Machinist Notes

Heads

KRP blocks will accept any small block GM head since the bolt pattern is the same for all - 23 deg, 18 deg, 12 deg, SB-2, SB-2.2, "Pontiac" with SBC pattern which is used by NASCAR, Chevy II, Mercruiser, Pontiac "Super Duty," or any "R" Iron Duke Head, all of which have 4.400" bore spacing. The 4-cylinder Pontiac SD, Chevy II and Mercruiser have altered bolt patterns, but the same bore spacing.

Ford small blocks: 302, 351W, 351C, 351M, Yates-style head, etc., whcih all share 3.980" bore spacing and small bolt patterns.

MOPAR small block: 318, 360 and so on. MOPARs are limited to 4.0" bore due to wider bore spacing, 4.460". MOPAR classifies these as "A" engines.

Custom Build Options

Crank flange style: 2pc. small block Chevy type (early style) or 1pc. Pontiac style. Late model GM "Marine" 3.6" crankshaft with an external 1-piece seal and a small block GM bolt pattern.

Bore size: 4" or 4.125". Bores are left -.004 / -.005 undersize for finish honing. Typically, the minimum cylinder wall thickness is approximately .125" at 4.125" bore in ring travel area.

Cylinder Head Type: Chevy. 23-thru-12 degree, SB2, Ford, etc. Head type determines lifter angle and bolt pattern. Cylinder head water holes can be omitted at request, such as in NHRA drag racing use.

Dry or Wet Sump Oiling: Internal oil pumps are costly to prep block - external pumps are much better setup.

Bolt Pattern on Bellhousing: Small block GM, Midget mid plate, Pontiac "Super Duty," Ford.

Lifter Diameter: All blocks have bronze bushings for .843" or special order .902" Chrysler-type. Oil hole in bushing is .093" diameter. Lifter bushings may require final honing to engine builder specifications.

All blocks have five-journal 2.250" cam bores for needle bearings only. 1.875" steel roller cam journal size. No plain type cam bearings or iron cams.

All deck to crank C / L are machined to approximately 9.174 +.010" over standard for custom finishing. Minimum deck height 9.000" and maximum is approximately 9.250". Deck is .750" thick at standard height.

Most GM head style engines have 1/2" - 13 tapped holes in front for engine plates or accessories.

Cylinders are Siamese and are solid on thrust side of cylinder 2 1/4" down from deck (push rod side).

Oiling system is setup for remote oil filter (#10 O-ring to #12 AN fitting).

Oil pan, timing cover and water pump are same as GM "R" "Iron Duke" or GM early marine 153 CID or 181 CID with two-piece rear main seal.

The stock crankshafts for these engines will also fit with the 3.6" marine being the best choice for strength. The first choice is the forged Pontiac "Super Duty" crankshafts now discontinued from the factory production.

Note: Lifter angle or location cannot be changed once lifter bores are machined. 

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