[DeTomaso] Hydraulic lifter pressure hole location

[Daniel C Jones]

Do you mean that your under the chamfer edge by 0.015" or above the
lip by the same amount?

Dan Jones

On Mon, May 24, 2010 at 4:41 PM, Doug Braun <doug at silicondesigns.com> wrote:
> Dan,
>
> I'm running the Crane 36532 hydraulic roller link-bar lifters so I agree
> that in theory I shouldn't have a problem.  But being the type that likes to
> double check everything in an engine build I took some measurements.  These
> measurements show that the top of the lifter pressure holes rise to between
> 0.015" and 0.040" of just entering the chamfered area of the lifter bore.
> The 0.015" measurement is the worst one I found.  The question is, is this
> normal and/or OK to run with?
>
> Doug
>
> -----Original Message-----
> From: detomaso-bounces at realbig.com
> [mailto:detomaso-bounces at realbig.com]On Behalf Of Daniel C Jones
> Sent: Monday, May 24, 2010 12:55 PM
> To: DeTomaso Forum
> Subject: Re: [DeTomaso] Hydraulic lifter pressure hole location
>
>
>> What's the recommendation on how close the pressure hole on a hydraulic
>> roller lifter can get to the top of the lifter bore and still be safe?
>> As you go with a cam with taller lift, the hole gets closer and closer to
>> coming out of the bore.  I talking about how close the hole can safely get
>> to the edge of the chamfer at the top of the lifter bore where pressurized
>> oil will just begin to leak.  I want to check this on my new stroker motor
>> to be safe.
>
> It varies from block-to-block and depends upon the size of the chamfer
> at the top of the lifter bore but, on many blocks, the oil feed is exposed
> at maximum lobe lift.  Some manufacturers (like Comp) will reduce the
> base circle of the cam so the OEM type lifters can be used.  As a rule,
> irregardless of how much lift that a camshaft has, the lifters generally
> all stop in approximately the same location at the top unless the base
> circle is deliberately reduced which can cause problems at the other end
> of the lifter bores.  With a reduced base circle cam, the OEM lifters
> will usually be safe at maximum lift but some blocks will have interference
> problems with the dogbones.  A local shop has a fixture to machine the
> block for clearance but it can also be done by hand.  Comps link bar
> lifters have the oil feed (and associated band on the lifter) in the same
> place as the OEM lifters so have the same problems at max lobe lift.
>
> The Crane/FRPP link bar retrofit hydraulic roller lifters have the oil
> feed placed lower on the lifter body and do not have the max lift problem.
> Erson also makes a couple of link bar lifters (one a less expensive street
> version and the other a more expensive race version) but I've not been
> able to verify them for fit.
>
> Dan Jones
>
>
>