Cams feel tight

Soft foot = unsupported foot that bends down or distorts the frame when you tighten bolts.
One of the weaknesses of trying to make a 4 legged machine sit flat, much better with 3 legs as all 3 legs always sit on the deck no matter how crooked.
 
Had same problem once.......bought new later head..and barrels, and cam blocks billet type and had Keith straighten cams!! Cost a fuckin fortune that lot ...but seriously sweet now, sorry to sound smug.send the lot to Keith to sort out. Meat and drink to him...
N
 
nick7 said:
Had same problem once.......bought new later head..and barrels, and cam blocks billet type and had Keith straighten cams!! Cost a fuckin fortune that lot ...but seriously sweet now, sorry to sound smug.send the lot to Keith to sort out. Meat and drink to him...
N
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I'm sure Rob will get there in the end. Just remember he is having to work upside down.  :D :D

                                                                                                        Dave
 
Well just got up after a good nights sleep, check the cam again and the fairies must have had the night off!!!
Was wondering if the cam bearing could have collapsed a dick hair, after all it is 32 years old and done 170k kms
What I can't understand is why it's ok till the torque reaches18lbf then progressively gets tighter as the torque increases.
Shimming under the cam bearing to me is a dodgy fix. Is it a normal practice??
It was binding less so with 0.04mm shim, I'll try and find something that measures 0.06mm and see how that goes.
 
Someone is smiling on me today, having searched high and low for that shimming material I knew I had and only came up with 10 thou,
I just stumbled on to another packet of brass shim, 001", 002", 003" and 005". So with that lot I should be able to set up #3 bearing to be spot on.
 
Rob I am confident your diligence is going to pay off. Your almost there you have isolated the problem to the #3 bearing, you know it needs to be shimmed, you got it. Shimming is an acceptable way to solve the problem you are having. If you replaced it with a new bearing there is no guarantee you would not have to shim it in to get it to work on the same head,  Cheers Dave
 
motoddrob said:
What I can't understand is why it's ok till the torque reaches18lbf then progressively gets tighter as the torque increases.
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I think 18ft/lb is probably the point at which the cam starts to bend a little as the bearing is probably sitting in mid-air. As you tighten above 18ft/lb the bearing settles on it's mounting while distorting the cam.
 
Maybe the faces are not fully parallel and after 18ftlb they are pulled flat, tilting the cam bearing. Are the bottom and top faces of the cam bearing parallel? That should be easy to check, but if your cylinder head is warped then that is where you need to shim.
 
Hi Simon,
I would have thought 18lbf was enough to seat the bearing, the extra 7lbf is just tension, but obviously not!!
So I slipped 4 strips of 002" brass shim under the #3 bearing, one each side of the studs. Torqued it down to 25lbf and the cam was running perfect, even better than the inlet and I was way happy with the feel of that. So I made 2 shim plates routering out the stud holes so a nice clean cut. Reassembled and retorque and the cam is binding again, fuck me!!!

Grant, the top of the cam bearing around the stud holes are well worn and recessed from the washers after 32 years of shimming the valves. Also had to run a 9mm drill down the stud hole as the ally is calapsing around the hole making it tight to lift off the stud.
I'm wondering if the bearing has distorted. Maybe a new set of bearings might be in order. Still reckon the head isn't straight.
 

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Rob reckon Maurice has hit the nail on the head cant beat fresh new blocks also they used to call those early blocks crumblers back in the day.. yours have well earned their keep. My guess is when you pulling down the extra torque you are pulling the washer further into the block and it is distorting the journal.. you might be able see the witness marks there.
You could torque then down without the cams and then give a light hone but at the end of the day you less grief by getting a set of Red's..
Mine been running for a good while now on a dodgy cam and no issues at all. My exhaust cam had "seized" before it was blue when pulled but just give it a clean, threw in a set of Red's journals inspected not long ago after they have been in around 20K and still looked good as new really.
Reckon they cheap insurance.
 
Rob, Try using a different cam block (from the inlet cam say).Be carefull in seating block in head.
If the cam frees up chances are the problem lies with block not the head.If it does free up try using the original block on the inlet cam.
Worth trying?

Andy
 
Reckon your right Maurice and 2622. I'm now having trouble removing the centre top half as it's now closed on the stud threads so they must be soft. There doesn't seem to be any consistency from one fitting to the next. The cams have be in and out like it was a honeymoon! Running out of ideas. New cam blocks might be the solution then.

Kermit, have tried swapping the blocks with all number of combinations and the cams tighten up. Currently the inlet is sorted and shimmed, just the ex is giving me trouble now.

Cheers
Rob
 
Maaate. 300 bucks for a set of cam blocks that aren't made out of cheesealloy. Cheaper than the time you have already spent, not to mention the frustration.
 
Hey Rob

I feel the timing is just right ...............

I'll give you $ 100 for the bike >>>>>>>>>>>>>>>> :LOL: :LOL:

Stick with it, we've all been there, the last battle I had was with cam timing, turned out I'd got it 180 out........ :-[ ........Fitted my timing disc on opposite side of the motor and it's times like this after several attempts at getting things right and getting more frustrated that I'd have sold the bike for $ 100 or set fire to the Fuka. Once a problem is solved the frustration turns to delight....... 8)

                                    Cheers
                                            Matt
 
Hi Rob,

Are you confident in the accuracy of your torque wrench?  It might not affect the binding issue, but could explain your deforming cam blocks, if it is applying too great a torque.

Having asked the question, a solution is not so easy.  Many expensive wrenches are surprisingly inaccurate, never mind the cheap ting tong ones, and all need checking, ideally pre-use.  I have been trying to find an Acratork rig that does not cost the earth (though even they need periodic calibration), but have not yet found a reasonably priced one in the typical car/bike torque range.

Cheers, Andy
 
 
Andy,
Collapsing cam block holes is not that uncommon, majority of the Cam blocks suffer from it.
Early shaped Blocks are by far the worst, majority of the time I just change those out on engines to our billet alloy Cam Blocks as part of the engine rebuild.
Even seen them that bad that they have bent the top of the 9mm stud.

Blocks shown in Rob's photo are the 2nd generation units, generally the area below the nut stays fairly uniform but they do still close up the hole.
I drill them to regain the bolt clearance same as Rob has done, is common issue.
Not caused by over tightening.

The deformed cam blocks are caused by 32 years of being clamped tight and being subjected to numerous heat cycles I believe.

Rob, have Billet Cam blocks in stock at the moment, ready to post if needed
You can choose standard hole position or 0.2mm or 0.4mm offset holes to regain some shim thickness, all in stock.

Good luck
Red
 
Are you confident in the accuracy of your torque wrench?  ..............Many expensive wrenches are surprisingly inaccurate, never mind the cheap ting tong ones, and all need checking, ideally pre-use.
Click to expand...
 

Worth checking out ebay for some of the older (mechanical) Snap-on torque wrenches.  In the mad rush for all things digital, they are being traded off for little money. They are very well made and extremely accurate (not actually made by Snap-on, but a quality sub contractor). Brand new low torque and high torque wrenches cost me just over ?100 the pair.

They were tested before used - very accurate and a joy to use.

Pete
 
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