O.K. here we go, for better or worse,
the final assembly. I'll explain each picture in order.
1) The first picture is the engine with the retainer, spacers, dog bones, lifters, cam.....everything ready for pushrods. With FelPro PT9441 head gaskets the distance is exactly 8.400"...
WITH NO PRELOAD. Comp Cams suggests a lifter preload of .030" +- .010".........
so the total pushrod length required for my setup is exactly 8.430" (ball-end to ball-end.) This length was measured independantly on five different lifters, on both sides of the block......all were within 2/1000th of an inch. Yes, the lifters were positively sitting on base circle. You should be able to use these measurements with any head gasket, just subtract, or add the difference in compressed thickness between the PT9441 and yours........as long as everthing else in your combo is the same as mine. You should measure your own just to be safe though.
2) The second pic is of the 5/16th" tapped holes (using a 5/16th NC18 tap) in the lifter valley. Very important to get these drilled straight up and down, the retainer requires the spacer to be perfectly parallel to work properly. Notice the forward hole drilled right through into the oil galley. I made sure the threads were oil free, and mixed some JB Weld and lightly coated the threads of the hex stud before installing. I figure you almost need to drill into the oil galley to get enough "meat" for the stud to hold really well. If you get nervous here, and don't drill deep enough, the retainer may shift. Ideas?
3) The third is a shot is of the spacer I used (5/16th" version of the same nut we use to make our wastegates adjustable...... there are two cut down to 1.040" long....your height may vary a little) The other is of a hex stud (5/16th" by .75 inches long) that the spacer is screwed onto. This provides the mount for the retainer. The .75" long body bolt holds it on. Use your own imagination here if you don't like my idea.......but it's super strong, and should hold extremely secure. Make sure the hex stud doesn't move when you wind the spacer on....ideally, there should be just as much thread in the block as sticking out.
The hardest part of this build was getting the retainer placement perfect........there is not a lot of room for error here. To make things easy, install the cam, lifters and the dog bones. Put the retainer on the dogbones (make sure the half-circle hole is at the front of the engine.....the retainer only really fits one way) then bend the arms down a bit.......it will require some adjustment to contact the dogbones correctly. What's correctly???.....the little bump at the bottom of each arm must not slip off the dogbone, even when it's bolted down. Try to keep the arm adjustments even.....If you bend one, then bend them all the same amount. When you have it sitting exactly the way you want it, look straight down the retainer mounting holes and mark exactly where to drill the hole. (I used a tiny drop of White-Out paper correction fluid) Make sure you use the correct drill-bit for the 5/16th NC18 tap.....it's not a 5/16th bit.....it's smaller. You'll also notice I rather crudely knocked the corners off the bottom of the spacer a little, this was so it wouldn't hit the lifter bosses, which were quite close. Even so, this mounting method is plenty strong. Like I said, if you don't like it, use your imagination, the are certianly other ways to do it....as shown by 87BuickRacer. The push-rod order goes in tomorrow.
The total for this mod should not exceed $430.:smile: If you noticed, I'm
not going to use the stock cam button seen in the first picture.....I just wanted to see if you were paying attention.
Cheers!:smile:
P.S. Overall this is a pretty easy mod........I'll get back to you and tell you how well, or not, the 980 springs worked.