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C-8 Head Bolts

2608 Views 83 Replies 10 Participants Last post by  jrd
Today I was able to successfully remove all 12 head bolts from my C-8. I’ve been spraying them with a little PB Blaster from time to time, and decided to attempt removal today. I started by attempting to tighten each one just a touch, and then loosen each one just a touch before tightening again. After that, all the bolts unthreaded easily.

Before replacing the gasket, any recommendations besides cleaning up the cylinder head? Also, what is the best way to clean up the head? How about the piston and valve heads?

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None of us here knew anything when we started. One day you'll be the expert, and will pay it forward :)
BTW, for what it’s worth—I’m glad you all have the free time and willingness to help out people like me who know next to nothing about this stuff!
On the L there may be shims under the axle housing where it joins the trans. Carefully clean and reinstall those, but don't add any more gaskets or anything. If there's a gasket when you disassemble, mic it and install one same thickness.

The two axle housings are custom fitted to each unit, to center and set the preload on the big tapered rollers that hold the axle. You want to keep that clearance undisturbed.
3. Reassemble axle housing. (Replace gasket/seal while doing this?)
Good tip. I’ll pay attention to that.
On the L there may be shims under the axle housing where it joins the trans. Carefully clean and reinstall those, but don't add any more gaskets or anything. If there's a gasket when you disassemble, mic it and install one same thickness.

The two axle housings are custom fitted to each unit, to center and set the preload on the big tapered rollers that hold the axle. You want to keep that clearance undisturbed.
There is a lot and good group.

I really appreciate everybody’s help. I learn so much here.
Is there just the one hole in the end of the rod?
Some have 2, the older models. From memory .

1. Drain the oil
2. Remove left side axle housing and inspect and clean out oil pick up screen. Plus check for loose hardware.
3. Reassemble axle housing. (Replace gasket/seal while doing this?)
4. Connect compressor at 15 PSI as shown above, and ensure crank is in correct position. 15 psi or less, you have sludge in the crankpin which you do not want to stir up.
5. Apply air and watch for oil to exit rod hole.
6. Reconnect oil line and fill back up with oil.
Correct to above, red info added.
Treating this as a keeper, :)
Pics added below. Note large ID of crankpin. Sludge builds up here.
Pic 2 note the locking tab is missing on the swifty bolts.
Pic 3 Some swifty's had lock had lock washers which failed

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:D

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So true. I miss Roger B.
None of us here knew anything when we started. One day you'll be the expert, and will pay it forward :)
Thanks for adding to my list in red.

Great pics illustrating the issue with the bolts. Hopefully mine has the locking tabs vs lock washers.

Regarding the sludge, what can/should be done to remedy that?
It just happens. The wear of parts over time. Maybe every 10 years of use chase the sludge.
Change oil after 40 hours of run time.

Regarding the sludge, what can/should be done to remedy that?
On the L there may be shims under the axle housing where it joins the trans. Carefully clean and reinstall those, but don't add any more gaskets or anything. If there's a gasket when you disassemble, mic it and install one same thickness.
Follow this process. I use rtv on shims/gasket and have no oil leaks.
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I would definitely use a good thread tap on the bolt holes. New bolts, thread lube, proper torque and tighten pattern.
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Thanks again for all the tips thus far. It will be a bit before I get a chance to move forward, but I’ll post updates once I do.
For bolt holes I use a thread chaser instead of a tap whenever I have the right size in my set. A tap will remove metal and give a looser bolt fit than cleaning the threads with a chaser.
Found a Snap On CF-19 valve spring compressor tool on eBay. Just waiting for it to arrive now.

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I can find inexpensive METRIC thread chaser sets online, but not inexpensive SAE sets. However, I can find some less expensive SAE taps. How important is this if bolts seem to thread OK?
If they thread good I wouldn’t worry about it.
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You can also cut groves the length of the threads on a bolt and use it as a chaser. Just don't forget to lube the hole well so the bolt doesn't stick.
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Good idea.
You can also cut groves the length of the threads on a bolt and use it as a chaser. Just don't forget to lube the hole well so the bolt doesn't stick.
Things have been busy, but I had a
minute to remove the retaining rings holding the piston, as well as remove the valves and get some measurements of the bore. I took two measurements at the top, center, and bottom and got the following: 3.25, 3.24, and 3.25. Interestingly, I read the standard bore size is 3.2535 - 3.2545, so it looks like my measurements are a bit off. Nonetheless, I imagine that after a quick hone of the cylinder I should be able to stick with a new standard size piston?

Attached are some pics of the valves and seats.
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Out of curiosity, generally speaking how does one know when the valve guides need replaced? I assume mine are fine, but thought I’d ask.

I started going through a parts manual and began making a list of things I’ll need. I thought I’d include the parts here in case it’s useful to anyone else in the future.


(2) 12731 valve spring washer gasket

(2) 12732 upper cover gasket

(2) 13076 piston retaining rings (if not included with piston)

(1) 14592 piston (standard size)

(1) 14594/20163100 piston ring set standard

(1) 12614 cylinder bottom gasket

(1) 12597 axle housing gasket
I would say so. How did you measure? Calipers? An inside mic? It's tricky getting a good measurement inside a bore like that.

Note also that the service manual specifies bore-to-skirt clearance, which IIRC is .002-003. As long as you're in the ballpark there you're good.
Nonetheless, I imagine that after a quick hone of the cylinder I should be able to stick with a new standard size piston?
Attached are some pics of the valves and seats.
Those actually look really good! I wouldn't touch 'em, just clean 'em and button it up.

Out of curiosity, generally speaking how does one know when the valve guides need replaced? I assume mine are fine, but thought I’d ask.
There's a spec, but that's even tougher to measure accurately.

What I usually do is just slide the valve in, almost all the way, and then try to wiggle the head back and forth. If it moves more than a tiny bit, your guides are probably worn.
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Thanks, JRD. I used a pair of calipers and a telescoping gauge like the one you mentioned.

Glad the valves and seats look ok.
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Just curious as to why you want to replace the piston? Is it because of the scratches in the skirt?
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