The Stovebolt Site Forums The Shop Area Engine Shop drilling oil gallery plugs on 396BBC w/geardrive

In the final stages of putting the engine parts together for the 396BBC im building for my 63 sb/ss. I plan on going with a gear drive, and have read about drilling out the front oil gallery plugs (by 1st cam bearing) .30 or .40 for better oiling on the gear drive. Does anybody have any input or experience on this? Im told that this will spray a light mist of oil, but does it effect pressure? What kinda pump do I need...stock, high volume, high pressure? Going for 425hp, street use/daily driver kinda deal.

Hy jon1963, any holes that you install where there was no hole previously will affect pressure, you may be able to compensate for the holes by installing a high volume pump. Were these holes suggested by the suppliers of the gear drive setup? Just for my own edification why are you going to a noisy gear drive on a street driven engine?

These were a factory option in some of the later big blocks that were high performance. I plan to go with a quiet gear drive. I just like the reliabilty of the gear drive systems...I think the chevy inline 6 like my 230ci is a good example. No chain to stretch also. I picked up a chevy big block engine book and it talks about the factory recommendation of drilling these holes to provide more oiling to the gear thrust face. Were only talking about a 1/32" hole. They use whats called a wire bit to drill it. I haven't talked to my machinest yet, but I was just curious as to the population of gearheads.

There was never a factory gear drive option on any Chevrolet V8 engine, they didn't even offer a gear drive cam for them, exept for one marine use reverse rotation cam. I would run a chain, as the engine was intended to have.

When I said a factory option, I was referring to the drilled oil gallery plugs. Chevy still has them on the shelf at my local dealer for $5 a set. Im not sure if the gear drives were ever factory, but they certainly had blocks w/drilled gallery plugs. I spoke with several people locally yesterday and one of the guys had a late 90's block that had these plugs. Although I respect your opinion, I still prefer the gear drive over the chain though.

I did it on my 73 454, it is in most of the performance build books and old shop guys all seem to do it. biggest thing to watch out for on these older engines is the oil you use. In the last 25 years, the government made them take much of the additives out that provide lubrication for flat tappet cams. You can get oils with the zinc/etc in them or you can use additives that have them. You see lots of advertisements now for them. I found out too late and had a cam go flat and had the engine rebuilt before I knew. If I had know sooner, I would have put a roller cam and lifters in. It cost more but reduces the friction/load on cam. You can also use more aggressive cam with roller lifters. Good thing it is a collector truck and not driven much.

Thanks for the advice. Do you remember what oil pump you used...stock, high flow?

I see what you're talking about now. I checked my GM race manuals, they make no mention of drilled galley plugs. Jerry might chime in with better info in this.
As far as the Great Oil Debate, lots of information out there, some of it true, some not so much. The main deal is using the ZDDP additive during break in. Once the engine is broken in, SM rated oil will be just fine for the average street engine, regardless of cam type. The real problems come from incorrect parts matching (exesive spring pressures), improper break in, improper engine assembly. Seems most engine builders prefer to pass it off on the oil manufacturers that take responsability for their own mistakes.
Something most people do not know is that engine oils are required to be backwards compatible, so while the ZDDP has been reduced, there has been anti-wear additives added to compensate.

Chevy used a gear drive on the the 366 BBC truck engine from 1966 - 1968 I think. You might check out how the drive was lubricated from the factory. I don't think the oil pump was anything special other than a unique distributor gear and pump drive.

SimS

Yes, the drilled plug is a good idea. Be sure to angle the hole where it squirts directly onto the gears. I'd reccomend a hole about 1/32" or so, and the top oil gallery, the one that does not supply oil to the lifters would be the one I'd choose to supply the lube to the gears. A Melling high-volume oil pump would be a good idea, but it's not absolutely necessary unless you're also running race-engine clearance on the rod and main bearings, .003" or so instead of the usual .0015". Do you plan to run hydraulic or solid valve lifters? If you're running solids, there's also a set of restrictors available to limit the amount of oil that gets pumped up to the cylinder heads. Our round track engines used to fill the valve covers with oil and starve the bearings unless we installed restrictors, and I'd enlarge the holes in them slightly to supply the low-bleed-off hydraulic lifters we ran. If you're going to be doing offroad running or round track, keeping lots of oil in the bottom end is essential!
Jerry

Its just for my pleasure. Dont have 4x4, so no off roading. Love the 63, love the big block and like the gear drive system, so I plan to merge them together. The engine is probably overkill on what I need for hp, but its my toy...so I want the 425hp big block. Dont plan on running at the track either, but I would like to build a solid engine. Haven't gotten to the cam and lifters yet..but for now planning on a Lunati Voodoo 227*/233* .522"/.538" or 219*/227* .530"/.542" hydraulic flat-tappet cam/lifters. I dont have tons of experience w/picking cams, but would like 0-5500rpm and that killer big block choppy lope. Also...the two plugs on the front of the block by the cam...your saying to drill the left one as were looking at the block?

OOPS! I was thinking of the small block engine, which has three oil galleries, not two like the rat motor! Drill either plug- - - - -it will only slightly increase the flow past the lifters on one side. The 265-400 engines have a third oil gallery that runs down the middle and supplies the cam bearings and crankshaft, independent of the lifter oil galleries. That's the one I drill for extra cam drive lubrication on the small blocks if necessary.

I'm sure you probably know that gear drives are horrendously noisy - - - -I can hear an engine running half a block away and recognize that it's got a gear drive.
Jerry

Yeah...I know they are noisy...Im going to try on of the "quiet" gear drives. Ive seen the left plug drilled typically on the big blocks, so il probably just go with that one. BTW- Any advise on the cams?

The nice thing about a big block engine is the fact you don't need to go radical on the cam profile to make plenty of power- - - - -there's enough torque available that the RPM can be kept down to a reasonable speed and you don't need a radical cam grind.

I like the Comp Cams High Energy or Magnum series, either the 268H High Energy, or the 280H Magnum models. Here's a spec sheet out of the current Comp catalog:

http://www.compcams.com/catalog/COMP2010/jpg/COMP_Catalog_2010_202.jpg

The 268 works well with stock compression and rear end gears, while the 280 needs a compression bump (9:1) and either a high-stall torque converter or low rear end gears with a standard transmission. If you're running a 3/4 ton or 1-ton rear axle, you've probably got low enough gears already to use either cam. The 280 will definitely give you an idle lick, but you'll lose a little low-end torque in the process.
Jerry

Be 3 speed tranny, 12 bolt 4:10gear, haven't gotten the pistons yet, but running oval port open chamber heads (slightly over stock). Whats the max amount of lift I should be looking for? .50? I think the comp cam 280H is a good candidate. Im not running anything vacuum operated except the factory vacuum gauge (rare option for 63), and eventually power booster for drums. The dist. is a mallory dual point and have a factory high rise 1967 427 intake w/750 edelbrock. Forged crank, heavy duty rods.

The 280 spec sheet shows a .520" lift, so be sure the valve guide height and the oil seals are correct. On some high-lift cams, I've had to shorten the top of the valve guide a little to prevent things from getting together at max lift. Always assume everything is wrong, until you prove it's right. When you get away from stock parts, you become the engineer, and it's up to you to make everything work together.
Jerry

Moffit machine here in Fayetteville does all of my engine work, and the shop has for 20 years. This is only the second big block that Ive built from the block up...all the others were running. I appreaciate all the help.