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Can’t reinstall exhaust camshaft

Oliver Boy

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Hi
First time engine rebuild- I am learning a lot 😝
Full disclosure; I thought I had completed the engine rebuild on my ‘81, until the fact I had zero compression led me to realize I mistimed both cams on installation.
I do understand I may have damaged valves, we will see.
( If you can think of a name I did not call myself, feel free to insert it here.................)

I have removed both camshafts as per my Clymer and am trying to reinstall the exhaust sprocket on the shaft.
I’m pretty confident everything is lined up properly ( this time ) but I don’t quite have enough slack in the camchain to mount the sprocket onto the shoulder of the shaft.
The tensioner is fully locked in the slack setting.
I did read a thread here that seems to suggest installing all the bearing caps to snug the shaft down- but I couldn’t decide if this idea was being endorsed by AMC or not 😳.
My Clymer does not indicate any difficulty here, so any suggestions will be gratefully received.
 
The problem being of course if you snug cams down then at least a couple valves open and you bend them again. About 4-5 different things happening every time you so much as move one of those cams and your head has to be at ALL of them at once.

Go here..........

http://www.cb750c.com/modules.php?name=Your_Account&redirect=viewtopic&t=301

.........and enroll for free and then look up the technical documents section and download the OEM service manual for free and ditch that Clymer, there's no telling how many engines they have ruined.

It's always hard to get that cam sprocket on, you just have to do it as carefully as you can. The order of things absolutely cannot be changed, part of it being to arrange for the crank to be in such a position as to not bend, vary at ALL and you got bent parts as it is a very small window there.
 
Hi
First time engine rebuild- I am learning a lot ��
Full disclosure; I thought I had completed the engine rebuild on my ‘81, until the fact I had zero compression led me to realize I mistimed both cams on installation.
I do understand I may have damaged valves, we will see.
( If you can think of a name I did not call myself, feel free to insert it here.................)

I have removed both camshafts as per my Clymer and am trying to reinstall the exhaust sprocket on the shaft.
I’m pretty confident everything is lined up properly ( this time ) but I don’t quite have enough slack in the camchain to mount the sprocket onto the shoulder of the shaft.
The tensioner is fully locked in the slack setting.
I did read a thread here that seems to suggest installing all the bearing caps to snug the shaft down- but I couldn’t decide if this idea was being endorsed by AMC or not ��.
My Clymer does not indicate any difficulty here, so any suggestions will be gratefully received.

You and me both mate, its a bloody nightmare :cussing:
 
(Booberhead)

Hey, you asked ;)

Look on the bright side, lessons learned the hard way are not easily forgotten.

I have a laptop in the garage for service manuals and music, an old one running XP and isolated from the network. Anything I need on it is transferred via a flash drive. Hondas, auto and cycle, are very finicky about following design specs and procedures.
 
If you are at TDC #1 cylinder, 1.4 T, you should be able to install the cam bearing caps and camshaft of ONLY ONE camshaft without bending valves. One camshaft opens 2 valves, the other cam will open the other two valves. With only the exhaust camshaft installed, only one pair of valves will only be able to open. This should allow you some more slack to get the chain on. Note: even with the cam bearings installed, the chain still requires some manual force to install completely, but it should at least install 2/3 of the way on the sprocket after torqueing caps. Lastly, I used a set of channel lock pliers and a small spade bar to pry the chain on the sprocket. Also, you may need to "stretch" the chain [ towards you] by placing a spade type bar or screwdriver on the inside of the partially installed chain, and push it the chain towards the front of the motor or towards you, so it stretches and goes onto the sprocket. Don't stab yourself in the chest lol. Also, only stretch the chain onto the sprocket only when you are at 1.4T, the cam lobes are towards the #1 plug, the sprocket is aligned with the block and everything looks good. The chain should again be 2/3 installed before stretching. I know its hard to imagine, but the chain does 'stretch' a little. You might have to "push and pull" with both the pliers and channel locks. Push on the chain towards you, and simultaneously grab the chain with the pliers and laterally force it on the sprocket. Hope this makes sense.
 
'...1.4 T, you should be able to install the cam bearing caps and camshaft of ONLY ONE camshaft without bending valves.'

NO.

You can bend the valves by hitting them together in a lock OR you can bend them at TDC as well, the fully open set then hits the top of piston all the way up. They are ONLY safe at max lift as the piston is creeping up on them or drifting away both before and after TDC but at TDC they WILL hit. Exhaust usually the easiest to do that.

Wez still has the correct idea as modified by actual use. The sprocket of course goes on easier with the cam all the way down and bolted tight by the caps but some valves are open then enough to bend. OEM lift is either .290" or .310" depending on cam so just over 1/4 inch. You can both move the cams a little off the marks and open the valves by tightening the caps down a bit but the last bit of valve lift is what kills you. You have to watch the effects of ALL the cam lobes as they hit valve tappets to drop them and stop with any one getting down too far, this limitation of yourself is what gets the sprocket on easier but it also makes you risk bending and why I commonly get real quiet rather than say to do it. I have done it all day long and successfully, but many can't, it being a skills thing.

Consider dropping the piston a bit to before TDC, it gives you room to tighten caps down a bit. Get sprocket on the pilot and then move the crank back to TDC while still considering where the cams are at.

This may help...................the exhaust valve hits piston easiest about 5-7 degrees BEFORE TDC, the intake hits easiest around 5-7 degrees AFTER TDC. Anything in between those two points is whack one set of valves or the other if they are at max lift.
 
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