Valve Adjustment
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Freshman User
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Valve Adjustment
I just got a new motor, thought it was locked up, turned out to be a giant piece of carbon not letting a piston complete its stroke, thought it was a valve stuck open so I took off all the rocker arms. Then it came time to put the rocker arms back on, I got on here, ran a search, came up with a dozen different answers. Sooo ~1975 300 motor, how do you tighten down the rockers?
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From: DeKalb, Ill.
You have to turn the crank shaft so that you're working on every cylinder at TDC.
Spin the push rod with your fingers. Tighten the rocker nut until you can't spin the
push rod any more. Then give the nut one more full turn. Rotate the crank 'till the
next cylinder is at TDC, repeat.
Murph.
Spin the push rod with your fingers. Tighten the rocker nut until you can't spin the
push rod any more. Then give the nut one more full turn. Rotate the crank 'till the
next cylinder is at TDC, repeat.
Murph.
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Thanks Murph but I already got her figured out. I adjusted the valves yesterday, tried to fire it last night, nothin. Got home from work today and ran compression, 2,4,5 were all nonexistant. (lifters were probably collapsed when I adjusted yesterday) 4 and 5 adjusted no problem but 2 has given me nothing but trouble, finally I just left 2 unadjusted and tried to fire the motor, it finally chugged to life, shot oil everywhere (no valve cover) roared for a minute and then I let her die. Tomorrow I'll put it the rest of the way together, radiator, alternator, power steering, clutch linkage, you know all that good stuff. Being a junkyard motor I inititially thought was locked up and had rust on the cylinder walls and valve stems I just wanted to hear it run for a moment to make sure it wasn't already ruined. She did me proud. Once I get her the rest of the way together I'll get her in time, adjust the carb, make sure nothing is leaking and hopefully be able to drive the old girl by wednesday evening.
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From: Halifx Pa
You have to turn the crank shaft so that you're working on every cylinder at TDC.
Spin the push rod with your fingers. Tighten the rocker nut until you can't spin the
push rod any more. Then give the nut one more full turn. Rotate the crank 'till the
next cylinder is at TDC, repeat.
Murph.
Spin the push rod with your fingers. Tighten the rocker nut until you can't spin the
push rod any more. Then give the nut one more full turn. Rotate the crank 'till the
next cylinder is at TDC, repeat.
Murph.
+1, and EXCELLANT description on what to do. I did a lot of research on this topic till I found the answer. I ask a lot of very knowledgable mechanics and was supprised at the different answers I got.
Now, not to muddy the waters, but a few mechanic freinds also told me who know of the one full turn as factory spec said they learned to go 1/4 to 1/2 turn instead of the full turn, they said they found the motor to run a little better, and was not so tight. Just food for though.
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no you're right, you have pedestal mount rockers, you should just have torque them to spec and thats all she wrote, non-adjustable valvetrain. the older motors have stud mount rockers which are sort of adjustable but really you just have to adjust them once for the life of the lifters unless you mess with them or a nut backs off or something goes wrong in other words.
Elder User
Joined: Sep 2008
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From: DeKalb, Ill.
I actually went through the firing order multiple times, only tightening when the push rods would spin.
It was interesting to see how much play was created by a turn through the firing order.
After adjusting 1 through 6, there was considerable play by the time I returned to #1. Multiple times!
Sometimes I don't feel comfortable suggesting an idea of mine that varies from the Gospel (75 Ford shop manual).
It's nice to see others with the same ideas
Murph.
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