Checked the spring rates on the Comp 948 springs last night, using a cheap, simple, Proform spring tester I ordered from Summit.
Just to get a baseline and to see how close of a reading the tester gave me to Comp’s stated seat pressure of 336# @ 2.10” I.H., I first tested the full triple spring with the retainer installed. At 2.10” it showed 340#, so it seems pretty close to what it should be. In any event, it gave me a baseline.
Next, I removed the inner spring and tested it again with the retainer installed at 2.02” and got 300#.
So, based on what I’ve learned on this thread, I can use the 948 converted to a double spring, and install it at 2.02-2.03 and that will be better than using it as a full triple spring installed at 2.10.
So far, I’ve installed 4 of the intakes at 2.03”. With the standard locks, there’s plenty of clearance between the rocker body and the retainer:
BUT, note position of roller tip on exhaust valve…
I haven’t installed the exhaust springs as yet, because after carefully checking the stand heights again, it looks like I will have to use lash caps to get the right rocker geometry on the exhaust rockers, since I can’t get the stand any lower and the rocker tip is too far back on the stem even at the fully closed position. As you can see below, using the T&D #750 checker tool, the tool is showing zero clearance between the rocker shaft and the tool, although I’m supposed to lower the rocker shaft by half the difference between .750 and .816. That’s with the stand sitting directly on the pad, with no shim under it:
So, I threw a .080” lash cap on it, rechecked the clearance and moved the rocker through its full range (closed to .816”) and it looks much better in terms of sweep and position on the valve tip and at mid-lift (measured) the roller tip sits right in the middle of the lash cap.
Exhaust valve half open:
Exhaust valve fully open:
Please let me know what you think.
But before anyone says anything about I need to machine the heads or buy new valves, let me say that’s not happening, because one of these heads (which I just got back from Brodix in December) is on the motor already and the valves are brand new Inconel valves that I just bought from Brodix when they reconditioned my heads.
So, on the premise of a man has to do what a man has to do, it looks like I’m going to be running lash caps on the exhaust. The only problem is that I don’t have locks that are recessed for the lash caps (I’m sure I do, somewhere, but can’t find them), so I’ll have to order some from summit. Always fun, these projects…