[DeTomaso] 4V heads valve lift.

[Daniel C Jones]

> What is the maximum valve lift for stock 4V heads? What to do if one want
> to increase the valve lift?

There will be two areas of potential interference.  One will be piston
to valve clearance.  The maximum lift you can run will depend upon the
duration and lobe center of the cam but I've run up to 0.590" lift with
stock type pistons.  If you have clearance issues, the pistons will need
to be cut for deeper valve notches.  The other area of potential
interference is the rocker arm to pushrod.  There were two types of stock
rocker arms (lugged and unlugged).  The ones with the lug on top may have
a clearance problem with cams of 0.550" or greater lift.  The pushrod tube
may contact the lower position of the rocker arm when the valve is fully
open.  This can bend or break the pushrod.  See:

 http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album04/album24/OHOnews16of38.jpg.html

for details.  For additinal clearance, you may want to mill ad drill the
heads for studs and guide plates and run roller rocker arms.  If you retain
the stock rocker arms, make sure you use the steel 4V sled fulcrums.  The
2V fulcrums are aluminum and can come apart under load.

Dan Jones