Technical Small Block Chevy 12 and two timing tab issues

Yes, I have a "dial back" Snap-on light, but how am I going to find TDC regardless of where I place the knob if I don't accurately know where my dist is currently sitting? That is what I am asking.

I think what is being said here is if my marks are at zero on block and tab when I start the engine, and I dial back say 15 degrees to get the light on zero position on the tab, then 15 degrees back on the light knob is my actual engine's 0? Is that what is being explained?

 

I am just gonna do the stop and be done with it.

 

Good move.

 

Have yo checked if the vacuum advance is actually working? With the engine at idle, pinch the vacuum hose going to the can, the engine should slow down. If it doesn't, the advance plate in the Chinese distributor might stuck in the advance position. Easy enough to check.

 

I apologize. I was trying to help with timing and you’re still looking for TDC. Continue on with the piston stop procedure.

 

Vacuum time it always works

 

More than one has suggested that you find true TDC with a piston stop and add a degrees marked tape on the damper. Be sure it’s a 0 balanced damper and not a 400 with added counter weight. Then you can set a adjustable aftermarket pointer right at zero TDC. All those different stock timing marks are usually never accurate anyway . When you dial it in yourself then it will be perfect . Those spark plug piston stops are inexpensive and very easy to use and set perfect .


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How about using a advance timing light?


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Gonna do the piston stop tomorrow morning and be don't with it all. Thanks to all.

 

I wouldn't say you'll be done with it, but it will give you a reference point to start diagnosing from. Good luck.

 

With the engine not running, you find TDC with the piston stop. That lines up the line on your damper with 0 on your timing tab.

With the engine running, your timing light shows when the distributor is firing #1. With the vacuum advance disconnected, and the engine idle speed below where the mechanical advance starts, you’re now reading the timing advance set by turning the distributor.

On a stock SBC, the base advance is usually going to be around 10-15 degrees BTDC. Your timing light will show this by lighting the line on the damper while it is in line with a mark on the timing tab.

You can use the dial back feature of the light to bring the damper line back to the 0 mark on the tab. Then read the dial to get the actual advance set at the distributor.

Your engine is not stock, so stock timing specs like 15* BTDC don’t do you any good. But your timing light light works the same.

So establish TDC. Then start the engine and let it warm up. At idle, point your light at the tab, and turn the dial until the damper line is at the 0 mark on the tab. Read the dial, that’s your static advance at the distributor.




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B


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Porkchops,

With a dial back timing light you will always see the mark at zero
IF
And when You Adjust the lights name sake.
Then look at the light's adjustment to know your timing setting.
Just be sure the vacuum to distributor is disconnected and plugged on engine side,

As you adjust the light the mark on the dampener will move. That's the cool part about a dial back timing light and You should never have to guess at marks other than zero.

When it's all said and done you're looking for is hard acceleration and no pinging on acceleration and no hard hot starts. What the timing ends up being to get that doesn't really mean anything nor will you find it in a book

 

I guess I am a crotchety old SOB, but I hate all this newfangled, half functioning electronic shit. I would never trust a dial back light. Put a timing tape on it or get a degreed balancer. Then you never have to wonder if that damn light is working right. Read it right off the tape. If my 30 year old light is blinking I know it is working correctly.

 

Since you're looking for accuracy you can try this:

https://www.jalopyjournal.com/forum/threads/ancient-egypt-helps-time-a-flathead.1129881/

 

Suggest you shouldn't need a degreed damper or timing tape on a street rod or cruiser.
Just use you timing tab. Carefully add 3 marks @ 10, 20 and 30 before.
Use you dial back light at advance, set at zero, then run it back to 0 on the tab, to check it.
Been using a Snap Out light for almost 40 years, and it still zeroes out.

 

Last time I checked a timing tape cost a lot less than a dial back timing light and accomplishes the same thing without having to precisely dial in "0". Yes, you can mark your own balancer using a little math. Not trying to pee in anybody's Cheerios, but this is just the way I have done it for more than 50 years and it works. I also don't own any digital calipers, mics or indicators for the same reason. All dials. I know. I'm a dinosaur. And I'm going to stay that way until I die.

 

He already has a dial back light. So, right now, the tape would cost him more, and he’d have to wait on shipping. He can use the light he has right now.


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Thirty opinions make it hard to pick the right one. It is a sure thing that knowing where you are makes it much easier to get where you need to be. Your decision to find TDC is the correct start.
Pete

 

I’ve been trying to put these pieces together,,,,

-Checked mark against tab at assembly
-Has dial back light
- tab at 2:00 on timing cover
- uses dial back light but can see mark at 12:00

So the picture is still fuzzy with the light
Not working? Improper operation? Lack of understanding?

 

Distributor is in the wrong place, or the timing mark...Pick one.

 

No one has asked.... Are you using a MSD6 ignition box? Some dial back lights do not read accurately with them. I have seen them be around 15* off. I have a Cornwell dial back... Won't read right on a MSD6 box but will on a 7.

 

if it runs right, it is right....

 

Since I generally avoid working on tuning engines and I could be totally wrong, here's my opinion. The timing mark on the harmonic balancer/ damper whatever is in the wrong spot because it is made for the timing tab that is somewhere around 12 o'clock since most SBC's produced since 1969 use the long water pump and you can point a timing light down there. We, on the other hand, are partial to the old short water pump and those chrome add on timing tabs are made for this setup too. I have tried two different harmonic balancers - the 6 and 3/4" dia. one and the 8" dia. one and both have the timing mark at the same spot and don't line up with TDC which I established by making a tool through the spark plug hole. However, on my 1968 327 that is a short water pump engine, with its original harmonic balancer, the timing mark lines up.

 

Goll-eee! How did you ever find this place on the internet??

 

While it costs more, I prefer using this rather than the timing tapes which can fly off the dampener so easily.

https://www.proformparts.com/produc...over-for-sb-chevy-using-6-3-4-in-damper-black

I also like the adjustable pointer with the item above.

https://www.amazon.com/Moroso-60110-Timing-Pointer-Small/dp/B009RL2V96



Phil

 

It was tough, but it's a good thing I'm not driving this computer around. The fucking thing would leave me stranded at least once a day.

 

Am I the only one that read that when th O.P. put the distributor in and big heavy wheel looking thingy on, the timing marks lined up perfectly and the engine fired right up? He checked the timing with a light and found the timing Mark @ 12 o'clock. Then he, again, checked for tdc on #1 compression and found everything was where it was supposed to be. My question is this, how could everything line up statically, yet when checked with a light, with the engine running, be off by 20 degrees or more? To me it seems, that either his dial back timing light is fucked up or the advance plate is stuck in the distributor. Regardless of piston dwell at tdc, it seems like a very excessive amount of advance to be running properly with no hard, hot start issues. Let alone be running smoothly. I know I'm pretty dense sometimes, but I just don't get it. Could someone please explain? I'm confused. I'm not being a smart ass either, I really don't get the extremity of this!

 

Look at post 80 and pick one

 

Aaaaahhh... Got it!