Timing Chain Tension

[Aaron Datsun]

All, I am trying to eliminate the noise from my engine when I really get on the gas, I thought it was many things, that it has not been. 

 

I had the valve cover off today and noticed how loose the timing chain is. My question to the group is this too loose? See video below.

 

It seems like it is too loose to me, but I will be the first to admit, I have not really gotten into the internals of engines very much in my time with cars, so this is an area where my experience is lacking. 

 

 

[datzenmike]

The diver's side is called the tension side. The crank turns clockwise so it is pulling DOWN on that side against the resistance of the cam/rockers/valve springs. That you might have some looseness there is just the way the engine stopped, but I assure you it's very much tight when running. Any slack in the timing chain is gathered over to the other side and this is where the chain tensioner is.

 

The tensioner is just a spring loaded shoe on the outer side of the chain pushing inward to prevent it flopping around.

 

Put a wrench on the crankshaft bolt and turn it clockwise and that slack will disappear.

 

I don't have a good picture of the tensioner in place. This is what happens down inside the timing cover if you do not secure the tension from pushing out when you remove the cam sprocket. One it gets out the only way to fix it take the timing cover off to get at it..... avoid this at all costs by knowing what to do before hand.

 

 

 

The spring is very stiff and there is an oil supply from the block on the back side. This would exert an additional 7-8 PSI as the engine revs up and the oil pressure rises. I don't think this significant but the oil does lubricate the the sleeve and piston and drips onto the chain. 

 

 

I would make sure your valve lash is properly set. If lose, it will make a racket.

[Aaron Datsun]

7 hours ago, datzenmike said:

The diver's side is called the tension side. The crank turns clockwise so it is pulling DOWN on that side against the resistance of the cam/rockers/valve springs. That you might have some looseness there is just the way the engine stopped, but I assure you it's very much tight when running. Any slack in the timing chain is gathered over to the other side and this is where the chain tensioner is.

 

The tensioner is just a spring loaded shoe on the outer side of the chain pushing inward to prevent it flopping around.

 

Put a wrench on the crankshaft bolt and turn it clockwise and that slack will disappear.

 

I don't have a good picture of the tensioner in place. This is what happens down inside the timing cover if you do not secure the tension from pushing out when you remove the cam sprocket. One it gets out the only way to fix it take the timing cover off to get at it..... avoid this at all costs by knowing what to do before hand.

 

 

 

The spring is very stiff and there is an oil supply from the block on the back side. This would exert an additional 7-8 PSI as the engine revs up and the oil pressure rises. I don't think this significant but the oil does lubricate the the sleeve and piston and drips onto the chain. 

 

 

I would make sure your valve lash is properly set. If lose, it will make a racket.

I was hoping you would reply, or someone as knowledgeable as you. I turned the engine clockwise and sure enough it all tightened right up. Thank you. As for the valve lash I set that a couple months ago, and I checked everything over again today to ensure it was all set. 

[datzenmike]

L series are considered a bit noisy by today's standards. 

 

Any chance that you may have a small crack in your exhaust manifold or maybe a leak at the downpipe connection or against the head?? What I have done on a cold engine is start it up and quickly run your hands over back side of the still cold manifold pipes. You'll feel any leak bowing out. You have almost 10 seconds before they are too hot. On another day feel around the down pipe gasket. Exhaust gets louder with engine load. 

 

I assume you are running no less than 10W40 oil? Nevada gets warm, try 15W40. It's a little thicker so the oil pressure will be slightly higher at low RPMs when it's hot. I run Shell Rotella T4 an switched from 15W40 to 10W30. I'm far to the north but only dive in the summer. Rotella is a diesel oil that still has the same ZDDP levels as 40 years ago. Oil makers today have reduced it to about half what it used to be. Engines today don't need as much zinc anti scuff ZDDP and it ruins the catalytic converters so it's slowly being phased out. Our engines DO need it. Oil makers say there's nothing to worry about but I'm not taking any chances. I encourage you to look up the ZDDP controversy and decide for yourself.                    

[Aaron Datsun]

The noise is only present at very heavy load (read wide open throttle). If I drive conservatively I do not hear it at all, it is like something is having metal on metal contact. I will try and make just a short video soon. The entire exhaust is only about 6 months old. It could very well have a leak, but I am nearly positive that isn't the noise I hear. 

 

I am running 5/30, but right now the highs are around 65* I will try running the different oils, it is about time for an oil change anyway.

Edited February 6, 2022 by Aaron Datsun
Updates

[datzenmike]

Never run any oil with a 5 in it. It's for temperatures that never get above 60F. Select an oil 'W eight' based on the highest temperature expected before the next oil change. 10W30 is much better and good down to 0 F. 

 

Wide open throttle... while driving, do you mean revved up very high speed with the gas floored? or at any speed with the gas floored??

 

The valve train chain, guides, sprockets, cam, rockers, valves do not know if the engine is working hard or not, all they do is open and close the valves. Valve train noise doesn't get louder just from stepping harder down on the gas.

[Stoffregen Motorsports]

Change in valvetrain noise is strictly RPM related. Timing chain noise too. As Mike said, load doesn't matter for those.

