NEEDforSPEED

The cam reads 643.CPC.BC.5
anyone know what cam this is, thats all thats on it and thats all i know beside the fact its after market

RB83L69

305 5spd / 350 AT
(LB9/ L98) 14093643* .404 .415 202 207 114.5 (115/-114)

From the tech data page

That's how GM marks their cams

Doesn't look aftermarket to me

gmgod

What about a 238 cpc bc? I took this out of a 350 I took out of a Camaro and am curious if it is worth keeping.

RB83L69

I don't recognize that number....

Was this 350 a 4-bolt main with roller provisions that weren't drilled & tapped? (could have been a roller block but wasn't completed for that, and came with a flat tappet from the factory)

gmgod

No, it was a 2-bolt completed factory roller. Some remanufacturer had converted it to 4-bolt mains, put this cam in it and stuck swirl ports on it

RB83L69

Rebuilders don't "convert" to 4-bolt mains. The motor won't sell for one dime more, in exchange for $200 worth of machine work and parts and hassle. They simply don't do it. Period. If the block has 4-bolt caps on it, it came to them that way. Believe it.

You probably have exactly what I was guessing; a truck TBI motor, with the truck 350 TBI cam.

Which, with a GM cam in it, probably means that it wasn't a rebuild at all. What makes you think that it was rebuilt?

Not that it really matter much what cam it is except as a historical curiosity. Especially when amalyzed on the basis of the crucial question: what would you do differently with it if it was some one particular stock cam, vs some other stock cam? Would that determine how forcefully you fling it into the dumpster?

Xceleratemaro

hey rb....i bought a block from a faimly friend that worked at a mashine shop... few years ago anyway this was said to be origonaly 2 bolt main and is now a 4 ....not sure why..he said that the guy paid for it all but never picked it up so i got the deal and he bored the motor 30 over..i was also told it was line honed...now the motor is in my car its a 355 now my question for you is when i bilt the motor i "thought" i know what i was doing but i look back and shake my head i used 30 over rings and stock 350 barrings unfortionaly i didnt know to check the clearnsess...do you think this will run ok...what are the strangh difference between the origonal 4 bolt and 2 made 4 bolt? o yea and i have some "grate rare optional " 882 heads.. i know, arent they grate...lol...actually they have 202 164 valves in them...thats about it...there going in the trash as soon as i come up with some money.

keep up the good work with the tech post.. i learn something new every time i read one of your post...

gmgod

It was .040 over and has a "remanufactured" tag on it, the #4&6 cylinders have been sleeved and the crank was turned .020 under. I don't know why someone would have gone through the trouble to save it. I had it checked out by a machine shop, threw the rotating assembly away and went from there. The block itself had no cracks and cleaned up with a hone to .042, but one of the aftermarket 4-bolt caps was cracked. The machinist is a LONG time friend of mine and went through a bunch of factory 2-bolt caps, found 5 that would work with an align hone, put the studs in and align honed it. He said it was WAY off........ he also said that one of the decks had a pretty big high spot on one of the corners like it had'nt been milled all the way across. In another thread someone had called engines like these sweatshop rebuilds, that about sums it up.

RB83L69

WOW! My bad, I assumed too much on the part of the rebuilder, like common sense; this must have been a non-profit type of shop or something. Sounds like somebody made a lifetime hobby out of futzing with that block. He's got about 3-4 times as much tied up in fooling around, as he could have just gone to the junkyard and got another one for. Oh well, I hope you can get some use out of it, FWIW.

X, it's hard to say about strength differences. The factory 4-bolt is designed for truck applications, where motors just kind of run at moderate RPMs at moderate load for a long time. That's in contrast to a car situation for a stock motor, where the motor typically accelerates quickly through the gears, and then cruises at low RPMs under very light load. They're not there to add "strength", but rather a little extra stability, under truck operating conditions.... moderate loads and moderate RPMs. They are of virtually no use in a racing type application, where the RPMs are higher (and consequently the forces trying to move the caps around are also MUCH higher).

The best situation for a high-performance application is a 2-bolt block, with less flexible (billet) main caps, better hardware holding them in place, and splayed outer bolts. That will do a vastly better job of holding the caps where they belong, under the conditions that racing imposes on engines, than the factory setup; which was designed for something totally else.

And thanks for the good words, I try to be useful, I'm glad someone is getting some benefit.