How far should timing actually be advanced?

Looking to squeeze as much power out of this engine as possible with the mods we've put on it, I wonder how far advanced people actually have their timing set. It was running at 12 btdc for a while (stock setting) but we raised it to 13 after putting in the electronic ignition. Recently I raised it to just above 14 (just barely above the factory scale), but I wonder how far I should advance it. What would you guys recommend for my engine?

Well the best way to time any engine IMHO is to attach a vacuum guage to it and advance the timing to the point of highest vacuum. If it pings at that setting then keep retarding the timing a few degrees at a time until no more pinging. If you don't have access to a vacuum guage then advance the timing 2 degrees, drive it and listen for pinging. If no pinging then keep doing this until it pings and then back it off a few degrees and you should be set. Keep in mind that ambient temperature, compression ratio and grade of gasoline will also affect pinging.

Thanks, Gene. I was going to write that exact advice.

You would do well to get a vacuum gauge. They are relatively cheap. With a vac gauge, you can set up your idle and advance.

Put the vacuum gauge hose on one of the vacuum ports of the manifold directly below the carb. If you have to detach something, like the AT modulator or power brake line, plug the holes.

Block the wheels and start the car. Now, with the vac gauge attached and the engine idling in 'drive', adjust the idle mix by turning the mixture screw below the choke cam inward (clockwise) until the engine starts to run rough (aka: stumble). Back the screw out (counter-clockwise) until you reach the highest vacuum reading you can. This should be somewhere above 18*. If it isn't, then get the highest vacuum and give it another 1/4 turn.

Then, with the distributor advance hose not connected, advance the distributor to where you get the max vacuum. Leave it there. Set your idle to 750 or so in drive.

Reconnect all the vac hoses and take it out for a drive once it is completely warmed up. Find a hill and press the accelerator as you go up the hill. If it pings, rattles or knocks (all mean the same thing), back the distributor off just a touch until it does not. If this does not change the knock/ping/rattle condition, then get a higher grade of gas. That is what I ended up doing once everything was tuned to spec electrically.

You can get pretty accurate results with the vacuum gauge until you can spring for a timing light and dwell tach.

Engine re-builder's Love that Method to time an engine because it almost guarantees you will detonate it before its time , Your ears ARE NOT The Way to Time an engine , if its a way to get a vehicle to run until you have access to a timing light , or the balancer has slipped and its the only way to get it to run until its replaced fine otherwise ITS NOT !!, but Don't listen to me its your money. Get a light , Know your Totals

Correct you are. And I have a light and dwell tach with which I got it to true spec.

However, the vacuum gauge method is not 'by ear'. John Enyart of Pony Carbs shows the vacuum method on the set up instructions for his carbs. Many people have $25 for a vac gauge. It's a little bigger step to a decent light and meter for fine tuning.

If you think he has the correct method , fine use it . I say its wrong , its only your engine , ask any of the Comp Cams Dyno Shoot out Builders ( of which Ive done Distributors for ) , Or a NASCAR Builder if its a way to fine tune , I will say no more on this , good day

Old Man would add advance until engine tried to kick back when trying to start it. Then pull back just enough for it to start. And that where he raced it. Worked for him but drove the others watching crazy---

I use the vacuum as a tool but I have found a good engine temperature gage is a big help too. Most of the time the lowest temp is trhe best inital set point. Also as a starting point I might take as much out of the total as added to the initial as a start. I always dial in the mechanical before messing with the vacuum advance if I use it at all. Most of the time the amout of the advance added by vacuum advance is way to much and needs to be restricted as to the amount of advance and the vacuum at which adds it in.

Timing lights are dirt cheap these days - the Equus 3551 is $30 on Amazon.com, pennies more than a good vacuum gauge. There is zero reason not to own one.

But knowing what your timing is and knowing what it should be aren't really the same thing. The only way to reliably detect pinging is with a knock sensor (although they have their own issues) or datalogging with EGT and wideband O2 sensor over a period of time. Every engine is different - x degrees may work on one engine and not another, so just being reliably able to set x degrees really doesn't address the question IMHO.

I'll reply to this last post as its a relevant question , How Much , That depends on many Factors , That's why a distributor Recurve is such a benefit , No one person uses a car the same , it may be all stock ( but tired after 40+years ) or modified , ( cam ,Higher comp etc) so why would the Manual be a etched in stone deal , well it isn't , Stock specs are a starting point and It keeps the warranty valid ( not that there is one any more ) along with Smog specs , I will give you a general number on theses Motors ( Falcon 6's) ( cant be specific without all the info ) BUT I will say this they are Detonation prone, and do NOT like a lot of total 32-34 is usually Max ( that does not include the vac adv because that's a different part of the equation )

Now is it the stock 66 distibutor? Load a matic? 14° initial sounds a touch far. Gotta remember that the mechanical advance will throw it 20 to 30 degress more depending on the slot its in. thats potentionaly 44° total advance. my 2 cents

Howdy 200:

And welcome. As you've already found out this is a very helpful website. I've got a couple of questions first. You mentioned that your rebuild included a roller cam. I'm guessing that you mean a cam gear set with a double roller chain. Is that correct? Did you replace the stock cam in the rebuild? Also what is your current Compression ratio? What distributor are you using with your Petronix Ignitor? All of these are factors for getting a ball park idea for an optimal initial advance. If your distributor is the stock OEM for a '66 200 you will need to know how much advance is built into the distributor before guessing at the initial.

