<VV> Valve Lifter Summary

[BobHelt@aol.com]

Corvair Valve Lifter Specs
There are no original-type Corvair lifters currently available, so any lifter 
being purchased is either a standard Small Block Chevy lifter or a modified 
SBC lifter (with the exception of a very few specialty lifters like the Rhodes 
lifters).

Height, diameter and finish*
Foot curvature and finish*
Check valve*
Piston adjustment range
Piston leakdown rate*
Pushrod seat shape
Oil metering valve design and oil flow rate/pressure


* = No known problems using standard SBC lifters. 

Piston adjustment range.

    This is a critical spec because ot the wide operating temperature range 
of the Corvair engine. Adjustment range should be approximately 0.147 inches 
which translates to approximately 2 full turns of the rocker nut. Many standard 
SBC lifters incorporate sufficient range, but others do not. All Corvair 
vendor supplied lifters should meet this requirement. The only known ways to assure 
any lifters have sufficient range are vendor literature, or actual 
measurements of lifter, or adjustment range on the engine.

Pushrod Seat Shape 

    Deep seats are to be desired because of the possibility the pushrod may 
fall out of the seat if it is too shallow. Small Block Chevy engines have their 
pushrods at an angle of about 45 degrees while the Corvair pushrods are 
essentially in a horizontal position, making it more likely they may fall out of 
the lifter seat if excessive clearances occur due to lifter pump up. Most 
Corvair vendors will be able to tell you if their lifters have deep seats that are 
similar to the original Corvair lifters.

Oil metering valve design and oil flow rate/pressure

    This a critically important consideration for your lifter choice. The 
problem here is that all standard SBC lifters are designed for SBC engine needs 
and not the Corvair's requirements. Because the SBC engines are upright V-8s, 
oil being metered to the valve train flows through the pushrod to the rocker 
where it is released and combination of gravity flow and rocker "flipping" cause 
the oil to be widely disbursed throughout the rocker box. The Corvair in 
contrast, must flow its oil thriugh the pushrod and then force a squirt of oil 
some four (plus) inches UPWARDS to properly oil the valves. Most SBC lifters do 
not have this capability and thus the Corvair rocker boxes may get marginal 
lubrication affecting both wear and temperature control of the valves/rockers and 
heads.
    There are no known ways of determining whether a lifter has sufficient 
oil flow to meet the Corvair's requirements other than obtaining vendor and user 
comments, making your own actual comparative flow observations on a running 
engine, or doing a physical disassembly and knowledgeable inspection of the 
lifter.

Regards,
Bob Helt