Competition Lets Talk About Lifter/Valve Adjusting

[Todd T]

OK, I’ve tried to take a more scientific approach to this over the years and just wanted to see what the experts are doing and maybe get some pointers.



First, I've taken number one injector out and with a mic and flat edge I scribed the gear cover for TDC and 180 out. I use a mirror to line the marks up and always bar the engine in the direction of travel. If I go past, I take it back past and bring it back up to account for gear lash. to take it a step further, I installed a pointer and marked the dampener from below so I can see the marks as I bar the engine from below (my twins inhibit the ability to bar it from above and I don’t like the ratchet on the alternator trick)



Are we good there? Any tips?



Now, we've established I have it at TDC/180 out as precisely a possible each time (i hope). Next I set the valves in the order the manual states. This is where it gets foggy for me. I’ve always used . 010 for intake and . 020 for exhaust. I use a feeler gauge and set them to be firm with the feeler in place. My assumption here is that in a perfect world this is the spec for valve adjustment not just the range the manual tells us to use . 060-. 015 intake for example.



Any ideas here, sound good, way off base, watch ya got for me here?



My thinking is that I try to duplicate with the verified scribed marks, exact timing mark placement taking care to account for gear lash and then setting to the prescribed “perfect world” adjustment (. 010 and . 020)



Has anyone looked at this in this way, or better yet, have you played with valve adjustment to effect lift and what results have you seen there and using what measurement?



my thinkins is, we have solid tappets so we are not taking into account any preload like in the hydraulic world. The best I can gather is we just need to focus on maximum lift to achieve the best results out of the camshaft.



Discuss…. thanks

Todd

 

[COMP461]

Here is the easiest way, and the best way to adjust valves, on any 4 stroke motor , be it diesel , or gas.





Start at the front when you see the exhaust rocker start to move, stop and set the lash on the intake, this is on the back side of the intake cam lobe.



When you see the intake rocker close stop and set the exhaust . This method is even easer on a diesel where the cams are very short compared to a Pro Stock motor

 

[sbentz]

Comp is right. We have done this on all engines, and it helps keep the cam loaded right, and nice even loading.



Easier stated:



As the intake starts to close - set the exhaust

As the exhaust starts to open - set the intake



Repeat 5 times

 

[Todd T]

OK, thanks Scott and Greg. I set the valves using this method over this past weekend and i first have to say what a PITA. i barred on that damn thing for hours it seemed. this procedure IMO is best for an engine on the stand.



I set the intake to . 008 and the exhaust to . 018 which is 2 thousands tighter than i've ever gone. first observation was the engine fires quicker on start up but feels tight above 1800 or so. it just doesnt seem to want to free up on the top end. it feels good and strong just doesnt seem to e as free as with . 010 and . 020 settings.



any comments?



I'm going to check them agian using the TDC and 360 degree method again just to see if any are too tight or out of whack but my first impression is its too tight!

 

[COMP461]

The tighter you run them the better it should rev, unless something is wrong, the difference in a few thousands is too small to feel, I lash my at . 008 and . 008

This is not that critical, the reason you see most racers running the valves in not for adjustment, but to see if something is coming apart

 

[Todd T]

why so tight on the exhaust are you trying to scavenge some sort of overlaping effect?



I dont think anything is wrong, i just had the head off and was the reason for the retorque and valve adjustment plus it (head) was rebuilt about 18K ago. I could just be imagining things! may be the cold weather too.



I'll check them again and see where they stand.