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Old 04-18-2016, 05:43 PM
SteveH SteveH is offline
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Default FJ40 - 2F head work - valve job needed?

I was all set to replace the valve stem seals in the '77 2F in my FJ40, so I applied shop air to the spark plug holes, after removing the rocker rail. This was to hold the valves shut for the stem seal swap. I heard quite a rush of air from all 6 holes, with #5 being the worst. The breeze past the valves was enough to blow out a kitchen match (lit and stuck in the hole). You can feel the air rushing out on your hand, too.

The engine has 90K miles, has always had regular valve adjustments, shows 105 psi compression (at 7000') on all 6, and only jump 3-5 psi with oil added to a cylinder. The engine runs absolutely fine.

It now seems that a valve job is likely in order - do you agree? I presume that you should not be able to feel air rushing out of the intake or exhaust ports with this kind of applied air pressure ~100 psi? I tapped a few valve stems to see if I could reseat the valves under pressure, and it made no difference in the leakage.

Is Gunn still the place to take this, if I should decide to take it to Denver? Also, I had considered having .020 or such taken off the head to bump the compression a bit. I know you can take more, but don't want to go crazy on this. Would any of you recommend a mild shave at the same time as the valve job, and can Gunn do that? Our local NAPA can reface a head, but cannot remove significant material.

Thanks - Steve
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Old 04-19-2016, 12:22 PM
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I was all set to replace the valve stem seals in the '77 2F in my FJ40, so I applied shop air to the spark plug holes, after removing the rocker rail. This was to hold the valves shut for the stem seal swap. I heard quite a rush of air from all 6 holes, with #5 being the worst. The breeze past the valves was enough to blow out a kitchen match (lit and stuck in the hole). You can feel the air rushing out on your hand, too.

The engine has 90K miles, has always had regular valve adjustments, shows 105 psi compression (at 7000') on all 6, and only jump 3-5 psi with oil added to a cylinder. The engine runs absolutely fine.

It now seems that a valve job is likely in order - do you agree? I presume that you should not be able to feel air rushing out of the intake or exhaust ports with this kind of applied air pressure ~100 psi? I tapped a few valve stems to see if I could reseat the valves under pressure, and it made no difference in the leakage.

Is Gunn still the place to take this, if I should decide to take it to Denver? Also, I had considered having .020 or such taken off the head to bump the compression a bit. I know you can take more, but don't want to go crazy on this. Would any of you recommend a mild shave at the same time as the valve job, and can Gunn do that? Our local NAPA can reface a head, but cannot remove significant material.

Thanks - Steve
One of the engines I built, I lapped the valves and was quite happy with the result. I did discover that the little suction cup thingie that came with the lapping kit was pretty worthless and devised a method to do it by chucking the stem to a drill. As you might imagine, you must be meticulous in removing any lapping compound when done!

Lapping probably isn't as thorough as cutting, but it is a heck of a lot cheaper, and the turnaround is entirely under your control.

While I was at it I removed the carbon on the undersides with a 3M abrasive wheel.
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Old 04-19-2016, 12:39 PM
SteveH SteveH is offline
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That's an excellent idea if I see that the valves aren't obviously burned or damaged. Thanks! I have always suspected that the suction cup thing couldn't really work....
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Old 04-19-2016, 02:08 PM
frontrange frontrange is offline
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The suction cup thing works, it just takes forever!

Using a length of vacuum hose from the valve stem to a drill is faster, but awkward...

Best thing I found for lapping is a suction cup in a drill, still takes a while, but less awkward and you have one hand free for a beer.
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Old 04-19-2016, 03:18 PM
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That's an excellent idea if I see that the valves aren't obviously burned or damaged. Thanks! I have always suspected that the suction cup thing couldn't really work....
I would love to see pictures of the valves and seats if/when you dig into this.
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Old 04-19-2016, 10:57 PM
SteveH SteveH is offline
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Well, I pulled the head and removed the leakiest valve #5 exhaust. Seat looks good (to my untrained eye) but the valve has some recession from the seat. Valve stem seals are totally shot, as I knew. The cylinder bores looked excellent.
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Old 04-19-2016, 11:40 PM
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Love the bottles and cans of stuff in the background and the (image of) the iPad in the foreground...Steve why aren't you coming to Cruise Moab?
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Old 04-20-2016, 06:41 AM
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powderpig powderpig is offline
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Wow, those margins look real wide. The nice thing about having the valve ground and the seats cut, is you return your the parts back to the margins that it would be best for sealing and heat transference. The wider the margin(width of the seat and valve) you have the more likely you have to burn a valve.
Anything over 1/8 (and over time these areas will widen) will create less heat transference and thus potential to burn a valve over time.
I can also see where the valve is grooved, this does not allow all the air to full get into the engine, and the valve will not fully open that little bit. every little bit helps in efficiency of the engine.

Do your self a favor and have a machine shop do a valve job, mill the head .030-.040 and enjoy the new found power and smoothness that you will have.
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Old 04-21-2016, 09:49 AM
SteveH SteveH is offline
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Robbie and Jeff - thanks for your thoughts/observations. I called Gunn and will be taking the head there ASAP. The Gunn guy definitely seemed to understand what I wanted and said things that sounded right.

I would like to get to CM, but after raising kids for 18 years, my wife and I are taking an extended vacation (without kids) early this summer to a far away place (Scotland). This is the patient woman who supports my 'cruiser hobbies and drives my old semi-beater cars without complaint. Seems the least I can to to indulge her.
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Old 05-15-2016, 05:36 PM
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Default Block prep for head replacement?

OK - I got the head back from Gunn - they were nice to work with. Took 3 weeks instead of 2. They were quite friendly and had no 'attitude' at all. $245, including $30 to tap and plug the oil galley (didn't know a '77 had one), and .030 shave for a mild compression bump. Valve job, of course, and they used the Toyota valve stem seals that I supplied. All the hard parts were good (guides, seats, valves, springs).

Anyway - they suggested I just scrape the engine block surface with a fresh razor blade to prep it for the head gasket. There's a lot of baked on crusties on the block, and it seems each time I scrape it, I get more off. In the past (on iron-block Camrys) I used a light green Scotchbrite disk on a power drill and simply buzzed the block until it was clean. (This was a specific Scotchbrite disk for this task - not just a kitchen version). Gunn seemed wary of affirming this approach, as they thought it could leave the block wavy.

The Scotchbrite I used was far too mild to remove any iron, unless you hogged on it for a long time, which I obviously would never do.

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