Identify SBC Cam

[Terry B.]

I removed this solid lifter cam from the 327 in my 60 Corvette about twenty years ago. I thought it was too much cam and suspected it was a GM# 3927140. I replaced it with a Crower # 242 Hydraulic cam advanced 4 degrees.

However, I got the solid lifter cam out of storage today and noted there are these numbers 7141 stamped on the end along with GM C8 and possibly a pink paint mark? I could not find any info on the internet or old hot rod small block manuals.It is in good condition and I doubt it has 500 miles on it. What do I have??

[William C.]

Re: Identify SBC Cam

the 7141 was the blank ID that the 140 cam was ground on, you have a 140 cam as you suspected

[Duke W.]

Re: Identify SBC Cam

It would bet million to one odds that it IS a 3927140 camshaft, which is totally unsuitable to anything less than a purpose built racing engine with headers and open exhaust due to its extreme amount of overalap.

The actual "ID number" molded into production camshaft castings is the part number of the finished camshaft. The service part number is the part number for the "assembly" of cam and dowel pin. All of the production cams are machined from custom blanks in order to minimize machining time, so the finished camshaft part number is in the casting molds. In the case of the 140, the fact that the finished camshaft part number is stamped rather than molded into the casting indicates that it was machined from a "generic blank", and this makes sense since it was strictly an OTC part, with no expectation of high volume production.

For example, the Duntov camshaft service part number is 3736097, but the actual finished camshaft part number is 3736098, which is the number molded into the camshaft blank. (AFAIK current aftermarket vintage SBC flat tappet cams, all vendors, mechanical or hydraulic lifter type, are ALL ground from the same generic blank, but I don't know the source - at least not yet!) In later years usually only the last four digits of the finished camshaft part number was molded into the cam blank casting.

Many camshaft and camshaft/pin assemblies are sequentially numbered, but not all. For example the early (groove in rear journal) L-36 camshaft service part number for the "assembly" is 3883986, but the actual finished camshaft part number molded into the casting is 3883944, and this "dispersion in sequence" of "42" is about the widest I've found among the vintage Corvette camshafts. Some, like the LT-1 camshaft are not sequential, but much closer together, 3972178/3972182.

Duke