when I recently pulled my motor apart I found a grind mark across the two slots of the cam followers. I asked one VW business about this and they didn't know why. I have done searches on here and other vw forums and no one seems to do this or mention it (maybe secrets held close to their chest) 😂😂😂
Then I found the Bob Hoover website and he does this modification and it is solely for the purposes of supplying more oil to the rocker gear / heads. They also state that due to the extra oil it greatly assists in cooling the heads. The below site of Bob Hoovers also shows other mods, but the one I am talking of his about half way down the page.
Basically we are starving the top end of oil, with oil only getting there during 8% of a cam revolution and this mod will up that to 100%
Just wondering why I haven't seen it on other peoples engine build threads that I read. I'm about to do this to my new followers, but thought I would ask others thoughts here first.
Yep, do it on all my builds, also helps lubrication with bigger cam lifts and as much as I don't use regorund cams or lifters, if you did, the lifter becomes out of alignment with the oiling holes
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
Kev , you need to ask yourself the question first , Do I need extra oil at the top end of the engine . In all my experiences the rocker box area is always full of oil to the extent that sometimes it can't travel down the push rod tubes fast enough to return into the engine case . I have seen in many cases people adding extra oil drains off the valve covers or the rocker area of the head to speed up the oil return to the case . The VW valve gear is designed to be a splash fed area from the oil . I am yet to ever see or hear of an engine that has ever run dry in this area . On the other hand , by doing this modification and adding extra oil to the top end of the engine , you are taking oil away from the bottom end . I have seen many engines starved of oil in this area . Some speedway engines did however add extra oil squirters to one side of the engine as in oval track racing the oil will always get forced to the outside of one particular side of the engine thus starving the inner track side of oil . In your new engine program I would think that the amount of cam lift you are going to have would render this modification useless . If you have a camshaft with a lot of lift thus causing the oil hole in the case to part company with the oil grooves in the lifters , I would say it may be worthwhile , ROD.
More boost + More fuel = More power
1968 Beetle fastest run 8.96 sec @ 161 mph 4th Nov. 2001
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There are two ways of getting oil to the heads, the crank slinging action through the pushrod tubes hence left side gets more oil and through the lifter/pushrods directly to the rockers for a very short time.
This is what the lifter groove mod seems to improve: the almost constant supply of oil to the rockers and NOT to fill the rocker cover box with oil.
Rod is correct in needing to evacuate the oil from the rocker cover and back to the sump quickly.
In my opinion, the groove IS NOT about suppling more oil, it's about suppling oil with modified engine components. With larger than stock cams and different ratio rockers the oil grooves are often out of sync with the oiling groove, the slot helps this. The other consideration that they address is to help with supplying oil to the lifters that are second in line in the oiling system. The oil supply is fed from the middle cam bearing, the middle two lifters get fed oil first from the gallery, the second set ie. the fwd and rear most pair rely on oil feed through those oiling rings so a constant supply helps here. The actual rocker lubrication is relatively secondary and supply is restricted to the no-load timing while the valve is resting on the valve seat, so I don't believe they increase oil volume to the head, except if using whilst out of sync with the oil grooves.
Valve cover area's do need to have improvements to get the oil back to the sump when higher rpm and larger oil pumps are being used.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
I like that this is bringing out different opinions and that is what a discussion is all about. I also said that the extra oil is aiding in cooling and the facts show in Bob Hoover's site would support this.
Rod - I know that others have added extra oil return lines from rocker cover to sump but there are 4 x 20mm return tubes there (minus push rod volume) for oil to return. Does one extra line of 12-15mm really make that much difference. I'm sure it could aid oil return, but on the other hand in hard cornering oil could pass back up and into the heads as this extra line is lower in the sump area.
As a rough guess from me, the 4 tubes per side would equate to about a 40mm return pipe (this includes area removed re push rods) and surely oil can flow through something that size. I don't think this is as simple as a vertical 40mm pipe draining oil through it.
Rod as you correctly say, this will take away oil from the bottom end and this is corrected in my case by adding a deep sump (I hope). You also say that the amount of cam lift I have makes this modification useless. My understanding and again going off Bob Hoovers site shows that oil only gets through the push rod and to top end when cam is on full lift. As he points out this is only about 8% of cam rotation, meaning it starves oil for 92%.
Mat - as you point out this is about getting more oil to the top end in a modified engine and not relevant to a standard motor to which I agree. If nothing else, I think it is better to have more oil in this case to the top end than possibly not enough. The only issue I see as Rod points out if the oil can't return easily to the case. (maybe another discussion here).
Ben (fish26) - as you mention, oil could normally be thrown up the push-rod tubes as oil is slung out by the crank. Firstly this modification would bypass having to rely on that process and oil is trying to come down through these tubes and I think that would make it hard for oil to be thrown up there, if that makes sense.
Again, this is just a discussion and I'm not saying Rod is wrong. I'm just trying to build the best reliable performance engine I can and want to ensure that I have enough lubrication to the parts that need it. If others have views, either for or against this modification please tell us.
Cheers, Kev
I thought rebuilding a VW would be cheap - Shit I was wrong, just don't let the wife know !!!!
Camo wrote:Mat - as you point out this is about getting more oil to the top end in a modified engine and not relevant to a standard motor to which I agree. If nothing else, I think it is better to have more oil in this case to the top end than possibly not enough. The only issue I see as Rod points out if the oil can't return easily to the case. (maybe another discussion here).
Cheers, Kev
I agree Kev, I believe the excessive oil in the valve cover is a different subject.
For me, it's purely a case of increasing the oil to the lifter bores
and rocker gear.
I also recommend checking the lifter bore clearances and usually coating the lifters with a ceramic oil retentive coating. Most lifters I find are minimum size and 0.005" of coating helps getting it to within factory spec.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
might be worth looking into oil spray bars in the heads,I know Volksenginering has done it with good results.But as some people know John dosen't build "performance"engines.
