289 Timing...What determines the Differences?

[renaissance man]

My timing is set to 10 degrees BTC. This is according to a manual that I have. I just checked another book and it states 6 degrees BTC ???? All the same info: 289 HiPo, 4bbl, 4-speed...Only thing that is unknown is the ignition. I'm using an MSD-6A. What do you all have your timing set to and how do I tell if it's right without pulling the plugs after every run to see if it's running rich or whatever?????

[HighPlainsDrifter]

There are many things to determine your timing. If you have vacuum advance,compression ratio,grade of gas your using,camshaft overlap,etc.The simplist way is to mark your harmonic balancer at 36 degress BTDC[before top dead center] Now disconnect the vacuum line to the distributor and plug it.Rev the engine to 2,500 rpm and check timing with the timing light.Set the advance to the 36 degree mark.This is a good starting point.I would put an adjustable vacuum advance module [accel] and adjust it for 10 degrees vacuum advance extra at idle,when the throttle is opened the vacuum drops and the vacuum advance dissapears and you run on mechanical advance only. The vacuum advance will give much better gas mileage and drivability. if you have aluminum heads you can run 2 to 4 degrees more timing.
Perry.

[Jeff Frigo]

renaissance man:

There are only 2 ways to determine what the best timing is for a particular engine. One is a dyno (either a chassis or engine) or the drag strip. Adjust until you get the most hp or the fastest time. Sorry.

[renaissance man]

Now that the car is set properly at TDC. This is the cam that I have. So what to I time it to???? Meaning how many degrees BTC or ATC???

[renaissance man]

Anyone have any input on this?

[HighPlainsDrifter]

That is your camshaft timing card. It gives you the parameters for the valve timing ,opening and closing, duration ,valve lift, valve overlap,etc. This is built into this particular cam. The only variable is when the cam is installed is to advance it for more low end or retard it for more top end performance. This is a mild street cam so it's best installed straight up. The mechanical timing in your distributor is a separate thing. It's best to pull the distributor out and put it on a distributor machine and spin it up to get the exact advance curve. The springs and weights in the distributor can be changed to vary the timing and curve. You will want 20 to 22 degrees advance all in by 2,500 rpm in the distributor. Add that to the 10 degrees initial and that gives you 32 degrees total timing. That is a safe advance for todays pump gas.
Perry.

[Chad Johnson]

Credit to Hot Rod or some other magazine


The rule of thumb is that the higher the compression ratio, the less total timing it can handle before detonation, and also the higher octane rating it needs to control detonation. Low octane fuels ignite faster, thus require less timing advance. Conversely high octane fuel can handle slightly more advance. Dyno testing has shown that most small block Fords with 9:1 to 9.5:1 compression make peak HP with 38-42 degrees total advance. Engines with 9.5:1 - 10.5:1 run best with 35-38 degrees total, and above 11:1, should not go higher than 35 deg. total. When using power adders such as nitrous, super or turbo chargers, the timing should be advanced accordingly.


The second step is to dial-in how fast the distributor achieves the total advance. This is controlled by the springs which hold back the weights, under the breaker plate. A stock distributor usually has one light and one heavy spring, and brings the timing in really slow, such that the distributor may only reach the total timing at very high engine speeds, 4500+ for example. For performance driving, the best acceleration comes when total advance is achieved before 2500 rpm. To adjust this rate, you can replace the stock springs with lighter tension springs. You can also bend the tabs on which the springs connect to change their tension.

[renaissance man]

I appreciate the input but, I'm totally lost. The timing card is above from Isky.

I guess what I'm asking is based on the cam card above, what do I set the timing to? A Ford manual for a standard 289 shows 10 degrees BTC. With this cam in what do I set the timing to? 8 Degrees BTC, 12 degrees BTC??????? When timing the car I'm twisting the distributor to advance or retard the timing based on the timing marks on the dampner.

The 650 DP I'm running has no vacuum. Strictly mecanical secondaries. Compression is like 9.3:1 or 9.5:1.

