Been thinking about how to modify my valvetrain and cam to get more ponies but not sacrifice driveability. One thought I had today was to leave the cam and get new rockers with a bigger ratio. Supposedly, my current cam has a 207 intake duration and 213 exhaust - not too shabby, seems like kind of down the middle for a cam in these cars, not too peanutty and not to crazy at all. Lifts are supposed to be .415 IN and .430 EX. Just wondering if I were to increase the lifts some with new rockers with different ratios, if air flow would be improved into the cylinders at all and if there would be any noticable increase in power? Also, assuming this can be done and isn't a dumb idea, will it change how the engine runs/idle quality?

Just asking cause it was something I thought of and I really have no idea if it would be worth while or not, or if it can even be done.

Thanks all,
K

 

1.6 ratio rockers will increase your valve lift by about 5%. You might notice a small improment in performance.

If you do this swap, you will need to set the valve lash.

And you should check for coil bind on the valve springs.

 

It is a good mod to do if you don't want to dive into the motor and you are not looking for huge gains. You will notice a improvment but nothing earth shattering. And it is usually a good idea to change the springs to a newer set with the new rockers.

 

Ok. I hadn't thought of valve spring bind - that is a very good point. What about lift and valve-to-piston clearance? Is that something you have to worry about too?

Also, if I do go to a 1:1.6 ratio, will that be compatible with a different cam if I do change it later on? I guess the springs too - would those have to be changed again with a new cam?

Thanks
K

 

If you went with a 1.6, that rocker would be compatible with a new cam. As long as the rocker was a roller and the cam as well. If you change the springs now, there wouldn't really be a need to change them later. Especially if you call somewhere like Comp Cams or whoever and tell them you want the rockers and springs now, but will buy a cam in a year or two, they would hook you up with the right combo.

 

with that size cam you will be fine with that lift,i used the slp 495/510 in a 305 no clearence problems,ran good for an 87 a4 car with a 2500 stall no ex. mods at all,14.7 w/3.23s and radials.