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Old 04-30-2020, 03:25 PM   #41
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City: Brookline, NH
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Originally Posted by KDA View Post
Ken, I have a Lehman 120 - I believe it is a Dorset model but don't quote me on that. I have the manual and I believe it has to be hot before you can adjust the valves. The gap is different for intake than for exhaust. My problem is that I don't know how to identify the intake valves from the exhaust valves.
Got it. My confusion is that this is a 135 thread and I could not find your original post asking for info. And yes, a 120 is a Dorset and the valves are done differently than on the 90/135 Dover engines.

I've just looked through the service and owners manual and there are no illustrations of the head pointing out which valves are which. I can offer 2 suggestions: 1. You might be able to kind of "trace" the valve location with either the exhaust or intake manifold spout between the block and the manifold. The exhaust outlets usually have more burnt looking paint. 2. The exhaust valve spring "caps" have a slight cone upwards toward the center while the intake spring caps are flat across.

If none of that works, you could turn the engine over slowly with a wrench (in normal direction of rotation only) and watch the valves progress.

As a final sanity check, you should not expect the valves to be far out of adjustment. So if you measure some you should see something close to the .015 or .016 for the intake and .012 for exhaust. I *think* you'll find the valves are - starting from the front - IEEIIEEIIEEI. Or some pattern like that.

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Old 04-30-2020, 03:42 PM   #42
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City: Colonial Beach, VA
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PM me your email address. I have the full procedure on how to do it, with diagrams in the factory manual. I just went thru this exact thing myself 3 weeks ago and was just as clueless. Trust me.

Valves are numbered from 1 to 12 from the front of the engine.

1, 3, 6, 7, 10 and 12 are EXHAUST.

2, 4, 5, 8, 9 and 11 at INTAKE.

When 1 and 4 are open, adjust 9 IN and 12 EX.

When 8 and 10 are open, adjust 3 EX and 5 IN.

When 2 and 6 are open, adjust 7 EX and 11 IN.

When 9 ad 12 are open, adjust 1 EX and 4 IN.

When 3 and 5 are open, adjust 8 IN and 10 EX.
When 7 and 11 are open, adjust 2 IN and 6 EX,

Intake is adjusted to .015"
Exhaust is adjusted to .012"
"Everything on your boat is broken.... You just don't know it yet."
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Old 08-02-2022, 09:59 AM   #43
City: Inverness, Fl
Vessel Name: Splendid
Vessel Model: 1985 36 Marine Trader Europa
Join Date: Feb 2015
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Redhook98, your method is the method described in my manual as well. I've spoken with 2 lehman parts and builders and they use the technique in the manual also. I just adjusted my 135 and when I finished I tried the "overlap" method mentioned by the OP, to check my work. It appeared that my valves needed further tweaking. I decided to trust the manual. If someone has a different experience than me when comparing the two methods I would love to hear about it.
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