stevesxm

great info all ... and thx. tyler seems the guy w/ the answers and will contact him for his opinion and reccomendation if he is willing to give it.

re "harmonics" stumbled on neat little piece of info that might save your ass someday... found one ad for rockers from major mfg ( will re-find and tell you where) that made reference to their rockers being made in such a way as to NOT trigger the knock sensor on certain injected motors and if you think about it ...the frequency etc and the type of "noise" a rocker could make, that could be one of those " bizzare injection problems " you have someday that makes you insane. found ad...see text below...

BROWSE PRODUCTS
Gold Race Extruded Aluminum Roller Rocker Arms for LS1/LS6

Crane Cams Gold-Race, full-roller aluminum rockers for the LS1/LS6 engine family add up to 20 horsepower over stock! These rockers were designed for quiet operation and do not trigger the stock GM "Knock Sensor", which retards spark advance and reduces power output! They feature the exclusive Crane "Quick-Lift" design, which moves the valve off its seat quicker, initiating flow into the combustion chamber earlier, thereby increasing port efficiency and horsepower output! They are available in a complete kit (rockers, rocker studs, pushrod guideplates and pushrods) or separately, and are an easy bolt-on. They also clear stock Chevy LS1/LS6 rocker covers. Stock 1.7:1 and optional 1.8:1 ratios available.


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Griff

If you change to roller rockers, you will also need to grind off the oil drip tabs on the inside of the valve covers.

Outdrive1

Has anybody every had problems with harmonics setting off the knock sensor? First time out my motor pulled fine, I easily hit 5200 rpm's a couple of times and had tons of midrange. I changed plugs and wires, went up a little in the heat range and couldn't pull more than 3500 rpm. Motor shuts down like it's hitting the rev limiter or something. I put the other plugs back in, (nkg5671's) and still had the same effect. The only difference is the new plug wires. I can't find anything else wrong with it. Even in nuetral it rev past 3500 with out triggering the limiter.
This is a Mefi3, 502 mag with Dart pro 1 heads, Vortech charger, remapped ecu, extruned honed intake, hydraulic roller with 623 lift in. and ex. at 246 duration, Harlin Sharp roller rockers.
I guess the knock sensor could be bad, I only run av gas and it never pings. It actually runs really rich right now, lots of black soot.


Ideas??????????

stevesxm

see post 11 in this thread

mjb

I just completed this upgrade on my '97 gen6 502 mpi's. The rocker arms are Crane # 13767-16. These are pre notched so they will work with the stock valve covers. The rocker studs are ARP # 235-7202. Hope it helps.

mjb

.....and with these pre notched rockers you still have to grind the dripper tabs off of the underside of the valve covers. You will also need to use a steel core rubber gasket, not the stock o ring. You will need to grind off the spacer tabs on the mating surface of the covers where they sit on the heads so they will work with the new gaskets. A mill works best for this but a die grinder will work just fine. Be very careful not to grind any deeper than the plane of the mating surface.

Pat McPherson

Did you see any gains?
20HP/1-2mph would be worth it to me...

I have a set of 1.7 Crane Golds and the APR conversion studs in my stock pile, but I've been too busy boating to take the time to make the switch...

vandeano

That will never happen At least not for me

pachangalpina

I know the drippers have to be removed but do you really have to change over to the old style gasket? The HP500/525 efi still uses the o-ring gasket with the crane rockers and I thought the covers were basically the same with the addition of that expensive blue paint. Also did you know the o-ring gasket was more expensive than the head gasket?

mjb

Pat-I changed rockers at the same time I did other major modifications so I can't say how much the new rockers helped the performance.
Pachanga-I did spin the motor over with the o rings on the valve covers. It seemed to clear but it was so close that I wasn't comfortable with it...so I changed over to the thick gaskets. It may have still worked ok if I left the o rings in ???