S92RS

iTrader: (1)

Following the advice of a few people on here as well as talking with a couple of my friends. I think I'm gonna go ahead and get a set of 1.6 roller rockers to replace my 1.5 stamped steel rockers on my motor. Right now my cam has .442/.465 lift and with a 1.6 ratio that will make it .471/.496.

I need to know about lift and valve springs, I think I'll be ok with the ones I have but I need a little more info. I have GM "624" heads with a little bit of work done to them. They supposedly have heavy duty springs, I don't know what kind. They are stock 1.25" diameter, and are NOT shimmed. The heads have screw in studs and guideplates. I bought them from a friend of mine awhile back slightly used.

Another option is to get a another set of springs such as the "Z28" springs used on the LT1, which would work. I may decide to do new valveguide seals while I do the rockers. Motor smokes a little at startup.

But sometime probably by the end of the year I plan on getting a set of aftermarket heads, so I don't know if I should even bother with the springs and valve seals if I don't have to. I want to do the 1.6 rockers to gain some power now.

The rockers I'm thinking about getting are the Crane Energizer 1.6 full rollers. Will they clear stock height valve covers, mine are Edelbrock.

What do you all think?
Thanks
Steve



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1984 Z28, non-computer 355
Edelbrock Performer carb and intake
214/224, .442/.465 lift cam
Hedman headers, and 3" Flowmaster exhaust
Powertrax Performance Locker with 3.23's, Lakewood LCA's
Nose, bumper and ground effects from an 89
-
Best ET: 14.537 @ 93.67 MPH
http://members.fbody.com/s84z28

Vader

S929,

I have a set of LT1 valve springs left over from my last build. They are 1.250 diameter and are maybe good for 0.480" lift - MAYBE. I would suggest the LT4 valve springs instead. This will require some seat machining but will be well worth the effort. The LT4 springs are conservatively rated at 0.525" lifts as a service limit, not a "stacked" height. The GM part numbers are:

Valve Spring Kit 12495494 (16 PCs of 12551483) $35.95GM 1.3415"OD x 0.901"ID, 2.150 Free height, 101 Lb@1.780" 0.217"x0.180" wire

Retainer, Lightweight Steel kit 12495492 (16 PCs of 10212808) $15.54 GM (14.45g steel)

Key kit (keepers) P/N 12495503 $6.83

For a reasonable price, you can have a decent set of springs and 10° retainers and keepers. For about $80.00 in machining and another $100.00 in gaskets and assorted supplies, you should have it covered. As a hint, if you have the seats machined, you might want to go to a larger oversize, like 1.600", and spend a few extra bucks on spring cups. If you ever want to go to a larger diameter spring, the machining is already done, and all you have to do is change the cups or eliminate them, depending on the springs. The cups can also prevent spring seat wear on aluminum heads. This would enable you to change springs without removing the heads, too.

Later,
Vader

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"Some Body...Someone"

S92RS

iTrader: (1)

Thanks for the info Vader, but I really don't think the heads are worth doing all that work to. They are "624" casting 76cc heads, that have screw-in studs and guideplates, and "slight" port work. I plan on replacing them down the road for something better, and if I go through the trouble to pull them off they aren't going back on.

The valve seals are bad in them, smokes a bit at startup. The heads were done and then run for a couple months on a motor, and then sat for a while. Then I got them and bolted them on. The only thing I think I would consider doing is the valve seals and putting some springs on them without removing the heads so I know it would be safe to put 1.6 rockers on it. I don't think it's worth having these "low perfomance" heads machined fo big springs or anything. The 1.6's would give me some performance now with these heads, and I'd keep the rockers when I got new heads.

The motor itself has only about 12K miles on it since I built it.

What do you think? I need some ideas.
Thanks
Steve

------------------
1984 Z28, non-computer 355
Edelbrock Performer carb and intake
214/224, .442/.465 lift cam
Hedman headers, and 3" Flowmaster exhaust
Powertrax Performance Locker with 3.23's, Lakewood LCA's
Nose, bumper and ground effects from an 89
-
Best ET: 14.537 @ 93.67 MPH
http://members.fbody.com/s84z28

S92RS

iTrader: (1)

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