Assuming i run the same cam as i have now, the CompCams #CC503, 224/230, .503"/.510" lift... will the springs that came with my trick flow 195cc heads work? Looking at the spec, the main difference is the spring rate. On my other heads, i've always ran the compcams #986-16 springs.

The spring rate is higher on the new springs. What effect does this have?

Here is the basic description i pulled off of summit racing:
986 springs: Part # CCA-986-16
Valve Springs, Dual, 1.430 in. Outside Diameter, 322 lbs./ in. Rate, 1.150 in. Coil Bind Height

TrickFlow Springs: Part # TFS-31400414
Valve Springs, Dual, 1.460 in. Outside Diameter, 438 lbs./ in. Rate, 1.100 in. Coil Bind Height,

 

Seat pressure on those springs is the minimum I would run, but that is a baby cam and you will be fine. You will have 125/340

 

dont forget to mention you are going with a turbo... you'll need more seat pressure.

 

^ what he sai. Gunna be running a turbo on a built bottom end, low compression.. 15 pounds of boost

 

Hey realquick, can you explain why seat pressure is more important on a turbo setup

 

For simplicity sake, think of it like this:

The spring is pulling the valve closed. With FI, when the valve closes you have boost pushing against the valve trying to open (boost is fighting against the spring). This tells you that you would need more spring pressure when boosted then when N/A.

 

Well put.. i guess i never thought about that. thanks for the info

I saw on another post that comp cams suggested bee hives for FI. You agree?

 

What is the pressure ratio on the turbo you are using?

 

Don't have the specs off hand, its a precision T76

 

I'd email lloyd elliott or bret bauer.

 

You need to know the pressure ratio, it will effect spring pressure.

 

It not that i mind changing them, thats no bigger. I jus wasn't sure what was required in springs for a FI engine. What are other turbo guys runing?

 

But you also have the pressure in the cylinder pushing back on the valve when the piston starts coming up too.

 

"For simplicity sake"

 

Talked to compcams. They agreed, spring pressure if a crucial factor for boosted engines. Not that i didn't believe you, i found another post that were arguing whether or not it mattered.

They recommended their 977-16s. 150 on the seat pressure and 441 on the spring rate.