Timing question

[elektrik]

Hi guys. I'm sure this has been covered a gazilion times here somewhere, but I can't seem to find a tutorial on how to adjust my timing. Looking for not only what I'm supposed to set the timing to (I have a 350 engine) but what the actual timing mark means (after using my timing light, I noticed the mark is "above" the "A") and which way to adjust the distributor, etc.

Any links or help would be appreciated.

Thanks!!!

[theyammieguy]

http://67-72chevytrucks.com/vboard/s...d.php?t=290498

http://67-72chevytrucks.com/vboard/s....php?p=2536026

that should cover it

[VetteVet]

check the sticky's on top of the engine and drivetrain forum.

[elektrik]

thx gents. I'll try to study them, as they look kinda complicated for the laymen.....

<gripe>Where the heck is 'timing 350's for dummies'</gripe>

Update: Ok, I've looked at them, but neither of those links tell me *what* I'm supposed to adjust the timing to (Ex. 2 degrees before tdc)..

[elektrik]

No one responded, so I'm assuming that was too noob of a question...?

[68gmsee]

It's easy if you have some experience with this type of work or if you have seen someone do it. I'd recommend inviting a buddy that has done it or knows someone that can help you. You will need a book and a timing light, the year 350 and specific specs. You can get it pretty close if you at least know the year of the engine. Most of them are at 6-8 degrees BTDC (before top dead center).

The timing marks are graduated in 2's. In other words if your engine timing calls for 8 degrees BTDC, it means that your crankshaft pulley mark should be 4 notches or scribe marks before the "0" or TDC (top dead center) mark. This is with the #1 piston in the compression stroke and at the top of piston travel.

Now if your distributor has been off and you are trying to set the timing for the first time, here's what I do..

forgot to add... I usually check the spark plugs and/or replace them now that they're off. And if I haven't done it in a long time, I also check the compression of cylinders with a compression tester. No sense in doing work twice if I don't have to.

1. I disconnect the battery cable and remove all of the spark plugs to make it easier to turn the engine.

2. I use a long screw driver and place it in the #1 piston spark plug hole. This is to see when the piston is coming up.

3. I use a 1/2 inch wrench and socket on the crankshaft pulley to turn the engine clockwise until I see the piston coming up, then I place my finger in the hole to see if I feel compression as I continue turning the engine. If I don't I keep turning until I do -that is on the second time around. (Some people use a rag or other divice to plug the hole to feel for compression.)

4. As the piston is coming up on the compression stroke, I again use the long screw driver and feel until it's at the very top. At this point, your crankshaft pulley should be aligned with the indicator at "0" or TDC. If it's not, then either the indicator is off or the crankshaft pulley is off. I still would make a scribe mark on the pulley to line up with the "0" at this point.

5. Now I look at the rotor inside the distributor cap and it should be pointing to the #1 piston. If it's not, rotate the base until it does. At this point you are fairly close to where your engine should be.

6. Paint the scribe or mark on the pulley with white paint and with a timing light finish your timing adjustments by moving the distributor one way or the other to get to whatever the engine specs calls for.

[elektrik]

Thanks for the reply. Let me ask a quick question before I start screwing with all this.

When I check the timing with the light and it shows the mark on "A" does that mean the timing is too far advanced? The reason I ask is because of the "dieseling" that the engine does when I turn it off. When I brought my truck to the mechanic in Texas to have it "restored"-they didn't do anything to fix the fuel system (which needed a new gas tank, etc., which I did myself) and I'm wondering if they compensated with a lack of fuel by messing with the timing....

[68gmsee]

The "A" or advance is at the opposite of "0" or top dead center.
Depending on your indicator, it could mean you have it set too advanced.

It may be too advanced or it may be that's what the engine calls for. I''d play with it and bring it back to 8 degrees and see what it does. That's why you have to know the engine timing specs. Some engines require anywhere from 2 degrees to 12 degrees before tdc.

As for the dieseling, they do it for several reasons including timing too advanced. Most of the time it's carbon buildup which you can usually take care with fuel additives. It may take several tries at it.

Other causes are overheating, bad gas, or carb leaking fuel after it's shut off.

[elektrik]

gotcha! Thanks for the info!

[elektrik]

Ok, please bear with me-I'm taking baby steps cause I don't wanna screw this up.

No, I don't have "a friend" who knows how to help me with this, so I'm gonna go extra slow.

Is *this* the bolt I loosen to advance/retard the timing?


Thanks!

P.S. I'm not doing anything yet, just gathering as much information as I can so I don't have to do a 'HELP' post!!

[C20-67_N_MO]

Yes that is the distributor hold down bracket and bolt.

You shouldn't have to loosen it much just a little.

Good Luck.

[68gmsee]

If you plan on just eyeballing it and moving it one way or the other, make a mark on the base of the distributor where it meets with the engine block for reference. The distributor rotor turns clockcwise so if you want to advance you rotate the dis slightly counterclockwise. To retard it go clockwise.

[elektrik]

Ok, good advice....

One (hopefully) last question. If the timing is too far advanced, and I end up retarding it, will I have to adjust the idle up?

[68gmsee]

Originally Posted by elektrik

..... If the timing is too far advanced, and I end up retarding it, will I have to adjust the idle up?

