What difference make 1.7 or 1.8 rockers??? It has to be with valve size, push rods length???? Which is better?

 

1.8 rockers will provide a little more lift and the overlap triangle opens a bit. They won't change valve events. Depending on the replacement 1.8 rocker, yes new pushrods will be required. Regardless, new valve springs are required.

This is an expensive upgrade for the amount of hp gained. Used with a GM Hot Cam or ASA cam they might be worthwhile though.

 

Thanks first. The thing is that there is a guy selling at ebay a kit which includes TB, intake and this heads (aftermarket) and the heads comes with 1.8 rockers. The set is for a LS1.

 

One aspect of larger ratio rockers is the relative decreased time differences of smaller ratios when looking at the increased valve velocities with either intake or exhaust valves. Decreased time with increased velocity means a better ability to maximize potential airflow of the heads cross sectional area quickly and efficiently. Usually with larger ratio rockers and/or aftermarket cams it would also be wise to consider lighter valves in effort help decrease rotational valvetrain mass.

 

Well summarized.

 

This is the difference between 1.7 and 1.8's on a bolt-on ls6

 

 

You may need to send him a PM as he may not see this thread has been revived. Although, his answer here would be good for others in the future.

 

With the 1.8 rockers, you need to make sure you don't get spring coil bind and break a spring.

 

i used psi1511 with stock pushrods. Harland sharp rockers.

i would probably use a bit more spring if i were to do it these days.