Cluster F*** Timing

[robert8096]

With the engine at TDC compression stroke the location of the timing mark on the balancer will dictate which tab you should use.

 

[MrMarty51]

Pull the number one plug and rotate the engine by hand to find TDC on the compression stroke. Place a mark on the timing cover in an area where you can hit it with a timing light. Then place a mark on the harmonic balancer that corresponds to the mark you made on the timing cover. Use these marks for 0 TDC reference. Get a timing light with the advance/retard feature and use the advance/retard feature to set your 6-12 degrees based on your TDC marks.

The only real accurate way to find the exact TDC is to have number one down,does`nt make any difference which stroke,then take something like a spark plug with a length of rod welded to it{A tool for this puirpose can be purchased} then after installing the tool by screwing it into the number one plug hole rotate the engine clockwise,gently,until the piston gets against the tool.Make a mark on the on the timing cover at the TDC mark,then,rotate the egnine counter clockwise until the piston again touches the tool and make a mark on the timing cover at that place,half way between the marks is TDC.thats all.for now.

 

[HotRodPC]

Yes, you don't have to have a timing tab IF you can be assured you have your #1 piston up on TDC (Top Dead Center) And for the mark, it doesn't even matter if you're on compression stroke or not. You just want to make sure the piston is at it's very top. And if you're off by a couple degrees in either direction, so what. Chances are you're off that much with timing chain slop anyway. That's all the Tab does for you anyway is nails down TDC location on the balancer. And then the degrees marked are for those to use a cheap timing light. But you can even eyeball guesstimate without a tab too. Are you using a degree wheel timing light or a just a standard no dial light? I like dial lights and then you don't need a tab at all, even to check vac advance and full advance at high rpm as long as you have a mark for TDC.

The tab you will need will all depend on which balancer you have. Motor doesn't matter, water pump doesn't matter, cast #'s don't matter, period, all that matters is the balancer and where the TDC mark is in refernce to the crank timing keyway. I'd have to do some digging now to tell you which is which. Whethere the balance be a bigger diameter, or thinner or thicker balancer IIRC is what matters as far as measurements. Forgive me, it's been awhile or I'd know this **** right off the top of my head, but I sometimes now get confused between Big Block, SBC 400 and SmallJournal SBC, since they all vary. Then there is those that don't have a timing tab, they have a hole for a probe. That was GM's better idea thinking it would keep shade tree mechanics from working on their own vehicles.

 

[crazy4offroad]

First measure the balancer to find out if you have a 7" or 8" balancer. Then pull #1 plug, put your finger over the plug hole and turn the engine over with a ratchet on the crank bolt. When you feel pressure you're on compression stroke. Stick a small screwdriver in the plug hole and CAREFULLY and SLOWLY turn it over some more till you feel the piston push on the screwdriver. pull it most of the way out while still slowly turning the crank till you can feel the piston stop moving or ever so slightly going down. Look at the balancer, you should see a mark. Clean it up and determine if you're closer to 12 o-clock position or 2 o-clock. My money's on 2 o-clock. Now all you have to do is buy a bolt-on timing tab for the size balancer you have, for the (most likely) 2 o-clock position! Mr Gasket makes some for less than $10 and worst thing you'll have to do is remove the power steering pump to bolt it on, instead of removing everything from the front of the engine to install a new timing cover with a timing tab made on it. The rusty place on the cover is more than likely where it was spot-welded and somehow it broke off.

 

[HotRodPC]

I guess Marty and I were typing at the same time, my response was longer so he beat me to it. But, his method is a way of being more accurate on the where as I said, being off a couple degrees isn't going to matter much, unless you're tuning a race car. And this tool he's taking about making, I've actually gotten buy just using a straw and you can feel the piston hit it. But, our points are the same, just get TDC figured out and mark your cover with opaque paint or get a knife and scratch the paint off your cover, whatever works to make a permanent mark.

 

[HotRodPC]

First measure the balancer to find out if you have a 7" or 8" balancer. Then pull #1 plug, put your finger over the plug hole and turn the engine over with a ratchet on the crank bolt. When you feel pressure you're on compression stroke. Stick a small screwdriver in the plug hole and CAREFULLY and SLOWLY turn it over some more till you feel the piston push on the screwdriver. pull it most of the way out while still slowly turning the crank till you can feel the piston stop moving or ever so slightly going down. Look at the balancer, you should see a mark. Clean it up and determine if you're closer to 12 o-clock position or 2 o-clock. My money's on 2 o-clock. Now all you have to do is buy a bolt-on timing tab for the size balancer you have, for the (most likely) 2 o-clock position! Mr Gasket makes some for less than $10 and worst thing you'll have to do is remove the power steering pump to bolt it on, instead of removing everything from the front of the engine to install a new timing cover with a timing tab made on it. The rusty place on the cover is more than likely where it was spot-welded and somehow it broke off.

