How far should timing actually be advanced?

[Explorer]

^ 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?

Don't confuse initial timing with total timing. If you're running that Holley carb and LOM distributor, thats wrong to start with. You should be using a 68 or later distributor with centrifical and vacuum advance.

 

[Frankenstang]

Don't confuse initial timing with total timing. If you're running that Holley carb and LOM distributor

:duh: I skimmed right over the carb type...chances are a ported vacuum source on your carb is delivering a stronger vacuum signal than the stock scv carb would deliver...here is the 'basic' load-o/scv curve from the '66 FSM:
Dist-rpm......Deg-Adv........Vac/Hg
800..........(.75-1.75)........(.79)
1200.........(3.75-4.75)......(1.9)
1600.........(5.75-7)..........(3.0)
2000.........(7-8.25)..........(3.80)

EDIT: Double the figures for crank degrees, I believe...not enough coffee yet

 

[200ci66]

Don't confuse initial timing with total timing. If you're running that Holley carb and LOM distributor

:duh: I skimmed right over the carb type...chances are a ported vacuum source on your carb is delivering a stronger vacuum signal than the stock scv carb would deliver...here is the 'basic' load-o/scv curve from the '66 FSM:
Dist-rpm......Deg-Adv........Vac/Hg
800..........(.75-1.75)........(.79)
1200.........(3.75-4.75)......(1.9)
1600.........(5.75-7)..........(3.0)
2000.........(7-8.25)..........(3.80)

EDIT: Double the figures for crank degrees, I believe...not enough coffee yet

Okay, so if my carb is putting out a higher vacuum than my stock carb, should I have theoretically lowered the timing then? xtacy said that 34 degrees is the limit at which an i6 should be able to handle, so am I going beyond that point by 4000 rpms?

I guess my question has changed from "how far should I take it?" to "is 16 degrees too far?"

 

[FalconSedanDelivery]

I have to respectfully disagree with Extacy's Initial timing concerns , Lots of initial is usually because of low cylinder pressure , whether from a big cam and lots of overlap bleeding of Cylinder pressure , or from low mechanical compression , on most engines I recurve Dists to use up to 24 initial with limited total , And many other engines I recommend a similar curve , a 12-1 Motor does not need lots of lead as the cylinder pressures are so high that it burns faster and more efficient without a big lead , All this applies to the Dual Advance Distributors , I will not even touch a Loadamatic as, you will get better results by running a big initial ( static ) and leave it unhooked , the system is so old and most parts have been / are worn out that it raely advances the way designed ,and is usually just a vacuum leak , I used to run my 62 sedan-delivery with the 170 and a loadamatic at 28 initial ( and of course that was also total ) ran great 31 mpg ) as for temp concerns Yes it will raise combustion chamber temps , but its a good thing ( unless you believe 10mpg with low NOX numbers are better than 25mpg with slightly higher NOX numbers , sorry Ill take extra power and MPG over so called smog producers everyday , The falcon 6 ( log Head Engines ) have poor chamber design compared to modern heart shapes , that can be helped by reducing squish , but it takes lots of milling to get there , I run a 69 head that Ak miller said had the smallest chambers and the biggest ports and valves ( it was a 1971 article ) , the late 200-250 heads have better log volumes but the combustion chamber is WORSE , its a very open design with no squish, if you compare that head chamber to CI's combustion chamber you can readily see the better design in the aluminum version

 

[thesameguy]

^^ 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?

Don't you generally want to set base timing with vacuum to the carb plugged? That's how I've generally seen it done on most cars. Sounds like that's what you're doing, but I just wanted to be sure.

 

[MPGmustang]

^^ 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?

Don't you generally want to set base timing with vacuum to the carb plugged? That's how I've generally seen it done on most cars. Sounds like that's what you're doing, but I just wanted to be sure.

the Proper way to set the initial static timing is disconnect the dis vacuum,
plug up the vacuum line from the carb, (to get no vacuum leak)
set the static timing at idle to be around 8-12* max (13*+ is too much for the LOM!) I liked 9-10* on my LOM and I'm roughly the same elevation as you.
then reconnect the carb vacuum into the vacuum canister on the distributor. the timing should move!! that's normal and a good sign.
next set idle to 1100+ rpm, change air/fuel ratio to get the highest rpm you possibly can then give 1/4 turn more gas.
next change idle to desired 650-750rpm. lower if manual higher if auto.
there your timing and carb tuning is done for a stock motor.

some people will disagree with my opinions but this is from my experience of trial and error, things I learned the hard way.

 

[turbo2256b]

My 10+ to 1 compreaaion 460 likes 27 ish initial and 38 total. My 302 Grand marquis runs 20 at idle by 1600 rpm its around 36 I think dizzy is locked in just a start retard. 302 is about 9.0 to 1
Got no idea what my 256 is havent realy screwed wit hit for 30+ years.

All of them are dialed in by watching engine temperature for the most part.

 

[200ci66]

You mean to tell me that I've been running my engine with an incorrect distributor for the past 4000 miles? I'll check my distributor when I get home today to see if it is in fact a load-o-matic, but it may have been changed when the engine was rebuilt.

We bought a 1968 200 ci motor for 50 bucks (the owner swapped a V8 in his car, he just didn't want the motor anymore. This engine is sitting in our garage as a spare, the original 66 engine is still in our car as the tag on it confirms) With the distributor. Will this 68 distributor work on my engine?

 

[MPGmustang]

yes you have the wrong dis for your carb... your 68 dis will be loads better and you get a nice mech advance. Post a picture of both distributors' for us and we will confirm what you have so you won't have to guess anymore.

 

[jamyers]

Don't confuse initial timing with total timing. ...

