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Mind-bending timing problem on AQ211A

S

shaunleveque

New member
Hi All,

I have a timing problem that is really"doing my crust" that I just can't fathom, so any help is greatly appreciated.

I posted a problem in 2010 regarding problems with my Volvo Penta AQ211A, which you helped me sort out. That engine has since gone to the scrapyard.

I have fitted a recon Volvo Penta AQ211A to my boat, but have never been able to get the timing "right".

My apologies if this is long-winded, but I know that in order for anyone to help I'll need to tell the whole story.

The original AQ211A engine destroyed itself after being winterised for over 2 years (I have some interesting photo's, but that's another story).

So,I bought a reconditioned engine, complete with cylinder heads from an Ebay marine engine reconditioning company. I believe the block was new (at least, that's what they told me). The heads were re-conditioned ones.

A lot of parts from the original engine were swapped over, including the carb (now replaced), distributor,cam-chain timing cover, pulleys, Exhaust and inlet manifolds.

However, I had to use the harmonic balancer from a slightly newer engine, and I believe it's from an automobile. But, the key-way and TDC marks were in the same places as the original.

My problem is the ignition timing. But it's NOT as simple (or maybe it is) as it first appears.

So, I rotated the engine and found TDC. No1 piston at the top, valves closed, rotor arm pointing at No1 lead.
Checked firing order (several times), as far as I can see everything "static" is correct.

So, now is where it gets weird...... The engine refused to start, so I rotated the distributor until it fired-up,checked the timing (should be 6 Deg BTDC @ 750 RPM) but found that it was *initially* at around 16 - 18 Deg BTDC.

If I reset the timing while it's running (using an advancing timing light - a brand new one) to 6 Deg,the engine runs rough. At this point, if I open the throttle it mis-fires through the carb and stalls.

So, I set the timing"by ear". When I do this, ignoring timing marks, I can get the engine running sweetly, instant response on the throttle,easy starting, no misfiring, steady idle, all as you would expect.

And this is where it gets really really weird! ....Iput the timing light back on and dialled-in until I could see what the timing actually is. It appears to be: 20 Deg BTDC @ 750 RPM(should be 6 Deg) and 34 Deg BTDC @ 2500 RPM (should 14 Deg BTDC)according to the cam-chain cover marks. (using the deepest V as the TDC mark).

I confirmed this (as best I can) with a standard non-advancing timing light, several times.
I suspected something somewhere is way "out-of-whack", so I stripped the entire HT ignition setup down, started from scratch, one lead at a time,re-confirmed firing order, rotation of rotar-arm (clockwise). Still the same!

So, I stripped the distributor. The distributor is a Prestolite (I think) but the points have been changed for an electronic (hall effect) pickup. Centrifugal weights move freely (cleaned and lightly re-greased pivot-points anyway), springs are intact and firm, everything appears to operate as expected. (No vacuum advance on these things).

But,still the timing appears to be "way off their marks".

Someone suggested "Well, if you've done it by ear and it runs, close it up and forget it!", but that doesn't work for me.
I want to know that the timing is as accurate as I can get it. Besides, I just can't get my head around why the timing can appear to be so far off the marks, and run infinitely better than if it's "timed correctly".

Could it be something to do with the hall effect "points"? Is it possible the cam-chain cover from the original engine has the timing marks in the wrong place for this engine? (They are on the right-hand side, down between the cooling hoses).
Did the V8 ever have timing marks in a different position (more round to the left-hand side)? Maybe if the block was originally an automobile engine? Or, maybe the block would normally be used by a different boat builder and would normally have a different cam-chain cover?
I have no idea what the origins of this block are.
Am I being stupid and missing something fundamentally simple?

Any help is greatly appreciated.
 
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This one is going to require me to roll up my sleeves, one large cup of coffee and perhaps 3 cookies!

shaunleveque said:
............................

I have fitted a recon Volvo Penta AQ211A to my boat, but have never been able to get the timing "right".
......... According to my VP info, the AQ 211 is a SBC engine.

A lot of parts from the original engine were swapped over, including the carb (now replaced), distributor, cam-chain timing cover, pulleys, Exhaust and inlet manifolds.
......... Did you verify that the camshaft was phased in or indexed correctly?

