93 lt1 vette

A good friend is building a motor for his 69. He seems to be set on 1.6 rr. I told him that he needs the right cam to begin with for his set up and use the 1.5s. What sayith the experts. I was under the impression you stepped up to 1.6s when the cam installed was to small and more lift was needed for more tq and hp.

gkull

If you have done all the calculations on spring weight, spring installed height, coil bind, piston to valve & rocker to spring retainer clearance. Why not?

I have sets of steel 1.6, 1.65, & 1.7 steel RR's. higher lift is not a penalty like higher duration numbers

ykf7b0

I have pondered this same question. If the right cam is installed to begin with what is the point of the extra spending unless of course one is needing new rockers anyway.

bluedawg

George said it, lift adds power with out Taxing the low end.

Jebbysan

1.6 rockers are a great way to get more lift when installing better heads without having to remove the cam......

In my 66' 327/350....I broke a valve and I repaired the heads while enhancing them quite a bit.......I loved the sound of the L-79 cam but the lift was pathetic.......(.447). With 1.6 Crane rollers I was able to get .477 out of the stock cam. It was a BEAST in the mid range for 331ci motor.....this would be the car in my Avatar.

My own 406 in my 72' is a .501 lift cam (244/244 @.050). It is a flat tappet. I did not want to attempt to break this cam in with a 1.6 rocker as I would have been at .534 lift and I already had a set of Magnum roller tip rockers......now that the cam is broke in nicely....I plan on a set of 1.6 rollers.....(Maybe Harland Sharp..) to bump the lift number as the heads are still climbing after .500 lift as far as flow.
This engine will pucker your A%# with the 1.5's......I guesstimate the 1.6's will be worth 10-15 horsepower.

I built a 305 (yes 3-0-5) for a 54' Chevy pickup and to keep it smooth and streetable....stuck a Comp 206/212 cam in it with .432/.444 lift....I of course ported the heads (Gasket match/bowl blend) and they flow respectably for the small valves.......that is when I decided to try the new extruded Comp budget roller rocker in a 1.6....for .460/.473 lift....with headers, 9.7 to compression and Edelbrock 2101/1406 setup you would swear it is a good running 350 and knocks down 19 MPG with a 3 speed and 3.08 rear gear.......

There is no real reason not to use a 1.6 or a 1.5......it is how the numbers stack up to your package.


The previous posts are correct that lift is a great thing.......just throwing out scenarios for those who are deciding.

Jebby

7T1vette

If you have absolutely maximized your engine build...except for rocker arms, then you might want to go to 1.6:1 ratio rockers. Otherwise, there are 'bigger fish to fry'.

MotorHead

The cam in my 427ci has enough duration that I am happy with. However the valve lift on the cam wasn't enough to match the flow numbers on my heads so I went with 1.6rr to get the valves to open further.

93 lt1 vette

Thanks for the quick replys. A little background may be in order. He had a motor built for the car last year 350 4 bolt block 327 large journal crank .030 AFR heads, full roller motor, victor jr with a 780. Great high revving motor balanced the whole 9 yards. Not good for daily driving in the city but a legit 7000rpm motor. Seems the builder forgot to put the harmonic balancer bolt in the crank stout and you know the next part. The balancer came off at about 6000 rpms in second gear. The vibration was so bad that you couldn't see out the windshield as he was coasting down. That motor was torn down the crank was broken in half, the valves hit the Pistons in the number 1 and 7 holes. Pretty much grenaded the entire build. He now has an intake carb and roller rocker that remain. I guess he trying to minimize the cost until everything over with the builder. He has a the original motor fuelie heads .480 230 flat tapper cam.

cv67

Eesh how do you forget that bolt!
Had one come off on an old Camaro (press fit only) man did that cause damage. One minute fine, a bad vibration then bang! WP radiator timing cover etc all had to be replaced, had to sleeve the crank too. Lousy idea on GMs end.
Hey lets put somethign that weighs a few lbs on the end of a fast spinning piece of metal see what happens with no fastener

7t9l82

Engine builders have used 1.6 rockers for various reasons. I have them in my car,as has been stated as long as you check for coil bind and a good pattern on your valve stem and pushrod clearance they can be an effective tool.

doorgunner

Rookie here: I put 1:6 stamped steel rocker arms (no rollers) in my stock 1992 350 SB just to try them on the INTAKE valves only....there was a noticeable increase in power that pepped up the "lazy" engine. For the money spent on stamped rockers it was well worth it for another 15-20 horsepower.

Cavu2u

Hey!
You just made me go out to the garage and check the torque of that dude on my 383!

Steve