Play that one by ear. That's what I do.

One other thing you can try: Some guys say that they advance the distributor timing until it starts to "ping" under a load like going uphill and then back it off slightly until it stops pinging. What they're trying to accomplish is to advance it to the maximum without premature detonation. I haven't tried that one yet...

[elektrik]

Originally Posted by 68gmsee

Play that one by ear. That's what I do.

One other thing you can try: Some guys say that they advance the distributor timing until it starts to "ping" under a load like going uphill and then back it off slightly until it stops pinging. What they're trying to accomplish is to advance it to the maximum without premature detonation. I haven't tried that one yet...

Wait, I'm confused. Why would you *want* to have the timing too far advanced?

[68gmsee]

Originally Posted by elektrik

Wait, I'm confused. Why would you *want* to have the timing too far advanced?

No, I didn't say "too advanced." But, some say it's for better performance.

Gas is burning at a constant rate. As you increase the speed the parts are moving faster inside the engine. The idea is to get the maximum power by advancing the distributor so all of the gas will be burned at TDC without the premature detonation. I mentioned this just in case you wanted to do it.

Hope I didn't confuse you. A timing light and adjusting it to the specs- usually at 4-12 degeress BTDC should get you there. I'd start with setting it about 8-10 degrees BTDC.

[elektrik]

Originally Posted by 68gmsee

No, I didn't say "too advanced." But, some say it's for better performance.

Gas is burning at a constant rate. As you increase the speed the parts are moving faster inside the engine. The idea is to get the maximum power by advancing the distributor so all of the gas will be burned at TDC without the premature detonation. I mentioned this just in case you wanted to do it.

Hope I didn't confuse you. A timing light and adjusting it to the specs- usually at 4-12 degeress BTDC should get you there. I'd start with setting it about 8-10 degrees BTDC.

Excellent. Thanks for the help-I'll let you know if I blow anything up

[theyammieguy]

used to do it that way on my 86 camaro. 305, edelbrock intake, holley carb, headers, MSD 6AL with, HEI with external coil. 700R4 with corvette servo and b&m transpak kit, with 3:73 gears.

Would advance by ear far enough to where it wouldnt ping under WOT.

In high school when I did it so didnt really know what I was doing but that engine lasted me for 318,000 miles until I threw a rod racing down the highway. I use to rag the crap out of that car.

[mycool72]

I set my balancer on 0 TDC, pointed my distributor rotor at plug wire one and started mine...leave your bolt loose and adjust until you get where you wanna be...it's really pretty simple.

[El Jay]

Originally Posted by mycool72

I set my balancer on 0 TDC, pointed my distributor rotor at plug wire one and started mine...leave your bolt loose and adjust until you get where you wanna be...it's really pretty simple.

I use a "Sharpie" to mark the distributor body in relation to the #1 terminal on the cap. And then turn the distributor to where the rotor was pointing at that mark.
I have yet to have an engine that didn't fire 1st time, every time.
Crude, but effective.

Then came the "fine" tuning.

[oldblue1968chevy]

unlosen that bolt just a lil turn the distributor wtih your hand... be sure to plug the vacum on it..clamp the timing lite on the nubmer 1 spark plug...and go for it, any more ?'s just ask, i just leanred to do this like 3 days ago so dont lsten to me too well lol sorry bout the typin im i tired lol

[68gmsee]

Couple of other things to remember.

If you're going to use a timing light, disconnect the hose going to the distributor vacuum advance and plug it on the carburetor side. I use a golf tee.

The other thing to remember is to set the idle speed so it's at the correct level. Too fast and the mechanical advance in the distributor will kick in and throw you off.

The mechanical advance will "advance" the timing as the speed is increased. This is normal. Don't confuse it with the vacuum advance which uses manifold vacuum to increase the timing at idle and lower speeds. When both are combined, the advance on the engine is increased to where the timing mark may go off the indicator on the timing chain cover. All this is normal with everything hooked up and working properly.

[elektrik]

Originally Posted by 68gmsee

Couple of other things to remember.

If you're going to use a timing light, disconnect the hose going to the distributor vacuum advance and plug it on the carburetor side. I use a golf tee.

The other thing to remember is to set the idle speed so it's at the correct level. Too fast and the mechanical advance in the distributor will kick in and throw you off.

The mechanical advance will "advance" the timing as the speed is increased. This is normal. Don't confuse it with the vacuum advance which uses manifold vacuum to increase the timing at idle and lower speeds. When both are combined, the advance on the engine is increased to where the timing mark may go off the indicator on the timing chain cover. All this is normal with everything hooked up and working properly.

Ok, ow. You hurt my little head. Can you break that down in little tiny "noob friendly" words? If I understand it, you're saying that there's two timing "advances"?? How do I know when/what to set my idle to so that it won't throw off the "mechanical advance"? (I have the original (ok rebuilt) Rochester 2G carb if that helps). For that matter, that opens a whole other can of worms on which of the two screws to adjust my idle on the carb, if that's what you're talking about...

As for the previous post, it doesn't sound that easy to me

[oldblue1968chevy]

eleketric its purty easy once u get it down...u need a helper tho cant really do it alone easy......