Totally lost........

[Chad Johnson]

Ren man,

The cam card deals with valve timing. I was under the impression you want to talk about ignition timing. The cam would be degreed
during the building process; once the engine is buttoned up, that is a done deal.

Ignition timing is generally accomplished by distributor adjustment.

Initial ignition advance is the number of degrees BTDC
that #1 cylinder fires; 10 - 20 degrees is common and is in direct proportion to camshaft duration (the more duration the more initial timing that may be desired). Based upon your cam card 8-10 degrees should be fine. This is set using a timing light by rotating the distributor clockwise or counterclock wise with the engine at idle (vacuum advance if applicable should be plugged) until the pointer is on the desired degrees on the harmonic balancer. Too much initial advance will sometimes cause an engine to kick back or struggle to turn over (like a dead battery). Therefore some racers who lock their distributors at the desired total advance (see prior post regarding compression ratio) have a box to retard the timing when starting the engine.

Mechanical advance is a function of weights and springs attached to the advance assembly. The amount of mechanical advance is established by a limiter that prohibits advance assembly rotation. On MSD's there is several different "stop bushings" that can be installed to limit the amount of advance (standard are 28, 25, 21 and 18 degrees).

Total advance is the combination of initial advance and mechanical advance. In my case I run 14 degrees of initial advance with a 21 degree stop bushing so that I have total advance of 35 degrees (again refer to prior post on compression ratios)

Finally, for peak performance your distributor should be curved or tuned to provide total advance at the optimum RPM. Many high performance engines like full advance at between 2500 and 3000 RPMs. This "curving" is accomplished by changing the mechanical weights and springs. Lighter springs will allow the advance to come in sooner.

Do some searches on the web and you should find some additional information.

[renaissance man]

Chad,

You were correct in assuming that I was talking "ignition" timing. I thought that ignition timing was dependent on what CAM you have installed. I may be mistaken? According to my Ford engine book, a stock 289 has timing set to 10 degrees BTDC.

So my question is,
1.) If I have an MSD-6A ignition/distributor setup and the above cam, does this change how my timing should be set? Compression is about 9.3:1 on the car.

2.) I've also been running 93 octane gas and noted that the plugs are becoming fowled. Perhaps I should only be using 87 octane based on my current timing?

3.) Plugs come pre-gapped for a 289 at .035". I was told that I should open the gap to .045" to reduce the fowling????

I wish there were a reference that dictated if you have this and this and that....set to this. etc......

Regards,

[Bill Wells]

I have a modified K code in my 65 Stang, bored .040 over (now 294.3 cid) , balanced, solid lifters, aluminum roller rockers, pertronix electronic ignition (in distributor only), stock coil, high rise Shelby intake manifold (dual plane) , 715 Holley carb w/stock jets and some other minor engine tweaks. mated to a tremec 5 speed and ford 9" rear end, , 3.89 gear ratio.

my plugs are gapped at .035 and are just fine, and have been fine as well with previous plugs (I have been using Autolite 45's). I use 93 octane fuel, no problems.

the 65 Mustang owners manual says for a 289 to gap plugs between .032 and .036 (my copy does not say specifically if the K code is different as it lumps the 289s together) . the 66 shelby gt 350 owners manual says to use BF32 plugs and gap them between .028 and .032. the NAPA guide book today says gap them at .035.

timing, I can't recall what it was set at , my notes are missing from my file. I do plan on taking it to a dyno shop though to maximize the settings once I get it going this spring (real soon) as have never felt it was optimized by my seat of pants adjusting. chassis dyno shops here typically get $125 for first hour and $100 thereafter for 'fine tuning' of air/fuel mixture for carb tuning/jet changes and timing adjustments plus the printouts. I don't really care what the true rear wheel hp is (there is so much variation it seems between one chassis dyno and another) but am real interested in the DIRECTIONAL changes due to tweaking the carb and timing.

the 66 GT 350 shelby owners manual says initial timing should be 12 degrees BTDC . my 65 mustang owners manual says initial timing at 8 degrees, but again, my book does not indicate K code specifics, just generic '289's, so perhaps a specific Ford K code reference would recommend different plug gaps and timing. I follow the 66 GT 350 book however, except for the plugs gapped at .035 and since they have worked fine at that gappig thru several plug changes, I will leave it there.

good luck. bill wells.

