timing for dummies

[yukonj]

This will probably sound stupid to most of you, but I have never set the timing on an engine before. From other threads I know there can be a lot of variation in timing. I know my timing is currently set to factory specs, but I don't feel like it has the power it should. It is a new engine with an RV cam and the TFI upgrade (minus the MSD box). Now for the question. Can anyone walk me through the process of timing an engine? And I am talking timing 101 (assume I don't know jack--which is about right). I know where the timing marks are, but beyond that I have no clue where to start, or proceed.

[tuck]

I don't know if I did mine right, but the motor runs better than ever, so good enough for me....

Since you already found the marks, the hard part is over. I assume you have a timing light. I used an ancient model, two leads went to positive and negative on the battery and then another wire goes between the spark plug and spark plug wire on the driver's side cylinder that is closest to the headlights.

You will need to loosen the bolt that holds the dizzy to the block, once it is loosed you should be able to turn the dizzy freely. Don't turn it though, it will affect your timing and may make it hard to start your motor.

You may want to mark your timing marks with chalk, I set mine to factory spec, so I just marked the factory mark. Where you modified your motor you might need to change yours so I would search around get an idea of where you're going to be.

Once you've chalked your marks, and your light is all hooked up, start the motor. I timed mine while it was in park. I'm not sure if others put it in drive or not.

It helps to have a friend help out because you need to keep the wires from the timing light from catching on the fan blade, and you'll need to turn the distributor while someone watches the timing marks. As you turn the distributor you'll notice the motor sounds different, and as you watch the marks line up you'll know where you are and hopefully the motor will be purring and happy. Once you get the timing set right, and everything feels good, shut off the motor and tighten the bolt to the distributor without altering the dizzy's position. I would restart the motor and check the timing again to make sure your marks are still lined up and everything is okay. I know where you're coming from, the first time I timed a motor I was thoroughly confused because I had never seen it done before. I just borrowed a light and went at it.

Hope this helps a little, the experts will chime in with specifications and any needed corrections. Good luck.

[turtle jim]

HI yukonj,
tuck's instructions sound real good,but he forgot to mention that you should unhook the vacuum advance line from the dizzy,and plug the rubber hose while you are checking/adjusting the timing.

[Fingers]

i think you also have to bump up the idle to around 1100 rpm.

[Nathan]

Maybe another dumb question. . .what's a dizzy?

[turtlejoe]

dizzy = distributor :cool:

[oddfire]

The only other issues you will have is when you adjust your timing you will also effect your idle mixture and idle rpms, real easy to dial it in if you've got a vacuum guage, about $15. at any parts store. BTW 1100 rpm sound a little high, more like 800. Also make sure your engine is warmed up prior to doing anything............phil

[tuck]

told ya the experts would chime in ;)

[timmirvin]

Never done this with the aid of a friend, so a couple additional "might want to think abouts"......

I route my timing light wires around and behind enough stuff so that there is less danger of the wires coming in contact with belts or pulleys.

With the engine off, mark your distributor and block so that you know its original setting, then loosen the dist. just enough so that it moves with effort, but will stay where you move it to. That way you can fine tune it a degree at a time, step back, listen to the enigne, re-adjust rpms, re-adjust fuel mixture, etc. without the vibration of the engine changing the timing.

Then when you get it right, shut the engine off and tighten everything up. Then start the engine back up and re-check the timing to make sure by tightening it up, you did not change from whaqt you were trying to set it.

And I usually have my idle set at 650-675 rpms in Drive and foot on brake....if ya got an AT....

Thoughts to ponder from the Gulf of Mexico.....

tim

[4DWUDS]

If you are REAL CAREFULL around a fan blade capable of taking off a finger or at best throwing a 9/16 wrench through a window,you should tighten down the dizzy with the motor running and keep checking your marks. That way you will see if your tightening it all down has changed your settings.

[Lindel]

one more thing, if you'll run a chalk mark down the front of the balancer where the timing mark is, it'll be much easier to see, and you can adjust the distributor and watch what happens to the timing mark.

and yes, be careful about hair, jewelry, clothes, etc hanging down, the fan just loves to batter things around a bit.

[sailingjeep]

I sure found this thread helpful.
Does somebody want to write it up for the tech section? If not, I will.

[Serious Johnson]

Yuko':

Very good advice above -- now for finding the appropriate advance for your modified motor:

First, it's important to know what spark knock (pre-ignition, detonation -- same thing) sounds like, because letting it occur for too long is very unkind to the whirly bits. Best I can do offhand is that it sounds sorta like loose marbles thwacking around.

Now go ahead and crank the timing up past the stock setting by maybe 50%. You'll have to interpolate and estimate the reading because you'll have run out of timing marks. Precision isn't important yet. Hook the vacuum advance back up and rev it hard a couple of times while listening for unusual knock. If you hear any, back off a wee bit until it stops. If it starts and runs fair that way, go out and find a steep hill.

