Hey all
i finally got a tach hooked up and i went to do my ignition timing and realized there is no timing mark to be found anywhere...

Is it possible to do it by ear? My engine runs ok but loses power and pings uphill/acceleration at lower rpms 4th gear. It runs at idle just fine though so I'm not sure what i should do. Any advice is much needed thanks guys

 

If it pings you have too much ignition advance so need to back it off a couple of degrees, which is really tough do w/o an indicator.

 

Yep, My 302 does not have a timing indicator either... What to do....

 

Yeah. so no timing mark means no timing adjustment? i have to do something about the pinging.

 

Where did you get "no adjustment" in the above? You can, it is just more difficult. BUT, you WILL have to have a reference. I would clean the block where the dizzy goes in so it is spotless and then put a line on the base of the dizzy and a matching one on the block w/a light-colored Sharpie. The smaller the line the easier it is to match the two. Then loosen the clamp and back the dizzy off ~2 degrees.

To figure out how much 2 degrees is I just measured the base on my dizzy, which may be bigger than yours. It is 2.125" in diameter, or 1.0625" radius. Circumference is the radius time Pi, or 3.34". Normally you'd say that 3.34" divided by 360 degrees gives the radial distance for 1 degree. But, a dizzy is working at 1/2 the crank's rotation so it is actually twice that, or ~.0185" per degree. So 2 degrees is a bit more than 1/32 of an inch of movement at the base of the dizzy.

 

If what Gary is describing is difficult for you, you may use a vacuum gauge to set your timing. Basically all you do in this case is to adjust your timing while eengine is idling to maximum manifold vacuum reading, then back it off approx 1 " of vacuum, maybe even 2", then lock it down and road test it..If it pings under load, adjusting down a smidgen more. Pretty simple, to adjust your engine up or down to the "ping" with the grade of fuel ur using..I don't even know what my engines are timed at..I always use the vacuum method.

 

JR - I'd rep you but I can't. That may just work for them. It wouldn't work for me as my engine isn't sensitive to initial lead and I could back it off quite a few degrees before getting any change on vacuum. But it may just be what they need. Thanks.

 

OK this is two questions, one getting a mark and timing without a mark.

First getting a mark, a mark is just a mark, all you need is a pointer and some timing tape(graduated marks on the balancer) Timing tape is easy you can buy it in many places and forms. A pointer is almost as easy, it's just a pointer, a wire, a piece of sheet metal, whatever many can be bought for that to. The challenge is finding TDC. On that note first it isn't really necessary, timing is more a question of variation then actual degree. That is knowing you have 20 degrees of change from idle to 3000 RPM is more important then knowing you have 16 degrees initial compared to 14 degrees initial.

Finding true TDC isn't that hard though, it just takes a way to mark the balancer and a piston stop, that is a bolt in a spark plug hole. Remove all the plugs so it turns easy by hand, put in the stop, turn till piston hits stop, mark balancer, turn other way until piston hits stop, mark balancer, TDC is right between those two marks.

Second, timing by "ear" can of course be done, a vacuum gauge is helpful but not really needed. But before that, it's really about the ping, I'd start by unhooking the vacuum advance and leaving it off to see what difference that makes. If it still pings, rig up some marks, don't need the actual numbers only when and how much they change.

Pinging of course isn't always and rarely is solely a timing issue, it has many contributing factors, it's possible for the timing to be perfect and still ping due to a lean mixture and something causing ignition such as a hot plug or carbon buildup.

 

FWIW I disagree with this, it's too simple an explanation for something a little more complicated. I could explain my method but it really doesn't matter yet, the simple truth is that the OPs distributor very likely has too much advance. Cause of which base timing which is all you'll even get close to with that is all but irrelevant.

That said my method for finding base and idle timing is different, largely cause I use manifold vacuum, but the method holds true. Idle, vacuum unplugged, advance timing to max RPM and vacuum adjusting down the carb to maintain idle speed. This is ideal idle timing, the issue is in most cases this is in the 20s and is too much for it to start. At which point retard the timing until it starts easy when hot. This is the ideal base timing.

 

This is pretty much what I did and worked just peachy. The engine ran like dog poo when set to the factory recommended 8*, it simply had no power.

I didn't use a vacuum gauge, rather I set the distributor by ear. Find a place on the dizzy where the engine idles. As you adjust timing further retarded, the idle speed will drop eventually to where the engine barely runs. As you go advanced, RPM picks up along with the engine idling smoother. When you get to the "too advanced" threshold, the engine will begin to stumble and miss at idle. You want to back off and lock the distributor down where the engine is running at the highest RPM that still offers a smooth idle. If it stumbles at all, you're too advanced, even if you can get the RPM higher.

I've found that when setting it this way, a test drive reveals that it's a tad too far advanced-- I'll always get pinging under load in 4th gear at lower RPM. So I back the distributor off in very small increments until the pinging goes away under all conditions that I drive in.

Setting it this way improved power dramatically over factory timing, and I picked up a mpg or so, which is a big deal, about a 10% improvement.

 

I just made my own timing marks. Several ways to do that. I just marked TDC on the compression stroke and used a dial-back timing light. I also set timing using a vacuum gauge; set to max vacuum and then back of a couple ticks. Checked with timing light. Pretty basic. It IS easy to set way too much advance using just the vacuum gauge so you need to back it off a bit.

 

Exactly, I find there is a LOT of power and efficiency to be found in proper timing beyond the common specs. All but this right here, this is where it gets more complicated.

This is where the type of vacuum timing and RPM advance settings come into play. This happens cause your idle timing is so close to ideal at idle that it's much easier to go to far right off idle. If set up with manifold vacuum as the throttle opens vacuum lowers as cylinder pressure rises, lowering timing just as you need less advance do to the higher cylinder pressures. If set up ported then as the throttle opens timing increases, this increase can be too much depending on settings and can lead to a ping. This however is a reverse catch 22 cause you often can't start the engine with enough timing to idle without manifold vacuum advance at ideal.

 

All of the factory balancers I have messed with have marks. You just have to get on your back and clean the harmonic balancer off till you can see them. You do not have a scale on the engine like a chevy, you have a pointer. The marks and numbers are on the balancer.

 

I have mine on ported vacuum. I tried it both ways and seem to remember getting a couple tenths better gas mileage with ported.

As far as power goes, it was difficult to tell. The butt-dyno couldn't tell which was better, so I left it where I got best fuel economy.

I don't recall having any issues with starting unless the timing was way too far advanced.