Concern - Slight side to side play in Cyl #4 exhaust rocker arm - TCCoA Forums

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post #1 of 6 (permalink) Old 03-03-2017, 01:45 AM Thread Starter
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Concern - Slight side to side play in Cyl #4 exhaust rocker arm

TCCOA Braintrust:
I worked on my tbird again today to prep it for my race. After doing some piddly double checking of some brake stuff, I decided to continue with my engine reassembly by installing the pushrods/rockerarms.

Background:
- Rocker arms are original from the GT40 Heads w/ 185K mi on them
- Pushrods are Sealed Power and new since my last rebuild (19 laps + 1 full race old). All were cleaned, oiled, and inspected for wear at the end tips (none) as well as being straight (rolling on flat surface).
- Valve Lifters are FRPP and all new since my last rebuilt (1 race old); replaced because several had collapsed.
- I did notice the two bolts in the valley that hold the plate that holds the lifter retainers were loose but I tightened those back up.

Reassembly of these items is fairly straightforward but in my inspection of the rockerarms with their retaining bolts torqued to spec (25 lb-ft), I found that the rearmost rocker arm on the pass side (Cyl #4, left rocker aka exhaust IIRC) seems to have some side to side play.
- NONE of the other rocker arms exhibit this behavior on either side of the engine
- FWIW, there doesn't seem to be any play up/down (around pivot point of the rocker arm). I seem to recall that when the lifters collapse they exhibit they become slopping along THIS AXIS (up/down) vs side to side as I'm seeing now.
- Finally, I tried rotating the engine by rotating the crank and the behavior/sloppiness doesn't change (still with that rocker arm).

Q: Is this something to worry about considering I'm going to run this engine hard for the next race (14-16 hours @ 3K-5K RPM constantly)?
Is the lifter starting to go? is the rocker arm out of spec/worn?
If so, what should I replace? Just that rocker arm assembly (with pivot), just the pivot, the lifter, or some combination of the above for both the intake/exhaust for that cyl?
I'd rather solve this issue now when I still have time to mail order parts vs right before the race (or evern worse -- during the race).

Please advise.
Thanks,
-g

PS. Tonight I plan to swap parts on that side with another rocker arm/lifter to see if this is causing the issue.

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post #2 of 6 (permalink) Old 03-03-2017, 12:56 PM Thread Starter
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I called a machine shop friend for advice and he suspects that the issue is because that specific lifter has probably just bled down. When the engine was last stopped, that valve was open/shut/whatever and the lifter was drained.
- If I swap the lifter with another one and the sloppiness follows that lifter, it's probably the that it was drained.
- If I see wear on the underside of the rocker (on the pivot) and the issue moves to a different valve if I swap rockers, it'll be the rocker.

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post #3 of 6 (permalink) Old 03-03-2017, 02:19 PM
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I would swap the rocker arm around before swapping the lifter. As a matter of fact, some lifters you can't get out without pulling the heads.

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post #4 of 6 (permalink) Old 03-03-2017, 02:35 PM Thread Starter
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Quote:
Originally Posted by MadMikeyL View Post
I would swap the rocker arm around before swapping the lifter. As a matter of fact, some lifters you can't get out without pulling the heads.
OK mike.
Q: Do you think it's just a dry lifter?

- I kind of remember swapping them before with the heads on but i don't recall for sure.

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post #5 of 6 (permalink) Old 03-03-2017, 06:04 PM
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It could be. If the lifter bleeds down, the spring pressure is not enough to hold everything tight, but if it is a collapsed lifter, it should be tight when the cam has that valve open. At this point though, swapping it with another one is an easy test to verify that.
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-91 Cougar LS, coming soon, complete overhaul with a 427" Windsor.
-90SC 5-speed, MP2, coated rotors, double intercooler, 15%OD, ported heads, comp stage 1 cam, 85mm TB, 90MM LMAF, 80# injectors, soon to be transplanted into...
-90 XR7 5-speed black on black w/sunroof
-98 Mark VIII LSC, Procharger P600b, TR3650 swap and 3.73s.
-70 Torino GT Fastback project car. Needs EFI and a manual trans, but I'm not sure what motor to go with yet.
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post #6 of 6 (permalink) Old 03-05-2017, 02:26 AM Thread Starter
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Quote:
Originally Posted by MadMikeyL View Post
I would swap the rocker arm around before swapping the lifter. As a matter of fact, some lifters you can't get out without pulling the heads.
So MadMikey is right again: you CANNOT pull out a hydraulic lifter without having the heads off the block. Damnit.

I did swap the rocker/pivot with the one next to it and found that the side to side sloppiness follows the rockerarm+pivot. Upon closer inspection, you can kinda see where it's a little shiny in the pocket. Gonna buy a new one now ($8.50 shipped from rockauto).

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