Here is a video I came across that I thought was interesting. I have been considering doing this on a non-chevy engine. I'd like to see opinions pro/con on doing this.
That's Tony Sizemore of "Headbytes Porting", he is known to be a bit of a flake. Out of business now, AFAIK for bad business practices and ripping people off. All that driling he just showed you is worthless, for two reasons: #1, there was no good reason to increase oiling to the lifters, they get more than they need already and for serious high rpm circle or road course use they are often even restricted smaller than stock with .060"-.090" diameter oiling restrictors screwed into each lifter passage at the rear of the block, so you don't waste too much oil volume pumping it through the lifters to the valvetrain and into the valvecovers #2, drilling the large central feed to 1/2" did nothing, because he overlooked one key thing....all the oil going to the mains has to travel around the outside of the cam bearings in that annulus groove in each cam bearing bore....since he didn't set up in the boring mill and cut all those grooves bigger/deeper, drilling the holes feeding out of the main galley and feeding in to the main bearings was a total waste of time....the groove is still a restriction. His advice is the kind of hack modification you need to avoid.
My nut does not fall too far from the stock tree. All I can say is it's risky. Even on a SBC there's plenty potential for disaster. How do you get one of those long bits out if it breaks? What if you drill through? What oil pan? He mentions one, but which one? What is the application 1/8 mile? Even with a big pan, will you pump the sump dry, say going down the interstate? What about seals? Again is this compatible with a street engine? The non Chevy, what affect will it have? This is something you need to research. Until I knew more about the oiling system and proven real world experiences by reputable people that have done similar to that particular engine, no way.
He wasted his time but oil hole in the main bearings isn't the main problem with what he did. If you meant cam bearings those holes have nothing to do with main oiling, they are just there to oil the cam journals.
I meant holes in main bearings. Having built hundreds of SBC race engines & had the opportunity to look at many of the top NASCAR engine builders blocks back when they ran the SBC there are other mods done to main bearings & main bearing tunnel in block need performed.
I have a high volume oil pump , a 6 at pan with a windage tray & crank scraper , I run down the interstate at 3500-4000 rpm @ 75psi , engine has 30 k miles after 10 years , the pan has never pumped dry . Call Melling , they'll be happy to tell you that pumping the pan dry simply doesn't happen
Not wanting to argue here, just getting opinions and trying to "discuss" some things. I looked at some old books I have and there are some things in them that somewhat support what the video shows. There was some info from Hendrick Motorsports that says Bowtie blocks come with a larger main oiling passage right from GM. Thats a priority main oiling system. They also mention that they enlarge the holes to the 2,3,4 mains......which agrees with the video. They say this is unnecessary in the Bowtie block, so I guess that means they are talking about the common non-Bowtie blocks. They also mention insuring that the oil grooves for the cam are the correct size. The thing I am thinking is that whether its a racing engine or a high performance street engine, the important thing is getting plenty of oil to the main bearings. EricNova72 correctly mentioned that the restrictive passages around the cam bearings would keep a builder from getting any benefit from increased oil passage sizes. Also you don't want to put too much oil thru the lifters and flood the valve covers. The question then becomes.......Why does Hendrick do it if there is no benefit or the top end will become flooded? What I'm thinking is that reducing the resistance in the major oil passages should have the effect of letting whatever excess oil comes past the cam bearing grooves go easily to the mains. Pressure isn't being increased, so why would the small orifices in the lifters and the pushrods pass more oil? Couldn't the oil grooves around the cam bearings be widened or deepened to provide more flow? If top end flooding became a problem, drain tubes installed on the back of the head to the oil pan could return any excess. Not likely people will want to do that, but oil does cool the exhaust valve stem and the valve springs. I even saw a picture where a valve cover was equipped with spray nozzles to keep springs cool. Remember, I'm trying to learn from Chevy because I want to try some things on a different engine that doesn't have the worlds best oiling system......so I'm just pokin around.
I was always taught that the Small Block Chevrolet had the best oiling system stock with no modifications needed. Sent from my iPhone using The H.A.M.B. mobile app
On the stock block SBC oiling system, the enlarged main holes on 2, 3 and 4 are a good modification for high rpm use BUT MUST be accompanied with enlargement of the annular groove behind the cam bearings to complete the work...don't do the groove re-cutting and you wasted your time with the rest of it. Also helpful on the mains is the "3/4 groove" main bearing, where there is about 3/8" of so of teardrop shape groove at each end of the normally solid face bearing half, it provides a continuation of the groove in the upper half of the bearing to increase the amount of time the crank oil feed hole to the rod journals has access to the pressurized oil feed. Full groove main bearings are not recommended for many engines, SBC and BBC for sure, the full groove lower half loses over 1/2 of its load carrying ability if it is fully grooved. Drilling the lifter feed galleys oversize just does nothing productive, it isn't needed. The info ekimneirbo posted has a misprint/typo in it....if you do groove the lifter bores for increased cam lobe oiling, it is NOT a .100" deep groove, it should read .010" deep(author/publisher didn't proof read or something). Since the common tool for this is a .015" wide cutter, an .015" x .100" deep groove would be a huge oil leak...16 of them. The EDM cut oil hole in the face of Direct Lube/Cool Face/Camsaver lifters is somewhere between .022 and .028" depending on brand...so you can see how that coincides with a .010" x .015" square groove in the lifter bore. How a lot of this info transfers over to other brands and engine designs entirely depends in the design of the oil sytem in that engine.
