FAST99Z

I bought my ARE stage 2 heads cam setup a year ago. The valve stems are 11/32" diameter and can not accept the new (reliable) CC 918 springs and retainers. I was told to replace the 941 springs (which are prone to break) with the K-750s.

1. Are the K-750s made of the same materials as the 918? Same spring pressures?

2. Are there any issues with the K-750s handling high revs?

3. Has anyone swapped the 941s for the K-750s?

4. Has anyone broken a K-750?

ONYXSS

I had 941's in for a long time with no problems. When I suspected valve float from the springs wear, I decided to change to K-750's. I don't think there's an inherent problem with the design of the 941's, but instead a quality control issue that caused some batches to break prematurely. And yes, the 941's are made of the same material that the K's are.

GTP LS1

I broke a k-750 last Saturday after 1,800 miles. I also have ARE Stage II heads with the 11/32" valve stems. I am sending my heads to ARE to have double springs installed. I don't trust the K-750's.

Other people have had good luck with the 750's but I don't trust them. Just my .02.

Go FasTA

I have a set of 941's that I'd be willing to part with for cheap if you're interested in staying with those. I have no experience with the other single coil springs, as I had double springs put in when my heads were ported. These springs only have 5 miles on them.

FAST99Z

I would like to get the double springs put into my ARE heads but it would likely cost me $1000 to pull the heads (labor), ship them, and have the work done.

FAST99Z

ttt, 941s break, 918s won't fit, K-750s same material as 941s which break,... $1000 for double springs. What is the answer?

jmX

You can pull your heads off in like 2 hours if you have some hand tools. No need for labor. I'd just do that and be done with it.

FAST99Z

Unfortunately, I'm not a mechanic. I was quoted $700 to remove and replace the heads plus the new head gasket. Also shipping to/from ARE and new springs brought the tab to $1000. The heads cost $2300 new.

Jackyl_30

I have been doing some looking around and I have read that the 941s are made from steel. The k-750 are made from H-11 steel. So they are not made of the same material.

Pressures are also different:

941: Seat pressure: 135 lbs. at 1.750 in.
Open pressure: 359 lbs. at 1.250 in.

K-750: Seat pressure: 130 lbs. at 1.700 in.
Open pressure: 380 lbs. at 1.150 in.

Fireball

iTrader: (21)

941s are H-11

well we have an ARE car here with 750s with a broken spring...we are yanking the heads and installing doubles <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> (stupid 11/32 valves)

Jackyl_30

where do you see that they are H-11? Summit Racing is listing it (941) as steel. If fact both Summit Racing and Doug Herbert Performance classify it as a pacaloy (what ever that is. some sort of alloy I am guessing) material.

Comp Cams:
http://www.herbertperformance.com/Ca...e_springs.html

K-Motion:
http://www.herbertperformance.com/Ca...e_springs.html

<small>[ May 03, 2002, 11:33 AM: Message edited by: Jackyl_30 ]</small>

Fireball

iTrader: (21)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Jackyl_30:
<strong>where do you see that they are H-11? Summit Racing is listing it (941) as steel. If fact both Summit Racing and Doug Herbert Performance classify it as a pacaloy (what ever that is. some sort of alloy I am guessing) material.

Comp Cams:
http://www.herbertperformance.com/Catalog/Valve_Spr ings_Retainers__Locks/CompCams_Valve_Springs/compcams_valve_springs.html

K-Motion:
http://www.herbertperformance.com/Catalog/Valve_Spr ings_Retainers__Locks/K-Motion_Valve_Springs/k-motion_valve_springs.html</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">ok...here's the deal...I tried a replacement spring Crane Cams 99846-16. This is listed as a H-11 spring on cranes site. Guess what...it broke EXACTLY how a 941 did on me in the past. H-11 is one of the common ways they are making high spring pressures with a single coil spring.

Call it what you want...but its an H-11 spring (the crane/comp springs were identical in appearence and properties)

Grave Danger

I broke a K-750 2 weeks ago. T1 - Stock heads.

I put another back in, I'll find out if it was a fluke.

Jackyl_30

I still am not certain of all this. Unless you have a degree in metallurgy I am not sure anyone knows except for the manufacture.

I was going off the assumption that the K-750 was a better product, therefore being different than the 941 based upon this thread: https://ls1tech.com/ubb/cgi-bin/ulti...c;f=1;t=004757

Read what Nick says towards the bottom.

In any matter I have decide to go with Comp Cams 987 springs.

FAST99Z

What is the comp 987 spring like? properties?

Fireball

iTrader: (21)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by FAST99Z:
<strong>What is the comp 987 spring like? properties?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">double springs <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

FAST99Z

So, I am back to putting in double springs for $1000 or more because the heads came with 941s which are basically unreliable (many failures) and the replacement 918 springs will not fit my retainers. Honestly, doesn't this seem like a warranty type issue? The 941s have failed how many times with bent valves and damaged heads? Also, no one uses these springs anymore because of the failures. I only have 1500 miles on my heads and frankly I am abit scared to drive the car. Thats my situation and opinion.

Nick Agostino

Manley just came out with a new spring for the ls1 and fits your application, let me know if you need a set. Not everyone had problems with the 941's, I would say less than 5% of the ones we did had any issues(I think there was a time there when a bad batch got out?)

The Manley spring is similar to the k-750 and 941 in material and specs.

FAST99Z

I am not an expert but it seems to me the PROBLEM is the type of material used in the spring. If the Manley, 941s and K-750s use the same material they are going to fail in the same way. I don't see how the Manley springs made of this material can solve the problem. It looks like the only proper solution is to go to double springs like ARE LS1 and others in this thread have done. I just can't afford $1000 to get it done.