blue corona

This timing thing has me confused. I have a crate 392 from Ford that has been changed over the last year or so such as AFR 185 heads, new forged pistons (changed geometry which upped compression from 9.7 to 10.7 : 1)

I have an MSD billet distributor (mech. advance) and a new ATI blancer, Demon carb...I run no vacuum lines, they are all plugged.

How do I even know where to time this thing as far as initial timing? Should it be something like 5, 10, 12, 15, 20, 25?

It runs right now and sounds great, drives good, but is something around high 20's at initial and up to high 40's at advance....this sounds insanely high to me and I'm worried about damaging stuff, but any retarding of the timing from those numbers makes the headers start glowing molten orange....no joke. I'm 99% sure we lined up the cam and crank dots, but I'm sure everyone always thinks they're sure of that when sometimes they may not be.

If the timing is off one tooth and the dots aren't aligned when putting the timing chain on, would the car even run good at any timing? I can literally make the headers glow within 10-15 seconds of retarding the timing to something like 20 degrees at 1500 rpm...if I put it back to say, something like 30 degrees or 35, the glowing goes away.

Is 93 octane ok for 10.7 to 1?

Thanks for any help.

mdvaldosta

For starters, with your compression ratio, anything over 14* initial and high 30*'s may cause detonation, even with premium fuel. 20* initial is extremely high, and of course 20* total is extremely low. Somewhere around 35* total is where you want to be, but really it should be a test and tune type thing. You pretty much want to set the timing as high as you can without getting detonation. I would think somewhere around 14* / 38* or so would be a good agressive number to shoot for, but every engine is different. You just gotta play with it until things work out (haha double meaning... ewww)

blue corona

Ok,

Here's another question that may sound goofy, but I've really never heard detonation...what does it sound like at idle, and at say, 3000 rpm. I might also mention that this is on a cobra replica w/ sidepipes that aren't very quite so it could be hard to hear....who knows.

Whenever I try to retard the timing any, the damn headers just start instantly glowing like fire. If I am way too advanced, then how could retardation result in glowing like this. Also, would the car start very easy if it was horribly advanced?

Thanks

mdvaldosta

Retardation will most always cause headers and cats to glow, becuase your not burning all the gas in the cylinders, alot of it is still burning in the headers and cats when you don't have enough timing. Detonation usually isnt heard unless theirs a load on the engine, so you wouldnt hear it at idle. Trying something like putting it in 3rd gear in lower rpms and giving full throttle would be the most noticable place for detonation. It usually sounds like a rattleing sound or a knocking sound. It would probably be easier to hear with the windows up and radio off, and having the air on would be a good idea as well for the increased load, just keep the fan turned low as to not make much noise. Its also best to do it after the car is warmed up and its warm outside for the most detonation to look for.

JD1969

Is the engine lean. Do the headers glow at idle or under throttle? What I do when setting timing. 1. lock out the mech. advance, sounds like you have a pretty serious motor here and are not concerned with gas milage. 2. set it at a safe number,say 33* I never worry about what the initial timing only the total, if you have trouble starting the engine then go back and unlock the mech. advance. 3. take it to the track and go up in 1* increments until the mph slows down, you will prolly find that it makes the best power around 36-38*. You will now know where the timing needs to be for best power, you can now bring it back to say34* for cruising around town. Depending on your cam, at 10.7 compression with alum. heads you will be fine on 93 octaine. You guys would never beleive the compression I run on pump gas

mdvaldosta

prey tell

JD1969

Oh yea one more thing. Double check that your timing marks on the balancer are lined up correctly. To do this take off your distirbutor cap and find the terminal for #1 cyclender. now crank the engine over (a helper makes this alot easier) until the #1 cyclender is coming up on the compression stroke(taking of the valve cover makes it easy to see when you are on the compression stroke, by watching the rockers,both valves will be closed) Now line up the timing marks at 0* on the balancer, the terminal on the distibutor should be pointing at or very close to the #1 plug wire. If it is way off your distibutor may not be in right or the cam timing may be off. ^MD is correct too little timing will cause unburned fuel to make your headers glow Good luck

JD1969

The Nova has an honest to god 11.8 small block in it, and I run 93, but I back the timing down to 34*. At the trackI put in better fuel (110) and bring the timing up to 38-39* for motor runs. On the Juice I bring back to 28-30* to be safe. My cam bleds off alot of compression (a ton of overlap) and the alum. heads allow you to get away with more copmression with less octain

blue corona

JD,

Initial is set at idle (~ 800 rpm?) and full advance at ~ 3500 rpm? Does this sound like the places to hold the throttle when setting the timing?

Thanks

JD1969

The idle is ok, you might pick up alittle power by making your full advance come in at 2500-3000 rpm, how much does the car weigh, generally a heavier car 3500lbs and up will like a little slower advance.