^-- Maybe if the engine has 300,000 miles and the valves have recessed into the cyldiner head...



Even then...

Otherwise they can touch, especially at higher RPM's.

 

Didn't want to get into this because of the "HUGE" debates that spawn out of it...

 

I am running 4.88's with a engine that had 250,000 miles on it..

I was running 5th gear at 80mph when my timing chain broke. That's almost 4500 RPMs. I didn't touch anything. Trust me I feared the worse. Not realizing my chain broke I cranked my truck over trying to start it. Once I heard only the bottom end turning I realized what had happened.

I searched multiple threads and even asked fellow members if I junked my valves. I received mixed answers on it. So I decided to do my own experiment to determine If they could touch. And they can not. Or at least not on my engine.

 

^--- Very interesting and very lucky.

But if had to guess the high mileage probably saved the engine as silly as that sounds.

Could just be lots of luck... with the camshaft "springing" back and ect. and ect. and ect.....

The valves do not occupy a huge amount of the piston travel space but a they do.

 

so i took off the throttle body and cleaned it and now it idles and runs pretty good, im not sure if cleaning the throttle body did it or if adjusting the tps did it since i had to remove it. next thing i need to address is that horrible valve ticking that i hear now, thanks for all the help everyone it is much appreciated

 

Glad to see the good progress.



Adjust your valve clearance(lash).

^-- *Make sure the engine is warmed-up to operating temperature*

 

If I recall right the valves are .08 and .12 but dont remember which on intake or exhaust. I dont have my book, but seems like it has been recommended or suggested tha .07 and .11 for adjustments. These do like to to tick. Even after adjusting them I have still got them to tick. One trick I do is after getting it running, is to use a mechanics stethoscope and it will help determine which ones are still noisey and then I recheck and readjust them making sure I stay in parameters.

It doesnt necessarily tell me if it is the intake or exhaust valve, but it gets it to the cylinder. Otherwise it is kind of difficult for me to see which cylinder it is.

 

so i just took the runner in to get a smog check and i did a presmog because i figured it wouldnt pass and the guy told me it was running on 3 cylinders at 22deg btdc, so im thinking maybe i did bend a valve by breaking that chain or this has been running on 3 cylinders since i bought it.

now i need to buy a compression tester and maybe an air compressor and leakdown tester