ROSS BROWN wrote:DOC
Food for thought.
Solid lifters , words I love to see ,those other nandy pandy disgusting hydrualic thingies belong in Ganmas car ONLY.
Those little horrors have a little GREMLIN built into every one of them,some to lazy to push & some push to hard. Which in turn becomes the source of a multitude of problems.
Prolonged high rpm will have some pumping up & some pumping out.
WHY IS IT SO ?
At a guess I would say you were getting both pump up & pump out, it was probably the later that helped undo your rocker stud & also created a high percentage of the blow by that started putting unwanted pressure on your seals as the valves were staying closed to long ,
SOLID LIFTERS is an excellent step in the right direction.
POSITIVE changes to your oiling system .
Deburr all sharp edges & daggs through the oil feed routes ,so little bubbles cant be created ( often neglected point ) there are some anti foaming additives that I know your are aware of . but there is also the option of shifting over to high quality motorcycle oils. as some of those little suckers can rev to 19000 rpm with plain bearing cranks.
CHEERS Ross.
Ross, you're too kind. But yeah you're right about "research".... each time I've mentioned the lifters I made the point we didn't really know whether they were pumping up or collapsing but from the way the speed suddenly went away it had to be them. The likely reason that we got the oil leak was that on the 192 run I saw the speed drop and got straight out of it, the next time I couldn't read the tach or the GPS and just stayed in it til I saw the 7 mile flag , I may well have been back down around 170 by then with the valves hanging open/staying shut like stunned mullets. From what I've worked out we are victim to a couple of phenomena.
1./ the oil pressure relief may be poor thus allowing excess pressure at sustained high revs.dubious.
2./ The oil is "going around" so quick it isn't getting a chance to disperse the bubles ( hang on he's a singer) the BUBBLES thus it is foaming, the lifters are collapsing...
3./ a combination of the two. The lifter oil gallery would be sized so as to run at optimum in the usual rev-range of a road car, that's not us. when the revs rise above this the exposure that the lifters have to the gallery limits the fill/drain time AND the pressure along it would not be constant....and we get problems.
We have a single home-made vac-u-pan arrangement at the moment, I intend to fit another AND a non return valve to the crank-case. This will prevent any nasty consequences just in case the blow by exceeds the vacuum we are generating in the crank case. I'm also considering drain backs from the rocker covers.
It was almost without a doubt the lifters that brought us undone this year but the fact is the car wouldn't have gone that much faster on the available track.In top gear it was putting on 12mph/per mile. Before we gear it down we need a little more power because lets say that figure dropped to 10 and we left the 1/4 trap at 180...we'd need 3 miles to get to the speed that the car will run at 7000rpm...if we have a full track we might get 180 by that point but this year with the short run up we were only at 155, 160........ If we don't have more power we will be out the back door when we are still accelerating.
So that's where the heads come in.Better flow, more accurate valve control.....more power.
In the meantime I'm hoping that next year the track is smoother and the wind isn't as strong because I had a busy time with it at 193, there are various things I want to sniff over that were slightly different than the year before when the car was a pussy, other than the speed.
We've got plenty to do now, for the next three years or so....bring it on.
(wash my mouth out ) use a vac pump from some model cadilac, when first testing this idea pulling seals was an issue . they then put the seals in backwards .this solving the problem.