OK, there we go, is that the difference on the 350 balancers Curt? 7 or 8 inch diameter, and not thickness? Then the Thickness is how you tell you the 350 from the 400 balancer. Makes sense starting to come to me know.

 

[Boone83K10]

ok, it is an 8 inch balancer with TDC at 2 o clock. Dammit.

If I look down from an angle I can see the entire groove on the balancer. I must stand at the front of the truck, directly lined up with the steering shaft and then look down to the bottom left of the AC compressor and to the right of the water pump. Do you think if I shoot the light from that same angle I can time it instead of direct line of sight from the side of the motor? BTW, that "rust spot" everyone referred to is crud, I wiped it clean. This entire motor has been repainted so...

If I can then I will do it that way. Man all this just so it wont run a little rich and black up the bumper. I wish it didn't irk me so much.

 

[crazy4offroad]

OK, there we go, is that the difference on the 350 balancers Curt? 7 or 8 inch diameter, and not thickness? Then the Thickness is how you tell you the 350 from the 400 balancer. Makes sense starting to come to me know.

Been my experience 2 bolt main is 7" 4 bolt main is 8".

 

[crazy4offroad]

Do you think if I shoot the light from that same angle I can time it instead of direct line of sight from the side of the motor?

I think you'll be able to see it fine, it's just a strobe light and when the light hits you see the line for a split second and it will be aligned with whatever mark on the timing tab, doesn't matter what angle the light is coming in.

 

[bucket]

With the engine at TDC compression stroke the location of the timing mark on the balancer will dictate which tab you should use.

I just don't understand what the issue is. I've had lots of SBC's with the 2 o'clock position and all the accessories on that side, never had trouble seeing it with the timing light.

Also, the only ones I've had with the 12 o'clock tab were low output 305's with the hollowed-out 6.75 in balancer. TPI 305 got the thick balancer (also 6.75) with the 2 o'clock tab like the 350's.

 

[Boone83K10]

I'm so use to it being on the other side with nothing in the way on Fords. I will get the right tab, shoot the light down the angle I said and go from there.

I think half the problem is that the brackets on the motor are for a 12 o clock tab. They are so bulky unlike the setup that you would see normally for a 2 o clock tab. This truck originally had a 1983 low-altitude 305...

 

[HotRodPC]

Been my experience 2 bolt main is 7" 4 bolt main is 8".

I guess that could be true, cuz I thought the difference was Passenger Car or Truck. Most trucks are 4 bolt mains.

 

[HotRodPC]

I just don't understand what the issue is. I've had lots of SBC's with the 2 o'clock position and all the accessories on that side, never had trouble seeing it with the timing light.

Also, the only ones I've had with the 12 o'clock tab were low output 305's with the hollowed-out 6.75 in balancer. TPI 305 got the thick balancer (also 6.75) with the 2 o'clock tab like the 350's.

You're right, I've never had a problem getting a light on the tab either. If he had a timing tab, he'd understand also. If you see the angle he took the pics from, he thinking you come in at a 90 degree angle to see it, and that's not the case. You come in from the from the front of the motor just over the fan blade, not over the top or the side. He'll get it when he installs a timing tab. If I think about it, I"ll try to snap a pic from the right angle off the 85 K1500.

 

[chengny]

Just as general info:

Diameter of the balancer is not the issue.

More likely it's a parts specification problem. Often, a post-1976 balancer will be mounted on an engine with a pre-76 timing chain cover. The timing mark on a 76+ balancer is not compatible with the location of the timing tab on a pre-76 chain cover. In 1976 GM moved the slot on the balancer - CCW about 12 degrees.

Before the shift, when #1 cylinder fired and the distributor was properly timed, the balancer mark was at around 2 o'clock.

When post 76 SBC's are timed correctly, the balancer mark will be at about 12 o'clock when #1 fires.


Here are some images to help explain.

This shows a late model balancer on an engine with an early timing cover. The drawn-in arrow points to the hub keyway on one end and to where the timing mark would be on an early SBC. The actual mark is what you would find on a post 76 balancer:

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A 1986 350 with stock balancer and timing cover/tab:

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An aftermarket balancer with dual timing marks:

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[89Suburban]