Exactly. Disregarding the pesky LOM system, there are 3 kinds of ignition timing/advance:

1. Static or Initial: Physical position of the dizzy. Set at idle with vacuum plugged = no mechanical or vacuum advance input. Goal is the best, smoothest idle.
2. Mechanical: more advance as rpm increases, controlled by centrifugal force, weights, springs, and the shape of the weights or their carrier plate. Goal is to light the fires sooner so that peak cylinder pressure is always reached at the same point on crankshaft rotation - more rpm needs more ignition lead. This is what's most often referred to as the "Advance Curve", noting that it begins with the Static or Initial Timing #.
3. Vacuum: more advance with less load, as measured by manifold vacuum. Usually a linear rate of increase, controlled by a spring behind a diaphragm inside the dizzy's vacuum canister. Goal is to increase fuel economy, since a lightly-loaded engine can take more ignition advance (more cylinder pressure sooner in crank rotation).

Each one needs to be set independently, and in the above order. Then they all work together to give you the best ignition advance curve / profile under various driving conditions.

 

[turbo2256b]

Inital these days like to be more than in the old times. It is due mostly to the way fuel burns today. Today the burn starts out slow then speeds up. Old fuel started out slow the speeds up. So ignition timeing needs to be reversed on older motors more initial and less total to have them perform closer to when they were built. So 18 initial + 8 in the dizzy might work (8 x 2 +16 crank) would be 34 total. It varries with every engine to some extent.

 

[200ci66]

yes you have the wrong dis for your carb... your 68 dis will be loads better and you get a nice mech advance. Post a picture of both distributors' for us and we will confirm what you have so you won't have to guess anymore.

I checked it today when I got home. Yeah, I have a LOM distributor, no doubt about it. The two springs gave it away. Maybe this explains why I wanted to raise the timing so bad.....


This is the 68 Distributor we have.

What will it take to swap the two?

http://i950.photobucket.com/albums/ad34 ... 6_0001.jpg

What do I do with the vacuum advance on the side? What do I do with the two vacuum lines on the side (to the right)? And will my Pertronics ignition work with it?

 

[Frankenstang]

EDIT: Vacuum closest to the dizzy (inboard side of diaphragm) is for vacuum retard (emissions)...you can just cap/plug it. I'd run the vacuum nipple furthest out on the canister (outboard side of diaphragm) to a ported source on your car, if available.

Sorry can't help you on the pertronix compatibility...might compare the part number at rockauto

 

[MPGmustang]

one would think if the LOM had points the 68 dis has points they would interswap... but I would still check to see if they fit, you might be lucky and the just plug and play I would hope. but you don't know unless you try.

 

[200ci66]

Bigger problem, the 68 distributor won't fit in a 66 engine block. What's next?

 

[MPGmustang]

you really have to finagle with it, it's going to be a tight/hard to seat distributor, I thought the same thing on my DUI but found out I was going in the wrong angle just slightly.

they will be inter-swap-able, guarrenteed... (I'm sure my foot won't need to reach my mouth this time )

 

[CZLN6]

Howdy:

A '68 distributor should fit a '66 block?????? '64 and earlier blocks had a smaller hole where the distributor goes into the block. Are you sure you have a '66 block????

The difference between the two distributors will likely be the alignment notches in the rotor. It may, or may not, swap. check it out.

Also, FYI the inner nipple on the vacuum diaphram is for vacuum retard. Do not cap or use it. Leave it open. If you cap it it will impede the function of the outer vacuum advance function.

With the '68 distributor you will have centrifugal advance for performance. Vacuum advance for economy and initial to play with. With the initial advance at your elevation you'll be safe in the 14 degrees of initial advance range. But be sure to run the vacuum advance line to a ported vacuum source or you'll end up with way to much advance at idle and steady road speeds.

I know you said that you didn't know much about the previous owners rebuild, but know that your engine may be down on power due to less compression, unless the rebuilder milled the head enough to compensate for new, composite, head gaskets, which are about .025" thicker. There is no easy way to determine. Less CR can handle a little more initial safely.

Keep it coming.

Adios, David

Adios, David

 

[200ci66]

Well, I was trying to get the old distributor back in just so I could drive it back into the garage, and I'm having the same problem with the old distributor (of course, amateur mechanic what do you expect.)

The plate and bolt that hold the distributor in are down tight, but I can still pull the distributor in and out. That's why I assumed the 68 didn't fit. What am I doing wrong here?

EDIT NEVERMIND! The distributor wasn't seated all the way! Sorry, 16 years old and the first time I've ever swapped a distributor. I'm learning as I go here, but I feel pretty accomplished right now. Distributor is in there now. I'll be swapping the Pertronics over tomorrow. I'll finally set that timing and put and end to this never ending thread of troubleshooting!

 

[woodbutcher]

Ahhhhhhhhhhhhhhhh,my dear young gentleman.Trouble shooting NEVER ends.It just gets easier,and more interesting, with experience.Might even give you a few premature gray hairs.Enjoy the fun.Remember,the only dumb question is the one not asked.
I was in your shoes at the age of 16.That was 50 years ago.Yeah,I know.I`m getting to be an O.F. :rolflmao:
Good luck.Have fun.Be safe.
Leo

 

[200ci66]

Thank ya'll! I switched everything over today, went and picked up a fresh rotor, and took it for a trip up and down the road. It's a lot better now! It accelerates a lot easier and cruises at higher speeds much easier. I see interstate trips in the future!

I'm at 13 degrees, and I see leaving it there.

Thanks for everything everyone!

and CZLN6: I've run a compression test, and it's running pretty close to stock. The engine was rebuilt by a local performance shop, and the motor always ran strong even before we started playing around with some bolt on upgrades. I don't know anything about how crazy it was built to run, but I'm pretty happy with how it's running now.