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Can I Remove Cam Tower and Leave Heads on Engine?

Hi,

Just got my 77 2.7L engine stripped down to the point of removing the cam nuts. In Wayneís book, it shows taking the cam housing off with the heads. I had some odd leakdown numbers with air escaping at the head region- thought I hadnít got the tester sealed in the plug hole due to the sound of the leak. Tried several times and same result- got almost perfect readings in half the cylinders, so I think the tester works.

I want to try and see where the air is leaking and if I have an engine problem or a problem with my test and I think having the cam business out of the way would make it easier to verify.

So, can I just remove the cam housing and chain boxes leaving the heads bolted down?

Thanks,
Rutager
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1977 911S Targa Chocolate Brown
Old 02-26-2018, 04:06 PM
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Yes, but you have to be conscious about not moving any of the heads because you have 18 studs that need to be lined up to replace cam carriers.
Bruce
Old 02-26-2018, 05:38 PM
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Thanks Bruce,

I will be removing the heads afterwards as I got a foreign object in #5 that iím pretty sure wrecked the exhaust valve as I got a lot of air out of the tailpipe, so this is just a investigative step on my way. Iím hoping to leave the pistons and cylinders alone, but will send the heads out for sure.

Best,
Rutager
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Old 02-27-2018, 02:58 AM
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Maybe a stupid question, but if youíre going to pull the heads anyway, why not just pull the cam housings/heads as a unit now?
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Old 02-27-2018, 04:22 AM
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Quote:
Originally Posted by Steam Driver View Post
Maybe a stupid question, but if youíre going to pull the heads anyway, why not just pull the cam housings/heads as a unit now?
Read his first post.
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Old 02-27-2018, 07:10 AM
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Quote:
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Yes, but you have to be conscious about not moving any of the heads because you have 18 studs that need to be lined up to replace cam carriers.
Bruce
You wouldn't need to worry about lining anything up because leaving the heads torqued without the cam towers on, then ONLY torquing down the cam tower is 100% the wrong way to do it.

If OP does this, he must do his tests with the heads torqued, THEN loosen the head bolts. Then, replace and torque the cam towers, and finally, torque the head bolts once again.

Cam towers are ALWAYS torqued before the head bolts. So if you loosen the cam towers......
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Old 02-27-2018, 08:35 AM
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The original question was. Can it be done? My explanation was of the original question with what to watch for.
Not that I recommend that way of assembly, I ve build engines from completed sub assemblies, as in many of the pictures I’ve posted over the years. that’s the way I worked in auto production, body shop until retiring and played with my Porsche’s building motors.
But the answer still is, you can build an engine any way you want as long as you can get it together.
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Old 02-27-2018, 10:23 AM
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Hi guys,

Thanks for chiming in on my question, just for clarification, the whole cam and head business are eventually coming off, just wanted to put air on the heads and cylinders to try and troubleshoot my odd leakdown experience. Getting the towers out of the way will give me better plug hole access and take the cam/rockers out of the equation of any issues.

I will follow proper protocol when putting it back together.

My initial thought on the engine was a repair of #5, but it is looking likely that a top end including pistons and cylinders might be called for.

Best,
Rutager
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Old 02-27-2018, 01:39 PM
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Quick update, removed all the rockers with my just today purchased Snap-on stubby Allen sockets and 1/4 drive ratchet for the 5mm, it fit in nicely.

Gently pried the cam housing off without breaking any fins.

Got the leakdown tester on and air was blasting out the exhaust ports on 1 and 2. I may try and fit a plug in there to stop the air so I can see if my rings and intake are healthy.

Rutager
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Old 02-28-2018, 05:35 PM
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If you don't have air coming out your intake ports, intake valves are probably OK. But this is of no consequence - you have to take those heads off to replace the bent exhaust valves. With the head on the bench it is easy to check valve seal with Windex or soapy water. Combustion chamber up, solution sprayed on valves, squirt air into port. At normal seat pressure, if they seal you won't get bubbles. If there is a leak, it will show up with just a little air pressure - it is not as if it won't leak at low pressure but will at high.

I used some rubber on a piece of aluminum with holes for the intake studs to hold it in place. Put a fitting in the center of it so I could attach a hose. When grinding my valves and seats I'd drop the valve in and blow in the hose while pushing down on the soapy valve heads - if bubbles appeared, back to the valve grinding machine.

I suspect you could just put the nozzle of your air gun in the port and pull the trigger, and that would be enough to create bubbles if there was a defect in the seat with the valve springs installed.

Interesting idea about trying to see if your rings are doing OK, though generally, absent physical damage you can see or measure when all is apart, you aren't apt to have bad rings on some cylinders, and good rings on others.
Old 03-01-2018, 09:44 PM
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Good information and suggestions Walt, thanks.

I did put the leakdown tester on a couple good cylinders and could hear air from the crankcase breather port, so some air is getting past the rings, albeit probably very little.

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Old 03-02-2018, 02:46 AM
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My experience is that there is always some air you can hear when you put a tube in your ear and stick it down into the inside of the case, like via the oil breather. As long as the actual leakdowns are good, I don't think anyone worries about that. If you had bad numbers, but no bubbles around the intake and exhaust valves (spray soapy water or Windex into the ports with an engine with the intake and exhaust off), that would be different.
Old 03-04-2018, 12:29 AM
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