Chain's too tight

[siteunseen]

Recently rebuilt 2.4 with a super tight timing chain, I started off new in #2 hole on cam sprocket.  It seems like I might be losing some power with that setting and want to go with hole #1.

Would that loosen the chain up a little?  Relieve some of the strain?  Thanks for any help/direction. 

[djwarner]

The different timing holes do not affect the tension, it only adjusts the relative timing between the crank and cam to account for chain stretch. The chain tensioner takes up any difference in the overall length of the chain. If the chain you used was new, there is no advantage in not using position 1.

Mounting the cam sprocket with a new chain can be difficult both because angular misalignment of the stiff chain before the sprocket mounts. Also, the chain tensioner does not make thing any easier. You can try to ease things a bit by using a thin tie wrap to get the maximum squeeze on the tensioner before mounting

[heyitsrama]

was the block decked or the head resurfaced?

[Zed Head]

How do you know it's too tight?  The notch and groove will give an idea of where cam timing will end up if you move to a new hole.  Did you mean too tight or too advanced?

[madkaw]

Cliff,
What does your butt dyno tell you that you think your cam is not giving all the power ?
Not sure someone could tell without a dyno.
If your engine seems a bit doggy there could be many reasons other than cam timing .
Only way to be sure of cam timing is a degree wheel


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[Chickenman]

As per FSM, #1 hole is factory position for new chain and components and unshaven head. If you actually got the cam sprocket on the Cam.. the chain's not too tight. New chain with new guides and tensioner can be an SOB to install. Double check the notch and groove for Cam timing as mentioned. As long as they're in spec, you should be Golden. Head or block shave may require using #2 hole to align notches.

I usually prefer to have the Timing Cover removed and the oil pan loose when I setup a new chain, tensioner and guides. Two head bolts loosely installed in the back of the head. I position everything but leave the top bolt loose on the curved guide. Then I swing the curved guide in to position and adjust it to provide the specified amount of clearance on chain tensioner. Then install the TC over the dowels. Secure TC with fasteners. Check that bottom of TC is flush with block. Assemble and torque head bolts, then bolt up the oil pan last.  Honsowetz recommends that method... seems to work well.

 

Edit: I just checked my 1976 280Z FSM and tensioner protrusion, with all new parts, is supposed to be set at 0.0mm by adjusting the curved guide. However, I do like to have a bit of clearance there just to make sure things aren't too tight. It also makes putting the Timing Cover on easier as you can move the head up a bit and fit the TC over the dowels at front of block.  .050" to .100" should be sufficient clearance with all new parts

 

 

 

Edited January 13, 2017 by Chickenman

[siteunseen]

Thank you all for the replies. 

I had one helluva time setting it up, like Chickenman says it was a SOB to get the sprocket on.  I had the valve cover off  yesterday and tried squeezing the chain in a little but NO movement, tight as a guitar string still.  I guess I haven't driven it enough to put wear grooves in the side guides?

Steve my old #110 that I sold was an older build and it just seemed looser and had a better rev up through the gears.  This one has a new to me/it 5 speed and aluminum flywheel so it go through gears fast, I'm not used to that.  It feels like it needs more timing but I can't go any more with the plate's groove.  I'll put some miles on it and think about what to do next.  Thanks again guys.  Cliff

 

[siteunseen]

11 hours ago, Chickenman said:

Edit: I just checked my 1976 280Z FSM and tensioner protrusion, with all new parts, is supposed to be set at 0.0mm by adjusting the curved guide. However, I do like to have a bit of clearance there just to make sure things aren't too tight. It also makes putting the Timing Cover on easier as you can move the head up a bit and fit the TC over the dowels at front of block.  .050" to .100" should be sufficient clearance with all new parts

I remember using a pry to get the curved guide as tight as possible.

I can see it in this picture.  And what looks like a gap on the tensioner plunger is actually a black rubber washer, it was tight!

[Chickenman]

You may have over done the tightness a bit with the prybar. It doesn't have to be that tight. The good news is that it will loosen up. Pour LOTS of oil down the curved side of the chain before starting!!

As the chain wears and stretches, the Cam timing retards. Same thing if you shave the head. #1 hole is Zero advance. #2 hole advances cam 4 crank degrees ( to offset retardation from stretching of old chain ) #3 advances Can timing by 8 crank degrees. I've never seen a L seriers have to use hole #3. Advancing cam from " Straight up " install ( Hole #1 ) usually results in a gain of some bottom end Torque, at the expense of some top end power. Sometimes useful if engine is Over-Cammed ( See Racer Brown's articles ). However, you really need to degree the cam to be sure, as has been mentioned.

Generally, on a DD or mild Competition engine, I will just install a Cam straight up. Otherwise it's Dyno time to see what the effects of advancing/retarding camshaft really are. .

[siteunseen]

Thanks Cman!  

I used a long screwdriver probably to get the guide into it's tightest position.  One day it'll loose  up. 

[madkaw]

Did you try moving the cam during install? Sometimes a fraction of an inch will let the sprocket fall on the hole.



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