However, I had to use the harmonic balancer from a slightly newer engine, and I believe it's from an automobile. But, the key-way and TDC marks were in the same places as the original.
......... If in doubt, you will need to perform a PPS (Positive Piston Stop) procedure. This will allow you to find true #1 TDC, and then make your new TDC marks accordingly.

My problem is the ignition timing. *But it's NOT as simple (or maybe it is) as it first appears.

So, I rotated the engine and found TDC. No1 piston at the top, valves closed, rotor arm pointing at No1 lead.
Checked firing order (several times), as far as I can see everything "static" is correct.
......... As you know, you will begin at #1 TDC on the Compression Stroke. If the camshaft is indexed to the crankshaft correctly, both intake and exhaust valves will be closed.

So, now is where it gets weird...... The engine refused to start, so I rotated the distributor until it fired-up,checked the timing (should be 6 Deg BTDC @ 750 RPM) but found that it was *initially* at around 16 - 18 Deg BTDC.
......... At 16 or 18 degrees BTDC, most any SBC will "buck" or "kick back" etc during cranking!

If I reset the timing while it's running (using an advancing timing light - a brand new one) to 6 Deg,the engine runs rough. At this point, if I open the throttle it mis-fires through the carb and stalls.
......... If using the harmonic balancer TDC line against the timing cover marks, I would say that something is very wrong here.
The PPS procedure will tell you!

So, I set the timing"by ear". *When I do this, ignoring timing marks, I can get the engine running sweetly, instant response on the throttle, easy starting, no misfiring, steady idle, all as you would expect.
......... Interesting.... but as you know, timing is very critical, and should be done using the correct procedure and tools......... not by ear!

And this is where it gets really really weird! ....I put the timing light back on and dialled-in until I could see what the timing actually is. *It appears to be: 20 Deg BTDC @ 750 RPM (should be 6 Deg)
......... As per above, a BASE or Initial advance of 16, 18 or 20 is very much incorrect.

and 34 Deg BTDC @ 2500 RPM (should 14 Deg BTDC) according to the cam-chain cover marks. (using the deepest V as the TDC mark).
......... Yes, 34* @ 2,500 RPM will eventually kill this engine.
......... Again, you need to perform a PPS procedure.

I confirmed this (as best I can) with a standard non-advancing timing light, several times.
......... You will do much better (after the PPS has been done) by marking off the balancer up to approx 35*, and by using a standard, non-digitally-advancing timing light.
This removes any user or equipment error from the equation. In other words, you will be seeing Real Degrees in Real Time, as apposed to relying on the electronics of the digitally advancing timing light!

I suspected something somewhere is way "out-of-whack", so I stripped the entire HT ignition setup down, started from scratch, one lead at a time,re-confirmed firing order, rotation of rotar-arm (clockwise). Still the same!

So, I stripped the distributor. *The distributor is a Prestolite (I think) but the points have been changed for an electronic (hall effect) pickup. *Centrifugal weights move freely (cleaned and lightly re-greased pivot-points anyway), springs are intact and firm, everything appears to operate as expected. *(No vacuum advance on these things).
......... If you have access to a shop who owns/operates an Old School Sun, King or Allen distributor machine, they can verify the advance curve for you. See your OEM specs for this. (it will not be the same as Automotive)

But,still the timing appears to be "way off their marks".
..... Suggestions:
.....verify the camshaft-to-crankshaft indexing.
.....perform the PPS and re-mark the balancer and/or timing chain cover markings.
.....start again with a standard timing light, or with your timing light in "standard" mode.

Someone suggested "Well, if you've done it by ear and it runs, close it up and forget it!", but that doesn't work for me.
......... Please DO NOT take that person's advice. He will lead you to severe and costly engine damage.


I want to know that the timing is as accurate as I can get it. *Besides, I just can't get my head around why the timing can appear to be so far off the marks, and run infinitely better than if it's "timed correctly".
......... See all of my above.

Could it be something to do with the hall effect "points"?
......... I do not care for the Pertronix system and that cheezy, small diameter, magnet embedded triggering wheel..... however, if the triggering unit is working, it should not be the root of the problem.


