Belly_up

i thought about this myself. The fittings look to be about the equivalent of -12 braid, but you could probably get away with -10. To attach the fittings, after removing the originals, i'd either: 1) get the existing hole in the rocker cover tapped (either to a pipe fitting, or just a metric fitting for use with copper sealing washers), and then screw in an appropriate adapter to go from my chosen thread to -12 AN. The only thing i was unsure about when i looked at it, was whether or not there was enough "meat" in the rocker cover to tap the next largest metric fitting above the size of the existing hole. 2)buy a pair of alloy weld on bosses (in -12 AN), and get your friendly local welder to tig them onto the rocker cover. Cheers Belly_up

My timing gear was seized on the crank as well, and i got a local engine builder to remove it for me, they just drilled small holes in the timing gear from the front, extending from the center of the gear out to the edge, and then just used a cold chisel to create a radial split in the gear, and off it came. obviously a new gear was required.

I believe that JUN do make some of their own gear. There was an article a while back in Zoom where they went to the JUN factory, and they had some shots of their rods being CNC'd from a block of billet. I do recall that their piston blanks are made by cosworth, but specially cast for JUN. ie, if you look at a JUN piston, it will have both "JUN" and "Cosworth" cast into it. Of course there's nothing to say that that isn't the only difference between normal Cosworths.

I think they're talking about valve recession, not the normal operation of the valve. As the valve seats wear away (or are ground deliberately), the valve spring will be allowed to expand slightly, and will thus not be pulling the valve back into the seat with as much pressure as originally. Which is why they were talking about shimming the valve springs to maintain a constant spring pressure on the valve.

if you look at the bottom of an rb20 block in a GTS4, it has 2 complete sets of bolt holes for the 2 different sumps. The 4wd sump bolts up to the outer set of holes using 8mm bolts, whereas the 2wd sump bolts up to the inner set of bolts using 6mm bolts. There are also different oil pickups between the 2wd and 4wd models, although this would be easier to fix if you're going from 2wd (rb30) to 4wd, than it was for me to go the other way (i'm using a GTS4 rb20 in a rwd configuration, and it was a complete pain in the arse, despite the assurances of the import wrecker)

If we are talking about an air to air intercooler, then it is physically impossible for the post intercooler air, to be at ambient temperature, unless the turbo is in backwards and is decompressing the air. No air to air intercooler is 100% efficient, so it can't happen.

seeing as how IC's are so good at collecting vapours, maybe we should use a chunck of IC core as a catch can j/k and i agree with browny that all the connections on the RB20 (silver top) are on top of the rocker covers.

Nah the magna definately ran the blow by through the filter, but it had bit of a deflector and little bit of foam to semi-filter it, kinda like a mini catch can. we don't want to filter out the used air, we just want to take any oil etc out of it. But i think you might be right about it making it run rich, i guess it would just depend on how significant the amount of blow-by actually was.

Ok here's a question, not related to any particular setup mentioned here, but just in general. Why, instead of venting the blow-by to the atmosphere, or plumbing in between the afm and the turbo, don't we plumb the gas back into the airbox (for those of us who still have an airbox)? that way the air gets filtered by a nice big filter, and the air still goes through the engine, so no EPA problems? Is it because the low-oxygen blow by will affect the afm? or is there another reason? I know this was how my old carbied magna was plumbed from the factory. any ideas? Belly_Up

It's a conversion, but the old tank was EFI (mmmm BMW goodness : ). i think i'll go the surge tank anyway, as i'd like to do some track days eventually, and like you say, it's cheap insurance.

Yep thats what i'm sayin That avo ad doesn't seem to mention what, if any, filtering material they have inside the catch can. I'd be inclined to give them a call if i were you and ask them. But other than that, it sounds good.

if you've still got the breathers connected to the plenum, then the catch can probably won't do much. You've given the air two paths to take, and going straight into the plenum is much easier than going through the filter in the catch can. So there probably isn't much air going into the catch can, thus the lack of oil. I think if you block off the line going into the plenum things may improve. Also make sure that the catch can actually contains some filtering material. Some of them rely on the assumption that you'll have one of thos cute little k&n's attached to the outlet to do all the filtering. If this is the case with yours, then without the little filter all you are doing is running the blow-by through a can, which won't do much at all.

no surge tank at the moment, although i'm starting to think i might grab one, as i doubt the baffling in an early 80's fuel tank is sufficient for what i have planned. what i was worried about, is that when the lift pump pressurises the line leading to the main pump, there will be air in that line that will get forced into the 910, and may become trapped depending on the orientation of the pump. I may be worrying about nothing though...

GiJOr33, you reasoning is right, however Sydneykid indicated that the airflow in the GTR / GTR Style manifolds was biased *towards* 6 & 5, rather than the other way round, so they run lean. He also stated that this (air distribution) was not a problem on the 20/25's, so *if* there was going to be a cooling problem at the back of the engine, it would be cooling related, not mixture related, so changing your mixtures would be working against the goal of optimum tuning. IF testing with EGT probes (not lambda in this case) or similar indicated that there was a problem with cooling, then you would be better off tapping in a coolant line to the back of the block to better distribute the coolant. And upgrading the water pump and radiator on any high po engine, esp a turbo one, is never a bad idea. Provided your thermostat works properly, then you can't have too much cooling : )

I wouldn't think it would be a set percentage, you'd really need to have provision for EGT sensors in each primary, and monitor all the temps while you adjust the cylinder trim. I've seen pics of RB26's (may have been one of the big jap drag cars) where the head and/or block is tapped at the back to accept a second coolant hose to better control temperatures. But that may have been due to the RB26 manifold enleanment mentioned above. Still, if the fundamental problem is heat, and not actually mixtures, then more cooling at the back of the engine may fix the problem, rather than just treating the "symptoms", ie richening the mixtures.