hey guys i'm trying to set my valve lash and need to know how to tell that number one cylinder is at TDC. I read through shoebox's site and i get the concept of valve lash and everything. I just need to know when TDC is. I have the intake off so i can see the pushrods moving.


Thanks

Jason

 

both valves on #1 will be closed. that is TDC.

 

The most accurate way to find TDC is to take out the spark plug and stick a rod or screwdriver in the hole. Then move the crank to feel when its at TDC. I had to do it that way with the CC306 because when both valves were closed, it was still about 10* off of TDC.

 

agree wit above...there is valve overlap on some more aggressive cams.

but, the easiest way is to stick a pen or something SOFT, NOT A SCREWDRIVER, in the hole. when it sticks straight out it's up high...

 

You cannot set lash at any TDC, it has to be TDC on the firing stroke - otherwise because the valves open BTDC you will setting the lash incorrectly.

The easiest way: When the exhaust valve begins to open, stop and adjust that cylinder's intake valve. Then continue to rotate the engine that intake valve will go to full lift and then begin to close. When the intake is almost closed, stop and adjust the exhaust valve on that cylinder. Move on to the next cylinder, or as you rotate the motor through, watch for the above indications on any cylinder and adjust the corresponding valve.

 

Yep, that's they way to do it!

It's the way most often recommended by the cam companies and how the "Big Boys" do it at the track.

Jake

 

F'ing A...I just realized I believe I may have completely set my lash incorrectly last night...

I pulled an all-nighter in the garage, towards the end of which i set the valve lash, and completely neglected to use my cylinder leak down tester to find top dead center (like I normally do). I cranked over the motor and watched the exhaust lifter open/close, then watched the intake lifter/rod open/close, after the intake valve closed I believe I turned it a lil' bit further (with no lifter movement) then proceeded to set lash on both valves on that cylinder...

....so uh, I'm not sure what exactly that changed...I'm pulled another long night; not exactly in the clearest of mind....do I need to reset all lash now? I just got the motor in the car a few hours ago...

 

Oh, YES. You have to re-adjust the lifter preload (I'm assuming you're running a hydraulic cam).

If you set BOTH at the same time, one of them is definitely mis-adjusted. The engine will run like a 'DOG' if it even starts and runs at all.

Just use what we call the E/O I/C method that was posted here earlier.

Remember, watch the EXHAUST to set the INTAKE; then watch the INTAKE to set the EXHAUST.

Keep us posted.

Jake

 

Ok, I'll add it to today's "To Do List". Out of curiosity, I'm trying to wrap my head around why it would be off. Theoretically if i watched both lifters bottom out then their lobe low base must be aiming up, meaning both valves are completely closed, correct?

Or is their movement that my eye isn't catching? You want to set zero lash with the valves completely closed right? If so, then shouldn't my lash be set correctly if I watched to make sure on each cylinder both valves were completely closed?

I have a feeling I'm incorrect, just trying to clearify/learn more about this.

Thanks,

 

Okay, try looking at it this way:

There are several different ways to adjust lifter preload (hydraulic cam) or valve lash (mechanical cam). All of them will work if done correctly. What it boils down to is that one method is less prone to error than the others.

In setting lifter preload/valve lash the most critical of all the steps is to be ABSOLUTELY sure the lifter is on the base circle of the camshaft lobe when the preload/lash is set.

Just as in phasing (degreeing) a camshaft there is one step that is the MOST critical - making absolutely sure that TDC has been established. In phasing a cam and finding TDC, like when setting lifter preload/lash, there are different ways to establish it but it's just that ONE WAY is less prone to error than the others.

Back to lifters: I've tried just about all the methods of setting preload/lash-except the one that came out of left field where it was recommended to use a dial indicator. I settled on one that always gave consistent and positive results. It's the E/O I/C method. Coincidentally, it's the same method that you'll find in the CompCams, TPIS, Crane, etc., catalogs.

In the "Heat of Battle" and "going through the valves" at the track between rounds, it's crucial to use a method that's reliable with virtually no chance of error. The E/O I/C method fits the bill.

Other methods may work well, it's just that you'll run the risk that one of the lifters is actually on the ramp and not the base circle (heel) of the lobe.

Which method to use is one of those topics that is continually debated on various Forums; each has his own view. Same thing as how much preload to use; 1/16, 1/4, 1/2, 3/4, etc. TPIS now advocates in their LT1 book, TWO FULL TURNS OR MORE!! Guys who have experienced lifter failures might want to re-consider their preload setting.

But like other things, it's your call. Best I can do is give the best advice I can and pass on the results I've experienced over the years.

Hope this helps.

Jake

 

Thank you very much.

I'm going to give this E/O I/C method a shot.