I just finished my timing belt and was setting the ignition timing...I advanced the timing a tiny bit more than before (but timing is still really retarded) and hear no pinging or knocking at idle. If there is no pinging/knocking at idle will there be any at WOT or when vtec lobes are in use (since those pushes the valves open deeper). I am assuming pinging/knocking=valve-to-piston contact; if not, that is what I was really concerned about. I just don't want my valves to come in contact w/ the pistons since my head is milled really low. So if there is no valve contact sounds at idle can it be safe to say I won't get any at all through the entire power band?

 

no, pinging is NOT valve to piston contact. that's valve float, and it is BAD.
pinging is preignition, uncontrolled burn of the mixture.
most of the time pinging is not present at idle. and in most honda application only happens at part throttle when the mixture goes lean. at WOT ECM goes gross rich and dumps fuel. set your timing ahead, then drive it in high gear (third works for me) at low speed, if you hear "***** bouncing around" or pinging, back it off.
stan

 

Hey thanks Stan; so what about them valve contacting? If I don't hear any during idle, should I still be cautious and look out for the sounds anyways around vtec (due to the changeover to bigger lobes)?

 

there is really no way to know if you will get valve/piston clearance problems. unless you clay the motor when you assembled it.
stan

 

Well said, 90crxsi

 

"no, pinging is NOT valve to piston contact. that's valve float"

valve float is when the valves stay open when they should be closing this usually happens at very high rpm's where the valve springs are not rated to go. this can result in valve slap which is where the valve make contact with the piston.


[Modified by NonovUrbizniz, 5:34 PM 11/7/2002]

 

just what i said, maybe not the best wording
stab

 

I know that, but my head is milled more than .040" + higher lift cams; that is why I asked.

 

I will disagree. Honda engines ARE interference engines. That's why there is so much damage when a timing belt breaks. If they weren;t, people wouldn't worry about replacing them until they break.

Set your ignition timing and give it some throttle and see if you hear anything. If not, take it for a drive and see if you hear/ feel anything. But watch yourself, advancing the timing TOO far is going to hurt performance! That's why you get on the dyno and see where you need to set it at. Also, when you mill your head .040 and use high lift cams, I would HOPE that you would clay your engine during assembly or know how to tune, cause this is how you ruin your engine...

 

i agree, a guy i know here in louisville who pulled a 5-2 downshift (not intentionally), and voila', 6 bent exhaust valves.

 

I'm a get on the dyno soon, thanks.