man this is pissing me off
a few years ago i bought a head and cam package from ARE stage 2 head 306 cam. well ever since i installed it i've had a high end miss problem. i ruled everything out but the valve springs. i'm suppose to have 987 springs, not sure if i have the right ones or not, ARE tryed to sell a smaller cam then i wanted.
well i just ordered some new 987 springs just to rule out having the wrong springs. now im trying to figure out what install hight i should use
well i've call comp cams 3 time and gotten 3 different anwsers.
first one was that the 987 are too weak for the cam, i need 986 springs well after talking to him for awhile about it i gave up.
i call back get a different person, he tells me the same thing but i had the spring pressure for both springs and he finally agreed with me. well then we started talking about install hight, he told me if i am using the 987 they probably have the wrong install hight. he said to install them at 1.800 and that would give it a seat pressure of 138. but when i looked at their tech page it said an install hight of 1.800 would only give it a seat pressure of 121. so i call back and the next guy tells me i need to install them at 1.800 and that i need a 121 seat pressure... so now i have no idea who to belive?
so what do i need?

 

i guess if no one knows im just going to set them at 1.75 so i can get the 138 seat pressure.

 

well i talked to them again, they told me installing them at 1.75 would not work with the amount of lift i have.

 

Are you shimming the springs or getting springs cups? That will take away from your total lift, but you can buy retainers that compensate for that.

I am going to run CCA-977-16 with a installed height of 1.85.

 

shimming them

 

this is what the cars doing
http://home.earthlink.net/~blkchevyz/dynosmall.jpg

 

Here's the deal the 987's have 138#s at 1.75 and 121#s at 1.80. But they coilbind at 1.150 so with the 306 cam with 1.6 rockers you would only be .026 from coilbind setting them at 1.75. But if you set them at 1.80 they will have .076 to coilbind and be should be ok. Frank95z

 

but setting them at 1.80 is only giving me a 121 seat pressure is that going to be enough?

 

I have the comp 987's springs with my XE236/242 and so far everything seems ok. We actually checked the seat pressure on my springs with a computerized spring tester and the coil bind was at 1.05-1.08, not the 1.15 as the book states. We ended up setting mine up at 1.770 which gave me I believe 132-138 lbs at the seat, and like 380 lbs+ open. I havent had the car on the dyno yet, but I cant see that I am having any valve float problems yet. I will know more when I get it dynoed. BTW, the lift on my cam is .555/576 with the 1.6's which gives me about .100-.115 before coil bind. I hope this helps you out.

Brian

 

i guess i could get them checked before i install them...
but how do you know what seat pressure you need

 

I would have your springs checked out first to see what kind of seat pressure they have. With the CC306, I think you would be fine setting the springs up at 1.800 installed height. BTW, are you using spring cups(locators) with your setup. I would highly recomend using them as they protect spring seat on the head.

About how much pressure to have-- The guy who flowed my heads does alot of headwork etc, and he recomended that I have about 135-140 lbs at the seat with this XE grind cam I have. He said if you are into the 230-240 degree duration @.050, then you will want that much seat pressure to keep the lifter on the cam lobes. He told me to set them up at 1.750, which was like 142-145 lbs at the seat, but I was afraid of coil bind at that installed height. I went safe and installed them at 1.770 and everything is great right now. Hope this helps.

Brian

 

well the 306 is a 230 244 so wouldnt i want a lot of seat pressure also?