Checking valve timing

[Azar]

Hello,

Is it possible to check if the valve timing is correct without taking the timing chain (front) cover off the engine?

I took the right side (cyl 1-3) valve cover out and adjusted the valves. The photo is showing sproket position at the TDC (the exhaust cycle, not compression/ignition).

The car has Volvo pistons with 9.5:1 compression ratio and the motor is not running smooth, nor has it full power since the rebuild.
I found this very useful site, it is showing slightly different position of the sproket: https://www.tmproductions.com/repairs-and-maintenance-blog/2014/9/13/30l-valve-timing , not sure it is TDC though.
Thank you!

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[Michael]

Maybe I'm oversimplifiying this but can't you just put a timing light on it and look at the plate?

PS...also shatfaced so, ....

[Azar]

Hi Michael, I am talking about valve timing. The ignition timing is perfect. But then again, ignition timing comes from the ignition distributor which is driven by the left camshaft. My left bank is running lean and my right bank is running rich. All injectors and ignition system as well as fuel pressure are new/perfect.

I suspect that my left or right camshaft is out of alignment.

[dn010]

Went through this last year or so. No real way to easily check it to be sure, as far as I know, without removing the cover and looking at the timing marks on the crank and sprockets. Not sure if the DMC shop manual has the procedure to check the timing after chain install, but the 3.0 Engine overhaul manual does. I thought I had done mine correctly until I did the valve timing check and realized I somehow was off. The attached should start right after you have done the "RH timing chain" install (which is really the left / non oil filter side of the engine) and the timing mark on the crank is aligned with the lower oil pump bolt. You then start the check by rotating the engine 180 etc. Luckily I still had mine on the stand, really sucks to find out you're wrong with it already in the car.
https://dmctalk.org/attachment.php?attachmentid=71673&d=1749668616

[Azar]

Thanks Dan!

Anyone happen to have the engine open, can set the TDC and see how the Cam sprockets should be? I then can easily compare to my cams and understand If I have it wrong! Thank you!

[David T]

The way to check it is to use a Dial Indicator and check a valve while watching the timing mark at TDC. you can compare the left side vs the right side. My suspicion is that if you were off you would get backfires so I doubt the valve timing is wrong but it is possible. While you are checking things, recheck the firing order. Maybe you got 2 cylinders mixed up? Maybe you don't have the valves properly adjusted? Also verify mechanical advance and vacuum advance is working and every cylinder is firing. Easy to do, use a IR temp gauge and check the exhaust port temps.

[Azar]

Thanks David! Can you elaborate on "use a Dial Indicator and check a valve while watching the timing mark at TDC. you can compare the left side vs the right side."? I presume you mean mean how the cam shaft oriented against the valves at TDC left Vs right?

Firing order is correct, valves are adjusted, the mechanical advance looks also OK - how to check the vacuum advance?

Interesting idea with the IR thermometer!

I have checked the ignition systems it's OK and I have also pulled each cable separately from the spark plug while engine was idling - same engine response on all plugs.

[David T]

You put a dial indicator on a valve and see when it starts to move (or stops moving) in relation to others. To check vacuum advance you use a timing light and measure the amount of movement when you put a vacuum source on the vacuum advance. Sometimes it is hard to find your own mistakes. Maybe get another set of eyes to go over things like the firing order.

[dn010]

Joe also had an issue with timing, his didn't backfire but had rough idle and the exhaust turned red on one side:

https://www.tmproductions.com/repairs-and-maintenance-blog/2017/12/2/ignition-and-rough-idle

I'd still opt to remove the cover, even if it's a PITA, over messing around comparing side to side with a dial indicator and hoping I'm making sense of the findings.

[Azar]

Thanks David and Joe!
David,
I think I found a way to check the valve timing without opening front cover. I can turn right cam sprocket to 45 degree, assume that this is where the pin of the crankshaft should point to, mark it on the main crank pulley. Turn the engine 270 Deg (90 Deg left since the engine is 90 Deg V) and check the alignment of my mark on the main pulley with the left cam sprocket. If it is not aligning means one of the cams is off timing.

Yes, I am consulting with two friends and also the mechanic who rebuilt the engine.

As for the vacuum advance - I don't see any movement connecting and disconnecting vacuum hose.
I know I get the vacuum on the warm-up regulator when the engine is cold.

Dan, thanks for the link! Yes, he corrected the timing and got a much better idle. Mine is not backfiring either but I need to check the temp of the exhaust pipes! His left side was 115 and right side 300-400.

I will post now the video where you can hear the idle and revving.

[Azar]

Here is the Video.

https://www.youtube.com/shorts/A2RtX5aKXGc

- Ignition system all new and new injectors spraying evenly, timing 13 deg idle, increasing to 20+ with the revs. Vacuum does not make a difference.
- No cat, empty case, stock exhaust
- Control and primary pressures are correct (both Warm-up regulator and fuel distributor rebuilt by DMCH proior shipping to Germany)
- Volvo pistons with 9,5:1 compression ratio.
- Left bank compression 10-11 bar, right bank compression 11-12 bar.
- Left bank sparks plugs like new, white. Right bank spark plugs dirty and black
- CO 2,5%, Lambda 1,2, HC above 350 (rich and lean at the same time!)

[David T]

Thanks David and Joe!
David,
I think I found a way to check the valve timing without opening front cover. I can turn right cam sprocket to 45 degree, assume that this is where the pin of the crankshaft should point to, mark it on the main crank pulley. Turn the engine 270 Deg (90 Deg left since the engine is 90 Deg V) and check the alignment of my mark on the main pulley with the left cam sprocket. If it is not aligning means one of the cams is off timing.

Yes, I am consulting with two friends and also the mechanic who rebuilt the engine.

As for the vacuum advance - I don't see any movement connecting and disconnecting vacuum hose.
I know I get the vacuum on the warm-up regulator when the engine is cold.

Dan, thanks for the link! Yes, he corrected the timing and got a much better idle. Mine is not backfiring either but I need to check the temp of the exhaust pipes! His left side was 115 and right side 300-400.

I will post now the video where you can hear the idle and revving.

You hook up the timing light and while watching the timing mark you apply a vacuum to the vacuum advance with a hand vacuum pump and see how much advance you get. Then, with the vacuum disconnected you rev the motor up and see how much mechanical advance you can get. Not sure about your method of checking cam timing.

[dn010]

Just. Take the cover off. And fix it!

:banghead:

[Azar]

It does indeed look like the timing is off. Left bank by 4 teeth and right bank one teeth. I don't understand how did this engine still run.
Now I need to find the reliable guidelines since my chains have no markings...
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[Azar]

Is there a reliable procedure how to set up timing without marked chains? Thanks!

[dn010]

Transfer the marks off the old chain if you have them. Otherwise, use the attached as a reference to mark your chains.

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[dn010]

Let me try the photos again. The replacement chains on my engine had no marks either, I used the old chains and marked the new ones with some nail polish. How was the timing set without any marks to begin with?
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Edit: Go by the long marks on the chain, I do not know what the white dot was for.

[Azar]

Hi Dan, I just saw your message! Nevertheless I did exaclty same - found my old chains and counted them. He did same when he was building the engine but he missed LH (right side) by one chain piece - two teeth!! Assembled everything again and it runs silky smooth now! Thank you anyway - I came up with the same solution yesterday :) Just finished assembling everything together - what a nice feeling after 3 years! Tomorrow is the test drive :)