4 replies to this topic

[Patriot]

Hi,
could anyone let me know what size and type valve guides to install in a 12g295 head.

Also,

what is the best spring set to buy.

many thanks

[mini-luke]

Standard cast iron valve guides are fine, there's only one size bar turbo spec

There many different ''best'' valve springs for different applications - e.g. standard springs are best for a standard engine. Don't just put the strongest springs you can find, the extra unecessairy pressure needlessly saps power and increases cam and follower wear

[Cooperman]

Valve guides are either cast iron or some sort of manganese-bronze alloy. IMHO the cast iron are best as there have been some valve sticking with manganese bronze. Now, as to valve springs, that will depend on the cam chosen and hence its optimum operating revs. You need to get the recommended valve spring data from the cam manufacturer, then set them to the correct fitted length.

[Patriot]

many thanks

[MRA]

Sticky valve guides are normally due to incompatible valve stem materials.

The A series has been fitted with many different valve guides over the years, as above the ones that will not be compatible are the turbo exhaust valve guides.

The main differences are in the application, the "nose" shape, length (ie diesel A Series are very long about 2.25") stem seal grooves, as the very early ones didn't have these.