Timing tab on timing cover

hi all i have a volvo 350 it dont have a time tab,would an auto tab that mount to time cover bolt be same measurements,thanx

It would depend on the harmonic balancer that has been installed. Some are indexed for a different tab location.
If you are savvy to using the Positive Piston Stop method, you can find TDC, and double check your markings. It's a PITA, but necessary if you are to find this with any sense of accuracy.

I'd be doing this so that you can set/check ignition TAT (total advance timing).
TAT is critical for any gasoline marine engine.
Without accurate markings, this cannot be done.

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yes i had to get tdc put in new distributor,the balancer has a factory groove,i just want it perfect at 8 btdc,can i use an auto timing tab,are they different,thanx

Well, that's what I'm saying. Unless the balancer and tab are "OEM for THAT engine", I would not know without checking.
For me, I'd do the Pos Piston Stop method, and then know that it is correct!

ok i will use a dial indicator and get exact tdc and go from there with degrees,thank you

A dial indicator will get you close... but close ONLY, as there is remaining crankshaft rotation while the piston appears to be at it's top of travel.

A dial indicator and a degree wheel will work if you take two opposing, but identical, readings @ approximately 40 degrees from one another!
(does not need to be 40*.... but 40* is a place to start)
40* split, gives you 15* BTDC and 15* ATDC.
When you divide this split, you have TDC!

If you want accuracy, you will want to do the positive piston stop with a degree wheel.
The procedure is similar, but more accurate due to the positiveness of the piston stop from each direction!
(If you have not done this, you will find instructions on the Internet)

Here is one type of positive piston stop. You can buy these, or make one!
The one to the left is superior because of the locking nut. The one to the right may have a friction pill in the threads... I don't know!


Then you need a 360 degree wheel and a pointer. The pointer can be nothing more than a piece of heavy gauge wire.



This article pretty much explains it as I would.

If you Google "Positive piston stop TDC method" you'll find many articles on this. Most articles are used for degreeing camshafts, but will work extremely well for what you are doing.

I've been doing this since the mid 60's.... I can tell you first hand that it works well and is very accurate.


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ok rick using degree wheel,piston stop,i moved crank near tdc backed up crank to 50 inserted piston stop,clock wise to stop at 35,ccw at 25,when i bolted degree wheel to balancer,o tdc lined up with a pointer,off on factory mark on balancer bout 10 degrees,im not sure,any help thanx

Yeah..I am agree with Rick..

Sticky, I'm not sure that I understand.... and you may not be understanding me. It can be tough to explain!
Shoot me a PM.... maybe talking on the phone would be the quickest way to do this.

Mean while:
It is a process of stopping the piston from reaching theoretical TDC and from an identical location from TDC while rotating the crankshaft in two different directions.
The piston is not allowed to reach theoretical TDC.

This also means that the crankshaft is prevented from reaching a TDC position (in degrees) that are identical in each direction.

All along you are continously changing the pointer to read the same as you continue to test..... back and forth... back and forth.
Only take a few tries, and you have it.

The pointer will eventually read the same in either direction of crankshaft travel STOP position.
It doesn't matter what the number of degrees are, within a certain range.... 20 to 30 from theoretical TDC would do just fine!

When you get the pointer to read the same degree reading for each direction of crankshaft travel, the PPS is then removed, and the "split" difference of degrees becomes TDC.
It's physics and geometry that can not be altered.
It is extremely accurate! Probably moreso than what you need.... but I know of no other means.

Bottom line.... you'll now know very accurately what your ignition Total Advance will be!
BASE advance is not the concern that TA is.

If there are any others that can add to this, or correct me....., please do!

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ok i have 25 on each side do i need to mark balancer,or move pointer to 0 tdc,then take out pst,there is no mark on balancer,thanx

sticky said:

ok i have 25 on each side do i need to mark balancer,or move pointer to 0 tdc,then take out pst,there is no mark on balancer,thanx

Click to expand...

Make sure that the PPS was very secure.... it cannot be hand tight ONLY!
Both the fixture and the shaft must not move once the correct depth has been determined!

Sounds like your crankshaft is stopping @ 25* BTDC each way..... This is good!

The two 25*'s become the "knowns".
We're using two "knowns" to find the location of one "unknown"!

When you remove the PPS (without touching or moving the pionter or degree wheel)......, and when you now bring the crank to ZERO (where it could not go before, with the PPS installed) you will now have TDC...... But maybe not according to the OEM timing markings.

NOTE: the OEM markings may not align..... in fact, they probably will not align! This is the entire purpose of doing this.

So now tweak or bend or move the tab.... or whatever you need to do, in order to get the OEM balancer mark to align with the ZERO on the tab...., but without moving the crankshaft.

Now you have dialed in OEM marks to a true TDC.

Wella.... You're done!