Nice, glad to hear that you are into high end engine building....I have actually been semi-looking for someone local to me if I decide to freshen my bottom end this winter/next summer.

Jason

 

Jason,

Do you just need a new set of rings, bearings, and springs? or do you want to upgrade. BTW what do you have in mods?

Bret

 

Either way I defintaly need to change out my valvesprings while the car is put away for the winter. Probably going to do a ring/bearing sometime next year...for now it is fine. I wouldnt upgrade at all since the internals are all forged, just refreshening.

The motor is 396ci LT1/LT4, forged/splayed bottom end, solid roller, AFR 210s, stud girdle, monoblade, etc...

Hopefully we can get together sometime this year at the track and meet. I am planning on being at NYI on Oct 27 and Nov 3.

Jason

 

I think a 1.7 roller rocker, besides increasing lift, is faster at opening or something to the effest of increasing velocity, as it has to open the valve to a higher lift in the same amount of time than a 1.5. I think it does increase velocitym maybe thats why the Big Bolcks, LS-1's and some Fords use them????

 

Most engines use a 1.7 to get more lift. The Clevland Fords, the LS1 and the BBC all need more airflow to make the power they do.

A larger rocker arm will increase duration at .050 a bit and it's major benefit is that it opens the valve farther to get more area under the curve with the same duration.

Bret

 

ANy idea how much more duration at .050 there is, is itas easy as saying 230 degrees at .050 for a 1.5, then divide by 1.5, and then multiply by 1.7 to get the new duration. I are no mathmetician?

 

You got it Vette...that's how to go about it.

 

Sorry guys, but you can't figure out the duration increase that easily, as the ramp has a definite starting and ending point. Simply dividing by the old rocker ratio and multiplying by the new ratio works fine for lift, but you'll need cam profile data to accurately predict the duration change.

Hope this helps,

 

Anohter person actually used a dial indicator on hi smotor while he was putting it together and got , from a 224 degree cam, and additional 1.2 degrees, when he went from 1.5 to 1.6 rockers.

 

Eric...

You are correct of course. I misread Vette's post, and thought he was looking for lift calculations...