This is just a little insight into what I do here almost on a daily basis and what we run into.
Setting up rocker geometry for a customer. Customer sent in their heads and another brand of rockers. We did the cam and provided new Morel lifters. This is a solid roller deal with about .740 net intake, .705 net ex lift. Heads are Dart 355 CNC heads.
I did my normal procedure and this was the first thing I noticed. This was on the intake:
This is where the roller tip sat on the valve @ zero lift with proper pushrod length for that rocker. To note; it will only move further to the outside as the valve starts to open. This is as good as it gets for these rockers;
Here's the Crane rocker, zero lift, proper pushrod length...;
...and here's where it sits. Something else to note; the pushrod length for the Crane rocker was .110" shorter to get the same geometry as the other rocker;
This is on the exhaust side.
Customer's rocker with proper pushrod length, zero lift.
This is with the Crane rocker, proper pushrod length, zero lift. In this case the Crane pushrods were .180" shorter for the same geometry.
The center to center distance of the fulcrum length was .045" longer on the customer's rockers than on the Crane rockers. Pretty obvious when you see where they sit in relation to each other on the valve tip.
There isn't much difference between a BB Ford rocker and a BB Chev rocker and some rocker manufacturers have come up with a "one rocker fits all" dimension for their BBF and BBC rockers. Something sort of half way between. Crane has a dedicated extrusion for every rocker they build. When you're just centering the roller on the tip of the valve, this isn't an obvious problem but as you can see here, when you try to establish proper geometry the problem becomes quite obvious.
Hope this gives a little useful insight into why we always recommend Crane Gold rockers for our stud mount apps.
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Setting up rocker geometry for a customer. Customer sent in their heads and another brand of rockers. We did the cam and provided new Morel lifters. This is a solid roller deal with about .740 net intake, .705 net ex lift. Heads are Dart 355 CNC heads.
I did my normal procedure and this was the first thing I noticed. This was on the intake:
This is where the roller tip sat on the valve @ zero lift with proper pushrod length for that rocker. To note; it will only move further to the outside as the valve starts to open. This is as good as it gets for these rockers;
Here's the Crane rocker, zero lift, proper pushrod length...;
...and here's where it sits. Something else to note; the pushrod length for the Crane rocker was .110" shorter to get the same geometry as the other rocker;
This is on the exhaust side.
Customer's rocker with proper pushrod length, zero lift.
This is with the Crane rocker, proper pushrod length, zero lift. In this case the Crane pushrods were .180" shorter for the same geometry.
The center to center distance of the fulcrum length was .045" longer on the customer's rockers than on the Crane rockers. Pretty obvious when you see where they sit in relation to each other on the valve tip.
There isn't much difference between a BB Ford rocker and a BB Chev rocker and some rocker manufacturers have come up with a "one rocker fits all" dimension for their BBF and BBC rockers. Something sort of half way between. Crane has a dedicated extrusion for every rocker they build. When you're just centering the roller on the tip of the valve, this isn't an obvious problem but as you can see here, when you try to establish proper geometry the problem becomes quite obvious.
Hope this gives a little useful insight into why we always recommend Crane Gold rockers for our stud mount apps.
__________________
Why we use Crane rockers at Straub Tech
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