[CobraEd]

Renman, Camshaft timing and ignition timing are two totaly different things, but ignition timing is *dependant* upon camshaft timing among other things.

A hot cam with lots of duration and overlap builds less cylinder pressure at low rpm, so you can run more base timing to give a little more throttle response and torque at low rpm to compensate.

Also:

All things being equal, a heavier car would run a little less base timing than a lighter car.

A stick shift car would run a little less base timing than an automatic car.

It is all a matter of cylinder pressure vs load and all the variables that affect that.

Ed

[cobrajeff]

Most of my 289 HiPo's have run well with 10-14 degrees of initial advance. Whether it is 10, 12, or 14 depends upon your car, your engine, the curve in your distributor, and the gasoline you use. Typically, you want to run with as much advance as you can without getting pinging (detonation). I'd bump yours up to 12 and see how the engine likes it.

Original 289 HiPo's came with Autolite BF32 plugs - the standard 289's came with BF42 plugs. The BF32 plug is a colder plug than the BF42. For street use, with an automatic, I have typically used BF42's, even in my HiPo, to try to keep the plugs from fouling. You should probably be using something equivalent to the Autolite BF32. If you have something colder (akin to a BF22 racing plug) that could cause some fouling. .032-.035 gap seems to work well.

Good luck!

Jeff

[renaissance man]

Thanks Jeff,

Actually I'm using "Bosch Super" plugs (not the platinum kind). Interestingly, this is what "AutoZone" has regarding fouling pugs on their web site....

"Cold fouling is caused by a rich air/fuel mixture or an ignition fault that causes the spark plug not to fire. If only one or two of the plugs show evidence of cold fouling, sticking valves are the likely cause. The plug can be used again, provided its electrodes are filed and the air gap is reset. Correct the cause of the problem before reinstalling or replacing the plugs.

NOTE
If cold fouling is present on a vehicle that operates a great deal of the time at idle and low speeds, plug life can be lengthened by using hotter spark plugs."

Right now the car is set to 10 degrees BTC on the timing indicator of the dampner.

[Chad Johnson]

Ren Man,

Carboned (sootie) plugs will generally be the result of carburation. What kind, size and jets are you running? My guess is that you need to go down on your jet size and check your floats to be certain they are not set too high (setting is based upon carb type).

Let me know.

[renaissance man]

Chad,

Tony "Mustang Mendez" also suggested that my jets may be too big. I'm running a Holley (I know, that's the first problem) 650 double-pumper. Not sure of the jet size as it's whatever came from the factory. Float setting is good as I've been intensively schooled by Tony Mendez and now have that down to a science. I've got the carb leaned out to the point that another 1/2 turn of the set screw will cause the car to bog and sputter for fuel starvation. I think you are right about the jets though. Tony has suggested going down 2 sizes as one size barely makes a difference.

Going to regap the plugs this weekend from .045 back to .035 as well. Then I'm going to retime the car as my new water pump (inlet on the passenger side, current one blocks the timing mark on the drivers side) and Griffen radiator and 9mm Ford Motorsport plug wires arrive on Friday.

Wooooo Hoooooo!!!!

Regards,

[Chad Johnson]

Ren Man,

Go to this site for some tips on carb tuning http://www.martelbros.com/cgi-bin/ws...h.htm&cart_id=

As you jet down watch your pipes and plugs as they begin to lighten up from the sootie black to a gray-tan. Be careful not to lean it out too much so as to burn a piston, etc. Barry Grant says the best way to tune for performance is to go to the strip and tune for MPH (not E.T.)

Good Luck