Accelerate up the hill in high gear with as much throttle as possible without forcing a downshift while listening for knock. If you hear any, then back off the timing very slightly (no need for timing light -- just twist the dist a touch) and repeat. If it doesn't knock at all, add more advance until it does.

Once it will go under high load/low revs without knocking, do some full throttle, full rev runs. This tests behavior at total advance. Get it good and hot by doing this several times.

Once knock free, go home and hook the timing light back up as before and reduce the advance by a couple of degrees to rule out subtle, inaudible pre-ignition. Note that reading and mark it with paint.

You may find that timing needs adjustment with changes in ambient temperature, fuel octane, altitude, further modifications, etc., etc.

Note that optimizing the ignition advance is a deviation that carries risk and benefit. Factory settings are appropriate on a completely stock motor if you want to go to Ouray or Tijuana and motor along happily forgetting where the wrenches are. When you change ANYTHING in the powertrain, or if you just don't mind fiddling, getting the best ignition setting rewards you with more power and better fuel economy. On the other hand, getting it wrong and ignoring the symptoms can put holes in the pistons.

Next class, optimizing the advance curve.

:-

[Jeepzilla]

I'll chime in here and say that I loosen the distributor hold down clamp with the motor running. (Takes a special reeeeealy long wrench--parts store, couple bucks.) That way you can never lose it and not be able to start.

Remember, too, that an RV cam will develop its power at lower revs and flatten out sooner. They are made for torque to move heavy vehicles off dead stop. Factor that into your performance judgements. Torque gets you moving, horsepower keeps you moving.

[ February 05, 2003, 11:56 AM: Message edited by: Jeepzilla ]

[timmirvin]

Serious Johnson......you do a very good job of putting this in an understandable manner. Thanx!!!!

Now....if no one else does, I am going to hold you to teaching us how to optimize the adavance curve!!

And it "Two-piss Road for real??????

I am orginally from TN, and we have alot of unusual names....but that is pretty freakin' cool!!!

tim

[Serious Johnson]

Tim:

It may be a while, if ever, before I get around to figuring out how best to describe advance curves. It's been over 30 years since I seriously fiddled with an old distributor, and my memory ain't what I'd like it to be (**** sixties).

Two-piss Road is, on the map, Chaffee County road 240 from Maysville, CO to Pomeroy Mt. I don't know who gave it the more colorful local moniker, but it seems a fair description of it's length when in 4wLo and drinking beer.

My old cabin is at the top of the road, right on the 12,000' contour, and my property line tops out just under 13,000'. Whenever you see me typing away on this forum, I'm in South Carolina exile. We have some rather nice names around here too -- Six-and-Twenty, Sugar Likker Road, Possum Holler, etc., but who could top French Broad River!

:-

[tito]

SJ,

Don't forget Sugartit, Due West, Ninety-Six and Six Mile. All towns in South Carolina. What brings you to exile here? Maybe we can work a deal, I'd love to exile in the Rocky mountains.

[Smooshy]

White out or white paint is good for timing mark because it doesnt come off. The week after when you realize your timing isnt quite right you dont have to re-mark it.

[tito]

Oops, forgot to thank YukonJ for asking the timing question in the previous post. I've been wondering about the same information myself.

[Serious Johnson]

Originally posted by tito:
SJ,

Don't forget Sugartit, Due West, Ninety-Six and Six Mile. All towns in South Carolina. What brings you to exile here? Maybe we can work a deal, I'd love to exile in the Rocky mountains.Yep, funny how most of the interesting names are in the upstate -- just confirms my theory that flatlanders lack imagination!

My Dear Wife is from Greer, and my family has been in the Carolinas for thousands of years. Before Andy Jackson took it away, our land included what's now the Uwharrie Nat'l Forest and the Town Creek Indian Mound in NC.

You're welcome to exile yourself to my place in Colorado any time, but you won't be getting there in a Jeep except in summer. Snowmobiles sink out of sight up there all the time, and temps hit 60 below on occasion.

If any of y'all want to take a look, go to Salida, CO. Take US 50 West to Maysville. Turn right on CR240. About 8 miles past the end of pavement (and snowplows), take the right fork toward Billings Lake. Once at the top of the road, about 1-1/2 miles later, look for a decrepit old log cabin above the road on the North face of the bowl. My place is basically from the road to the rim, from Calico Mt. to Pomeroy Mt.

Don't expect much in the form of amenities like a roof and all that. If it's summer, there's a fair chance I'll be there, so bring beer. If I'm not home, feel free to use the cabin (a blacksmith shop from the 1880's gold mining days). Just try not to burn it down, and please don't tear up the ground with your Jeep. Tracks up there tend to hang around for hundreds of years.

If anyone goes up, please e-mail me at Ted4Eagles@earthlink.net about what they find.

:- aka {{{{