I did a pretty elaborate search with nothing too helpful. What I would like to know (in plain english) is a few things

1: What is needed to make 987 springs work?
I've heard and read that they drop right in with the stock spring seats, just not retainers and locks. I've also heard the head needs to be machined, or the spring seats need to be trimmed.

2: Is the stock guide for the springs 1.25", and anything bigger than that needs to be machined?

3: In a response to question 2, I found some conical springs that are 1.25" at the bottom and they taper up to 1.454". Only problem I found while I was searching; the valve spring seat load should be 115-130# and the open should be around 300#. These conical valve springs have a seat load of 100# and an open of 280#. The car only turns 6000rpm and will most likely not see more. Are these springs strong enough so they will not create valve float?

4: Valve height, stock is 1.750", these springs install height is 1.750". i should not need shims or spacers with these springs correct?

Just need to clear up some things before I decide on a spring forsure.

ShibbyZ

 

You need to start with the cam and match the spring rate, open and closed pressure to the cam. This a decent primer on the subject: http://www.compcams.com/Technical/Cu...g/HTML/339.asp As per this primer, you are always going to need shims to get the installed height correct on all the springs. This is just part of setting up heads, so get used to it.

Assuming the 987 is the correct spring, they have an OD of 1.437". I have never used them in a stock head, but all you have to do is measure the heads. Most SBC heads can accept springs this size though. The seats are cheap, so not a big deal either way.

Machining the spring pockets is easy, BTW. I am not much of a mechanic and I can do it! All it takes is the correct cutter and a drill.

Rich

 

One other thing, conical springs should be installed with the large diameter at the bottom (head).

Rich

 

The stock spring seat will accommodate something up to around 1.46 without machining. As far as the correct spring and installed ht., you need to consult the cam spec card which will provide recommendations for their cam.

I would certainly not go with anything that was marginal as far as recommended pressures and coil bind: the springs are very important to ensure the valves are opened and closed properly and the rockers maintain proper contact through the max of the cam power curve.

I am using Crane 99893, dual springs with my little 210/224 cam. They are dual springs good to 6500 before float. I'm sure others have good recommendations for your setup: I don't know why some say that the max the stock seat will take is 1.25 when I know many have installed larger springs and have had no problems.JMHO

 

Ya need to look into the Comp beehives that are 150 seat and 350 nose. They will loose 15+lbs after a few heat cycles.
This depends on your cam and the manufacturers recommendation and your valve size. 130/325 is normally about max for a hyd roller.

 

Really? If 987's are only 1.437" then I will buy those. They have .6" lift which will be plenty for me, along with good loads.

What retainers/locks go with 987?

stock spring seats work?


EDIT: Also I have a stock cam but plan on upgrading to a CC306 at somepoint. Just kind of preparing for it.

 

Notice that Doug Herbert Perf. Parts has kit on sale that includes

spring CRA 99893-16
retainers CRA 99951
locks CRA 99097
shims, if needed, CRA 99050

The site shows 2 different prices 189.99 and 147.99 (don't know which one is the correct price (you will have to check).

The spring will fit stock seats.

You might try another vendor for a better price, but by all means, get the kit since it will always be cheaper. JMHO

 

BTW: Kit no. CRA 10308-1

 

Just to double check everything...

-Comp Cams 987 spring
-Crane Cams 99914 7* retainers for 1.430-1.500" spring
-Crane Cams 99094 7* locks
-11/32" valve seals

Here is another question though. What is the difference between big block and small block rocker arms besides the ratios? Why can't a big block 1.7 stamped steel or roller work on a small block as long as the stud is the correct size?

 

BBC rockers are larger in most every dimension compared to SBC rockers.

You need to add shims and seats to your shopping list.

The advice about a "kit" is good if you can find one that meets your needs.

Rich

 

Can't I just re-use the old seats? I forgot shims, to install the correct height, but why new seats? Are the stock ones too small? Most seats I see are 1.55" not 1.43"

 

You may not need seats. They are cheap, so I would get them to avoid an unnecessary delay. But you could wait and see if the new springs fit them properly.

Rich

 

May not need them? As in I do not HAVE to have them? I'll just have to order the 987's and do some trial and error i guess...