Hendrick & most other SBC NASCAR BUILDERS back in the day flooded the top end to cool valve springs then blocked all oil from drainage to crank case. That Ford &Chevrolet builders. Some even encased the cam so it ran in oil also. The then put a pickup in valley to scavenge with dry sump pump.
For the most part it does....constant high rpm use just requires a little fine tuning of the system since it is well outside the original design parameters. Other than the benefit of lifter bore grooving/EDM lifters for flat tappet, almost none of what is being discussed is necessary for a less than 8000 rpm street/strip SBC engine I get a big laugh out of the original posted video....he is doing all these "high rpm mods" on a 305 block!!!! that is being stroked to 334" with a 3.75" stroke crank....not exactly a screaming high rpm powerhouse there that needs all these modifications.
Ran sprint cars for 14 years and built my own engines. We did blow one engine, but it wasn't one I built. The only modification I did was open up the rod side clearance. My old driver felt that it let more oil to the edge of the rod bearings. I felt that it limited the oil getting to the top end and kept it in the pan. Whichever it true, it did work. After a season of maybe 20 races, the bottom ends always looked like new. I ran the stock Chevy LT1 oil pump and a circle track oil pan. I did change oil and filter at the mid point of the season.
"...Call Melling , they'll be happy to tell you that pumping the pan dry simply doesn't happen..." Years ago, we were heading south on I5 in a '53 Ford PU with a bone stock 64 Chevelle 283 in it, 2bbl and all. No radio etc. and kinda zoned out after a long day's work. I finally zeroed in on a sound I'd heard many times before, you know, you here it at the drags just before the lights, at the oval track just before the turn, etc. That 283 must have been running over 6K RPM for ever. Before you laff and fall off your stool, the '53 still had 4.27 gears in the back. So as I think over whether this is actually possible, I look briefly at the cheapy, 3 gauge cluster screwed to the dash. Just then, the oil pressure dropped big time. I bumped Uncle Cal and pointed. He lifted his foot. The oil pressure came up. Back on the floor went his size13. A short while later, oil pressure dropped again. I bumped him again, he looked and lifted. Happened a few more times...
Hmm. He's off base. I got away from high volume pumps in SBC, just generally not needed. high quality stock pressure pump, with deburred passages, true up the gear and plate faces is my go-to anymore. New or aftermarket pickup brazed on. I spend time bottle brushing the block passages but dont modify them, just boiling the block doesnt get the passages clean. I do open up the drain holes in the valley. Ill epoxy screens in the valley holes if Im using roller rockers, or building something that may use them in the future. Spend time to deburr the whole block, saves cuts later when working in the car. If youre overly concerned or plan to spend sustained time at high rpm, a high volume pump, windage tray, aftermarket 7 qt pan are worth looking at instead of following this jokers advice. With all the SBC'S out there and millions of people racing them for years, there's not a lot of new tricks.
No mater the engine I’m building the rod side clearances is always increased. I know it aireates the oil and slightly lowers the pressure but flow keeps the crap out and normally takes care of the solid lifters I like to run...
Lack of oil control ( no scraper , no windage, etc) can cause aeration / foaming & the subsequent loss of oil pressure , there's still oil in the sump .
Another thing I wondered about as the fellow in the video is running those drill bits through the lifter bores, what about the burrs left in each lifter bore as the drill went thru? He never mentioned it, but there had to be burrs left behind. How would you clean those up? Hone each lifter bore? Then I’d be afraid they would be too large. Sent from my iPhone using The H.A.M.B. mobile app
If you carry it around with you, it probably stays pegged ........ The thing about oiling systems is that the better high performance blocks all tout the fact that they have "priority main" oiling. That indicates that crankshaft/rod bearing oiling benefits from insuring more oil is always available. If a modification can insure more oil can flow to the bottom end, without having to buy an aftermarket priority main block, that would be a good thing. Once someone insures they have increased the oil to the bottom end, they can restrict flow to the top end if needed. Does this work as the video implies, I can't say it does or doesn't because I haven't tried it. It does however provide some "food for thought" when building an engine.
As I mentioned earlier in this thread, my interest in improving oil flow to the main bearings was not for a Chevy, but for an alternative engine. The engine is a Cadillac 500. The only info I found visual information for was a Chevy, so I used that as a basis for the thread. Now while some have denied that drilling can help a Chevy (and they have a point), it appears to me that other engines (like my Cadillac) may actually benefit from drilling. In the pictures below you will see that a Chevy has 3 main oil journals running lengthwise. Oil from the first galley must pass thru a possible restriction around the cam bearings before entering the LIFTER galleys. In the Cadillac (and possibly other engines), there appears to be only 2 galleys lengthwise. One on the left and one on the right. From these galleys there are small passages going directly to the cam bearings and lifters. There are also passages that go directly to the main bearings. These second passages do not have any impediment and do not affect......or are affected by any camshaft oiling. I think that drilling the passages out for the mains would increase oil volume to the mains but leave the oil flow to the cam "as is". I say that because the passages to the cam would remain factory stock. So it appears to me that some engines can directly benefit from enlarging the oil passages, while a Chevy would require opening the trough around the cam bearing to gain a benefit. Also, as I mentioned previously, aftermarket blocks often employ priority main oiling, so they must feel its beneficial to get more oil to the mains in performance oriented engines. If someone does this mod, it might also help to employ a higher volume oil pump and a larger pick up tube.
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