I found this and if everything is correct, it looks like it will work for him.

"Indestructableforce - 6930 is the last four digits of the cam's casting number, 3896930, which also has a horizontal diamond for the casting symbol. The Chevy part number for that cam is 3896929.

In 1967, it was the cam for the 283/195hp; 327/210hp, 275hp, 300hp; and 350/295hp.

The specs on that cam are: (read int lift, ehx lift, int duration, exh duration, rocker ratio) .390 .410 310 320 1.50

In 1968, it was the cam for the 307/200hp; 327/210hp, 250hp, 275hp, 300hp; and 350/295hp.

In 1969, it was the cam for the 307/200hp; 327/210hp, 235hp; and 350/250hp, 255hp, 300hp.

In 1970, it was the cam for the 307/200hp; 350/250hp, 300hp; and 400/265hp.

In 1971, it was the cam for the 307/200hp; 350/245hp, 270hp; and 400/255hp.

In 1972, it was the cam for the 307/130hp; and an optional cam for the 350/165hp, 175hp, 200hp; and 400/170hp.

In 1973, it was the cam for the 307/115hp; 350/145hp, 175hp, 190hp; and 400/150hp.

In 1974, it was the cam for the 350/145hp, 185hp, 195hp; and 400/150hp, 180hp.

In 1975, it was the cam for the 350/145hp, 155hp, 165hp; and 400/175hp. All of these applications had the same specs as the initial 1967 application."

 

It might be tricky in a photograph, but a reverse rotation SBC usually (always?) has the gear on the cam to drive the distributor cut differently than the std car versions (opposite helix)

 

As you pointed out, I'm seeing that number listed as being the same as the "929" cam that was the "universal" small block cam. I can't find anything saying otherwise.

For the same money this will do the trick and it comes with the lifters:

https://autosalesinc.pxf.io/c/40473...arts/sum-k1101?srsltid=AfmBOoqNWUgxvG7bmaZtooWJoWG_QOs_rosfUEuWiufnayYdjZRhQDxY

The miniscule difference in advertised specs is negligible here.

 

As you pointed out, I'm seeing that number listed as being the same as the "929" cam that was the "universal" small block cam. I can't find anything saying otherwise.

Yeah, that's easily the most common cam ever for small blocks. Several of my DDs and Family Trucksters over the years have used that cam -- 195hp/283, 220hp/283, 275hp/327 and a 255hp/350. Yes, I missed out on the factory hi-performance engines back then, but I did build a solid lifter 292 (+.060 283) that was lots of fun with a Muncie 4-speed and 4.56 gears.

Anybody know if that #3896930 core might have been used for other cam grinds, too?

 

GM loved that -929 cam

 

Marine cams were often just truck cams, and in some instances an R/V towing cam. Generally nothing special as they can’t be too wild with overlap due to the possibility of reversion

 

Thanks for the replies. I think that he wants to buy something older because of the quality of some of the newer parts. If anybody has any other thoughts please post so that maybe he has other options.

I'm going to give him a link to this thread so he can see what you guys are saying.

 

Nothing special about a marine cam. its just a truck / RV cam with very little overlap as Matt stated. most RH motors use LH cams. they just ran the crank backwards leaving the cam/oilpump/distributor to run the same as teh LH motors and changed the firing order.

I would get a new cam and lifter setup. lot more power to be made on the old 307 by swapping heads, and matching to a good cam.

 

I bought a take-out boat engine roller cam, and it worked just fine. I also used to have Mercury Marine in Oklahoma as a customer, and all the Chevy marine engines that I know were standard rotation.

 

If a marine engine was reversed rotation, it was a twin engine configuration. Later model stuff reverses the outdrive or transmission so 95% of the boat engines are standard rotation

 

Does he want something to just putter around in (which is fine); anything similar to the old 260H would be good. Its not an XE grind and its been used a LOT in 283s and 327s.
Cranes old 274H-06 was always an interesting choice, Im sure someone makes a clone of it.
My brother had a 307 with 2 cams in it over the years when we were kids, one was a -097 Duntov type, I think it was a Wolverine cam. The other was a Comp 256 Solid. Comp still has it and its listed at

Advertised Intake Duration	256
Advertised Exhaust Duration	262
Intake Duration at .050 Inch Lift	218
Exhaust Duration at .050 Inch Lift	224
Intake Valve Lift	0.465
Exhaust Valve Lift	0.477

Not gonna win races, but a small solid cam with a little gear in the car is fun

 

I'm not really sure what he wants but I gave him a link to this thread so he can see all the comments.

