will also give you more power. It's called "recurving" the distributor. If the car is a dual purpose car (street and strip) then you will have to accept compromises in the advance curve.
Very true. He stated he was running a stock style distributor so I don't think he will have any trouble with total timing but that would be something to check once he gets the issues lined out. Timing tape, timing light, and an advance curve kit from Mr. Gasket are cheap and easy.
... now i'm lost. I havn't had lunch yet so I will be back later to see if something in dumbass terms are posted. Going out for lunch now...
The part that is not so easy is limiting the internal advance to 12 distributor degrees (24 engine degrees) so you can actually use 10 degrees of initial advance. Most of the distributors that I have seen have more advance than that built in. You need to be able to build a larger stop or weld up the slot in the advance armature.
Just start with the basics. Timing tape, timing light, pad and pen. Set your initial advance at 10 degrees then bump the rpm's in steps (1000 rpm is easy....500 rpm is touchy) and record the timing at each step. This is a quick and easy way to "map" your timing curve. Chances are you won't need to have the distributor recurved or any fancy work done. Once you get the car running map the curve and come back here with the results. I'm sure Paul and I can confuse you further at that time.
Gene, where did you get lost? here are some definitions to help. Initial timing = the amount of degrees you set the distributor at when you set the timing. Centifugal timing = The amount that the distributor has built in to add to the initial timing as the speed of your engine increases. Two cams operate with the rotational force (centrifugal force) in the distributor to advance the timing. Internal springsadjust how fast or slow the centrifugal advance works and a positive stop limits the total amout of advance. Overall timing is the number of degrees advance at the RPM that all the centrifugal advance is at it's maximum advance at wide open throttle. The initial timing and the centrifugal timing added together. Vacuum advance = The amount of timing that the vacuum diaphram adds to the overall timing during part throttle cruise. This doesn't count in the overall timing because when you have your foot to the floor you shouldn't have any manifold vacuum strong enough to make the vacuum advance function.
You make it sound easy, which i'm sure it is when one gets to understand or know exactly how to. You say timing tape, this is going on the ballancer? Initial advance? Is this going to be my new "base timing"? Bump the rpm's in steps of 1000s... to how high? I am taking it, if it is 1000 at a time, I will end up with 6 readings if I go to 6000...? Should I have the vacuum advance disconnected or does this matter ?
Base timing and initial timing is the same. It is found in all distributors except the old all vacuum controlled Ford "load-o-matic" distributor. The springs are changed to modify the rate of advance in the mechanical advance. Vacuum advance adds to the total overall advance (base + cetifugal). for instance if you had 12 degrees of base advance and 11 distributor degrees of centrifugal (22 crank degrees) for a total overall timing of 34 and then add 10 degrees of vacuum advance when cruising with more than 15 inches of mercury for vacuum. That 44 degrees will give great economy but if you had that much with full throttle it would tear your engine apart. That is why we use vacuum advance - so we can get decent milage but still retard the timming under full throttle loads so the engine performs at its best. You can run without vacuum advance but you won't get decent mileage without it.
Fuel pressure tester I bought the same tester this weekend and mine did the same thing! I just returned it. Harbor Freight? I tested my vacuum and was going to do fuel pressure and the same thing occured. They had no others either. All that happened it is jumped hte stop, but you cannot take it apart. Interesting to see you had the same issue with equipment!.
Run it to whatever RPM your engine pulls to. If its stock, around 5000, if its pulls to 6500, stop at 6500. There's no reason to tune the engine past its power band. Vacuum advance should be disconnected while doing this as the engine isn't under load and will have quite a bit of vacuum running 6000 RPM at part throttle. If vacuum is still connected, you'll be waaay past the marks when checking at 2000 RPM. My little 74, low compression, probably factory timing chain and over 100k on the clock, likes 20~ initial. Doesn't bother it a bit. Damn torquey at 2000 RPM, doesn't pull as hard at high RPM tho, so it was run a bit lower and I quit checking it and set it by ear and the butt-o-meter. I'm fairly certain my timing chain is stretched a bit... and I know for a fact, regardless of what my timing is set to, she will not crank on 92 octane in 30*F weather. To the more experienced among us, I've been told its good to have full mechanical advance by 2000 RPM. Sound right?
Thanks. Call me a procrastenator of you want. I been too busy to fool with my GT. I will be referring back to this post for sure tho when I do get to it. Gimme about another year...
