Retarding Timing?
 

I'd heard of it done a few times in order to increase FE.

My question is, does it work, and if so, how much should I do it? Just a couple degrees?

retarding the timing wouldn't result in an increase FE. by retarding it, you are starting the burn in the cylinder later, which will result in the fuel not completely burning while in the cylinder. you'll be basically having still burning fuel go out on the exhaust stroke

so, you'd lose efficency, rather than gain it.

Pyro - Remember that almost all car manufacturers run their timing advanced from TDC of the piston. I think What Biff is shooting for is changing the timing from being 16° BTDC (Before Top Dead Center) to maybe 12° BTDC. I used those specific numbers because that is the operating range on most of the Honda motors for Ignition timing.

Biff - I'd check your service manual on what is a safe ignition timing range for your car as per manufacturer specs, then set it to the low end if it isn't already and see what that does for your MPG.

I've heard that you want the peak pressure in the cylinder to occur at somewhere around 14 degrees after TDC. To do this requires that the spark occurs before TDC. If you can increase the combustion efficiency and get the mixture to burn more quickly and completely, the timing will need to be retarded or the peak cylinder pressure would be reached too quickly and the engine would wind up working against itself. Also, speeding up the burn rate will reduce the NoX emissions because it won't have time to reach the temperatures necessary to produce NoX.

I am very well aware of this. you don't want to retard your timing either way. you WILL lose power and efficiency. You want that to spark ASAP to start the burn. too soon, you'll detonate, and if you have a new enough car, the knock sensor will retard the timing to stop this. The knock sensor will crank the timing up as far as possible till you almost reach detonation, and keep it there. thats when your getting the most energy out of your fuel.

longer its burning in the cylinder, the better.

I don't have a working knock sensor.

I have the timing set to the factory stock of 10* btdc.

I've noticed that turbo cars have timing far less advanced than N/A cars...

the timing for the turbo cars goes back to the detonation thing. Forcing more hot air in there, is going to raise the pressures in the cylinder more, and if you spark that plug too soon, the heat and pressure will start the burn extremely quickly, and start to apply power to the piston, before it is even over TDC. then you have detonation. not good.

most turbo cars run a boost retarded ignition, so when your just crusing (no boost) it will have the timing advanced as far is it can, then when in boost it will pull timing so it doesn't detonate.

his car is an 87 ford. i doubt it changes the ignition timing.

10 degrees btdc is pretty retarded already, no pun intended, i would NEVER retard the timing further unless the car was knocking. i know that you are not me, but if i were you i would clean out anything that would be lowering the octane level of the air fuel mixture and try to advance the timing 1 or 2 degrees for better fuel economy.

turbo cars have to retard timing for boost, thats why more modern cars that can control their ignition on the fly make a lot more power just by putting a higher octane fuel in there. they immediately advance the timing to an optimum range and can squeeze out the extra efficiency(power).

bottom line: advancing the timing within safe means is what will give you better mpg.

it probably has a mechanical advance, or vacuum advance, so yes it does. if it has vacuum advance, it can easily be made for boost.

all in all, don't retard it.

interesting. i didnt know that technology was employed back then...:thumbup:

out of curiosity what is this cars redline?

I know it does have some way to retard timing, because it comes with a knock sensor. Mine just doesn't work, so I unplugged it.

I do know that this was the single most high tech car that Ford made in '87. Fanciest, Fastest (2nd quickest)... Real nice. MT car of the year.

I redline at about 6.5k.

how did you know the knock sensor was bad?

If it is, get it replaced, and your FE and power should go up from the added timing.

Ran the engine codes. Wouldn't register knock even when I rapped a wrench on the intake manifold during diagnostic test.

And a lack of knock sensor in this car doesn't cause constantly retarded timing, it just never pulls the timing, so I just have to listen for knock.

I'll just advance timing to 12* and keep an ear open.

They don't just only pull timing though.... they adjust accordingly. They add timing till the point of knock. If it detects knock, it pulls some out. If working correctly, you should be running on borderline detonation all the time for max power and efficiency. I don't know if they had that kind of technology at that point in time, so I doubt that would be the case. If it was distributorless ignition, then yes. but the old coil, and distributor method, no.

Also the sensors are calibrated to detect the specific frequency at which detonation resonates. I don't think you can recreate what that sound like while hitting the block, or intake mani.

Modern knock sensors are like that, perhaps, but not this one.
It keeps timing set at whatever you set it to, and if it detects knock, or any similar sound (Which can be recreated by hitting the intake manifold with a wrench.) it pulls timing.

It may be a high tech 87 Ford, but it's still an 87 Ford.

