Personally Im just not a fan of vacuum advance. I like mechanical only advance, your base timing(typiacallly beteween 8 and 12) isn't as cruciual as your overall and by what RPM. I think mine is 10 or 12 base at idle (no advance) but again if I remember right it is 34-36\ degree all in by 2500rpm. My motor is alot more than a stocker so Im not sure what would work best for you. Some guys get away with 38 total and others only need 32 advance so its all in the combo as they say.
Funkranger.........I rechecked my book. Mark your crankshaft damper with chalk at the 6 BTDC, pull the vacum advance hose off your distributor and plug it with a golf tee or pencil, start your car and adjust the idle down low enough where it runs smooth, but any lower It'll stall....you may first have to move the dist closer to your mark befor adjusting your idle down because with it advanced so much it will be reving up. Heck you might not even have to touch the idle once you get the timing close. This should do it...then you can bump it a hair here and there to optimize performance. Don't forget to hook your vacum hose back up as this basicly tells the plugs when to fire in your cylnders....which is why you were getting the pinging. Like 1Badmav, I'm putting out a lot of HP so my timing is tweeked ya might say. I apoligize if this is all old news to you. Just thought I'd try to help. D. Ray
Thanks for all the help guys as soon as the rain stops I'm gonna go set it and take it for a spin I'll check back with the results. In the mean time have a cold one for all that hard work!
Here is a good article that will explain everything real good. I'm neew here and don't want to step on any toes so will suggest everyone read this.it is very good and even those that have done their own wrenching for ever may learn something. http://fordmuscle.com/archives/2003/03/timing/index.shtml I run the 351w in my F100 at 12BTDC with 36btdc all in by 2800. it's what it likes. i have all MSD ignition so setting the curve is easier but it can be done on points type or duraspark dist. easy enough. Everybody has mechanical advance and if you have a vacuum can on the side of the disrt. then you also have vacuum advance to go along with it. If inside the nipple on the vacuum caniser has an allen head type nut inside it then your vacuum can is adjustable. This helps alot since deepending on your car the vacuum canister may be pulling in ALOT of advance causing pinging when criusing. I disconnect and plug my vacuum advance until I get everything else right then tune the vacuum system. Also some vacuum lines have been routed to the full manifold port on the carb by mistake in the past with different people working on the cars. This can be set-up to work good but most run the vacuum on ported vacuum since it's alot easier to get a good idle using ported. There is alot of HP left on the table by not running a good timing curve. Hope this helps somebody and if anyone has any question please feel free to ask. I am by no means a guru and don't propose to be but timing has caused my alot of problems on my 351w and I feel like I have some experience to share because of it clint
This site does'nt like my link and I hope I did'nt break any rules posting it. If so I'm sorry. You can go to the fordmuscle site and look up the Timing is ecerything article in the tech pages. Very good article clint
Update Ok I set timing with the advance unhooked.I set it at 12* and it still pinged I backed it off to 6* and it wouldnt idle that low.So I reset it at 10* and keep my foot out of it for now.I hooked up a vacuum to the advance unit and it pulled over 30* of advance with about 15 inches of vacuum,so i left the advance unhooked.Also I noticed the secondaries arent opening up even around 5000rpm,so now I'm curious if a lean condition is my problem.It has a Holley with vacuum secondaries and with a spring change I can get those secondaries working right.The distributor is a large cap and looks similar internally to a solid state but it only has two wires coming out that connect to my MSD box I think its a duraspark.I spent about 3 hours today trying to get the pinging gone but still not much change other than it pings less with the vacuum advance unhooked?? Thanks for all the input but I'm obviously missing something.
How did it idle with 6 btdc and vacuum adbvance hooked up? It's not unusual to pull that much advance in with vacuum advance it just depends on how the engine runs with it. If it spark knocks with 12btdc then it might need to be recurved Remember vacuum secondaries will never open sitting still, they are load dependant and will only operate under load. clint
If you set it to 6btdc you said it would'nt idle? Did you try adjusting your curb idle screw, just tighten it up and raise the idle to where you want it. Timing has an affect on the idle that way. I have a pretty good grasp on setting up and curving the timing I just can't put it in words. lol clint
Check to see if you are using manifold or ported vacuum from the carb. I use the Holley 600cfm, and it has two. You need the port ABOVE the throttle plates, or else you have vacuum all the time, which makes you run 30degrees of advance all the time. The ported vacuum only advances the vacuum advance can when you put your foot on the throttle, and open the throttle plates. When you set the timing, be sure to pinch off the vacuum hose from the carb. There will be a small amount of vacuum leak if you don't, and it can effect your idle adjustment. Also, when you get the timing set, adjust the carb for highest vacuum, hose hooked up, and it should run fine. Hope this helps.
I have tried everything I know and this thing is still spark knocking I even put 112 octane gas in it and its still doing it.I adjusted timing,changed plugs,reset at 6* and didnt help I backed it down to 0* and went in 1* increments and it still did it.I did notice that the MSD box is making a humming noise,anyone ever had one go bad???
I ran into the same problem once after replacing my dist. The replacement dist had an adjustable vacuum advance unit and someone had cranked it all the way in. As soon as it got vacuum it was pulling in about 50 degrees of timing. Take a 1/8" or 3/32" allen wrench and run it into the nipple on the vacuum caister and see if it is adjustable. If it is back it all the way out carefull not to use much force or you can rupute the diaphram. Hopefully that's your problem. If it is then set your initial back to where you want to run it and get it running without sparknock, Then you can start test driving it and tightening up the vacuum adjustement until it runs the best without sparknock clint
Ok I have been tinkering with the timing distributor and jetting and still havent been able to get it to stop pinging.I got base timing at 14* and at 3500rpm Im making 32*.There is a tapping sound coming from the front cylinder on the left bank,which is where the pinging sounds like its coming from.These heads are stock with bigger valves and a mild port job.Not sure as to what springs and retainers but it has Crane roller rockers and a edlbrock cam.I am going to pull the head and check spring free length and tension . What else should I look for when I pull the head that would cause it to ping??? Any other ideas???
When you say it's coming from the front cylinder on the left bank is this at an idle? You should'nt be getting any pinging while at idle, only under a load. Is this the same sound you hear going down the road? If so it might not be pinging after all but maybe a loose rocker arm, wrist pin, exhasut leak, etc. Clint