Is it possible the cam-chain cover from the original engine has the timing marks in the wrong place for this engine? (They are on the right-hand side, down between the cooling hoses).
......... Yes..... and that is why you will want to perform the PPS procedure.
You can buy or make a spark plug port piston stop!
Stop the piston @ approx 30* on either side of theoretical TDC...... ( a 30* split will be more accurate )
Once you aquire an equal "split", remove the PPS and bring the crankshaft around to the ZERO pointer reading.
Now is when you will verify the TDC markings.


Did the V8 ever have timing marks in a different position (more round to the left-hand side)? *
......... Yes.

Maybe if the block was originally an automobile engine? Or, maybe the block would normally be used by a different boat builder and would normally have a different cam-chain cover?
......... Not sure.

I have no idea what the origins of this block are.
Am I being stupid and missing something fundamentally simple?
......... You are not being stupid, but I do think that something is missing.

*
Click to expand...
 
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Start with the PPS procedure.
That will let you know if you are looking at the spark lead (ignition advance) accurately.
You will need an adjustable stop, a degree wheel and a temporary wire pointer.
shopping


Disconnect the battery.
Remove all spark plugs.
Bring the crankshaft around to what you think may be #1 TDC.
With your degree wheel attached, adjust the wheel and the wire pointer to read ZERO.

Now back the crankshaft off some (doesn't matter which direction at this time).
Install the PPS.

Now gently bring the #1 piston up to the PPS. (hopefully it will touch at about 30* before reaching what you think is TDC).
If not.... adjust the depth of the PPS until it does.
It need NOT be 30*..... it can be 27* or 32* or 26* or 33*.......... as long as it is equal on either side of theoretical TDC.

Now rotate in the opposite direction until once again the #1 piston gently contacts the PPS.
Keep doing this until you come up with an Equal degree reading in either crankshaft direction.
Move the pointer if need be.

Continue going CC and CCW (reaching the stop in either direction) until you see an equal split.
In other words.... if the piston is stopped at 27* while going CW, it must also stop at 27* while going CCW.
If 27* is what you see, then 27* is your "split"!

When you come up with an equal split, remove the PPS, but leave the degree wheel and pointer untouched.
Now rotate the crankshaft CW (when viewed from the front) until the pointer reads ZERO.
Your #1 piston is now at TRUE TDC.

Without moving the crankshaft, remove the degree wheel.
See if the OEM timing marks align.
If not..... make your own NEW marks.... either on the balancer, or at the timing cover tab.








After having verified #1 TDC, you may want to verify the camshaft indexing.
If you knew the full cam specs, you could check this with a degree wheel and dial indicator.
Otherwise, you will need to remove the cover as to access the chain sprocket index markings.


FYI....
crankshaft chain sprocket has 18 teeth on it.
camshaft chain sprocket has 36 teeth on it.
one sprocket tooth off on the crankshaft sprocket = a 20* error
one sprocket tooth off at the camshaft sprocket = a 10* error




.
 
Last edited:
I have fitted a recon Volvo Penta AQ211A to my boat, but have never been able to get the timing "right".
......... According to my VP info, the AQ 211 is a SBC engine.

A lot of parts from the original engine were swapped over, including the carb (now replaced), distributor, cam-chain timing cover, pulleys, Exhaust and inlet manifolds.
......... Did you verify that the camshaft was phased in or indexed correctly?

No, I assumed that as these are a professional outfit, reconditioning hundreds of engines per year, that they'd index everything correctly.

However, I had to use the harmonic balancer from a slightly newer engine, and I believe it's from an automobile. But, the key-way and TDC marks were in the same places as the original.
......... If in doubt, you will need to perform a PPS (Positive Piston Stop) procedure. This will allow you to find true #1 TDC, and then make your new TDC marks accordingly.

OK, I'll try that.

My problem is the ignition timing. *But it's NOT as simple (or maybe it is) as it first appears.

So, I rotated the engine and found TDC. No1 piston at the top, valves closed, rotor arm pointing at No1 lead.
Checked firing order (several times), as far as I can see everything "static" is correct.
......... As you know, you will begin at #1 TDC on the Compression Stroke. If the camshaft is indexed to the crankshaft correctly, both intake and exhaust valves will be closed.