 

If your timing chain geometry is not set up properly, it will make noise and cause premature wear to the chain related components.

 

Valvetrain noise can come in the form of click-and-clack or a harmonic noise. The click-and-clack is improper valve lash, and the harmonic noise can be valve spring related, and usually at higher rpms.

[Aaron Datsun]

4 hours ago, datzenmike said:

Never run any oil with a 5 in it. It's for temperatures that never get above 60F. Select an oil 'W eight' based on the highest temperature expected before the next oil change. 10W30 is much better and good down to 0 F. 

 

Wide open throttle... while driving, do you mean revved up very high speed with the gas floored? or at any speed with the gas floored??

 

The valve train chain, guides, sprockets, cam, rockers, valves do not know if the engine is working hard or not, all they do is open and close the valves. Valve train noise doesn't get louder just from stepping harder down on the gas.

I mean any speed with the gas floored. 

[datzenmike]

Gets louder just from stepping on the gas??? Exhaust leak. Exhaust gets louder because engine is working harder.

[Aaron Datsun]

51 minutes ago, datzenmike said:

Gets louder just from stepping on the gas??? Exhaust leak. Exhaust gets louder because engine is working harder.

 

I wish it was, but I can't get it to replicate when not in gear, which makes me still think not an exhaust leak. I did feel all around the header, and even felt for soot, and could not find any it was clean. I appreciate your help I am not trying to be flippant with your advice. I will change the oil soon to a thicker viscosity. 

 

I could not get the car to replicate the noise today, and I pushed it very hard. I did capture the noise at ~9:00 in the below video, originally I could get that noise to replicate in every gear, in wide open throttle situations.

 

I have been avoiding that situation for the past couple months, and when I tried to recreate it a couple minutes ago, I could not get it to make the noise that I heard.

 

 

 

[datzenmike]

It probably won't do it in neutral and revving it up. There is not enough load on it. Drive it where the engine has to work hard to move the car.

 

Did you say header???? as in after market??? and NOT the cast iron manifold??? If you have a header it will definitely be leaking.

 

The bottom row of studs are between intake and exhaust and have a large washer that bridges across and holds both. The intake flange is 1/2" thick. Header flanges are never that thick, maybe 1/4" to 3/8"  and the washer sits on a slant and doesn't properly grip it. 

[Aaron Datsun]

23 minutes ago, datzenmike said:

It probably won't do it in neutral and revving it up. There is not enough load on it. Drive it where the engine has to work hard to move the car.

 

Did you say header???? as in after market??? and NOT the cast iron manifold??? If you have a header it will definitely be leaking.

 

The bottom row of studs are between intake and exhaust and have a large washer that bridges across and holds both. The intake flange is 1/2" thick. Header flanges are never that thick, maybe 1/4" to 3/8"  and the washer sits on a slant and doesn't properly grip it. 

I called it a header. It is the stock cast iron manifold. I will check all those again.

[Thomas Perkins]

Headers went out in the 70's with the hot rods,right...Header on a these 4 bangers,your funny...

Edited February 7, 2022 by Thomas Perkins

[Aaron Datsun]

I called it a header. It is the stock exhaust manifold. Sorry

[datzenmike]

Quite alright. Was hoping it was a header then it would definitely be a leak.

[banzai510(hainz)]

I do my valves .006 intake and 008 exhaust

the scheider cam spec I have says above

 

that but do what makes you feel ok with.. I did 010 and 012 for years but I like a little more quiet.

 

just take the valve cover off and rotate the cam lobe up and if the rocker wiggles then you know the valve is fully closed and your fine

[datzenmike]

Cam lobe down. confused with Z series setting.  My bad lobe up

 

The clearance at the actual rocker tip and the lash pad will always be more than what you set at the rocker and cam with a feeler gauge. The rocker arm ratio is 1.50 so if the lobe lift is 0.276" (per cam specs FSM) x 1.5 = the valve lift is 0.414" (again agrees with FSM) If you remove 0.010" from the cam lobe this, X 1.5 changes the lift at the valve to 0.399" or a difference of 0.015". A 0.012" setting becomes 0.018" NO WONDER THEY MAKE NOISE.

 

Hainz!... do you see any flaw in this. We are actually setting the cam lash but it isn't 0.012" and 0.010" at the actual valve. Your 0.006" and 0.008" is actually 0.009" and 0.012"

[banzai510(hainz)]

I just put the feeler gauge between cam lobe and rocker. as it says in the Schneider ca spec sheet I got and alwasy been using that since than.  Most book say 10/12 hot what I have read.  No big deal to me if others set if different.

Unless I understand the direction differnet than you Am, not getting it.

 

If I loose a cylinder I just do a wiggle check with the lobes pointing up and if rocker tight then its usually that rocker/valve not closing.

[datzenmike]

 Confused with Z series valve setting. My bad, cam lobe up.

 

All books say 10 and 12 but I think the actual lash at the valve is 1.5 times more and why they are so loud even set perfectly.

.

[banzai510(hainz)]

pewople should save this when getting a aftermarket cam and adjust the lash cap size This is for a Ford Pinto but almost exact copy rocker arm

Edited February 10, 2022 by banzai510(hainz)