roundman

yes because they increase the effective valve lift by 6.9% compared to the 1.59 stockers!

Milky

yes, plenty

bmorrisj

how about putting 1.6 on the intake valves and 1.7 on the exhaust?

TheGmKiller331

Nope!

Thay had EFI in 86 the roller motor in 85 was a 4bbl carbed version.

bobby

ok cool!! thanks to all that replied!!!

1hot88drop50

in order not to take up space in the forum i figured i would add to a post

I have heard that 1.6's are better the 1.7's roller rockers.. i have heard of a lot of people that had the 1.7's and then later switched to the 1.6's and liked them alot better. If i am looking for a mainly bolt-on upgraded motor w/ a rebuild w/ a my current exhaust setup what would be best for the aplication. I am looking for about 350-400 hp and somr 3.55's or 3.73's so what do u recommend i get for rr's and is there a brand that is better quality then the rest? Also along w/ the rr install what else do i need or should i get for optimum performance? thanks....

roundman

could be they never did much high rpm running. the rocker arms provide mechanical advantage from the cam to the valves. if the ratio was 1:1, the valve would only move the same amount as the max. lift on the cam. a 1.6 rocker gives you 60% more lift than the cam alone provides and a 1.70 rocker provides 70% more lift. More lift equals more air flow and more power! the choice of rockers still has to be made with the cam in mind to maximize the combination, but generally more lift is better!

diablo9861

Just as i was reading your post rodman, i got a little light bulb, but than a question mark, so why not go with a rocker bigger than 1.7, if bigger is usually better that is, also when i go to a bigger lift(which im about to do,due to ****ed up lifter) will i get the most i will outta of the lifter change straight away or do you have to mod anything else to get the full potential out of it.

roundman

you'll get the advantage of the bigger lift right away provided you check the piston to valve clearance and don't have the valves hitting the pistons. this is true with changing rocker arm ratios too, you can get yourself in trouble if you don't watch what's happening with the piston to valve clearance! I don't know about rockers with a bigger ratio than 1.7. There is a limit to how big they can go and still maintain the proper geometry with the pushrods and guide plates, you can only do so much without big mods to the heads, etc since the distance from the center of the valve to the center of the rocker is a fixed dimension. the longer lever arm of a higher ratio rocker starts to move the push rod back toward the intake at a bad angle and the whole for it in the head is only so big, so you run out of room to move after a while. I think this is why it's a lot easier to get more lift from the cam rather than the rockers.

vfast

well to futher update some after market cams advertise thier lift with a 1.6 some a 1.7 if you have one of those terrible abc cams then going to a longer type rocker on the exhaust will have a good benifit in flow