FYI- an engine; with an auto trans, with a longer than stock duration cam, or in a higher elevation location -can usually, safely use a little more initial advance.

In general I like Ludwig's suggestion for setting the idle mixture, but using the vacuum methed for the initial advance setting usually has the advance level on kill. It will usually result in higher engine temps and knock due to excessive cylinder pressures.

Your methods seem senseable to me. Keep advancing one or two degrees at a time, carefully listening for knock. I wouldn't go past 16 degrees unless; higher elevation, long duration cam, Or ???? The limiting factor for me is when performance or mileage stops improving I wouldn't go any farther. How to determine performance or mileage is with a stop watch and testing.

Before going on, how about some more information from you?

Adios, David

Let me clarify I am NOT doing it by ear. I DO have a timing light and I have been very careful not to do it too far. I am just wondering how far to take it.

I know you have a pertonix ignitor and such.. but what distributor are you running? is it the stock 66 Load-O-Matic? or some later 67-68 or DSI or DSII setup? I think it's important that we know, cause if it's the LOM you can really hurt ur engine and shouldn't drive it until replaced because that distrbutor only works with the carb that has a Spark Control Valve, and I'm sure your holley 5200 series didn't come with one.

but the timing light is good, 14* is usable in higher elevations? where are you located? that can help as teh lower elevation you are the less timing you can run. it all depends on location. that's why EFI is so nice cause people don't have to worry/think about that.

I used a Pinto carb on a 240 with a LOM. modified the dizzy a bit and it ran great.

Yes the timing light is brand new and works great. I never really thought of my area as high elevation. The local airport is 1140 feet according to google.

My engine was rebuilt by the previous owner and I know very little about the actual build. I assume it's the stock distributor.

I raised it two degrees to somewhere around 15 or 16, then lowered the idle (not quite enough) and took it out cruising tonight. It ran great! I feel like I gained enough power that I'm satisfied and I don't feel like it's worth it to take it any farther. Everything sounded alright to me, and nothing was acting funny. Does 15 or 16 sound way out of line? If so I will retard it back down. I don't think I'm going to take it any farther though, I'm perfectly happy with the way it ran tonight.

One way to check is pop the distibutor cap.off and if you see two springs on.the breaker plate its a load a matic.

30over200":buf0v4go said:

One way to check is pop the distibutor cap.off and if you see two springs on.the breaker plate its a load a matic.

Click to expand...

They are 'relatively' easy to identify with a visual inspection.



It is worthwhile to confirm TDC and make sure your balancer has not slipped (common issue on these engines), making timing marks unreliable.

It's possible, if it is a load-o-matic, that your vacuum advance system could be defective or malfunctioning and you're having to compensate with additional ignition advance to improve acceleration at higher rpms. Load-o-matics obtain all their advance through vacuum, and have no mechanical advance components. However, they can be extremely efficient systems (in terms of mpg) when operating properly, not known as much for performance (in terms of hp/tq).

Main thing to keep in mind...it's all 'relative' 8) . Good luck

Ever had a woman tell you, you better watch it when your maybee doing a river crossing in your 4 by 4. You do it anyway, and you hydraulic it, or get the diff caught and busted on a hidden boulder. Well, ignition is like that. It suffers the commentators curse, because a piston engine is detonation limited. Read Frenchtwon Flyers missive on how Ford set the advance curve and compression ratios on there engines. They spend millions on it just to ensure they don't break customer engines. And with just a few degrees and a timing light, we can undo it all.

Back in the day, Keith Duckworth said anytime an engine needed heaps of lead, it was because the combustion chamber is inefficent. So try to run less lead initial and total than what the engine runs best with, always.

The last Boss Mustang I dorve had 16 degrees static is what you'd see on a 290 degree car with canted valve head, same as what you'd use on say a X-flow 250 with the wildest cam. On my more modern 24 valve V-6 EFI, edis-6, alloy head 9.7:1 compression 87 octane runing 4 liter 205HP Exploder, it sits on 17.5 degrees at 600 odd rpm, and I've never seen more than 37 degrees total on it yet. I've seen it drop back to 5 degrees on trailing throttle, and 15 degrees under wide open throttle at 3500 rpm, where maximum torque comes in. That's a lesson to us all.



Though a stock engine will take that much advance and idle and sound fine, its hurting emissions and running close to heating things up. A conservative 9 degrees is better of emissions, and better for safety. 34 degrees total lead is a line that I'd never like to see transgressed on an I6.

Stock emissions engines have a raft of reasons for not going crazy on static advance, and the big big bang will stop an I6 in short order, they will sound nice until the stock rings loose it, and the outer cylinders lean out. Cylinder 5 and 6 can misfire and result in detonation, and you won't get any warning BEFORE IT DOES SUMMIT ORIBLE.

^ So what you're saying is that I should retard it back down until I'm sure about everything in order to not risk damage to my engine? I'm no where near 34 degrees, that sounds absolutely ridiculous.

^^ I'm pretty sure it's a load-o-matic distributor. (this may be a completely incorrect thing to say but) I'm also pretty sure the vaccum is working, because when you clamp off the vaccum line the timing drops (before clamping it is about 15 or 16, after you clamp it 13 or 14). Or are you referring to something else?