liamford

hi guy,

having the head off my small turbo cossie due to a bit of smoking, so changing the valve stem seals (after new turbo and breather fitted already fitted), just wondering is it worth changing the guides? if so what ones? burton power doing a set of 16 steel ones for around £38? or do you think the bronze ones are better? im not sure...

cheers guys liam

Karl

Hi,

As standard the small turbo head has cast iron guides, and unless they are worn, they do not require replacement. If they are worn you can use either the original cast iron items OR the earlier bronze guides. (Don't forget the bronze guides have a C clip that wont be fitted to the cast iron items you remove so will need to be purchased along with your new bronze guides)

cozmeister

iTrader: (1)

Can the cast iron guides be used in early model heads in place of the bronze guides?

tabetha

Guide wear is a chronic problem on cossies, the best material is COLSHIBO, expensive but only ever done once, this is what I use.
tabetha

OldDan

Why is it that a google search on your material "COLSHIBO" only brings up three results, the three of which are your posts on passionford?

Chip

iTrader: (3)

Cause he made it up or spelt it wrong I guess

sailorbob

Colsibro. It is an excellent guide material.

Chip

iTrader: (3)

Spelling error then.

OldDan

Was kicking my head in trying to find it, google kept trying to rename it to some japanese dragon!

tabetha

I must have misheard, or made it up, but it's the daddies stuff apparently!!
tabetha

chaffe

fpmsl

Rob_DOHC

iTrader: (4)

After speaking to the cylinder head shop in Surrey their opinion was that iron guides were much harder wearing than bronze, I chose cast guides because a) im tight and b) they are cut down and smoothed into the port so the loads on the guide will be higher combined with the faster wearing bronze might mean my lazy arse would have to change them more often.

They also sell what they call nucleous power guides, they make these from Colsibro, which they describe as being a copper-nickel-silicon alloy. If i was doing it again i would probably use them. Seems Colsibro is used in aviation engines a lot.

They also list a material called Trojan(?) which is even better than Colsibro.

http://cylinderheadshop.com/nucleus-...-power-guides/

Rob,

Chip

iTrader: (3)

Dont forget that harder wearing guides tends to mean more damage to valves, especially if they are non standard valves.

So for example if you have titanium valves you would want something softer for the guides so the valves dont wear out.

There isnt really an answer that applies to all applications.

So i would take Karl's advice about this specific application as its clearly one that he knows a lot about.