OK, i really need your help bad:
For some reason the books don't go into terrible detail about timing. Maybe it's because timing is not considered "sexy" or "glamourous" or exciting or whatever. But the thing is, without the so-called "mundane" stuff, none of the other stuff would be possible. So i say we should talk about it here and now and in great detail. (besides that, i need to get my engine running right)

1) How do we determine where TDC is with no timing tab---the engine i bought didn't "come" with one, or i forgot to ask, or i didn't think it was important 3 yrs ago.

a) i recently read in the "chevy i.d. guide" book that TDC on engines before say 76 is about 2 o'clock on the timing chain cover whereas engines 76 or so and after have TDC and more of 12 o'clock on the timing chain cover. Does this mean that the scribe mark on the balancer was put in a different place than on the earlier balancers?

b) Do you know of any good sources for O.E., timing tabs?

c) i want to use this new system to time my engine;
http://www.jegs.com/webapp/wcs/stores/servlet/CategoryDisplay?lang=-1&catalogId=10002&storeId=10001&categoryId=95328
Would it work with my setup, keeping in mind i have a/c and p/s bunched up in that (near timing cover) general area? ANDkeeping in mind that i have one of those "newer" engines that have (at least i think) TDC near the 12 o'clock position on the timing chain cover, so would this new system even work with my setup?

2) How would you, exactly step by step, time your engine. Again, the books don't go into terrible detail about it. So, i'd greatly appreciate your assistance.

I wouldn't buy that, at least not yet. It won't help figure out where your marks are supposed to be. what you need to do is find TDC on #1, look and see where the timing mark is. it it is at around 2 o'clock all you need is a $3 timing tab. bolt it one. there's several piston stop gizmos on the market, but keep in mind that all of them require you to turn your engine by hand, not with the starter.

With respect to finding TDC with no timing tab you can either make a pointer out of a coat hanger, which you would bolt to your timing chain cover adjacent to your harmonic dampner, or go buy a timing tab from your local dealer , auto parts store etc.
Pretty much any speed shop also will sell you the proper timing tab based on the diameter of your harmonic dampner.

To establish TDC with an assembled engine in the car the easiest way is to take an old spark plug of the type you use in your engine, remove its guts and weld a bolt into the metal body of the sparkplug. Make sure that the bolt sticks out of the plug 2 1/2 to 3 ". Then grind off the end of the bolt such that it is round and has NO sharp edges.

Insert that tool into the #1 cylinder spark plug hole. Remove all of the rest of the spark plugs. Now rotate your engine BY HAND until the #1 piston hits your tool. With a marker make a mark on the dampner at your timing tab zero point OR your coathanger pointer. Now rotate the engine in the opposite direction until your #1 piston again hits the tool you have in the #1 cylinder spark plug hole. Make another mark on the dampner at your zero reference on the timing tab OR your coathanger tool.

Next measure the distance between the two marks. TDC #1 will be exactly 1/2 the distance between the two marks. 99.999% of the time that 1/2 distance will fall directly on the factory reference cut on your dampner.

If it doesn't then either you did something wrong OR your dampner outer ring has "walked" around on the dampner hub and is now junk.


If you are using the coathanger method now is a really good time to go buy that proper timing tab. A coat hanger reference point is a truly lousy way to time an engine. Unless , of course, you have a degreed dampner, in which case its a great way to go. :)

Here's another thing:
I know the engine runs because i ran it a few times on my test stand a few times before i installed it in the car last week.

So, since the distributor is close to where it needs to be, could i just take the cap off and rotate the engine by hand and just see where the rotor gets to the #1 cylinder position and just note where the notch on the damper is?

i really need only to get a ballpark figure whether TDC occurs at the 12o'clock position on the timing cover or 2o'clock. Then we'll know which timing tab to get.


Being that it's a 305, wouldn't you be willing to bet that it's at 12o'clock?

that would work fine however the timing tab you need is determined by the diameter of your harmonic dampner and NOT the position of your rotor. In any event whatever tab you get will be bolted to the timing chain cover. Ihe only differences between the various timing tabs GM has used over the years is where on the timing cover the timing tab was mounted.

Regardless of what might have been on your engine when it came out of the factory you CAN buy a timing tab appropriate for your particular harmonic dampner at most auto stores in the nation. Simply bolt it to whatever pair of timing cover bolts align it properly.

Understood:
I've got a 6 3/4 damper. Does this mean that ALL 6 3/4 tabs will fit ALL 6 3/4 applications (i'm thinking so). In that case i don't have to go through will all the TDC jazz?

Now that we've gotten that stuff out of the way, it appears that there are two ways to time the engine: using a conventional tab---with all the different degrees on the tab, Or using timing tape put on the damper and using some sort of pointer.

Which is better and why?

with a timing tape you can do what is known as "Total Timing". With a conventional timing tab you cannot.

This site is crammed with "Total Timing" threads so a bit of searching around will give you a wealth of info.

If your car is a daily driver you may not care about getting 10/10ths horsepower. If you are looking for that last horsepower then get a timing tape and go for it. Just make sure that you apply the timing tape properly so that you don't drive over it and see it disappearing in your rear view mirror like I did the last time I stuck one on my dampner. :)

Is there another way to do it, i.e., degree wheel?

