mark kibort

maybe a combination of things. Sears Point's carrocel and thunderhill's turn 2 are pretty dramatic, high speed, high g turns. believe me, there is not a time where i dont look at the oil pressure guage or think to myself, "is this thing going to blow?". I spend a lot of time at sears too, infact,we had a double race weekend last month and im going there again in two weeks (oct 1st)

maybe its just luck of the gears for those tracks. certainly, the carocel at RA is the worst for the holbert car, taking the carocell at near 5k and ending up at near 6k at the exit. However, with PCA, i think we got 30 laps total for the entire weekend!

Mk

mark kibort

I know !! ha ha. Hey, when i pull out those results, i always talk about you now running 1:39.9 there now and that being your first time there. (plus a little extra weight, and DOT tires!). I think the next time you went there, you were on the toyos and then the PCA races where i thought you would run 1:47 and you ran 1:44 and joseph ran 1:45!! (on slicks ). I think there are not too many first time tracks where folks will have a longer learning curve.

anyway, the point is, that the old Holbert car is running as fast as some of those top drivers, like peter Kitchack, Scotty white, etc, with a lot less power!
More or less a tribute to the 928.

I just had to rib you right back. It is the way of the list.

It is amazing how little trouble I have had. trust me, it cracks up the teams at the SCCA events when i drive out of the paddock with my tires packed in and my stereo on!

MK

mark kibort

82 crank vs 84 crank. (old crank is the one that got chewed up by the #2-6 bearing failure)

GlenL

Mark,

The size difference at the rod journals is clear. Are the other holes similar? Any obvious differences in internal drilling?

mark kibort

The other holes meaning, the mains? yes, those are the same size.

as far as the oil paths, they all looked pretty similar. would i be able to detect a difference by eyeball or a wire path? what is the chevy drilling look like?
I think there was a detailed diagram someone posted a while ago.

MK

BC

Are you sure its not the driver?

GlenL

Like this one I have from 11/03?



There was another one from the side. I recall that Erik from Denmark did it. (RIP!)

Can someone confirm that's how 928 cranks are chebbified?

mark kibort

Thats the one.
so, how are those holes drilled?

If the lines you draw are the chevy ones, is this what you tell your machine shop to do?

any downside?

MK

hacker-pschorr

So when I pull the engine on my 79 (was just going to do rod bearings, just in case) I'm now going to drop in that 84 crank I have.

SwayBar

You've said that that car has been driven hard at the track many times and it hasn't spun a bearing yet. But since you're going to have the engine out anyway, I would definitely drop a drilled crank in since it isn't that much more work, plus, it's good preventative maintenance for a track-car.

hacker-pschorr

With an accusump (well, except now since the owner before me removed it jackass).

I was just going to drop the pan - change rod bearings. Since it's so easy to pull these motors, I figure it will then be a good time to upgrade to Cometic head gaskets, change out the crank. This motor will be boosted, might as well prepare now. Not to mention if my 81 holds up for the rest of the year, that 5.0 sitting out back may go in the 79. . 5 liter, 8:1 compression, 10psi with headers. I'm not a good enough driver for that combo, yet.

GlenL

Just to clarify, Erik provided the diagrams. (IIRC)

The mate to that pic showed more detail on the drilling. What I'd like to know is how the two mains feed the two rods, if that's the case.

adrian928se

Re crank drilling, can anyone who has modified the oilways on a standard crank tell me what equipment and drill type they used? The cranks are incredibly hard and the engineering company I normally use were not keen to drill them.

Thanks in advance

Adrian

928SS

isn't the stock 928 oil bearing only a 180 degree groove??? iirc, most hot rod cheby's are 360 deg grooved... seems to me under racing conditions, it could be the critical diff... iirc, on the 928 stroker cranks it's SOP w/cheby style drilling.

pmotts

UGH! That's painful to look at. I would rather see replays of Theismann getting his leg broke by Taylor.