Hot valve adjustment

[gstallons]

Yeah , SnapOn used to sell these clips that would go on top of the rocker arm so oil wouldn't shoot out the tip of the pushrod onto everything .  

 I'm pretty sure I still have them .

[Lucky Phil]

7 minutes ago, gstallons said:

IDK about a MG , but you can do it on a small block Chevy . It takes practice and patience or a lot of hubris .

I've seen it done on an old in line 6, they idle pretty low. Not sure what the point was.

Ciao

[LowRyter]

A small block with solid lifters?  Like a Z/28 302 or L79 327 or LT-1 350 or what?  Adjust while it's running?  

(When you say small bock, you don't even have to say Chevy.  It's a "small block".)

[po18guy]

Had a 283 bored to 292 with a 350hp/327 hydraulic cam. To keep the hyd lifters from pumping up at high revs, the trick was to loosen them (running) until the plunger was at the end of its travel - just starting to tap. Then 1/4 turn in and you were good for revs. 

[Lucky Phil]

4 hours ago, LowRyter said:

A small block with solid lifters?  Like a Z/28 302 or L79 327 or LT-1 350 or what?  Adjust while it's running?  

(When you say small bock, you don't even have to say Chevy.  It's a "small block".)

Unless you're a Guzzi guy.

Ciao 

[pete roper]

I've actually done some fairly thorough testing on this and generally with the 2V engines even running them hard on a rolling road while holding the rocker cover on by hand until they were scalding and then whipping the head off and finding TDC immediately the gaps would remain virtually unchanged on squarefin motors with the alloy rocker covers and would close up *A bit* with roundfins with cast iron rocker carriers. The only time I know of the clearances close up enough to cause problems is on engines run with the mid nineties 'US Emissions' clearances of two thou inlet and four exhaust on the squarefins. If engines are run really hard with these clearances in hot weather for extended periods the will stall if they come to a halt quickly, indicating, one would guess, that the tappet is riding the cam and the exhaust valve is being held off its seat. In 'Normal' use it isn't an issue.

With the roller tappet 1200 8V's the gaps will definitely open up as the engine gets hot and gets bigger the hotter it gets. If you look at the construction of the heads, valves and camboxes it is self evident why.

 

[gstallons]

8 hours ago, LowRyter said:

A small block with solid lifters?  Like a Z/28 302 or L79 327 or LT-1 350 or what?  Adjust while it's running?  

(When you say small bock, you don't even have to say Chevy.  It's a "small block".)

Either one .  After the advent of emissions and emission controls laid all over the engines  , you would follow the service manual and bar the engine over unit the # 1 cylinder valves were overlapping and adjust certain ( I used to remember ) valves , rotate the engine 1 revolution until # 6 valves were overlapping and adjust ( I used to remember ) the rest . Install the valve covers and all the clutter & you were done . 

[LowRyter]

4 hours ago, gstallons said:

Either one .  After the advent of emissions and emission controls laid all over the engines  , you would follow the service manual and bar the engine over unit the # 1 cylinder valves were overlapping and adjust certain ( I used to remember ) valves , rotate the engine 1 revolution until # 6 valves were overlapping and adjust ( I used to remember ) the rest . Install the valve covers and all the clutter & you were done . 

yes, but while the engine is running? 

[LowRyter]

9 hours ago, Lucky Phil said:

Unless you're a Guzzi guy.

Ciao 

Got me.

[gstallons]

5 hours ago, LowRyter said:

yes, but while the engine is running? 

Uh , no . You did this on a cold engine . This was getting 1 turn after zero lash . These were factory camshafts with hydraulic lifters .

[po18guy]

So, TDC is found by looking in the spark plug hole? No nifty cap to pull on the crank nose with a rotor clearly marked "TDC1" and "TDC2" on them?  

[GuzziMoto]

10 hours ago, po18guy said:

So, TDC is found by looking in the spark plug hole? No nifty cap to pull on the crank nose with a rotor clearly marked "TDC1" and "TDC2" on them?  

There is typically a mark on the flywheel. But it is easier to pull the valve cover and rotate the engine until the piston comes up (a pencil in the sparkplug hole will tell you that) looking for TDC of that piston with both valves closed. One TDC will have both valves somewhat open and the next TDC will have both valves closed.

As I recall, the mark on the flywheel is typically in Italian. S for Sinistra (Left in Italian). If you want to see the mark on the flywheel there is a black plug on the flywheel bell housing you can pull. Try not to loose the plug.