In the book "How to Hotrod Big-Block Chevys"
by Bill Fisher & Bob Waar, it has a couple of pages showing how to hydrostatically balance the idler gear of the oil pump. The pump already has grooves to balance the drive gear. They show where to grind grooves to do this. Has anyone done this, and is it really helpful or just a urban ledgend?

Dave

Dave I did it. I did not see how it could hurt. On the otherhand How could you substantiate it. I guess one could look at spark timing variation before and after. Lots of cool stuff in that book huh?

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67 BB Prostreet Camaro COMBAT RAT
71 BB Chevelle (SS clone)
80 Camaro Z28 355 SBC
2002 35th anniv. SS Z28

Miilan,

Yeah, there is a bunch of info in here all right. Problem is, a lot of it is disputed by this guy or that guy. For example, the bearing clearances and HV pumps. I agree with this book. All you should need is stock clearances and a stock pump. Two different engine builders now, have said that they like .003 clearance in bearings and HV pumps with 10w50 oil. I want to tell the builder to grind the crank at .0025, and run my 10w40. No guts I guess.

Dave

<BLOCKQUOTE>quote:</font><HR>Originally posted by SS_Dave:
Miilan,

I want to tell the builder to grind the crank at .0025, and run my 10w40. No guts I guess.

Dave<HR></BLOCKQUOTE>

Dave, An engine builder only sees part of the total picture. Next engine I'm building is going to be tight as I can get it. I'm planning on running 5W-30 oil.

Mike


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BDE 327:
Bored .030", balanced, TRW 9.35:1 pistons, Crane Energizer cam .454" 216 @ .050", Trick Flow heads, Edelbrock Performer, Quadrajet.
Home page: http://home.peoplepc.com/ppages/viewpage.asp?MemberName=mbey

Mike,
Do you get to see engine specs on the motors you check?
If so, what is the current theory on bearing clearances?
Or is that why you wil build a tight motor?

Thanks
dave

Dave,

Don't know the current specs, but most new cars run 5W-30, 5W-20, so the specs have to be pretty tight. There is a fuel economy advantage there. That means that there is a power advantage there as well. http://www.chevelles.com/forum/wink.gif

I'm certainly no pro engine builder. In fact I have little engine building experience. Being in the testing loop gives me a chance to think about things a lot and make a lot of first hand observations.

Mike

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BDE 327:
Bored .030", balanced, TRW 9.35:1 pistons, Crane Energizer cam .454" 216 @ .050", Trick Flow heads, Edelbrock Performer, Quadrajet.
Home page: http://home.peoplepc.com/ppages/viewpage.asp?MemberName=mbey

Dave I like to apply my limited understanding of physics and say that the quality of lubricants has dramatically improved over the last few decades and the mollecular shear strength of todays oils is greatly improved. The tighter the clearance the more controll there is over the inertia of the mass piston and rod when it changes direction. I believe that the more you can controll that "hammering" the longer the engine will last.I believe that there is more to clearances than oil presure and volume. If you create larger clearances you must fill those with oil but the more oil you fill them with the more oil there is to squish out. I there fore believe that the tighter the clearance (within specs) the better. the Japanese engines clearances are so tight (proportionatley)and look how long they last. I am not a engineer but it seem logical to me. Am I way off?

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67 BB Prostreet Camaro COMBAT RAT
71 BB Chevelle (SS clone)
80 Camaro Z28 355 SBC
2002 35th anniv. SS Z28

To dovetail off what Milan says, my machinist's opinion was that with modern oils, this notion f die grinding or ball milling channels in the oil pump are much less relevant. Lets that what he told me, and I was going to massage the stock Melling pump.

Sounds like you have a good engine builder Gene.

Reading about some builders who are still pushing 20W-50 and high volume pumps, you wonder if they lose track of the engines once they leave the shop.

Malibu_fan,

I smell what your steppin in. http://www.chevelles.com/forum/smile.gif
This is why I asked this question. I told this guy this is a street/strip car and will get some miles on it. You wonder if they are stuck in all out performance mode and have lost touch with reality. I called the guy today to tell him to make sure the rod journals are no bigger than .0025 max. But, he is sick with the flue. I'll try again tomorrow.

thanx
Dave

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#1104
1969 Chevelle 454, 3.73 posi, M21 4spd.
12.30 @111 mph
License Plate: NTHE 12S
Pass_Side (http://www.chevelles.com/showroom/SS_DavePass_side.jpg) Front (http://www.chevelles.com/showroom/SS_DaveFront.jpg) Motor (http://www.chevelles.com/showroom/SS_DaveMotor.jpg) NTHE12S_69 (http://www.nacs.net/~drunion/Drivers_side.jpg), IWNT11S_69 (http://www.nacs.net/~drunion/passenger_sid.jpg), My_Webpage (http://www.nacs.net/~drunion/First_Page.html)
The "Blue Thang" running a 12.63 (http://www.nacs.net/~drunion/MVC-001V.MPG)

He put .0020-.0022 on the rods, dont recall the mains, and only .015 side clearance " to keep the oil on the bearings where it belongs". Maybe thats the reason, the builder does little hipo stuff, just "normal" auto machine work. Old timers. Skirts are a little loose at .003-.0035, but guess that what was called for by the piston manufacturer.

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Gene
ACES / CanAm Chevelles
Old Red (http://www.chevelles.com/feature/october2000.html)