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'68 CL350 Engine Issue [message #301140] Sat, 31 August 2019 17:48 Go to next message
HubbaBubba is currently offline  HubbaBubba   United States
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Registered: August 2019
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(1) Club Racer
Hello All,

I bought a 68 CL350 with a seized engine. Tore down the engine, replaced cylinder jug and pistons with a +0.25 set, cleaned out everything thoroughly, and reassembled.

Now is my problem. When I try to turn it over, either with the kick or with a spanner, it gets stuck on the right exhaust valve. It won't compress. If I really push on the kick AND the wrench it will. The rest of the valves compress and release easily. If I take the rocker arm out for the right exhaust valve I can turn the engine over and over without hang-up.
I thought, Okay, let's get these serviced. Got the best guy around to do it. Still, it happens.
The valve does not indicate any bend. It moves freely with very minor wiggle in guide (no wiggle when oiled). Opening it up with the compression tool did not feel any more or less difficult than any other valve.
I switched rocker arms and pins between the lot. No other combination or valve has an issue. I checked and the piston is DOWN and not hitting or even close to hitting. Valve face, piston, and cylinders show no signs of touching or rubbing. Timing has been set the dozens of times I tried again, then double-checked.
I've tried setting the valve spacing to spec as well as opening it up as much as I can, for said valve as well as a combination with the rest.
Neither cam nor rockers nor pins show any significant wear nor measure out of spec.
What might I be overlooking?
Thanks for reading. I really appreciate any insights.

Re: '68 CL350 Engine Issue [message #301141 is a reply to message #301140] Sat, 31 August 2019 18:34 Go to previous messageGo to next message
Kakugo is currently offline  Kakugo   Italy
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(18) Geoff Duke
Not model specific, but on Lycoming aircraft piston engines (father was a pilot) stuck exhaust valves were pretty common and due to lifter and especially camshaft wear.

I had a check on a couple of parts catalogs and it seems on that engine the camshaft was replaced in 1969 and the parts are not compatible ... maybe a previous owner rebuilt the engine with what he could find and mixed and matched camshafts? It would also go a long way towards explaining the seized engine... Wink
Re: '68 CL350 Engine Issue [message #301142 is a reply to message #301141] Sat, 31 August 2019 19:34 Go to previous messageGo to next message
spagiratwink is currently offline  spagiratwink   United Kingdom
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(6) Moto1 GP Racer
Hi , could it be that the inlet and exhaust valves were swapped over,because reading this it looks like the valve seat diameter is larger on the inlet and may be interfering with the exhaust head as the open/close, just a thought
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Re: '68 CL350 Engine Issue [message #301145 is a reply to message #301142] Mon, 02 September 2019 00:37 Go to previous messageGo to next message
HubbaBubba is currently offline  HubbaBubba   United States
Messages: 2
Registered: August 2019
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(1) Club Racer
Thanks for the responses. The intake and exhaust valves are definitely in their respective places, just double checked my double check.
And looking into the newer camshafts - the old one gradually gets fat in the middle, which is what I have. Looks nothing like the replacement style.
I took everything apart in the head to make sure no springs were flipped. Then I started attempting various combinations of things. I found that I can get the right exhaust valve to compress and release if I remove the rocker for the left intake. Engine will turn over. Same again if I remove right exhaust rocker and put back in left intake. The occurrence of the lobes for these two on the cam are close. both valves are trying to compress, at different stages in timing, at the same time.
With both rockers in I cannot get it to turn over.
Re: '68 CL350 Engine Issue [message #301146 is a reply to message #301145] Mon, 02 September 2019 06:54 Go to previous message
spagiratwink is currently offline  spagiratwink   United Kingdom
Messages: 581
Registered: January 2016
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(6) Moto1 GP Racer
Hi ,do you have the CL350 manual, which I can send you if you don't, can only think its the assembly of the camshaft sprocket and those 2 bolts (which are different), never worked on one of these , so hard to figure your predicament , could it be the governor alignment pin on the camshaft (page 38 of the manual) when assembling
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