Quick question for opinions. I know vacuum advanced timing can't really be checked unless under load (e.g. climbing a hill) and listening for ping. But here's where I am currently at anyway. Wondering opinions.
1966 Mustang 289 2bbl:
Book says initial timing should be at 6 btdc. I have it around 8-10
Things I've read said that based on a compression ration of 9.1 to 9.8 +/- I should have a TOTAL advance of around 38-42 btdc. That would be assuming of course that the weights in the distributor are 15 each, equaling 30 btdc plus an additional 8 for the initial timing. Well, I have an aftermarket HEI distributor and not having looked at the weights (Didn't take the rotor off), max advance with initial set to 8-10 is around 30-33 btdc. Looking at the destructions for the distributor, this would seem correct considering they say that the distributor comes factory installed with silver springs which at max would only give about 23 degrees. Add on the 8-10 for initial, and that's about the 30-33 btdc I am seeing.
So, is it possible to get to the 38-42 btdc total that I see published, or is that a generic range? Also, when I hook up the vacuum line and go for max advance by reving the engine, it is around 42-44 btdc. Again, I understand that when idling, that is max vacuum and really can't be tested until under a load.
So, the questions become:
1. Am I fine, leave it alone?
2. Do I advance the initial to about 13-15 to get me close to the 38 btdc total?
3. The vacuum advance is adjustable, should I adjust it at all?
Help me out, at the end of the day this is a stock 289 2 barrell. What is it that your trying to accomplish? With all this research what is it that you want to gain?
Thanks for the response. Well, what I am trying to gain in most efficient running motor. Best combination of horsepower, mpg, engine temperature, etc... I will trade horsepower to get better mpg.
The problem is I read the haynes or chilton and all it says is initial timing 6 btdc. But I read all these posts of people having their initial timing set anywhere from 8-15 btdc. So I do a little more research, and read links where it describes the max timing. Then I go and have a beer and try and figure out which way to go.
A 42 year old car already has enough of it's little quirks and headaches. After having the car garaged for about 8 years, I finally got it back together. I had to replace the alternator, ps pump, hoses, ps hoses, plugs, flush radiator, etc... The points were giving me a fit and I got a good deal on an HEI distributor, so I replaced that. (Definitely a nice improvement for starting and running - no more bucking, stalling, etc...) So now, before I start on the interior and body issues, I'd like to finish with some motor tweaking. I need to either get a shroud for the radiator or replace the conventional fan with an electric to improve cooling issues. But of course things like TIMING have a major affect on the engine temperature. Hence the reason for trying to better understand timing this sweetheart.
So, any advice or info on timing would be greatly appreciately. thx... Mike....
Again, when you FINE TUNE THis 289 2 BL your gains will be what??? Are you a Engineer and over anylasing?? I say get it running good, but as far as staying with a stock 66 289 and thinking that your going to 40 mgh? I'm at a loss. I guess I don't unstand what you are trying to do.
Sorry if I seem at a loss for your responses. I really thought my questions were quite simple. Maybe I should rephrase.
1. The book says that initial timing should be 6 btdc. Yet, I see people saying to set it anywhere from 8-15 btdc. Depending on which post you read. So, which is it?
2. There is apparently total advance timing. Depending on what you read, it should be for a stock mustang approximately 38-42 btdc. Is it, or not?
Are these really that difficult of questions. If so, then I'm sorry. I don't see it. But because you made a generic statement, let me ask you a question based on that. You said; "I say get it running good,". Fine, I can live with that. My question to you then is how should I set the timing so it is "RUNNING GOOD"? Do I set it to 6 BTDC? Do I set it somewhere between 8-15 btdc? Do I advance it until it starts to ping and then back it off a couple of degrees?
Hopefully these questions are not so analytical. Because I bought a new/different distributor, and I saw reference to total advance timing being in the 38-42 btdc range, and mine ISN'T there, I thought that maybe because of my distributor I might need to compensate. Anyway, if you've got some answers to my questions, I definitely do appreciate it. If not, then sorry but I don't have any more answers for you. I really don't know how else to ask these questions any clearer or simpler. Thx... Mike....
