Coscast std valve guides?
Do vaux still do valve guides for the coscast head? SBD only list the bronze, and vaux parts dept dont seem to have a clue about the coscast head....i may need to replace mine....
only list the bronze? i thought that wa the difference?
sbd will get the 13mm bronze guides, as i am sure vxl will too if they do know what you are on about (mine would)
coscast head valve guides
Early coscast heads (88-90) cast iron 13 mm outside diameter difficult to obtain.
Later coscast heads (90-94) cast iron 11mm outside diameter
same as 8v
Oddball hit the same prob - I think 13mm iron guides aren't available any more - try by all means, but you may have to stump up for bronze ones.
and here was me thinking they were supposed to be 13mm bronze
might have to find a supplier/manufacturer for these, has anyone got a spare 13mm guide for a template?
i could probably get youa 13mm iron as a template. SBD's bronze guides are over a cm longer and dont have the retaining circlip which sits in a cutout at the spring seat. The guy fitting mine as taken these SBD guides and machined them to replicate perfectly the standard iron guides, clirclip, seating ring, taper at the valve end, hes machining out the valve throat, recutting the seat at 45 degrees, and all for 7 pound per hole.
Gary said that swindown race engines supply bronze guides akin to the originals spec.
infact i can probably bring home the good 14 standard iron guides if yunis4z wants them, or anyone for that matter.
But i think the turbo guides are 11mm anyway. me man has a turbo head on teh bench and thats 11mm.
why is bronze being used now? IS there actually any difference in the end?
(i thought turbo guides were 11mm too)
bronze is much harder, so next time your valves contact piston you dont get fragments of iron guide f ucking the rest of your engine.
next time? lol
bronze guides will not crack into little piston and head trashing bits at the slightest valve/piston contact - otherwise I don't think they hold any inherent advantages over iron guides.
they might be lower friction I suppose - bronze is a common material used for bushings and so on so the theory is the same.
when people say 'turbo' head you need to know whether it's a GM or coscast - afaik GM = 11mm (or 10mm I thought) coscast = 13mm.
there are subtle differences in the later coscasts put on some turbo engines - it's possible they reduced the guide o.d on these later ones.
what he said ^^
actually iron is harder - but far more brittle, so there
so not at all worth going out of your way to make/get hold of the OE coscast guides then
depends on how likely you are to do a whoopsie and whack a valve
I thought I'd never let that happen to my engine - but bolts will pop out the end of cams and lodge in the most valvebendtastic places you know