I need rockers for my SP II heads and was wandering what lift these 1.6's would make my XE262 cam. It is currently .462/.469. How can I tell before I buy them if the geometry will be a problem?. I was going to try Jegs Crane 1.6 stamped rockers to save a few bucks.

.493/.500 with the 1.6 rockers...may need longer pushrods. Check!

Originally posted by 75c10:
I need rockers for my SP II heads and was wandering what lift these 1.6's would make my XE262 cam. It is currently .462/.469. How can I tell before I buy them if the geometry will be a problem?. I was going to try Jegs Crane 1.6 stamped rockers to save a few bucks. =
.493/.500
You can't, you need to check it.
You should always check geometry when changing heads or valve train parts,,, it's just part of the deal ;)
At .500 lift, p/v clearance & spring, guide/ retainer clearance should not be close to a problem but it never hurts to look.
A lot cheaper than the alternative graemlins/sad.gif

Wow, I didn't think the lift would increase that much!. Thats more lift than the next size cam up(XE268). I hate to sound like a dumb azz but how do I check to see if longer pushrods will be necessary? graemlins/clonk.gif

I believe you want put some grease or use a felt marker on the tip of the valve stem and put the rocker back on and run it through its motion and make sure the rocker is pushing on the center of the stem, not off to one side. Also make sure the push rod doesnt run into the guide in the head. And also check spring bind and rocker to retainer clearence.

I got better clearance from the retainer with Comp Magnum 1.6 than stamped steel rockers.

If you want to know lift with 1.6 rockers....

Take the lift... (.462) divide by 1.5 = (.308)

Multiply (.308) by 1.6 = (.492)


With a higher lift, if you don't have screw in studs, you may want to think about them or pinning them.

I run the XE262 cam, and 1.6 rockers slowed my car down. But every combo is different, so it may be worth a try.

Slowed it down??? :eek: . I was hoping for at least a minimal gain.

1.6 rockers not only increase lift, but they also increase duration and overlap slightly, so you lose a little low speed torque. Depending on the rest of your combo, trading low speed torque for higher RPM power may either help or hurt ET, you won't know until you try it.

Thanks Mike. Last question, will 1.6's rev a tad higher???

Originally posted by Georgia69:
1.6 rockers not only increase lift, but they also increase duration and overlap slightly, so you lose a little low speed torque. Depending on the rest of your combo, trading low speed torque for higher RPM power may either help or hurt ET, you won't know until you try it. =
Not completely true. ;)
Going from 1.5 to 1.6 will increase seat timing on a hyd cam only a very slight amount & I use the term slight,,, loosely :D
If you use the .006 tappet rise number you are moving the valve .00096 instead of .009 for the same .006 tappet lift. Six tenths is not a lot of duration. :D
On a solid you should adjust the valves slightly looser (actually 6.7%) to bring the seat to seat timing back for a real comparison
The lift curve at the valve will seem a little larger but the amount of total seat to seat timing difference is almost at the point of not being measurable.

I have had mixed results. Usually 1.6 rockers seem to pick up power on the intakes but there are no set rules, as stated, you would need to try them but the gains are usually pretty small if at all.
I have not had real good results with most of the XE series cams & 1.6 rockers & my thinking is these cams are already to the point of losing control of the valve so raising the ratio is probably not the best plan unless you are going to run some pretty aggressive spring pressures.
Just my thoughts on the XE's
We do run 1.6's on most of the circle track stuff we do & it seems to be of benefit in almost all cases but again, not much & not always.
Right now we are doing a 311 sb & it is using 1.8 intake & 1.75 exhaust :eek:

1.8 intake & 1.75 exhaustI like those Crower stainless steel rockers, with the offset trunnions.... really helps keep the rocker geometry from going into the ozone.

This is an 18 deg Jesel shaft deal.

I looked at the new Crowers at PRI & like that someone finally moved the part that screws up the works on the higher ratios so you don't spend a week trying to move the stupid stud ;)

Hey,,,maybe we could just use some of those elcrappo import studs being sold on ebay where the top & bottom aren't concentric, market them as "adjustable studs" & locktight them in so they set the trunnion wherever we want it :D