[DeTomaso] Techno Question: 351C lifter bore diameter

cengles at cox.net cengles at cox.net
Tue Jan 22 12:05:04 EST 2008


Dear Daniel,

Thanks for the comments. I do appreciate the report from Dave McLain's measurements in multiple used blocks for comparison to my numbers. I am shooting for a .0015" clearance.

The lifter bores were measured with a snap guage and micrometer. My dial bore gauge won't go that small.

Warmest regards, Chuck Engles


---- Daniel C Jones <daniel.c.jones2 at gmail.com> wrote:
>>I have the numbers from the bores and wanted to compare them to what is
>>considered factory spec. At this point it looks like the bores spec out
>>to: 0.874--.875". Now, to check them against my measurements and the actual
>>diameter of the new lifters......
>
>We're going to bush the lifter bores on one of the dyno project engines.
>Dave McLain has measured a number of bores (in used blocks) and they measure
>0.876" to 0.877" diameter. When fitted with bushings and honed for oil
>control, they had 0.0015" clearance. With Comp roller lifters, the diameter
>ended up right at 0.875" diameter. With no other oiling system mods and a
>stock volume and pressure oil pump and bushed lifter bores, the engine held
>very good oil pressure (60 psi hot @ 6000 to 6500 RPM).
>
>When bushing the lifter bores for oil control reasons, McLain uses a 1 inch
>self piloting reamer that's been "sharpened down" to a diameter of 0.996".
>The reamer has a pilot on the end that's 0.875" diameter and is secured with
>a set screw so it would be possible to use it for repair work on other size
>lifter bores if needed. This allows the use of a press-fit 1 inch OD bushing.
>The bushing is 0.875" ID with a length of 1.5 inches drilled with the hole
>size of your choice (depends upon hydraulic, solid, flat or roller lifters).
>McLain does this on a Bridgeport mill with a 4 inch riser which is needed to
>give enough vertical clearance for the block and the fixture that he uses.
>once the block is set up, he uses an air float table from a seat and guide
>machine on the Bridgeport, so the lifter bores are vertical. This set-up
>makes it easy to go from one bore to the next by simply floating the block
>with air pressure. McLain charges $150 to bush the lifter bores. The 0.996"
>reamer (and maybe 0.001" wobble) makes for a tight fit on the bushing when
>you knock them into place. McLain finishes the ID to 0.875" with a Sunnen
>hone and says it's important to put a very slight chamfer on the end of the
>bushing and also to take a couple of minutes with a cartridge roll to deburr
>around the galley hole.
>
>Be aware this process does not correct the lifter bore positions like the BHJ
>fixture does but, if your purpose is to provide better oil control or fix a
>damaged block, it works just fine. BTW, are you using a bore gauge or a set
>of calipers to measure the bore diameter?
>
>Dan Jones
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