Yes, they are both closed.

So, now is where it gets weird...... The engine refused to start, so I rotated the distributor until it fired-up,checked the timing (should be 6 Deg BTDC @ 750 RPM) but found that it was *initially* at around 16 - 18 Deg BTDC.
......... At 16 or 18 degrees BTDC, most any SBC will "buck" or "kick back" etc during cranking!

It certainly bucks and kicks back during cranking, but it's when I statically setup the timing using the usual marks and indexing.

If I reset the timing while it's running (using an advancing timing light - a brand new one) to 6 Deg,the engine runs rough. At this point, if I open the throttle it mis-fires through the carb and stalls.
......... If using the harmonic balancer TDC line against the timing cover marks, I would say that something is very wrong here.
The PPS procedure will tell you!

OK, again...I'll try it.

So, I set the timing"by ear". *When I do this, ignoring timing marks, I can get the engine running sweetly, instant response on the throttle, easy starting, no misfiring, steady idle, all as you would expect.
......... Interesting.... but as you know, timing is very critical, and should be done using the correct procedure and tools......... not by ear!

Absolutely! By ear was the last resort to get it running.

And this is where it gets really really weird! ....I put the timing light back on and dialled-in until I could see what the timing actually is. *It appears to be: 20 Deg BTDC @ 750 RPM (should be 6 Deg)
......... As per above, a BASE or Initial advance of 16, 18 or 20 is very much incorrect.

Yes....it is worrying.

and 34 Deg BTDC @ 2500 RPM (should 14 Deg BTDC) according to the cam-chain cover marks. (using the deepest V as the TDC mark).
......... Yes, 34* @ 2,500 RPM will eventually kill this engine.
......... Again, you need to perform a PPS procedure.

I confirmed this (as best I can) with a standard non-advancing timing light, several times.
......... You will do much better (after the PPS has been done) by marking off the balancer up to approx 35*, and by using a standard, non-digitally-advancing timing light.
This removes any user or equipment error from the equation. In other words, you will be seeing Real Degrees in Real Time, as apposed to relying on the electronics of the digitally advancing timing light!

OK, I will do that, too.

I suspected something somewhere is way "out-of-whack", so I stripped the entire HT ignition setup down, started from scratch, one lead at a time,re-confirmed firing order, rotation of rotar-arm (clockwise). Still the same!

So, I stripped the distributor. *The distributor is a Prestolite (I think) but the points have been changed for an electronic (hall effect) pickup. *Centrifugal weights move freely (cleaned and lightly re-greased pivot-points anyway), springs are intact and firm, everything appears to operate as expected. *(No vacuum advance on these things).
......... If you have access to a shop who owns/operates an Old School Sun, King or Allen distributor machine, they can verify the advance curve for you. See your OEM specs for this. (it will not be the same as Automotive)

But,still the timing appears to be "way off their marks".
..... Suggestions:
.....verify the camshaft-to-crankshaft indexing.
.....perform the PPS and re-mark the balancer and/or timing chain cover markings.
.....start again with a standard timing light, or with your timing light in "standard" mode.

Someone suggested "Well, if you've done it by ear and it runs, close it up and forget it!", but that doesn't work for me.
......... Please DO NOT take that person's advice. He will lead you to severe and costly engine damage.

I didn't! I would rather listen to people that actually know what they're talking about (it's also amazing the amount of things you can learn...and I love learning!).


I want to know that the timing is as accurate as I can get it. *Besides, I just can't get my head around why the timing can appear to be so far off the marks, and run infinitely better than if it's "timed correctly".
......... See all of my above.

Could it be something to do with the hall effect "points"?
......... I do not care for the Pertronix system and that cheezy, small diameter, magnet embedded triggering wheel..... however, if the triggering unit is working, it should not be the root of the problem.

It does appear to be working correctly. In so far as it's stable, seems to be accurate (relatively speaking), and I have a very healthy spark.

