http://www.lunatipower.com/Tech/Valv...pringTech.aspx

I am betting the 1.266 OD is designed to fit stock spring pockets but measure. I like the beehive springs, Better valvetrain stability at High RPM, less spring pressure required to maintain control of the valvetrain. Make more of a difference in high RPM applications. Downside is options on size and rate are limited, most require +.100 valves or retainers and they are over $300 with retainers and locks. For your application, If the recommemded spring fits the pockets and it is just a matter of removing a shim to to be able to use your existing pockets, retainers and locks and get the correct installed height I would lean toward that for $70.

Make sure you check the spring pocket. I bought a set of springs 1.47 one time for heads that were cut for 1.43. Only four hundreds different they would not go in the pocket.

I would think surely 1.266 would fit. But thats what i told myself on the bowtie chevy head its only 4 hundreds difference lol.

Heads are Brodix IKs and 64cc. I'm also using 1094 head gasket and estimate CR around 9:1. Currently using the springs that came with heads which I'm pretty sure they are the 1.250. Specs here

Okay guys, here's what I got from Summit on my heads. They are cut for a 1.250" and a 1.550" spring. Current springs are 120 lbs seat pressure @ 1.700" installed height. 285 lbs @ 1.250" Max lift .520". I will call Lunati shortly...

I just got off the phone with Lunati and they said that my springs would work with the 60102 cam? :confused2:

How much is the spring rate on the springs summit supplied on the heads if you don't know find out ?.

That 73943 lun. valve spring ment for your cam has a high 462 spring rate for a reason.

For $71.00 and the 1.266 would fit your current retainers, you now have the right springs for your cam choice.

Unless the summit supplied spring has a faily high rate i'm having some doubts on your tech advice.

Just because the summit spring has enough .520 lift thats not everything.

I was thinking if I had to go through the trouble of removing a shim from mine, why not put the correct springs? It's the same amount of labor. So all I need is the cam and lifter kit and just the springs for $71 (plus gaskets). I don't need the whole spring kit with retainers, I can just use my current ones correct?

How do I ensure I get the 1.75 install height? Do I just need to remove a .050 shim? Are the shims marked with how thick they are?

Having not read all the posts on here why were you needing to remove a shim from the way the heads came already set up ?


I can't see a 1.266 spring needing a different retainer over the 1.250 spring.

If your going to make sure its right you have to measure all 16 of them.

"Having not read all the posts on here why were you needing to remove a shim from the way the heads came already set up ?"

I was going off of the below post by 63mako. I'm still learning here. I asked Lunati tech and they said the same thing about the shim to get to the 1.75 install height.

Heres what you know. The springs that come on your heads can handle .520 lift thats plenty for the cam your going to use. What if they have a very good spring rate ?. You need to find out more about the springs you have how they compare on rate before you consider them unusable.

This is all the info Summit has on the springs: 120 lbs seat pressure @ 1.700" installed height. 285 lbs @ 1.250" Max lift .520".

They said they would work fine with the 60102.

well you can believe both lunati and summit or just install the lunati spring.

If you look at a comp extreme fast rate cam same lift slightly higher duration. They recomend there 981 spring with 370 spring rate. 1.70 install height 1.254 dia. 1.150 to coil bind. At 1.250 it has 273 lbs pressure, 105lbs at 1.70 install height.

I will try Summit again during the day to see if they can contact the company that makes the heads for them to see what the spring rate is. They called them today for me to get me the spring pocket size. Summit wouldn't tell me who makes the heads for them.

That spring will be plenty for that cam. 1.700 is stock height is it not?

Spring rate on your heads is 367. Recommended Lunati spring rate is 462. I would change them. The springs you have will work. For how long is the question. To many flat tappet cam failures out there to take the chance for $70 and a little extra work.

To figure spring rate on the above spring take 285 (open)- 120(seat) =165 (rate @ .45 lift). 165 divided by .45 = 367 inch/Lbs rate. Same formula works with the Comp spring posted or the correct lunati spring.

Comp tech told this guy his springs would be fine. See what happened. You don't know who your talking to on the tech line. Might be some High school kid with a part time job.


http://forums.corvetteforum.com/c3-t...like-cr_p.html

http://forums.corvetteforum.com/c3-g...ieve-this.html

I agree with mako feel more comfortable at least using the springs
lunati shows to use for the cam.

Thank you! So I will get the cam and lifter kit as well as the Lunati springs and I can use my current retainers?

Your current retainers should work. Check them! I would setup the installed height at 1.750 as lunati suggests. Most aftermarket heads have been shimmed to get the correct installed height. Yours look like a 1.700 installed height. Spring setup should be within .020 of recommended. Use the link I gave you and check the installed height of each spring you have then you know what you need to do to get the new springs to the right height. If the existing are @ 1.700 you can take out a .050 if you have them on all you should be perfect. You might have to buy some shims. Most machine shops have an assortment of shims and they are cheap. You might be able to get what you need free if you tell the shop your removing .050 and you will give him back the extras. Take one of yours in to get the right size. Then vary thickness to get right height. It is pretty easy.
http://www.lunatipower.com/Tech/Valv...pringTech.aspx

http://www.compperformancegroupstore...ory_Code=HFTXE

Is this the Comp cam you are referring to?

I have a 2010 comp catalog. I looked at both there 262/268 extreme cams to see what spring they were using. both the 262 and 268 cam use the 981 spring with the 26981 behive spring as un upgrade spring.

Behive springs and retainers are going to be at least $200.00 so you may as well figure on the lunati springs at $70.00.

If your heads are 67 chamber 170 runner they were made by world products. There called the SR torquer by world products.