E-85 555 buildup- drag race by Jim Weise

5 minute(s) of a 87 minute read

6-5-2011

Cam and bearings..

This is the prototype set of TA 4550 Tomahawk block cam bearings, at the time they were installed, the only set that existed. The standard 460 Ford cam bearing is about half this wide, so I elected to go with this new bearing, and was very pleased with the decision.. these feature a slot to align the oil hole, a single back groove, and two extra oil holes, and are Teflon coated.

Installation was straight forward, and I finally got to use one of the other adapters in my cam bearing driver set! The edge of the block was broken with a light emery cloth before block wash, then after the block was clean, I oiled the back of the bearings and the pounded in perfectly. Cam bearing clearance was .0025, with .004-.0045 press fit of the bearings.

The camshaft is a solid roller unit, 270/280 at .050, with .400 lobe lift. His STG 2 TE heads only flowed 345 at .600, so I kept the cam lift on the conservative side. .630 with his roller rockers, with the valvesprings right at 600# on the nose, to help keep the rockers/valvesprings alive, on a motor that will see over 200 passes a year, in bracket racing.

The only area of concern was the thrust surface on the rear of the camshaft. While the bearings are bigger, the thrust surface remained at the standard 455 size, which allowed only a very small thrust lip. We debated counterboreing the block face, and using a one piece torrington bearing here, but in the end, decided it we were making much ado about nothing. The reality is, the cam floats in the block, set at .006 end clearance, so I just simply got ahold of a couple of .030 hardened steel torrington bearing races, at 2.5" ID/2.85 OD, and then carefully tig welded them with 3 small tac welds, around the OD of the race, to the steel cam hub.

IN the picture below, you can see the small thrust area, and how the washers greatly increased this.

These cams are electric pump only, as they have no fuel pump drive provisions.

The cam fit the block perfectly, with about 3 inch pounds of turning torque with oil.

The rear cam plug accepts a standard 2.25 inch deep cup plug, as it is much deeper from the back of the cam, than a standard 455. Note the extra bolt holes near the cam tunnel

Those holes are there to allow the installation of a cam plug retainer plate. Now, with this deep cup plug, installed with the normal Permatex #1 sealer, I was not really worried about the plug popping out when the block expanded, but then again, if someone took the time to lay out and add the op to drill and tap the holes, why not use them?

So we fabricated a retainer plate, from .062 aluminum sheet.

I then secured it with 2 button head 1/4-20x1/2 bolts, with loctite.

On the front, Since there was no concern about interference with a fuel pump arm, I selected grade 8 5/16x3/4 long bolts for the timing chain top gear, and then used a nice high collar lock washer with them, and locktite. The bolts were ground to be exactly flush with the rear of the cam hub, when installed, thus utilizing all the thread area.

And of course, don't forget to install the lifer bore galley plugs behind the timing chain.. these o-ring, screw in plugs, are first class pieces, just like all the plugs in this block.

JW