Valve Springs, Fred...Wolf...Brian...

[jbs4radio]

Motorworks doesn't like the LT4 springs that came in the Hot Cam kit and suggests the Comp Cams CCA-986-16. They leave .075 before coil bind compared to the .035 on the LT4 springs. The springs are rated a little differently so I need some advice. What's gonna happen if the avg lbs/in is lower overall (36lbs)? What if it were 12 lbs higher? Is it better to go with the 987's or 986's? Explain valve float a little better for me.

LT4
1.32" O.D
1.22 Coil Bind
101# @ 1.78"
332# (avg lbs/in)

CCA-986-16
132# @ 1.75"
1.15" Coil Bind
296# (avg lbs/in)

CCA-987-16
138# @ 1.75"
1.15" Coil Bind
344# (avg lbs/in)

[Injuneer]

Not something I know a whole lot about. It seems that there are an awful lot of LT4 HOT cams running around out there with the springs that came with the LT4 HOT kit.

[Kevin - Blown 95 TA]

Here's my guess. They are reasoning that the LT4 hot cam is more agressive than the LT4 OEM cam, so the LT4 springs might not be enough to control the valve at a higher rpm. They are worried that at higher rpm, when it is opening the lifter might fly off the lobe a little bit all because of not enough pressure from the valve spring. One thing to consider, though, is the weight of the components. If the LT4 parts are lighter than the CC parts (springs & retainers) then that can make a Major difference when float happens because weight is a factor, just like spring pressure. Then again, you do not have the LT4 valves, either, so your valves might be heavier. By the way, float not only causes loss of power, but it destroys the springs and is hard on the other valve train parts as well. Like Fred said, a lot of guys are using the Hot Cam kit without issues. If your builder insists on using the other parts, just make sure he guarantees his work, or go somewhere else.

[bn_bullet]

First, let me say that Fred and Kevin both offer excellent advice here. There are indeed many Hotcam users that have had no problems with the LT-4 spring. As I said before, I cannot dispute the success of many people that have used these springs with this cam.

Also, as Kevin said, make sure your builder/machine shop guarantees their work. They are the ones that you are paying and entrusting your parts to.

That being said, many people may disagree with my opinion here. I personally like the Comp Cams 987 spring used with the 4771 spring locator. Unfortunately, this requires that the valve spring pocket be cut to accomodate the 1.550" O.D. of the locator. I would shoot for a 1.825" installed valve spring height which would put the spring at 112# closed. The spring would be at 1.300" open and 293#. The spring is rated at 1.150" coil bind so this would leave .150" before coil bind. Well within the safety margin.

The LT-4 spring is rated at 101# at 1.780" installed and 275# at 1.255" open. So, the Comp Cams 987 would only be marginally stronger at 112# closed and 293# open. The advantage to the 987 is the safety margin before coil bind and longevity.

Anyway, these are only my thoughts based on my experience and preferences. Hopefully, I've been helpful.

Brian

[wolfdogs]

First, let me say that Fred and Kevin both offer excellent advice here. There are indeed many Hotcam users that have had no problems with the LT-4 spring. As I said before, I cannot dispute the success of many people that have used these springs with this cam.

Also, as Kevin said, make sure your builder/machine shop guarantees their work. They are the ones that you are paying and entrusting your parts to.

That being said, many people may disagree with my opinion here. I personally like the Comp Cams 987 spring used with the 4771 spring locator. Unfortunately, this requires that the valve spring pocket be cut to accomodate the 1.550" O.D. of the locator. I would shoot for a 1.825" installed valve spring height which would put the spring at 112# closed. The spring would be at 1.300" open and 293#. The spring is rated at 1.150" coil bind so this would leave .150" before coil bind. Well within the safety margin.

The LT-4 spring is rated at 101# at 1.780" installed and 275# at 1.255" open. So, the Comp Cams 987 would only be marginally stronger at 112# closed and 293# open. The advantage to the 987 is the safety margin before coil bind and longevity.

Anyway, these are only my thoughts based on my experience and preferences. Hopefully, I've been helpful.

Brian

Ed Wright set my pcm to 6400 red line on rpm. i took her up there 4 times before i parted with her.... she did fine.....

for the record.

[jbs4radio]

Thanks guys. I appreciate the advice. It looks like Monday they should have a spring kit in. Motorworks does guarantee thier workmanship. They however don't offer their 5 year guarantee with custom requests. They build 10,000 engines a year and have done so for 25 years. I trust thier work, just cautious as most folks usually are.

--Jared--

[Craig 94 TA GT]

I believe your 0.35 before bind is good enough. Just my opinion...I'm using those springs without a problem, taken to 5950 RPM. I think if you get the CC305 and beyond, then you might have a problem.