Chips are a flyin'! - ZR-1 Net Registry Forums

Paul Workman · 02-22-2009

Boy...My hat is off to all of you that have done the P&P on you uppers! The first hole on the plenum took perhaps 3-1/2 hours of try this and try that with a combination of burs and rotary files. And, true to what Marc H and Pete have said, "If you don't perforate the plenum at least a few times, you not tying hard enough." I managed to "burn thru" in a couple runners (so far) but hopefully the cause for that is behind me. Oh, well...I planned to repaint the engine anyway. Now I have the motivation to do it (after the holes are welded and ground down).

I bought the speed control for my electric die grinder fm Harbor Freight, but I also have a fairly good pneumatic, right-angle die grinder. As anyone that has done this knows, there is a art to getting a 3/4" open flute bur to cut w/o chattering - it is the chattering that is a real killer, because it can be rather violent! As it turns out, the pneumatic approach is working 10X better than the electric grinder (for me). The degree of control and power is far superior to the 'lectric die grinder, IMO. (For one thing, max torque on the electric is available only at "wide open", and there are times I want to go slow and still have sufficient torque to cut w/o the load dragging the rpm down. Then there is the ability to start and stop and start again by just pressing the air control lever and no inertial issues: instant on and instant off = much more to my liking! I'll relegate the electric to sanding chores later.)

Aside from my back killing me from being bent over for hours yesterday, I was pleased to be able to rough out (yet to be sanded) my last hole (so far) in 35 minutes w/o perforating the plenum, and w/o the bur chattering at all. (I figure the plenum is a good piece to start with. I want to be "comfy" with the tools and burs before I wade into the IH work (next).

I'm using the (carbide) burs with the rather large open flutes recommended by the tool maker for aluminum, and I think I'm good with that as far as the plenum work goes. However, if there is a different bur U experts would recommend especially for the IH - to say nothing of the heads (which will be done in place) this rookie is all ears!

Pix later. I hope I'm on the right track. I'm getting excited about the end product that I hope to realize at the track come spring! And, I want to thank Pete for the use of his balls!

(No, I'm not going to spit on 'em, Pete. But! I promise to keep 'em warm!)

P.

02-22-2009	#1
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,466	Chips are a flyin'! Boy...My hat is off to all of you that have done the P&P on you uppers! The first hole on the plenum took perhaps 3-1/2 hours of try this and try that with a combination of burs and rotary files. And, true to what Marc H and Pete have said, "If you don't perforate the plenum at least a few times, you not tying hard enough." I managed to "burn thru" in a couple runners (so far) but hopefully the cause for that is behind me. Oh, well...I planned to repaint the engine anyway. Now I have the motivation to do it (after the holes are welded and ground down). I bought the speed control for my electric die grinder fm Harbor Freight, but I also have a fairly good pneumatic, right-angle die grinder. As anyone that has done this knows, there is a art to getting a 3/4" open flute bur to cut w/o chattering - it is the chattering that is a real killer, because it can be rather violent! As it turns out, the pneumatic approach is working 10X better than the electric grinder (for me). The degree of control and power is far superior to the 'lectric die grinder, IMO. (For one thing, max torque on the electric is available only at "wide open", and there are times I want to go slow and still have sufficient torque to cut w/o the load dragging the rpm down. Then there is the ability to start and stop and start again by just pressing the air control lever and no inertial issues: instant on and instant off = much more to my liking! I'll relegate the electric to sanding chores later.) Aside from my back killing me from being bent over for hours yesterday, I was pleased to be able to rough out (yet to be sanded) my last hole (so far) in 35 minutes w/o perforating the plenum, and w/o the bur chattering at all. (I figure the plenum is a good piece to start with. I want to be "comfy" with the tools and burs before I wade into the IH work (next). I'm using the (carbide) burs with the rather large open flutes recommended by the tool maker for aluminum, and I think I'm good with that as far as the plenum work goes. However, if there is a different bur U experts would recommend especially for the IH - to say nothing of the heads (which will be done in place) this rookie is all ears! Pix later. I hope I'm on the right track. I'm getting excited about the end product that I hope to realize at the track come spring! And, I want to thank Pete for the use of his balls! (No, I'm not going to spit on 'em, Pete. But! I promise to keep 'em warm!) P.