SBC camshaft bearing width

For any SBC guru out there, I have a question regarding the #5 camshaft bearing on a 3914678 block.

Does this block require the wider CH4 style (1.00") #5 bearing, or can the more narrow CH8 style (0.75") #5 bearing be used?

My block was originally a 327 in a 1968 2WD C-10 pickup, it has the medium 2.45/2.10 crankshaft journals.

 

CH4 bearings are for the small journal blocks, CH8 are for the large journal block like yours.

 

At some point in time, my engine was overbored .030. I assume it was at that time the cam bearings were also replaced... with CH4. The bearings that I removed are marked CH4-1, CH4-2, CH4-3, CH4-3, and CH4-4.

The bearings that I bought to replace them (before removing the old) are Clevite SH290, SH288, SH287, SH287, and SH288.

 

Sh 290 and Ch 8 are the same application. 68 and later SBC. Evidently the rebuilder used the early bearings he had in stock at the time..

 

A couple of related comments... As I originally stated, the block casting is 3914678, which as I understand should only be 1968 (302, 327, or 350). The engine code stamping is V0305YH, a Flint engine cast on March 5th, and according to NastyZ28.com should be a 1966 or 1967 327 220hp. The date casting on the driver side rear is 'C2 8', which to me says March 2nd, 1968.

On the rear, behind the flywheel are the numbers: (left) H33, (right inside) 371 over 386, and (right outside) 636 over 6 8. On the right bank, rear are 2 date tag castings, the first is just a 3, the 2nd is C2 8

On the front behind the timing cover is 386 over 678 on the passenger side and G42 on the driver side.

I can find no serial number stamping so on the block.

Since there are multiple arguments for 1968, can I assume that the YH engine code was also used in 1968? The truck that the engine came out of was a '68 and I was told that it was the original engine.

 

It's been my experience that the casting dates don't lie. They may be altered by some unscrupulous numbers matching people but those date codes are pretty solid.

Pat

 

Pat, are you telling me to take the YH code stamping with a grain of salt? And accept the March 1968 date...

I was wondering if maybe the absence of a serial number means the engine was a warranty replacement.