What determines whether you need flat or raised guideplates? I just had my vortec heads machined at a machine shop for screw in studs, had the guides cut down and spring pockets enlarged. looking in the summit catalog they offer flat and raised SBC guideplates. Also does the pushrod hole need to be enlarged since the machine shop didn't open that hole up at all and I remember reading in a hot rod magazine a few years ago how you use a 1/2" drill bit to open the hole up trying to mimic the pushrod angle. Also running a solid lifter cam and in the comp catalog it lists lash caps as something that could be used on the heads, what are they and what do they do/are they even needed? running a 12-501-5 comp cam, .501/.510 lift tight lash grind on 106 lsa. thanks again everyone.

 

There's no "hard and fast" rule about what guide plates to use; it's personal preference.

I prefer the raised ones where applicable, but it's not a big deal either way.

The push rod hole should be large enough to accommodate 1.5 rockers, since those heads were designed to have self-aligning rockers on them. They may need to be lengthened toward the rocker stud if you go with 1.6 rockers. You'll just have to install and check; or do it pre-emptively just to be on the safe side.

Lash caps are good with big roller cams and rellay massive springs. Not really necessary for a street build.

 

I too prefer the rasied guide plates. Only issue I've had is when used with the center bolt valves covers, the upper internal ribs need to be cut away.

RBob.

 

If you're going to guide plates, I heard you just punch out the guide plate slot so you have LOTS of room, no chance to bind, since the guide plates are going to do the work of guide the valve. Just not too big that you harm the heads. 1/2" drill sounds good

You know how guide plates work? They just stabilize the pushrod, so if you try and stablize it lower, you need more force right? and you can still have more deflection higher up. raised just moves the guiding area up higher, so it's a little better, but costs an extra $3 or so for the extra machining process, *stamp*...