This newbie is trying to learn...and a bit confused!
I'm trying to investigate/set the timing on my 400. Interested in maybe an initial timing of 8ish, total around 36.
Using an adjustable advance timing light, here's what I get: 2300rpm: Setting the light to 50 puts the line at 0 Idle rpm: Setting the light at 18 puts the line to 0
Setting the light to 0 puts the line to 12.
Can anyone give me some instruction please? Much appreciated!!
1968 Firebird 400 Convertible Original: Engine, Intake manifold, Heads, Body, Stereo, 3.08. THM400. Engine rebuilt by Ken Keefer early 2012. New: Holley 4bbl 670 HP, hidden iPod setup, RobbMC mini starter, A/C, front disc brakes
Do you have a vacuum advance distrib? If, so did you pull the vacuum line at the distrib 1st and plug it (I usually use a pencil) before trying to take readings?
My 455 with E-heads runs best at your targets of 8 and 36 as found on the dyno at break in.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI
Sounds like you have the vacuum advance hooked up to ported vacuum. It wont come in until you open the throttle and get to a higher rpm. You stated you get 18 at idle dialing back but also noted setting the light to 0 it was at 12. Use the dialback reading. I have to ask why you're adjusting the timing? If at 18 and you want to try 8ish, is the car running poorly? Is your engine completly stock or built? You want to set your inial first. Diconnected from vac advance can. Once you get the car idleing well, dont change it. Now find out your mechanical. Get your RPM's up to 3,000 and you should be all in with mech. Take that reading. Subtract the inital # and you have mech #. Now connect your vac advance and take a reading at 3000. That's your total. You'll also be able to figure out how much advance the can is adding. The best timing is a couple degrees less from when you start to hear detonation. You dont change inital timing but adjust the springs & weights in the distributer or limit the amount of vac advance on the can. FWIW, I'm running 14 with vac advance connected to manifold for 22 inital. Mechanical is 14, so all in at 36. I had to weld a stop on the vac advance can but didnt change the springs or weights on the mechanical.
You should see a difference when the advance is hooke up.
When I dinked with my timing, I made my own degree wheel out of alumiminun tape, attached to the balancer, did the dirty, and removed it. Dat way, everthing stays stealth.
My best stealth is painted valve covers, and if people want to call it a 350, it's fine with me.
This newbie is trying to learn...and a bit confused!
I'm trying to investigate/set the timing on my 400. Interested in maybe an initial timing of 8ish, total around 36.
Using an adjustable advance timing light, here's what I get: 2300rpm: Setting the light to 50 puts the line at 0 Idle rpm: Setting the light at 18 puts the line to 0
Setting the light to 0 puts the line to 12.
Can anyone give me some instruction please? Much appreciated!!
For now keep the vac adv unplugged while checking the timing. When the gun is set to 0 it works as a plain ole timing light. So if you are reading 12 on the timing tab when the gun is set to 0 and you have to dial back 18 on the gun to get it to 0 on the tab, that right there is a problem. You shoulld only have to dial back 12. First, double check that right there. Whatever it reads on the timing tab when the gun is at 0, you should be able to dial back that exact amount on the gun and the timing tab should read 0.
You will not be able to set both the initial and the total mechanical advance individually without modifying your distributor. You may set one, and then you are stuck with the other.
I would adjust the total first. Set to 36 degrees and do this with the engine about 3000 rpms to make sure it is all in. Then let it idle back down and see where your inital is. You may need to adjust the idle at this point. If its anything reasonable then plug in your vac adv and re-adjust the idle.
