ignition timing-please help

[the engineer]

i am going thru doing basic maintenance, and while reading my haynes manual on timing, it says to refer to the sticker under the hood for factory timing specs. i am of course missing this sticker, so i have no idea what mine should be. if i wanted the best gas mileage possible, what should i set it at? i have a 76 w100 with 318, 727, 2bbl carter. any help would be extremely helpful. i've never set timing before.

also, which axle set up is the strongest out of the 8 3/8, 8 3/4, or 9 1/4?
my rear right side bearing went out, and after discovering i had the 9 1/4, i figured this one is the strongest. i was just wondering. thanks, casey

[JimmieD]

Could be a vacuum gauge is your best friend for this. You can use it to optimize that GREAT Carter BBD carburetor, plus get your ignition timing just right. Carb adjustment directions are in the Service & Repair Procedures topic area, should pop right up using search engine.

To time it with a vacuum gauge, after adjusting carb, attach gauge, loosen distributor hold down clamp. Obviously you don't want distributor flopping loose, neither do you want the clamp so tight that distributor suddenly breaks loose and jumps several degrees when you turn it. Start engine and warm it up. Watch vacuum gauge as you turn distributor. If engine speeds up that's the direction of more advance, if it slows down that's retarding. Turn distributor slowly until maximum vacuum reading, then turn [retard] distributor back 2-3 degrees.

Try starting engine. If it labors hard while cranking it's too far adavanced; if it cranks but won't fire it's too far retarded. If it starts instantly you're real close.

Finally take it for a test spin and apply medium and hard throttle, listening for pinking in combustion chambers, that sorta hollow ticking sound. That indicates it's advanced too far. Retard distributor until it quits pinking under load and you've got it spot on.

Good idea to go back and adjust carb once more with vacuum gauge, because one adjustment effects the other.

Oh, and with a timing light most 318's are either 2 degrees before Top Dead Center, or else TDC. On an older truck you usually have to accurize by ear and test drive even with a light, due to distributor shaft/camshaft wear etc.

[DODGEBOYS]

l like the power brake method with the vacuum advance plugged / have somebody hop in and put in drive and bring RPM,s up to anywere from 1500 to 2500 / turn DIST till it just starts to Ping then back it down so the motor stiil sounds good / shut it off and try a restart / if it labors or turns slow back DIST down a little more till it starts fine and your done / this method sets initial and total in one shot

[opqual]

l like the power brake method with the vacuum advance plugged / have somebody hop in and put in drive and bring RPM,s up to anywere from 1500 to 2500 / turn DIST till it just starts to Ping then back it down so the motor stiil sounds good / shut it off and try a restart / if it labors or turns slow back DIST down a little more till it starts fine and your done / this method sets initial and total in one shot

Thats interesting. I suppose you need to trust the person in the truck eh? ;-)

I've used that approach in a different way. I put in drive after setting correct curb idle, then adjust distributor to bring rpm's up to about 200 below idle. then I go back and adjust fuel idle.

Seems to work fairly well.

I would assume you don't here much about these methods, because of the danger/liability of telling someone to tune their autos while in drive. There would be body parts everywhere... LOL

[DODGEBOYS]

the method that l said takes into account the timing chain slack and motor wear / which setting timing at base idle does not because you can have it dead on and be way off

[opqual]

I am in the middle of replacing the timing chain. I also bought a replacement oem distributor cause they are cheap.

I have the stock distributor at TDC on the compression stroke. SB 360. It points the rotor straight down the middle of the manifold facing towards radiator.

I "assume" all I need to do is remove the bolt, pull it, and replace with the new one pointed the exact same way? Sounds easy enough, but that's what scares me.

Thanks in advance...

Regards,

Joel
Vancouver,Wa

[712edf]

Assuming the wires are oriented the same on both caps, yes that is correct.....at least it should start.

[opqual]

Great! Seems easy enough. I read in a thread that the gear is in the engine, and I will only be lining up the keyway on the distributor. Is this correct? Should make it easier, as it would only go in one way.
Regards,
Joel

[712edf]

Great! Seems easy enough. I read in a thread that the gear is in the engine, and I will only be lining up the keyway on the distributor. Is this correct? Should make it easier, as it would only go in one way.
Regards,
Joel

Or at worst 2 ways...50/50 shot as slot might go in 180 degrees off, but you'd know by looking at the rotor's position.