Skool me on timing w/o timing tab

[1low4x4]

Disclaimer: It's been a decade since I timed an engine. I remember how to unplug (and plug the line) the vacuum advance for initial timing, but, my front cover on my sbc doesnt have the timing tab. How do I time it, am i overthinking it? Can I just make a mark and run with it?

 

[legopnuematic]

Just use a piece of stiff wire and bolt it to the water pump or wherever convenient to make a pointer, then find TDC using a piston stop or other method, mark balancer/bend pointer to match mark.

Then you will need a dial back type timing light or mark the balancer with degree markings or use a timing tape on the balancer to give you degree increments.

Just imagine the degree wheel is a balancer. I think I used a piece of Tig wire for that on the slant six.

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[DoubleDingo]

You would definitely need to mark 0, and then some way of measuring the degrees, mark 10BTDC at the very least, but you really need the tab. It can be done by ear, but getting the whole thing dialed in is a dance of timing and carb adjustment until it's just right, and that's why the timing tab needs to be there.

 

[Turbo4whl]

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Many companies sell these. Look "small block chevy timing tab"

Find originals too: CLICK HERE

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[Ricko1966]

Or you can find a stretch of road where you can accelerate hard from one land mark and pass another.You will need land marks that will let you accelerate to about 60mph. Make your first run check your speed when you pass the second land mark,bump the timing a little,run again,Check your mph,keep bumping until mph starts to drop. Retard back to first place that you has max mph. You are shooting for best mph not E.T. This will get you MBT (Maximum brake torque) MPH is a very accurate method of what the engine wants,likes and needs. If you've given it to much it will detonate and slow your MPH before you can even hear it. Too little and you'll see because the MPH will still be coming up. You go back to lowest setting with best MPH to stay out of the detonation zone,and so the engine isnt fighting the extra timing on the compression stroke,so better MPG and Torque.

 

[edgephoto]

If you can mark TDC just use a timing light with advance. I haven't needed to time an engine in probably 15 years but I still have my old timing light. Looks like this one.

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[77Dmax]

Look at 12 o'clock for the timing tab. Some years had to down the water pump to set the timing. Don't ask me why this was a good idea..

 

[83Stepper]

Old skool method, do it by ear lol

Adjust timing by how she runs. Does she bog down and feel sluggish under acceleration, adjust timing. Does she backfire, chug and knock when shutting it off, adjust timing.

 

[PrairieDrifter]

Don't do it by ear. Less than 10% of people can get it even remotely close that way. Just get a $50 dollar timing light and don't melt your engine down.

 

[DoubleDingo]

Don't do it by ear. Less than 10% of people can get it even remotely close that way. Just get a $50 dollar timing light and don't melt your engine down.

And a timing tab

 

[PrairieDrifter]

And a timing tab

Yep. I bought one for like $10 lol

 

[1lejohn]

You have to be careful where you install the timing tab. I put one on my truck when I rebuilt the top end. I put it on the new timing cover over to the right side. Wrong the original was on top behind the water pump. I'm guessing it was the one with the site tube. I had to replace the cover due to running a hyd. roller cam. I had put a timing tape on the balancer, but's it gone. I didn't notice this mistake till I was trying to check the vacuum and total advance with a dial back light. WOW the TDC mark was way over to the left. I have since just used The Uncle Tony's Garage Method. Adjust it where it runs the best without pinging. I need to mark the balancer at TDC with the new tab. Oh yes a new project added to the list!

 

[75gmck25]

SBC timing tabs may be at the 2 o’clock position, or 12 o’clock (the ones I have seen look more like a vertical tube than a tab), and think there may be one other possibility.

To get started:
- Pull all the plugs, mark the #1 plug position on the distributor body (white paint, nail polish, etc.), and remove the distributor cap. Use the key to bump the starter over until you see the rotor coming around to just before the #1 Plug position.
- Now look at the balancer and find the factory line cut into it. Use your paint to put a mark on that line. If it's off toward the driver side at about 2 o'clock (with the rotor pointing near #1), then a simple bolt on timing tab will work well. If it's straight up, then you might just be able to mark the cover. Other locations will require a home-made tab.
- Buy or make a TDC tool and follow the directions to determine that the piston is at TDC. Line up your adjustable pointer so that the zero line on the tab is aligned exactly with the balancer line. Now you can always find TDC.

Put the plugs back in and the distributor cap back on.
- Start up the truck and let it warm up. Unplug vacuum line going to the distributor and plug it with a rubber plug. This means zero vacuum advance.
- Check the idle speed and set it to around 600-650 rpm in Park. This low rpm prevents mechanical advance from kicking in.
- Use a timing light to determine the current base timing. Factory recommends around 4-8 degrees BTDC, but the SBC usually runs better with at least 12. Loosen the distributor hold-down and turn it to set the timing you want. It's a lot easier if you have a dial-back timing light.
- Now increase rpm and look at how the timing advances with rpm. This is where you really need a dial-back light, because the tab markings probably go to only about 12 or 16 degrees. What you want to see is that timing starts to advance by around 1500-2000 rpm, and then by about 3000 rpm it maxes out at 18-20 degrees more than your base setting. This means it will max at about 30-32 degrees.
- let it go back to idle and then apply vacuum to the distributor vacuum advance port using a small vacuum pump or a constant vacuum line on the carburetor. With vacuum applied it should advance timing about 18-20 degrees.
- Vacuum advance will work differently when driving, depending on which carburetor port you use. If you have the line connected to full/constant vacuum it will always add 18-20 degrees, so you might have to set the curb idle lower. If its on ported vacuum it will have no advance at idle.
General guideline is to not exceed about 52-54 degrees total vacuum (base+mechanical+vacuum).

You want the vacuum advance to work because it helps fuel economy. You want the mechanical to work because it helps acceleration. Don't get confused by somebody who has a race car with locked settings and it makes great power. That's because it only operates in very limited rpm and load conditions. You want settings for a daily driver.

 

[83Stepper]

Obviously I was being silly, hard to convey that through the interwebs at times I guess.

But yeah a timing light will help, but without the timing tab being installed, it's going to make it harder to do if you're not well versed in timing engines and not sure what to look for in signs and symptoms of engines being too far advanced or retarded. Could write up a 30 min long instruction on how to do that, but the internet would be easier to search for it. Involves getting cylinder #1 to tdc, confirming the timing mark on the harmonic balancer at the right position (normally 12 o'clock, sometimes not), removing the cap and marking the distributor where the rotor is positioned, copy that mark to the intake manifold base of the distributor etc etc etc. Like I said, could go on for another 30 mins easily getting into why you're doing it in that manner and so on.

TL/DR; Get a timing tab installed in the correct location and use a timing light.