I want to run 1.6 RR on my engine, can the springs take in additional 0.030 or 0.035" of lift? Comp cams said they weren't sure. They said that if it could handle .550 then I would be OK. Can you guys help me? :hail: Oh great engine Gods:hail:

 

I am using those springs, got them from Competition Products. The specs they list are: 110# @ 1.700" height; 310# @ 1.250"; coil bind 1.160". They further recommend: determine installed height, subtract at-valve lift, subtract .050" for safety, don't go to coil bind. Assuming installed height is 1.700", .550" lift is too much.

 

The ZZ4/LT4 springs are only good to .525

 

Right, they are barely good to .525" lift. I'd recommend .515" or smaller with them for added safety. You'll need new springs for .550" lift.

 

Wow, you guys are being VERY generous. I wouldn't even use the stock LT1 springs past 0.500" with any kind of ramp at all. GM wouldn't even use them on the LT4 improvements to the LT1 engine, opting instead for a slightly larger diameter oval wire spring that would survive the relatively mild 0.525" lift of the LT4 cam grind. (GM P/N 12495494 springs)

Then again, the GM Powertrain guys were pretty picky about valve train components on the LT4s, refusing the Crane Gold Race aluminum rockers until Crane redesigned them with a stronger fulcrum trunion and improved bearings. (No, the LT4 doesn't use plain-old Crane rockers - they are too weak.)

Standard LT1 springs are really no different than L98 or any other factory SBC valve spring, in my book.

 

The springs on the ZZ4 aluminum heads are the one's that come with the HOT cam kit. So I would think they should be able to take the .525 lift.

 

The springs that come with the HOT cam kit, and on the Fast Burn cyl heads, from GM are good to .525 inch. At that amount of lift with recommended installed height the springs go to .035 away from coil bind. I spoke to a GM Partec High Performance rep about this subject. He stated that G.M. has sold thousands of these springs and have not received any complaints about breakage. Those are the specs that came with the HOT cam kit from the factory so I guess they know what they are doing.

So to answer your question, no. If you are running part # 12551483 spring, (this is the spring that comes with the HOT cam kit, and on the ZZ4, from GM) .550 inch would put you .010 away from coil bind. I would not recommend running 1.6 rockers unless you change springs.

 

As was mentioned in a different thread, the ZZ4 L98 heads have LT4 springs, not LT1 springs. I think the most I'd push them is ~.510".