Need a good set of valve springs to throw in the car when I install the 1.6 pro magnum rockers in a few weeks. I need them to be good with the stock cam but also able to handle a CC 305 in the near future. Will the 918's be a good choice for an LT1 car?

 

I went with Comp 981's, but I was pressed for time because the 983s Comp says fit don't ( I.D. too small for stock spring seat ). I did Comp ProMag RRs at the same time on stock cam. Picked up .7 on the 1/4 with springs, RRs, MAC mids and ORP w/cutout. HP peaked at 5100rpm on old springs, haven't had a chance to get it back on a dyno with the new parts to see how far up they moved peak HP.

 

612 package from Combination Motorsports.

 

So the EX-612-16 package will work fine with the STOCK cam and 1.6 rockers for now and then be able to hold up to a CC 305 with 1.6 rockers also? I just want to go ahead and upgrade the springs with the rockers now so I don't have to touch them again when the cam install comes around.

 

This is from the Combination Motorsports website...

EX-612-16 EX Components 612 Single Coil Extreme Performance Valve Spring Kit-fits stock head without machining, includes lightweight retainers and locks $109.97

 

I have the 612 springs with my 1.7 rockers and a stock cam and I am getting valve float real bad starting at 5800rpm. I have some much better springs on the way. Crane 10308 spring kit. I used these springs on my 306 and they worked great. You can get the kit for 147 bucks at summit. Do it right the first time!

 

K-Motion K800's.

 

612s with 224/230 and 1.6 rockers and having no problems.

Lloyd uses these springs on his LE1 packages which spin to 6200 with a CC305 ish cam.

Kreinmc, have you checked for correct pushrod length?

 

If you decide on the beehives here is the parts list.

26918 springs
795-16 steel retainers (10*)
or 794-16 titanium retainers (10*)
614-16 locks (10* +.050")
4705-16 spring seats

When installed on stock LT1 aluminum heads you
should end up with a 1.75" installed height. Check
out Speed Engineering in the supporting vendor page
for prices. Click Here

 

Is that crane 10308 kit strong enough for the 306 cam, has anyone else used this setup?! Here are the specs on summit:

Number of Springs Per Valve: Dual
Outside Diameter of Outer Spring (in): 1.460
Spring Rate (lbs/in): 408
Inside Diameter of Outer Spring (in): 1.075
Inside Diameter of Inner Spring (in): .803

I am looking for an easy replacement and this setup says that there is NO machining required.....which is FANTASTIC!!! Thanks for the info---

 

Crane 99893-16