19 replies to this topic

[bmcecosse]

Some of the best 970 engines were revving to 10,000....... That's when ultra light (= ultra expensive too) components may help. One problem with using non-steel pushrods is that they will expand at a different rate to the rest of the engine as the engine heats up from cold. So setting the valve gaps will become a bit of an adventure!

[TopCatCustom]

Yeah expansion is another thing! I'm using alloy roller rockers as got a set on the shelf so theres a little bit saved there, quite tempted to make up some titanium valve spring retainers too but might do that during the summer when I've actually finished my mammoth build that is VERY behind schedule!!!

[Cooperman]

Yeah expansion is another thing! I'm using alloy roller rockers as got a set on the shelf so theres a little bit saved there, quite tempted to make up some titanium valve spring retainers too but might do that during the summer when I've actually finished my mammoth build that is VERY behind schedule!!!

On my 1275 I use 1.5:1 roller-tip rockers (don't really gain much with them though), Kent VS2 double valve springs and it will rev to over 7400 without any problem.

[hhhh]

Yes this is true, but a pushrod is not a rotating part.
 

 

Actually it is rotating as well as reciprocating, watch this video: http://russellengine...haft-followers/

[ACDodd]

The most successful pushrods I have used were a set of 2 piece ones I made for the MLMotorsport sprint Minus. They are longer than stock help deliver a tad over 0.5" (that's with 240lb of springs fitted) of valve lift and have less unsupported length of a standard pushrod. Still 6mm and so far yet to bend one 8krpm limit). We have managed to break a rocker through fatigue!

AC

Edited by ACDodd, 29 August 2015 - 09:47 AM.