Steve, thanks for the response. I have a copy of the destructions that came with me wysco HEI. It says that from the factory, this distributor has the "Silver" medium springs for tension. That they provide the following mechanical advance.
That definitely coincides with what I am reading. I have idle (initial timing) set at 8-10 btdc. Revved up, I get about 30-32. That would be correct for 23 +(8-10). My question is about when I read of a stock 289 with a 9.1-9.7 +/- compression ration as performing optimum in the 38-42 btdc total advance timing. Seems like the only way to achieve such optimum timing would be a combination of more advanced initial timing and/or different springs. Thanks for responding to my post. Mike.....
This HEI I have runs at about 12 BTDC , i don't know the brand so I can't say how it is set up internaly (weights etc) and i havn't taken a look at the total advance so i can't say.
If i can help in any way let me know, i am happy to take photos of mine for you if required.
Please note, mine is on a 302 / 345hp ford racing motor and its settings will not match yours. although the compression should be about the same.
I guess you need to know where max power should come in, the "stop" should be at peak rpm / power, i am not sure about the 289 but someone here will know.
I read something else interesting about the HEI not providing what is required for over 4000rpm and thus needs an aftermarket "coil".
Thanks for the input steve. My HEI has an internal coil 55,000 volts. I think that's probably enough. I've been doing some research here. According to dyno tests that I've been going through, a stock 289 with up to 9.5 compression, does best with a total advance timing of around 38 degrees BTDC. I need to open up the distributor and look at the markings, but from my readings, I would say that they are probably in the 10L each area. That, plus my static initial timing of 10 is what's giving me arround 30 btdc total. I have to do some more research.
The springs are part of the curve, at what RPM you can get the total advance. The best performance for HP and MPG is to have the total advance hitting at around 2500-3000 rpm. Lighter springs or bending in the tabs can take care of this. So, to get to the 38 btdc, if that's what I believe is what I want, then I should be able to take the static timing up to around 14-15. That plus the 20-22 from the mechanical/centrifugal would be the 34-37. We'll do some more research.
I will take my OLD distibutor rotor off and look at the weights. If they are the standard 10L or 13L then that would explain the haynes manual and most books saying that static timing should be 6 dtdc. 10L or 13L X 2 (There's 2 weights) is 20 or 26, plus the 6 static is 26 or 32 btdc. That is very close to what is being described as the norm. Not optimum, but normal. But you can only take static so far, so the distributor if not configured optimum, could limit the curve and max horsepower and mpg efficiency. We'll see. Thanks again. You've got me thinking and learning. I appreciate it. later... Mike....
I am not sure it will help with stop values but is once again insightful.
Here is a picture of my original dizzy, you will see the stop value it is set to is 18L (or 18x2 as you say), this can be turned around to the other side to give 21L, this perhaps explains how i got started taking a look at these, needless to say it never did work well.
This reluctor arm is ideal foe a HIPO 289 I believe and not for the 289 that it was on.
The weights are constant and are the triangular free swinging thingies, centrifugal force acts upon these to push the reluctor arm to its end stop, the spring acts against it (springs not shown) and also pulls it back.
I am not sure the HEI has the same intercahngeable set up for the end stop, i have looked some more and am still drawing a blank.
Interesting stuff alright, i would like to figure out how an MSD set up works next just for kicks.
Thanks for the post and pic Steve. I will look at mine today sometime. I just like to know what it's set to. Based on my total advance timing without vacuum of around 30-33, it's probably a 10-11L. I definitely won't change mine or do anything until I learn some more about this.
The TOTAL advance has me curious. I've read a lot about how many cars, the older ones, were not really set up for optimum running. Because of new emissions and such, that is why a lot of cars lost power in the 70's and 80's. The dyno tests show the 289 most efficient, including mpg, at around 38-40 btdc with a stock engine with compression Up to 9.5. With a 9.5-10.1 compression, it's best at 35-38 btdc. They said that MOST by default, are timed and set to the mid to high 20's. That would make sense if the mechanical is 10L and the initial is 6 btdc like the book says. That's 26 btdc total.
