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Join Date: Jun 2014
Location: Scotland, UK
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Cam Tight In Housing

Rebuilding my '80 top end.

Right cam turns in the housing very easily with 2 fingers when fitted and torqued up.

Left cam is tighter and has to be turned by gripping with the fist - once it turns its very easy to turn but a little tighter than the right.

I've read waynes book and have loosened it all off and re-torqued using a different pattern but its the same. Tried 3 times now and dont know what to try next. My gut feeling is beacause it turns smoothly and isn't binding it will be fine but why is it different?

Questions i have are :-

Could the right cam be too easy to turn (worn) and the left cam is actually normal? (Probably clutching at straws there!)

Because the left bank has been torqued 3 times and released again will the head gasket rings need replaced. They must crush/compress when the head is tightened.

Thanks in advance.....
Old 06-09-2018, 10:22 AM
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In my situation, even though the height codes on the cylinders were the same, one was slightly taller than the adjacent ones. FYI, the P&C were a used 3.4 set I had bought, not the originals. I was able to identify which cylinder was high by loosening (one end at a time), the front and rear cam carrier hold down bolts. Looked like #1 was high. I then pulled off the cam carrier, installed hold down sleeves on the cylinders and using a flat edge and a feeler gauge to determine how high #1 was. Off with the cylinder and hand lapped the top edge on my home made surface plate ( a 2' x 2' piece of 5/8" glass with 220 paper glued to it). It was only about .004" high but that was enough to bind the cam. A pain to have to disassemble but you have to get that cam turning free or else. It's unlikely it's a worn vs non worn cam causing the issue.
Mine doesn't have head gaskets so I don't know what type yours are. But if they are solid copper, then you can re-use them by annealing them. And that is as simple as heating them dull red with a propane torch.
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Last edited by brighton911; 06-09-2018 at 01:29 PM..
Old 06-09-2018, 01:21 PM
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Does can spin freely if can housing not torqued down at all? If so you have an issue with cylinder heights
Old 06-10-2018, 12:21 AM
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HI craig245t

What sealer have you between the heads and the cam box.???

take the cam box off with the still Torqued heads (leave the heads on the engine) and clean up, re-fit the cam box with NO sealer and torque up, check the cam turns OK, if it is OK, use some sealer that will not go off before you get all the nuts/washers fitted and tighten'd up, if the cam is still binding, check the cam is not bent?, then check the cylinder hights and base gaskets as above.

regards mike
Old 06-12-2018, 03:05 AM
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Sounds like a cylinder height issue. Don't understand how as no machining work was done except valve guides.
Cam spins freely before bolting down. I've assembled cam housing into heads with no sealant and it became a little tighter than the right cam. It does rotate by hand though with no tight spots.
Using loctite 574 on cam housing and a little on copper base gaskets.
Old 06-12-2018, 03:15 PM
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HI craig245t

well there you go ,

" Sounds like a cylinder height issue ",

have you pulled the cylinder off the engine? and checked how thick the 574 is between the crankcase, base gasket and the bottom of the cylinders, it will not take much to put the top end of the engine out of line.
I take it you have put the engine together in the last 2-3 weeks in the weather we have just had, the sealer will be going "off" a lot sooner, with the engine parts temp' and the out-side temp'

" Cam spins freely before bolting down. "

it will do if you have the heads and cam box bolted together on the bench, as there is no load/twist on the heads at this point, untill the heads have been bolted down to the head studs.

I take it you fitted the cylinder and pushed them all the way down with the 574 on the copper gasket, which cylinder did you fit 1St on the side with the prob', as you may find the sealer has started to set and is holding the cylinder off the crankcase/copper gasket, unless you can travel as fast as a robotic arm in a factory where 574 comes into its own and on the later engine's with fine clearances, you will find you have to travel a lot faster to get things to gether and not have Prob's, I find I remove more 574 from leaking engine than I have in the tube, I have on the shelf collecting dust

if you like you can give me a ring if you would like to?

AND before every one jumps on the band wagon, each to there own, I am not a 574 user, and some like it, so do not start a sealer thread hear as there is one in oporation all ready, this is about solving a isue with a engine build

regards mike
Old 06-13-2018, 04:18 AM
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Thanks again to all who replied. I feel much more positive about it now and am glad i didn't just push on and keep building it up. Sometimes you just need to walk away from it and think about it / ask those who know!

Good to speak with you today Mike and thank you for your time.

I have confirmed a cylinder height issue. ~2 was sitting a little higher, hopefully caused by the 574.

I've bought 574 remover and will assembly everything without sealer to confirm no binding of the cam.

The cylinders 1-3 are Mahle and have the markings as follows:-

#1 is 95ZN1W3
#2 is 95ZN1W2
#3 is 95ZN1W3

They all measure the same as far as i can tell from the top of the cylinder down to where they contact the crankcase.

Why is #2 a different code?
Old 06-13-2018, 11:40 AM
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those are casting numbers
Height numbers are in a hand stamped triangle along the top base edge of the cylinder
I don’t see how 574 is going to cause a height problem
Bruce

Last edited by Flat6pac; 06-13-2018 at 12:22 PM..
Old 06-13-2018, 12:20 PM
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Thanks........

The proof will be in assembling it all without sealant. If all is well it's the sealant. Seeing how it had set on the copper base gaskets it's highly likely it's the culprit.
Old 06-13-2018, 12:31 PM
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With the heads off, put 2 hold down nuts on each cylinder (like I think you did). Lay a machinists straight edge [a real one or a piece of “ground stock”, not a ruler] *on its edge* across the top and check for light.
If it’s not all even, look at the base gaskets; Ive seen them get squished sometimes. I *think* it happens when you have a broken stud. If one of the base gaskets got squished, that could result in a height difference.


I’m a little puzzled on where the 574 is coming into the equation. Did you put that on the base gaskets?
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Last edited by ChrisBennet; 06-14-2018 at 12:45 PM..
Old 06-13-2018, 05:31 PM
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The use of 574 is recommended in Waynes book and also by a well respected uk porsche guy. However, I think it's caused an issue and after speaking with another well respected porche guy (Mike bainbridge) I'm cleaning it all of and starting again!!
Old 06-14-2018, 12:34 PM
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