Didn't GM have a lot of soft cams that went bad? I'm not sure when but it was a long time ago. I have to wonder if it's possible that the cam mentioned in the first post could have been one of those cams.

 

My old man used to moonlight at a dealership after hours doing fleet work. Phone company had a fleet of 307s that came in with bad cams and nylon-tipped timing sets. Some of em were running, some were skipping, some were DOA.

Was it something the guys doing PM's did wrong, or were they bad parts? Both? Who knows.

 

My high school friend put a custom ground crane solid roller jet boat cam in his 69 Camaro 396. The engine had dome pistons and rectangular Port heads and it ran really well. He still has the car and the engine hasn't been touched since 1980 and it still runs really well.

 

Update: He bought the cam that was on Ebay.

Thanks for all the replies.

 

Chevy up till the midish 1970’s Parkerized their cams. This made a nice wear surface but added manufacturing and environmental clean up costs. The 70’s following the end of the Vietnam war were pretty financially trying times where everybody was cutting costs and wrestling with initial governmental environment regulation. So around 1974 Chevy stopped Parkerizing cams which was immediately followed with field failures and customer law suits. The much to slow response to this problem was the eventual move to OEM roller cams. The government saved GM’s butt by getting the class action law suits thrown out. The result was increasingly the customer base moved to Toyota and GM’s financial woes steadily increased. In spite of the BS that flows from the likes of the Wharton School of Economics it seems the captains of industry have no appreciation of how errant short term decisions affect long term consequences.

Add to the SBC’s cam and lifter problems is the small diameter of the lifter and the lack of a thrust plate for the flat tappet cam. So the lifter and cam lobe see a higher unit loading because of less contact area and the angle relief of the lobe and convex surface of the lifter there to encourage lifter rotation n its bore then becomes also the means of controlling cam thrust movements. You can add 3 or 4 moments in this as the cam is not particularly thick so it’s given to its own moments of shake rattle and roll. Then the cherry on top of this Sunday is that like metals in rubbing really work hard to weld themselves together, this takes a lot of oil and that oil needs EP additives which have been reduced in recent decades to improve cat-converter life. Then we engine builders further exacerbate the problem by dry out the engine with windage trays and devices that reduce upper end lube which starves the drain back holes positioned between lifter pairs. All of this arrives at the cam and lifter wear problems that became so prevalent once Parkerizing was ended. The aftermarket also sells just machined casting cam shafts as well so the problem persists but many cam sellers offer Parkerizing and cold casing treatments at extra cost which brings the flat tapper cam‘s cost nearly up to that of a roller core.

Back n the good old days before the 1973 energy crisis that in a major way is what kicked off all this cost cutting we’ve lived with ever since Chevy recognized that even with Parkerizing cams with high performance cams there was a wear issue which they handled with really long ramps and very mild lift rates once past the ramps and made up for the lost trapped cylinder pressure with really high compression, that solution being not very suitable with today’s 91/93 octane fuels like it was in those yesteryear days of 100/110 octane fuels. Plus fuel gets into the oil by way of blowby thus the lead used for the octane gain also got into the oil and lead though really toxic to living things does make a very good EP additive to go along with the heavy doses of ZDDP used back then. This being also the days before Positive Crankcase Ventillation, what crankcase ventilation there was consisted of a road draft tube which unless you were movin’ and groovin’ didn’t really provide much ventilation to the crankcase. Then on the high performance cams Chevy also used a hard faced lifter which is something you can still find with some concerted shopping.

Bogie

 

The boat cam will be great for a street driver. It's torque biased, which gives it a very spunky feel but will limit high rpm somewhat. Should be good up to around 5000 rpm though, and will pull good from 1500-4000. Unless you plan on a lot of drag racing it will be great!

 

I used to build marine motors, and yes, it will work fine. The cams are basically like a factory lo-po economy cam like you might find in a truck or a passenger car. The number of reverse-rotation marine engines was always VERY small, and nothing majorly complex. Since the mid-70s, nearly all marine applications were normal rotation, and any counter-rotation was handled in the outdrives. Vee drive and inboard ski boats hung onto a few reverse rotation applications into the 80s, but it just stopped making sense when it's so much easier to pull a crate 350 off the shelf and drop it in.