Mmoony Posted July 17, 2022 Report Share Posted July 17, 2022 Hi everyone. Got an 84’ 720 that had the head gasket done right before I got it. I’m guessing that either the head was milled too much or the timing chain wasn’t replaced in the process because it is super loose. My question - is there a way to tighten the chain without replacing it? Quote Link to comment
datzenmike Posted July 17, 2022 Report Share Posted July 17, 2022 No. The chain has a tensioning device to take up any slack. The engine turns clockwise, the left side (driver's) is pulled downward by the crank shaft against the resistance of the cam and valve springs and remains tight. Any slack is gathered on the right side where the tensioner pushes against and supports it. If you rock the engine back and forth you will see lots of play but this does not exist while it's turning clockwise when running. Quote Link to comment
Mmoony Posted July 17, 2022 Author Report Share Posted July 17, 2022 47 minutes ago, datzenmike said: No. The chain has a tensioning device to take up any slack. The engine turns clockwise, the left side (driver's) is pulled downward by the crank shaft against the resistance of the cam and valve springs and remains tight. Any slack is gathered on the right side where the tensioner pushes against and supports it. If you rock the engine back and forth you will see lots of play but this does not exist while it's turning clockwise when running. Ahh so you are saying not to worry about the chain tension? With the engine idling I feel like I can hear the chain “slapping” against the cover which is why I was concerned Quote Link to comment
datzenmike Posted July 17, 2022 Report Share Posted July 17, 2022 There is a tension and a slack side rubber coated guide to support the chain. If this is worn off it will make some noise. The straight one is the tension side the curved one the slack side. The tensioner has a stiff spring forcing the rubber 'shoe' against the chain. Oil pressure is also applied but doesn't add much at idle. What oil are you using? Is it due for a change? Quote Link to comment
Stoffregen Motorsports Posted July 17, 2022 Report Share Posted July 17, 2022 Ideally there would be smooth transitions between the tensioner and the curved guide on the tensioner side, and between the two (upper and lower) gears and the straight guide on the straight side. Sometimes this means using a file to hog out the holes on the guides. This can also mean stacking multiple rubber washers on the tensioner plunger. If the head has been milled, you should take extra time to make the chain ride as smoothly as possible, so you don't wear out the new parts prematurely. Quote Link to comment
danarello Posted August 1, 2022 Report Share Posted August 1, 2022 Wow! This topic is exactly what I was looking for! My brother-in-law just bought a 1982 Pickup Z22s and its running very rough! We checked the valve clearances and adjusted them. We did notice also that the timing chain seemed very loose and our mechanic noted that the head had been removed recently. He assumed that the head was milled and that would account for the slack in the chain. In addition, my mechanic struggled to turn over the engine by hand to adjust the valves which he thought was unusual with all the 8 spark plugs removed. Our plan is to look for a new or used engine to replace the one in the vehicle. 1 Quote Link to comment
banzai510(hainz) Posted August 2, 2022 Report Share Posted August 2, 2022 milling a head 10 20 30 thou is not going to make the slapping sound the tensioner and slack side guide takes most of this up. 1 Quote Link to comment
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.