Checking timing chain in351m
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Junior User
Joined: Feb 2005
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Checking timing chain in351m
I'm wondering if my method of checking the timing chain on my 351m is accurate.
I rotated the crank with a socket on the damper bolt while another person observed the dist. rotor. I could rotate the crank 10 degrees in opposite directions before the rotor began to move. I could also feel the increased force required when the cam started to turn.
Would this give me an accurate picture? and is 10 degrees of slack excessive?
I rotated the crank with a socket on the damper bolt while another person observed the dist. rotor. I could rotate the crank 10 degrees in opposite directions before the rotor began to move. I could also feel the increased force required when the cam started to turn.
Would this give me an accurate picture? and is 10 degrees of slack excessive?
Laughing Gas
Joined: Jan 2006
Posts: 883
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From: New-brunswick,Canada
how many mile on your 351m ? If you have more than 50,000 miles don't bother checking-replace them.if not,turn crankshaft to tighten one side of chain and mesure the slack side.put a straight edge on the two gears and mesure the slack.Your not suppose to have more than 1/2" deflect between your straight edge(12-inch rule for ex) and the chain.Be sure to press on the middle of the slack side when you mesure.
New User
Joined: Dec 2004
Posts: 12
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From: Arvada CO
This worked for me.
Hook up a timing light, disconnect the vac. advance, Rev the engine to about 2K and hold that steady. Using the timing light watch the timing marks, if steady the chain is OK, If it swims up and down then replace the chain.
Mine would swim +/- 3 degrees B4 replacement, steady after. 1977 351M approx. 140K on the clock.
Hope this helps!
Hook up a timing light, disconnect the vac. advance, Rev the engine to about 2K and hold that steady. Using the timing light watch the timing marks, if steady the chain is OK, If it swims up and down then replace the chain.
Mine would swim +/- 3 degrees B4 replacement, steady after. 1977 351M approx. 140K on the clock.
Hope this helps!
Laughing Gas
Joined: Dec 2000
Posts: 780
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From: East Texas
Mustang 81 is correct, assuming the timing chain is stock, original, it has nylon gears. Typically not long lasting (though my original made 280,000 miles). Might as well change the timing set and be certain.
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Well I don't know what to think now. I was hoping to get by with not having to remove every thing if I didn't need to.
I read on one post somewhere that my method was the way to check it with out removing the cover and got the results I outlined above but just to be sure I tried '79 ford nuts ' method and it held steady as a rock.
Jeez I don't want to pull everything to get a look at it but I might have to. I guess with the slack I can feel its a pretty good bet it's bad and probably original.
I read on one post somewhere that my method was the way to check it with out removing the cover and got the results I outlined above but just to be sure I tried '79 ford nuts ' method and it held steady as a rock.
Jeez I don't want to pull everything to get a look at it but I might have to. I guess with the slack I can feel its a pretty good bet it's bad and probably original.
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I pulled everything off and got at the chain. I had about 1 in. deflection in the chain when the opposite side was tight. I have been told that there shouldn't be more than 1/2 inch so that answers that question. I ordered a new set from summit. I'll put it in in a couple weeks and see if that solves the problem I set out to solve which is low vacuum. Thanks for all your input