Is it possible the cam-chain cover from the original engine has the timing marks in the wrong place for this engine? (They are on the right-hand side, down between the cooling hoses).
......... Yes..... and that is why you will want to perform the PPS procedure.
You can buy or make a spark plug port piston stop!
Stop the piston @ approx 30* on either side of theoretical TDC...... ( a 30* split will be more accurate )
Once you aquire an equal "split", remove the PPS and bring the crankshaft around to the ZERO pointer reading.
Now is when you will verify the TDC markings.

OK, I've ordered a PPS tool. 14mm. Is that correct?


Did the V8 ever have timing marks in a different position (more round to the left-hand side)? *
......... Yes.

Could this be the problem? Would it mean I'd have to change the timing chain cover?

Maybe if the block was originally an automobile engine? Or, maybe the block would normally be used by a different boat builder and would normally have a different cam-chain cover?
......... Not sure.

I have no idea what the origins of this block are.
Am I being stupid and missing something fundamentally simple?
......... You are not being stupid, but I do think that something is missing.

It'll take a week or so for the PPS tool to be delivered, and for me to get down to the boat and verify things. But, I will report back.
Thanks again for your time.
​
 
Did the V8 ever have timing marks in a different position (more round to the left-hand side)? *
......... Yes.
Could this be the problem? Would it mean I'd have to change the timing chain cover?
Click to expand...

Possibly.
You can also do one of several things:
.... make a new TDC slot in the balancer and fill it in with white paint, and cross out the old one.
.... remark the tab if you have enough space to do so.
.... pick up one of these.
mrg-4593_ml.jpg





Ultimately, we would be using a marked-off harmonic balancer like this one.
pfs-80000_w_ml.jpg




In a perfect world, all gasoline Marine engines would leave the factory with a fully marked off harmonic balancer (as shown above) and a dialed in TRUE #1 TDC.



.
 
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Hi Rick,

OK, I bought a PPS tool and I can confirm that TDC is exactly where it should be. The mark on the balancer lines up with the deepest V on the timing marks.

I have had to take off the alternator at the moment (something else that's been giving me problems), so I can't run the engine for long.

But, if there's anything else I should/could check in the mean-time, please let me know.

I should be re-fitting the alternator by the weekend, so I can make a list of everything/anything else I need to go through.

Thank you,

Shaun.
 
Shaun, it sounds as though you are saying that you found the TDC Marks to be correct.
If so, please forgive me for questioning your ability on this.

Are you certain that you performed the PPS procedure correctly?

What degree of split did you come up with?

When you removed the PPS (after your equal degrees of PPS contact both CW and CCW rotation), by chance did the degree wheel and/or the wire pointer get bumped any?
 
Last edited:
Hi Rick,

I didn't actually write down the results (covered in grease and filth, and in and out of the engine-bay like a monkey).
I don't mind being questioned on it....I may well have messed-up somehow, so double-checking isn't a problem.

I *should* be back to the boat on Friday (assuming the alternator gets back to me in time). This time I'll have the wife to help.
So, I'll go through the process again and shout-out numbers for her to write down.

I'll be back with written results.

Thanks for your patience.

Regards,

Shaun.
 
shaunleveque said:
Hi Rick,
I didn't actually write down the results (covered in grease and filth, and in and out of the engine-bay like a monkey).
I don't mind being questioned on it....I may well have messed-up somehow, so double-checking isn't a problem.
I *should* be back to the boat on Friday (assuming the alternator gets back to me in time). This time I'll have the wife to help.
So, I'll go through the process again and shout-out numbers for her to write down.

I'll be back with written results.
Thanks for your patience.
Regards,
Shaun.
Click to expand...

Shaun, I do not need to see any results. I just wanted to verify that you used the procedure correctly.

I put together an image for you.
Since I cannot rotate an image of a degree wheel 30*, I had to use 90*, which means that my split will show 45*, of which is excessive.
So..... the 45* split that I show will be an example ONLY! You will be shooting for 30* or there about!

It can be 25*, 27*, 33* or close to any of those, as long as they are equal on either side of theoretical TDC.
The PPS depth adjustment will change the amount of degrees, or split.
You may be simultaneously adjusting both pointer and PPS depth, but you'll figure it out as you go!

