L79 Camshaft (GM # 3853151); who makes what

[Thomas H.]

Re: L79 Camshaft (GM # 3853151); who makes what

Hi Joe,
Do you have any pictures of your "aftermarket" 462
Tom

[Joe L.]

Re: L79 Camshaft (GM # 3853151); who makes what

Did you mean to say that the OD is 1.25" or the open height at 295 lbs? Typically beehive springs give a top OD and a bottom OD, since they are different.

Gary

Gary------


OD is 1.25" at the bottom. That's the critical OD dimension because of spring pocket size. I don't have the top OD.

[Joe R.]

Re: L79 Camshaft (GM # 3853151); who makes what

Hi Joe,
Do you have any pictures of your "aftermarket" 462
Tom

Hi Tom:

I'm writing a 2-part series for the Restorer that describes my engine build. The first part, on the 383 stroker short block, has already beed submitted but I don't know when it will be published. The second part will describe the rest of the build including the heads, and will hopefully include dyno results.

I'd rather not post a photo of the heads here because a full explanation of what I did would require a LOT of detail and I'd rather save that for the article. However, I can tell you that 80% of the exterior work was done by Brzezinski Racing, using a "disguise" package that involves a CNC milling machine:

http://www.castheads.com/disguise_work.php

Their CNC program for the 462 heads is incomplete, but it does most of the work for you. I finished the job by hand with a die grinder.

Keep in mind that you can do some very simple and inexpensive things to reduce the visual impact of aftermarket heads. If you fill the accessory mount holes with epoxy and paint the heads Chevy Orange, that helps a lot. You can also round off the corners with a die grinder to better match the contours of the 462 head. Some guys even try to add the "double humps" with epoxy. Sprinkling some sand in the paint helps to replicate the original cast texture. All of these steps are inexpensive and just require some time.

Also keep in mind that no matter what you do to try and disguise a set of aftermarket heads, the difference will always be detectable to a knowledgeable NCRS judge. The only reason to bother with doing this is to try and maintain a stock appearance for someone who is casually looking at your engine compartment. When I look under the hood of a vintage Corvette, I prefer to see a stock-appearing engine (I call this "NCRS Disease").

[Joe R.]

Re: L79 Camshaft (GM # 3853151); who makes what

Hi Joe,

I think I saw the first part of your article in a chapter newsletter. I was very intrigued by it. Please refresh my memory, did you manage to stroke a 327 block to 383 cubes?

Thanks,
Joe

[Joe L.]

Re: L79 Camshaft (GM # 3853151); who makes what

Hi Joe,

I think I saw the first part of your article in a chapter newsletter. I was very intrigued by it. Please refresh my memory, did you manage to stroke a 327 block to 383 cubes?

Thanks,
Joe

Joe-----

I can't speak for Joe C. However, a "30-over" 327 with a 3.75" stroke crank yields 383 CID. The 3.75" stroke crank is a fairly common mod for 4" bore small blocks.

Actually, I always wondered why GM never used this configuration for a PRODUCTION small block. It yields almost the same size engine as a 396 and in a smaller, lighter package. GM finally did "get on the bandwagon" with SERVICE-only Gen I small blocks of 383 CID, though.

[Thomas H.]

Re: L79 Camshaft (GM # 3853151); who makes what

Hi Joe (Randolph),
That sounds like another good read from the Restorer.
Tom

[Joe R.]

Re: L79 Camshaft (GM # 3853151); who makes what

Hi Joe,

I think I saw the first part of your article in a chapter newsletter. I was very intrigued by it. Please refresh my memory, did you manage to stroke a 327 block to 383 cubes?

Thanks,
Joe

Hi Joe:

Yes, the article I wrote for my chapter newsletter was about stroking a 327 to 383 cubic inches. I have submitted an expanded version of the article to the Restorer, but I don't know when it will be published.

[Joe C.]

Re: L79 Camshaft (GM # 3853151); who makes what

Hi Joe:

Nice to see you weigh in here (note that we now have three different Joes on this thread...). You are the guy who first told me about the LS beehive spring that fits into the stock spring pockets. I really like the attributes of beehive springs, so I think this is a great idea.

In my case I'm using aftermarket heads that have been carefully reshaped on the outside to resemble '462 heads so that I can maintain a stock appearance in the engine compartment (I call this "NCRS disease"). The spring pockets in my heads are 1.55" in diameter, so there is room for just about any spring. The spring that I'm using is the Comp Cams 26986, which has a 1.412" diameter at the base. The only down side of the big spring pockets is that I had to use a spring locator on the base of the spring, which lifts the spring by .060." I compensated for this with +0.050 valve locks.

Yes, now I remember. Good spring choice with very slightly more compliance (280 vs 312 lb/in) using a thinner ovoid wire, but very similar pressure profile. Spring cups are always better, if they fit into the pockets, then you should use them.

[Joe C.]

Re: L79 Camshaft (GM # 3853151); who makes what

Joe-----

I can't speak for Joe C. However, a "30-over" 327 with a 3.75" stroke crank yields 383 CID. The 3.75" stroke crank is a fairly common mod for 4" bore small blocks.

Actually, I always wondered why GM never used this configuration for a PRODUCTION small block. It yields almost the same size engine as a 396 and in a smaller, lighter package. GM finally did "get on the bandwagon" with SERVICE-only Gen I small blocks of 383 CID, though.

Hi Joe,
You mean to say "Joe Randolph" not Joe C. as I have not built up a 383. I prefer a short stroke-high revving 327, although the 383 is very, very popular (there's no substitute for cubic inches).

The reason GM never used a 3.75 stroke with the "medium journal" block might have something to do with journal overlap. When they went with the 400 SBC, they increased the bore and stroke (4.125" x 3.75"), and also increased the journal size. Less chance for fracturing a crankshaft.

[Tim S.]

Re: L79 Camshaft (GM # 3853151); who makes what

I better not say any more because the restoration police are watching.

Duke

Glad they did not catch me on this thread https://www.forums.ncrs.org/showthre...-engine-guru-s

[James B.]

Re: L79 Camshaft (GM # 3853151); who makes what

Gary,

E-Bay has a NOS #3853151 Camshaft for sale, I believe it is a byt it now. A little pricey though.

Jim