Camshaft Profile Question

Status
Not open for further replies.
Joined
May 10, 2005
Messages
2,731
Location
Toronto, Canada
I did a valve clearance adjustment on a Caterpillar C7 inline 6 truck engine. Firing order is 153624. I thought I had the engine at TDC at the end of the exhaust stroke for cyl 1 to adjust 1I&E, 2I, 3E, 4I and 5E. I found out later that I had not turned the engine over enough, the engine was only half way through its exhaust stroke and I was off by 90 deg/quarter turn. Similar situation for the second half of the valve adjustment when I thought I had TDC for cyl 6.

Do I need to pull the valve cover off again and recheck? Engine sounds normal now with no clatter indicating excessive lash.
 
Originally Posted By: George7941
the engine was only half way through its exhaust stroke


You might be fine, butt he ONLY way to be sure is check the valve lash again.

Trust, but verify.
 
Setting valves by the TDC method is too troublesome - set them on the back of the cam...so when No6 inlet is wide open, set No1 inlet, and so on. You can still set 2 valves at once because there will always be another valve nearly fully open. If you get confused, mark each valve you set.
 
I would absolutely 're check the lash.

I learned how to lash valves quickly and easily from a friend who used to crew a fuel funny car. The method works on any 4 cycle engine.

Start on cylinder #1 rotate the engine until the exhaust valve just starts to open, once the exhaust valve just starts to open, adjust the intake valve on the same cylinder.

Continue to rotate the engine over, once the intake valve has fully opened and just starts to close, adjust the exhaust valve on that cylinder.

Now cylinder #1 is done.

Repeat process for the remaining 5 cylinders.

The beauty of this method is that it works regardless of firing order and you can start on any cylinder. It's how I've lashed valves for at least 20 years now.
 
Originally Posted By: FlyNavyP3

Start on cylinder #1 rotate the engine until the exhaust valve just starts to open, once the exhaust valve just starts to open, adjust the intake valve on the same cylinder.

Continue to rotate the engine over, once the intake valve has fully opened and just starts to close, adjust the exhaust valve on that cylinder.


That's how I do single cyls, if I can't see the cam itself. But apart from triples and V twins, multi cyl engines will have one cyl 360 degrees firing from another cyl, so these ones are easy to do with the valve opening method - just so much easier to flick the engine over on the starter, see a valve fully open and adjust it's opposite number.
 
Originally Posted By: Silk
... But apart from triples and V twins, multi cyl engines will have one cyl 360 degrees firing from another cyl, so these ones are easy to do with the valve opening method -...
Apart from 5-cylinder engines, too.
 
Thanks for all the feedback. I will recheck valve lash.

Originally Posted By: andyd
Re- check. It isn't the noisy ones that burn.

No risk of burning from my error. There is a possibility of excessive lash, no risk at all of insufficient lash.
 
I have always used charts very similar to this one:
1293632403_408_FT2874_466valves_.jpg
 
Oops! I made a mistake in my original post. It should have been "I thought I had the engine at TDC at the end of the COMPRESSION stroke for cyl 1---".

Linctex's chart shows the exact way I did it.
 
Status
Not open for further replies.
Back
Top