I have read in a thread somewhere that the mods in the Dove book may have been improved upon. I read that it is now advised to drill all the way through the #1 cam journal. Is this the only thing I should do different from what it says in the Dove book? Has anyone made a list of every modification that should be done? Thanx for any info.
I'm not sure if the Dove book is where you saw them NOT drilling all the way through or if it was in my article. I've since corrected that error. Whether this is a complete list of stuff to be done is up for grabs; I'll leave that to the guru gang to supplement for you. For starters here's the link. http://www.buickperformance.com/oilflow.htm There's another article on the Buick Performance Club webpage on how to add the OP send unit at the rear of the block.
John, No, you still don't want to drill thru the cam journal. The intersection point of the passage, that runs from Number 1 main bearing saddle, up to the passenger side main galley, is just short of the cam bearing housing for the front bearing. You want to drill the main feed out (I will drill it from 15/32 to 17/32 depending on the application. More HP, more Rpm, generally gets the bigger holes. I have seen guys drill this hole 1/2 inch, and break thru the block.. the fix for that is to install a thin wall brass Tube in the hole. Some guys do this automatically. I don't.. I just aim the drill very carefully, especially when starting the hole. That hole is 27/64 from the factory.. but is a sloppy 27/64, so you could call it 7/16. Now we need to understand this.. After you drill up the main feed from the pump inlet/sender passage, you still have not increased oiling to the majority of the bottom end.. Why? Because that hole does not intersect the RH Galley, which feeds the mains/rods.. there is a short passage, Drilled up from the front main bearing saddle, that completes the link between the main galley and the oil feed hole, from the front of the block. That passage is a nominal 7/16 in size. Oil passes up the main feed hole, and then splits into three branches... to the front cam bearing, turns down to the number one Main and number one Rod bearing, and turns up a short distance to the RH main galley, which feeds the number 2-5 main, and the number 2-8 rod bearings. That passage up to the main galley, and down to the number one main, is the same hole, and this needs to be addressed also. I drill that hole the same size as the main feed hole from the pump/sender. On a race motor that is 17/32, I will install a plug in that hole, just under the main bearing, and drill it the same sizes as the rest of the mains-- typically 3/8 on a killer motor. But once again, you are in a dicy propostion, going thru the cam bearing housings with that big a hole. If you don't drill that passage, then drilling the main feed hole from the pump, has only increased the oil flow capablity to the front main, and the front cam bearing/LH galley. My spec on the level one motor is 15/32, for both those holes. And 11/32 for the number 2-5 mains. That is far and away the most common motor we build, I think we have about half a dozen of them in the shop now. I believe what you are talking about is drilling the mains.. Early blocks are 5/16, in the number 2-5 saddle. I normally drill those to 11/32, favoring the drill away from the cam bearing bores, all the way thru until you just break into the RH main galley. I still sweat every time I have to completely modify an early block, including drilling the pickup tube feed.. always a possibility of junking the block.. If the drill broke in the block, there is a real chance you would not get the broken piece out. That is always one of the concerns with doing a "numbers matching" early block. And sometimes, on a block with lot of core shift, that is slated to be just a stock rebuild, I won't touch anything beyond the oil pickup tube hole, if it is 1/2 inch. Plenty of motors lasted 100 K plus miles, with the factory hole sizes. Making factory type power. Make sure that you use nice sharp drill bits for this work. I do 2 or 3 early blocks with a set of drills, and then buy new ones. Drills are cheaper than engine block cores these days. Another tip is to radius the hole in the Main saddle. the position of this hole rarely lines up perfectly with the hole in the bearing, so the radius can help alleviate that issue. I use a round 1/2 ball stone, mounted to a mandrel, similar to the stuff that is available for a dremel tool, but on a 1/4 mandrel. You should find one of those at most industrial supply houses. Now.. a word of warning.. We must understand why we are doing this in the first place. All we are doing, is making sure we keep a film of oil, between the bearing and the crankshaft, at all times, under varying load/ rpm conditions. Bigger is not always better, especially in a street motor, that sees the majority of it's life at lower rpm. We have a positive displacement oil pump, meaning the faster it spins, the more oil it displaces, or pumps. So if you have big main/rod oil clearances, and huge holes in the block, you won't be able to keep the system under adequate pressure, at low pump output speeds (idle), and under quick acceleration, cylinder pressure rises rapidly, so right at that instant, the film of oil on the crank has to be strong enough to keep the rod bearings from touching it. The opposite of that is a race motor, which typically sits on the starting line at 4-5000 rpm, before the transbrake is released, and any real load is put on the bearings. Any pump on those engines puts out enough volume to be near the relief valve setting, and typically we fight with these motors, especially with roller cams, to be able to feed enough oil to them. That is where the main galley by-pass line we spoke about before really comes in. This is all a delicate balance between pressure, volume, clearances, pump output, and the forces the oil has to deal with. One other concern with our blocks is core shift.. remember, the holes are always more or less in the same spot on the blocks.. what will vary is the amount of material around those holes, as the casting shifts back and forth, due to variations in the molding/casting process. I think illustrations via pictures would be a good thing for a topic like this, I will have to take a bunch of pictures when I do Ken Lisk's block mods, coming up here shortly. Other mods.. Dist gear oiler.. anything that has a history of dist gear failure, or a brass gear. The oiler will double the life of a brass gear. Most motors get the Double grooved cam bearings, but not all of them. I let the motor tell me which we have to use, via a turning torque specification that we have devloped, using a custom built tool, which we have been using in the shop here for about 2 years now. And knock on wood, I have not lost a cam bearing in at least 3 years, and only recall one motor that we had an issue with, in the last 10 years or so. There are so many ways you can fail a cam bearing at startup, and so many different causes, that I will save that discussion for another time. But lets just say there is no magic bullet for that issue. I have seen the cam journal sizing talked about alot, but opening up that clearance often times is fixing the symptom, and not the actual problem. Keep in mind, you will get varying opinions on these subjects, so I am just telling you how I do it.. Good luck.
Thank you NotSS (cool name) for the help, always appreciated. Jim W., thanx so much. When I get to work tomorrow, I am printing this ASAP. I am building a short block for the GS, putting the current motor in a K5 Blazer, & swapping heads like a orangutan with a crack pipe. If I have any more quesitons, hope ya' don't mind a p.m. I appreciate it.
