valve to piston clearance

[fastback4]

Can someone direct me to a link that has specs for the int. / exh. valve to piston clearance on a 3100 and 3400 engines from 1997-2000+.........Tom

[86FieroSEv6]

I don't know if there are any actual spec.s available as it is so subjective a factor with regards to equipment being used. Here is a link from people who know what they are talking about when it comes to making power.

http://www.rehermorrison.com/blog/?p=186

[3400-95-Modified]

non existant when you put a big cam in and then strech your chain worse than a $5 whore... LOL My 240/568 exhaust lobe touched all of my pistons in the 08 season, no damage, but slight valve dents in the tops of the pistons.

[Rootie524]

your cam was that big that the valves hit the pistons? and the pistons didnt bend at all? wtf?! lol. and your timing chain stretched cuz of it? im alittle confused lol

[86FieroSEv6]

They don't call them "pop-up" pistons for nothing . . . LOL . On a really tight engine you can't allow it to get even 5 degrees out of mechanical time, that's just how close things are when you are going for max squeeze. Remember, a lot things happen within relatively short order in a modern engine.

[Rootie524]

no more than 5? wow..but does degreeing a cam actually help a good amount. (try not to rip me a new one for noob question..im learning lol)

[86FieroSEv6]

On a non stock cam, degreeing is a absolute necessity in my book. Production tolerances for the stock stuff will usually work okay. Even the trashiest performance cam will usually clean up within plus or minus two degrees. Unless you have some special requirement such as big torque low RPM or big horsepower high RPM, your efforts will be centered around getting the cam centerline to true zero.

[Rootie524]

so degreeing it +-2 degrees helps. im going for a good powerband that starts off with a decent amount of torque then picks up like hell for huge HP numbers after like 3k+ rpms. how would i need to adjust that. and true zero? meaning exactly where the cam should be with no degreeing at all? and by degree..is like one notch over on the timing sprocket a "degree"

[SappySE107]

You cannot degree a roller cam without a double roller timing chain. Then you can do +-3 or 6. The comp grinds have the advance or retard ground in them, so straight up is where they are meant tobe installed. That means as stock for installation.

[Rootie524]

so my comp cam should not be degreed..ill get its full potential in straight stock position?

[86FieroSEv6]

You can't "degree" a cam by moving it from tooth to tooth on the chain. That is farrrrrrr too much adjustment. Degreeing is to eliminate the small variances in production for razor sharp zero. Advance moves the power band lower while retard raises the powerband at the expense of off the line push. Sometimes a car that is too twitchy in the lights will be retarded slightly to soften the leave for less tire shake. I have seen several high end aftermarket cams need a quarter to a half degree to obtain correct mechanical alignment for best performance. Unless you're running for the money and need that extra tenth or hundredth of a second in your E.T., installing the cam "on the marks" will usually suffice just fine.

[3400-95-Modified]

Stretched timing chain from poor part quality and heavy springs and agressive ramp rate resulted in my timing being a little bit delayed, OR I just reve'd to too far and the valves couldn't keep up... I really do not know if this happened when I had my milzy cam, OR when I had this WOT cam... I'm only assuming this one because of the large exhaust lobe.

Either way the pistons are very soft so it just left a little nick in them so as Dave calls it, they are valve machined reliefs... lol I left them alone after getting the sharp edges off, and I had all the exhaust valves checked when the heads were done at the shop and he said they were all fine. They are quite beefy of a valve.