I'm just curious because the few places I've read about this, it's is pretty indepth and they say how simple of a tuneup this is. How MOST people don't know that timing is everything, but it's more than just throwing a light on the mark and setting initial timing. There's initial, mechanical, and vacuum. I'm just confused why this isn't spoken of more.
I do notice however that many who talk about "TIMING BY EAR", are probably taking advantage of the additional ADVANCE timing without realizing it. They probably have their initial timing set to around 14-15. The problem is, idle can only handle so much advance before it starts to ping from pre-detonation. That's where knowing where the centrifugal comes in. I am not sure if my new HEI is set up the same way. I will find out today. Obviously, the best set up would be if I had 15L capability. Then I could run 15L with initial of 8-10 btdc. That would give me the 38-40 btdc total that is recommended as good. Then put the right springs on so the max advance happens in the 2500-3000 rpm range for a normal driving car. But, if all I have to work with is 10-11L on the mechanical, then I would have to go 18 on initial timing, and a normal car idling can't really handle that. So, I would be relagated to staying in the 10-14 btdc initial. (Or wherever pinging is reached, and bacing off). I will play with that today.
Again, surprised that something so simple isn't talked about more. Especially considering it's just tuning/tweaking. Again, I think it's being utilized by many who time by ear, they just don't know it, or why. Thanks again steve for working this with me. Later... Mike.....
It has been nearly a year since going through this exercise myself so forgive me if i am a little vauge.
I had to double check a couple of things, here is a little gem: the distributor rotates at ½ the speed of the crankshaft the actual advance at the distributor is half that, this is why it is calculated like this: Initial 8 deg + 15L x 2 = 38 total
The responce i got when talking to people about the initial, mechanical and vacume operation of the old units was the same as you seem to be getting. Even my brother who is usually keen to dig a little deeper gave me the same responce, "just get it close and the vacume will do the rest" as you now know, this is not true. Neither is the "timing by ear" myth, the most important element is total timing. From memory 38 deg of total is correct for the 2 bbl 289.
Just looking at you previous post on the factory destructions for your HEI,i wonder if there is something wrong with your assumption. If the maximum advance is 23 deg then would it look like this: say 6 deg initial + 23 x 2 = 52 deg.
On the site http://www.pontiacstreetperformance.com/psp/distcurve.html they talk about an upgrade kit for an HEI (although it's a chevy site i guess we are talking about the same thing), this kit gives them the following mechanical advance:
6 deg @ 1000 (starts to come in at 900rpm)
and 19 deg at 3500rpm. This is a street and strip combo aparently. You could conclude from this that the numbers look something like this: 4 deg initial + 2 x 19 = 42 deg total, this isn't too far off what we are talking about.
If the numbers play out like this on your HEI then you may have way too much "total".
I have to admit that i assumed the total advance from my HEI out of the box would be fine and i have not questioned it. I am still running in the motor so i havn't "tested it" properly as yet. No destructions came for my unit so now after going through this with you i think i need to see what on earth i realy have as far as total advnce goes.
Steve
Last edited by steve sturgin; 08-23-2008 at 04:56 PM.
Reason: wrong link
Hey steve. Good day to you. I'm pretty sure that on my distributor, that the 23 degree max it's talking about, it TOTAL from the mechanical. I don't think I've ever seen weights that were naturally that high. I think 18 is the highest I've ever seen. So, not having opened it yet, it's hard to tell. I did try advancing my static (initial) higher. I currently have it around 15, but I'm not sure if the care really likes that. It isn't pinging, just doesn't feel quite right. I'll probably bring it back down to around 10 btdc. That would be about 30-33 degrees total.
When I checked the total timing currently, vacuum line plugged, revved at around 3000 rpm, static at 14-15 degrees, I was around 33-35. I don't expect the distributor to give exactly 23. I'm thinking more like 20. Plus, who knows the accuracy of the harmonic balancer on a 42 year old car. But today, I'll probably put the static back to 10 and then when the car cools down, remove the distributor cap/router/etc.. and see if I can see what size mechanical and spring I actually have in there. Thanks for all the input. later... Mike....
Timing; initial, mechanical, vacuum advanced 
