quick valve spring question

[Flyin Brian]

I have done a ton of searching and reading on here on the topic of what valve spring and seat pressure to run with a Comp Cams 218/212 hydraulic roller cam and 1.65 roller rockers on ported stock iron heads.

General consensus seems to be Comp 941 or PAC 1201 at a seat pressure in the range of 140 to 160 lb.
My max valve lift is .545. I have the heads off and apart at the machine shop now and I discovered that my seat pressure was 95 lb at 1.76 installed height. I thought I had K-Motion 750 springs so I had them check them at 1.7 expecting to see close to 130 lb but it was more like 110. So, either my 750's are real tired or they are actually 700's. In either case I need new springs. Height from head to underside of retainer is 1.8.

Quick question 1. Which of the above springs and what seat pressure?

Quick question 2. In either case should I shim the required amount (.05" or more) or do I need different retainers so I can use less shims? I am planning on using my existing retainers if possible but will buy different ones if that is the smart thing to do to avoid a tall shim stack.

Thanks

 

[fastblackracing]

Using shims under the locator plate is ok but you will get to a point where the bottom locator will
get into the bottom of the valve seal. There are also -.050 valve retainer locks that will help
get the installed spring height where you want it to be.

Really need to know what the lobe numbers are that cam was ground with,
this will show us if the ramps are aggressive or mild and the spring requirement
can change a lot with the different lobe families.

Depending on what you have a 941 spring maxed out may not be enough if you
are going to run some hi boost and rpm....especially with the 1.65 rockers.

Intake manifold pressure, exhaust back pressure and lobe design really put
extra demand on our turbo engine valvetrains that drive up the pressures needed for
a hard running T/R to perform its best.

 

[Flyin Brian]

I don't suppose the lobe number information would be on the cam card because that is all I have?

 

[fastblackracing]

I don't suppose the lobe number information would be on the cam card because that is all I have?

yes its on there like a 4 digit number ex 3190 or similar, or post a pic would be better.

 

[Flyin Brian]

cam card

 

[pacecarta]

if its the standard comp roller .. http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=48&sb=2

 

[Flyin Brian]

did some research on comp cams lobes.
I think I have lobe 3313 intake and 3312 exhaust but I could be wrong.

 

[David Husek]

With these lobes especially the 3313, you will want a min of 150# on the seat and with the 1.65 roller rocker, a min of 400# open. I like to see more pressure though. The pac will work, but it will be tight as the coil bind is 1.115-1.130" and this limits seat pressure. The k750 springs work well, but need to be installed at 1.640-1.650". You need to use a spring cup and -.050" locks and a shim or two to use them correctly. The 750 tends to fail when improperly installed. Feel free to contact me for more info....