When I bought my motor, it came with a timing tab for a 6 3/4 " damper. It took about 2 minutes to bolt it on. I don't think there is more to it than that. Is your motor heavily built or something? Most engines just aren't that sensitive to slight changes in timing. Since you know the motor runs, why not just bolt on the timing tab, start the motor and try your timing light? If it looks way wrong with the timing light, then you can start trying to figure out whether your damper is messed up or installed wrong (w/o the drift key) or some other problem.

I am in a similar position as you - most of the way through an engine swap with a growing need for the project to be done. Get it running first, make fine adjustments second. If it runs, you can always try things like "total timing" to squeeze more HP out of it later.

I hope to be able to drive my car tomorrow after installing my freshly rebuilt Muncie tonight. If it won't run, maybe I'll get behind the wheel and have my wife and kids push it!!!

with a timing tape you can do what is known as "Total Timing". With a conventional timing tab you cannot.


You can easily do it without a timing tape. Just make a 36° BTDC mark on your balancer and use the marks on the timing tab to set the timing. If you set the 36° mark on the 0 mark, you will have 36° advance. If you set the 36° mark on the 4° retard mark, you will have 32° advance, etc.

You can easily do it without a timing tape. Just make a 36° BTDC mark on your balancer and use the marks on the timing tab to set the timing. If you set the 36° mark on the 0 mark, you will have 36° advance. If you set the 36° mark on the 4° retard mark, you will have 32° advance, etc.


If only it were that simple. You need to have a test light OR a voltmeter hooked up to the (-)coil so that you can see exactlly when #1 fires( A "fire" occurs when the points open ). You can set your dampner on 3x* all you want but that doesn't mean you have your distributor in the correct spot.

First you insure that your distributor rotor is set to fire on the #1 cylinder. Then turn your dampner to what ever * mark you want your total timing to occur at. Then with the ignition on (at this point your test light should be illuminated and/or your volt meter should be showing voltage.)

Then turn your distributor until the test light extinguishes or the volt meter shows zero voltage. At that exact point you stop turning your distributor and tighten it fully down. You are done.

Remember your distributor rotor turns CW so you if you want advance you need to turn the distributor body CCW until you lose signal.



Failing that then you use your timing light and your tachometer to set your total advance. Raise your engine RPM high enough such that you see NO more advance at all. THEN set your timing to whatever spec you want at that RPM.If you want 30* total then set timing at that mark on your dampner timing tape. Thats what "TOTAL" timing is all about.

You are looking typically @ 3000 to 3200 RPM where all your timing should in. We are discussing "Mechanical advance" NOT vacuum advance. In fact for this evolution I'd disconnect vac advance and plug the line.

With respect to total timing you want your vac advance to be operated off manifold vacuum.

You DO NOT want venturi vacuum ADDING to your total timing via your vacuum advance.

If only it were that simple.

It is that simple. You don't need a test light, voltmeter or a timing tape. Set the engine to 10° BTDC on the #1 firing cycle, install the distributor with the rotor pointing directly to the #1 plug wire. You should be able to fire the engine at this point. Have your timing light hooked up, bring the rpm's up and immediately line up your 36° mark on the balancer with your 0 mark on the tab. Tighten the distributor and recheck to see that the total timing is 36°. Hook up the vacuum advance.

If only it were that simple.

It is that simple. You don't need a test light, voltmeter or a timing tape. Set the engine to 10° BTDC on the #1 firing cycle, install the distributor with the rotor pointing directly to the #1 plug wire. You should be able to fire the engine at this point. Have your timing light hooked up, bring the rpm's up and immediately line up your 36° mark on the balancer with your 0 mark on the tab. Tighten the distributor and recheck to see that the total timing is 36°. Hook up the vacuum advance.


Read the original post! It is not always that simple. Steve

Read the original post! It is not always that simple. Steve

In the original post we have a balancer with no timing tab. In the second reply we learn how to find TDC and put a mark there. We bolt on a timing tab, reference our TDC mark to the zero mark on the timing tab. We make a mark 1/10 the balancer circumference CW from our new TDC mark to get a 36° BTDC mark. We fire the engine as instructed and set the total timing to 36°. It's not rocket science....

Do all, for example, 6 and 3/4 dampers take the same tab? (i suspect so). If this is the case, then i don't have to go through all this TDC jazz.

The 6 and 3/4 damper is the really short, thick one. Also, you have to remember that by 76, there were alot of accesories crowded up in the engine to the point that you couldn't see the tab if it were at 2o'clock on the timing chain cover anyways. As you know, the 305 didn't come out until 76----"emissions era."

Dude you are making this way too difficult!

Go back and read the posts in this thread. EVERYTHING you need to know is contained in the posts above this one. I was an auto machanic up until 1989 and I have seen all of the timing tabs that chevrolet used up to that time. One characteristic they all shared was that the timing tab was afixed to the timing chain cover. It was normally welded somewhere in the 2 o'clock position.

From what you are saying I guess you don't have a timing tab anywhere on your timing chain cover. Ok..thats cool.


You already know what the diameter of your harmonic balancer is so go to your local speed shop tell them what that diameter is. Tell them that you want a timing tab and I am confident you'll get what you'll need.

I expect that you'll get the kind that has to be bolted to your timing chain cover. Fine!

All you have to do now is take that tab and hold it somewhere near the balancer on your engine and it'll be readily apparent which two bolts you'll need to remove fron your timing chain cover.

It'll be on the right hand side of your engine as you face the engine. Take those two bolts out of their holes , put the timing tab over those two holes and reinstall the bolts. Now you have a set of reference marks to use to time your engine.