PPS for true #1 TDC.jpg



After you find true #1 TDC, and after you make the timing mark corrections, you will now adjust your ignition advance again.
If things are still goofed up, then it will be safe to say that you have another problem that will need to be addressed.

.
 
Last edited:
Continued:

Rick said:
After you find true #1 TDC, and after you make the timing mark corrections, you will now adjust your ignition advance again.
If things are still goofed up, then it will be safe to say that you have another problem that will need to be addressed.
Click to expand...

Like said, after having found true TDC and after having set ignition advance correctly from true TDC, if things are still not right you have another problem.


It may be possible that the camshaft is not indexed correctly!
With your full camshaft specs in hand, and with the degree back in place and with ZERO indexed to TDC, and with a good dial indicator, check to see if the camshaft is operating the #1 cylinder intake and exhaust valves as per specified crankshaft degrees.



.
 
Hi Rick,

Well, I've spent the entire afternoon at the boat (6 hours). I went through the whole process you described with the degree wheel and the PPS tool.
Unfortunately, the wife was sick today, so I didn't have my spanner-monkey to help by passing tools into the engine bay.
I got a 32* split, and made sure the degree wheel and pointer didn't move.

The results were........The freaking TDC timing mark is 16* out! Who the heck produces harmonic balancers with the TDC mark in the wrong place!!??
I used a hacksaw blade and made a shallow cut at the new TDC point and painted it white.
Hooked-up the timing light, and everything came into the right positions. I timed it first with the standard "static" timing light, then checked it with the advancing timing light and they agreed with each other.

The engine now fires-up within half a crank, and runs smoothly. It revs-up without hesitation and no spitting back.
I'm going back tomorrow with the wife to take it out for a trial run. Hopefully it'll fire-up right away from cold (I can't see why it wouldn't).

I must have allowed the degree wheel to move on my first attempt, so your questioning my first results was well worth it.
I came on this forum to ask for help from an expert. And that's exactly what I got.

I am thoroughly worn-out, but very happy.

Thank you so much. Your advice and guidance is really appreciated. Thank you for your time and persistence with me.

I've added myself to your list of fans. :)

Regards,

Shaun.
 
.................................
shaunleveque said:
Hi Rick,

Well, I've spent the entire afternoon at the boat (6 hours). I went through the whole process you described with the degree wheel and the PPS tool.
Unfortunately, the wife was sick today, so I didn't have my spanner-monkey to help by passing tools into the engine bay.
I got a 32* split, and made sure the degree wheel and pointer didn't move.

The results were........The freaking TDC timing mark is 16* out!
Well.... there ya have it! Good job!

Who the heck produces harmonic balancers with the TDC mark in the wrong place!!??
It is possible that the outer ring slipped on the inner hub, of which would cause the issue.
Take a center punch and make corresponding punch marks on the outer ring and on the inner hub. This way you will know if it slips again.

I used a hacksaw blade and made a shallow cut at the new TDC point and painted it white.
Excellent!
Find a way to mark it @ 35* CW from the new TDC line.
Then go back and make marks @ 5* increments!
Or..... buy a Mr. Gasket timing decal. The decal must be correct for your balancer diameter!

You can use these degree markings for dynamic timing when using a standard strobe light.
Once you have the balancer marked off, do yourself and your engine a favor and see what the advance is doing @ 3,200 RPM.

Hooked-up the timing light, and everything came into the right positions. I timed it first with the standard "static" timing light, then checked it with the advancing timing light and they agreed with each other.
Excellent!

The engine now fires-up within half a crank, and runs smoothly. It revs-up without hesitation and no spitting back.
I'm going back tomorrow with the wife to take it out for a trial run. Hopefully it'll fire-up right away from cold (I can't see why it wouldn't).

I must have allowed the degree wheel to move on my first attempt, so your questioning my first results was well worth it.
Glad that you did it once again.

I came on this forum to ask for help from an expert. And that's exactly what I got.

I am thoroughly worn-out, but very happy.

Thank you so much. Your advice and guidance is really appreciated. Thank you for your time and persistence with me.
You are very welcome..... that's what the forums are about..... helping others!

I've added myself to your list of fans. :)
Fans...... what fans? ;)

Regards,

Shaun.
Click to expand...
 
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