im thinking about having a cam kinda like the cc 306 wit 1.6 rockers. would i need different rods? how do i know what size?

 

measure for them.
https://camaroforums.com/forum/4th-g...-length-51829/

 

i guess maybe idk exactly what a push rod is. do they not come in different lengths and i jus buy the length i need? or is it a standard length that is adjustable (and id measure to the length i need)? i thought if i got a bigger cam that i would need to get shorter push rods. am i wrong?

 

this is how i understand it, when changing to 1.6 rockers you change the area where the rocker contacts the valve, if you dont change the length of the pushrod then it will not make contact at the center of the valve as it should and will have a unhealthy wear pattern at best, bend a valve at worst.

 

The larger cam is to open the valve farther, thus letting more air and fuel into the engine, for a bigger bang and more HP. You can get even more lift using rockers with different ratios. But the length of the pushrod could change where the roller meets the valve.

It is a simple concept to understand.
Lets take for example the stock 1.5:1 ratio rocker. The 1.5 means that for every 1 unit of measure the cam pushes up on the rocker the other side of the rocker pushes down 1.5 units of measure.

If you get 1.6 rockers you will get .1 units of measure more valve opening.

This does NOT increase duration.

So if you have a Cam that has .25" of lift at the lobe then if we do the math 1.5X.25=.375" of lift at the valve. (these are just hypothetical numbers for the ease of understanding)

Now take the 1.6 rocker and you get 1.6x.25=.4" of lift at the valve.

This allows more lift with the same cam profile for added performance.

The way this is done can put the roller in a different location on the valve. You want the roller to meet the center of the valve stem for best performance and wear characteristics. If it is not centered you can get excessive wear on the valve guide, valve stem. which could lead to poor valve seating or even a bent valve. Some rockers are designed in a way that they will center themselves just fine with stock rods, others need shorter or even longer rods to make everything happy. I believe the link that craby posted has pictures of the rocker and valve meeting and some markings to show what can be happening and how to correct it.

I hope this helps in your understanding of what is going on.

Massey

 

You'll probably want to replace the pushrods anyways, unless they are very new. I went with 1.6rr with my cam and I used the stock ones to check how they seat. I didn't have any problems with seating, so then I purchased a new set the same length.

Massey did a good job explain the need for different length.