I’ve got a Lunati Bracketmaster II cam installed in my 400. As per the specs on the cam card, it calls for a valve spring with an installed height of 1.820 @ 120lbs open load. I’ve got a set of PAC springs Hot Rod 1900 that I want to use that call for a 1.880 installed height @ 98lbs open load. I have an understanding of what the terms installed height and open load mean but still fuzzy on the actual real world application.
My thinking is that the height of the spring and amount of pressure the spring exerts at that height is what holds the valve open. That has to be enough to seat the valve in the head. I’m not understanding why this is relevant for a camshaft profile, the lift the cam provides is for opening the valve not closing it but I guess there has to be enough pressure from the valve spring to close the valve at the proper rate of time.
How would you calculate how much wiggle room you have with the amount of valve height and pressure needed as I’m sure there must be something. I’m not sure if the rocker ratio I want to use is relevant either but its a 1.6.
My actual question is, can I use these PAC springs?
Thanks in advance!
My thinking is that the height of the spring and amount of pressure the spring exerts at that height is what holds the valve open. That has to be enough to seat the valve in the head. I’m not understanding why this is relevant for a camshaft profile, the lift the cam provides is for opening the valve not closing it but I guess there has to be enough pressure from the valve spring to close the valve at the proper rate of time.
How would you calculate how much wiggle room you have with the amount of valve height and pressure needed as I’m sure there must be something. I’m not sure if the rocker ratio I want to use is relevant either but its a 1.6.
My actual question is, can I use these PAC springs?
Thanks in advance!