From the nature of your question, I assumed that you meant retarding the cam timing. Everyone else seems to be talking about ignition timing. Which do you mean? (or don't you know?)

-Bob C.

we were just assuming he didnt have adjustable cam gears since he didnt have it in his mods and that he didnt feel like skipping teeth since that would just be a bad idea.

I used to drive a 79 Z28 Camaro with about a 375 horse 350. I tried all kinds of things to get power and economy out of the car for all round driving. What I found, Stock setting for the original engine for that car was 8 degrees advance with the stock weights and vacuum advance on the distributor. With the upgraded engine I would have to set it at 6 degrees advance to get through emissions. What I ended up with is 18 degrees initial advance adding and aftermarket mechanical re-curve kit that brought it to 38 degrees total advance by 3000 RPM. This gave me instant performance and very little throttle to get up to or maintain speed. As for economy, it didn’t make a difference between 12-18 degrease advance, which doesn’t make sense because I was applying less throttle at 18 than I was at 12.

One thing that may help an older car is a MSD 6A box, that provides multiple spark discharge to ensure complete light-off of the fuel. The one I installed made the engine run smoother from the 5000-7000 rpm range and made a huge difference on cold starting and low-end torque. Surprisingly it did not increase my highway mileage or make my car faster at the track. I never checked my around town economy because I was young, gas was cheap and I couldn’t keep my foot out of it. (Burnouts for the girls!) In my truck this box gives me better economy in the winter.

This car was fast and actually got more 2 mpg with the 375 horse engine than it did with the original 195 horse stock engine.

One thing you can try is hooking up a vacuum gauge to a manifold source and find a level area where you can do some tests. Drive a predetermined speed and read your vacuum gauge at that speed and throttle setting. Then adjust your timing a couple degrees and do it again. If your vacuum goes down you lost efficiency, if it goes up you gained. Keep doing this until you get the highest point.

One thing I want to caution you about. My car had aluminum heads and a large cam with a lot of overlap which relieves cylinder pressure. I pulled this engine out of my car and installed it in my truck along with a smaller cam with less overlap and a smaller exhaust. I can only run 13 degrees initial advance with this cam before it will detonate. Your stock engine will probably detonate if you try to run 18 degrees of initial timing.

Note: My truck and car are both carbureted.

Hope this helps!

jeez... when i had my altima i was running 22 deg advance. you guys are wimps :)

I've a question, my engine is suppose to be at 16 BTC from the factory, its a turbo car so it has a vacuum advance on the distributor, I adjusted the timing to 18 BTC as I was told I could run more turbo boost, now I don't care about performance, would having my engine at 18 BTC hurt FE?

If I set my timing to 14 BTC would this help FE?

I don't know much about turbos, but for NA engines, I have heard that a little spark knock from a hot engine at low rpms when you open up the throttle is a pretty good timing setting.

IMHO, more advance is usually better- unless you are getting a lot of spark knock (sounds like a rattle under the hood), lots of spark knock can shorten the life of the engine. Some engines have a knock sensor so the ECU automatically retards timing or richens the mixture if it senses too much spark knock- this would decrease FE.

Ford was getting sophisticated in 87. The distributor (if its old tech) will have centrifugal and vacuum advance (ported not vacuum). When the turbo kicks in the vacuum is gone and can actually be positive pressure, which will retard the timing whenever boost is applied. The distributor will have either one or two vacuum lines attached to it.

Hook up a timing light and pull the vac line off the dist, see if the timing is reduced. At idle the engine will run rough without the vac advance working.

Another thing about Ford ignitions of that era, don't underestimate them. My dads 84 had a bad ignition switch and wouldn't shut off. I pulled the coil wire off with insulated pliers and the spark jumped 6 inches to the engine block!

The first Porsche 924 (dog 1.7 liter) had a warning under the hood about the fact that if you pulled the wires off the plugs the spark could kill you.

I wouldn't retard the timing, it shouldn't help your mileage unless its too far advanced already. If you want to fiddle with it advance it 2 degrees at a time and see if it knocks. If so retard it immediately. Personally I would fix the knock sensor.

regards
gary

first of all, someone gave you bad advice , 18 BTC is 2 degrees advanced, which will not allow you to run more boost. 18 BTC will give you better gas mileage if it isn't pinging. what mpg are you getting?

There is a knock sensor on the engine which is plugged into the ECU, it cuts out the fuel injectors or spark, I have installed a red LED from the ECU next to the boost gauge so I can see the engine knock as a flashing light beam.

I do get some knock when I boost to hard, I think I need to by a timing strobe and adjust the timing back to 16 BTC as my FE is really bad, I am lucky if I get 20mpg.