The block I have is 3902406 A47 (1967 396 C.I.D. Passenger Block, January 4, 1967).

My machinist did all the bearings, but I ordered the cam from summit. Is it true only the '65-66 engines needed it?

The block I have is 3902406 A47 (1967 396 C.I.D. Passenger Block, January 4, 1967).

My machinist did all the bearings, but I ordered the cam from summit. Is it true only the '65-66 engines needed it?

Ask the machinist, he can tell by looking at the rear cam bearing housing.

Correct, and I believe 67 big blocks are also groved.

Dealing with 396 btw.

Well, I can't take just look anymore, the engine is complete. Just sitting on the engine stand, and someone said early big blocks needed a groove. I didn't know what was considered early. I found in my "how to rebuild chevy big blocks" book where it says:

"Eary engines - 1965-66 - use grooved rear cam-bearing journal and bearing." A picture shows left grooved cam & bearing and right ungrooved cam and bearing and says the right ungrooved are the '67 and later counterparts. "Ungrooved cam and bearing cannot be used in '65 and '66 big blocks; grooved cam can be used in later big-blocks"

So far I've seen in at least 3 books where they say only '65 and '66 engines needed this, and I know my engine is a '67 by the date code and cast #.

I also heard GM installed grooved cams in later engines cause it didn't matter on them.

Also lower down in the text it says:

Early grooved camshafts can be used on later blocks, but the bearing must be the non-grooved type.

Does this sound about right? I just want to be sure before I run this engine that I didn't make a mistake.

see if you can find the casting date codes on your block, might be helpful. Did you ask your machinist? Or did you install your own cam bearings?

Dealing with 396 btw.

Well, I can't take just look anymore, the engine is complete. Just sitting on the engine stand, and someone said early big blocks needed a groove. I didn't know what was considered early. I found in my "how to rebuild chevy big blocks" book where it says:

"Eary engines - 1965-66 - use grooved rear cam-bearing journal and bearing." A picture shows left grooved cam & bearing and right ungrooved cam and bearing and says the right ungrooved are the '67 and later counterparts. "Ungrooved cam and bearing cannot be used in '65 and '66 big blocks; grooved cam can be used in later big-blocks"

So far I've seen in at least 3 books where they say only '65 and '66 engines needed this, and I know my engine is a '67 by the date code and cast #.

I also heard GM installed grooved cams in later engines cause it didn't matter on them.

Also lower down in the text it says:

Early grooved camshafts can be used on later blocks, but the bearing must be the non-grooved type.

Does this sound about right? I just want to be sure before I run this engine that I didn't make a mistake.
This is correct, 1965/1966 non-grooved block, 1967 and on, grooved block.
Early cam bearings (rear only) have 3 oil holes and shallow groove, late ones have 1 oil hole and no groove. We've built many late BB's with grooved cam with no problems whatsoever. G.M. recommends restricting rear oil feed hole with early cam (grooved) and late bearing, but we've had no problems in that area. I would make sure this is all correct now, rather than when the engine is in the car! At that point it becomes a "nightmare". Thanks, Gary in N.Y
P.S. Try to talk to the "builder" and get the part numbers from the invoice or engine build sheet that are inside the ass'y, more specifically, the cam bearings they used. If you can't get straight answers, pull the cam, it's not a big deal.

if you find you need a grooved cam, most cam manufactures will put the groove in for a small fee. i have a 55 chevy prostreet, 1965 396 with a 671 blower. its been running great for 5-6 years.they charged me $25 to cut my groove in my cam. these are good motors, just find out for sure if you need a grooved cam or not..

On my Comp Cams spec sheet for cam, it states need of grooved cam 66' and earlier. But I knew this back in 1972 when rebuilding my 66' SS396 and found out all about the grooved cams. Good luck building your BBC!

Well, all my codes show this as a 1967 block.

The block I have is 3902406 A47 (1967 396 C.I.D. Passenger Block, January 4, 1967).

I heard from Summit, and they said: The rear groove is required in the 1965 and 1966 blocks only. In 1967 GM changed the oiling system.

I guess what happen is someone said I needed one and that my engine would destroy itself and it got me all worried and such.

Sounds like I'm in the clear on this.

The old -097 Duntov solid cam that I dug out of a junk motor that I reused in my junk301 had a groove cut in the rear cam main that looked like a Woodruff keyway, (Crank key), using a 4.5" angle grinder!

It was about 3/16" wide x 7/8" long x 1/8" deep!

I asked my Machinist about it AND he said I musta pulled it out of a '55 or '56, 265" block AND that it would do fine as is in my small journal early 327 block!!

He said it was common to hand-notch them back then for use in the early blocks..

pdq67

The old -097 Duntov solid cam that I dug out of a junk motor that I reused in my junk301 had a groove cut in the rear cam main that looked like a Woodruff keyway, (Crank key), using a 4.5" angle grinder!

It was about 3/16" wide x 7/8" long x 1/8" deep!

I asked my Machinist about it AND he said I musta pulled it out of a '55 or '56, 265" block AND that it would do fine as is in my small journal early 327 block!!

He said it was common to hand-notch them back then for use in the early blocks..

pdq67The groove in the 265's (the OEM's were actually flats ground on the rear journal) allowed oil to pass when it lined up with the 2 holes in the rear cam bearing. If you do any of these castings you can just modify the passage by drilling an intersecting hole, at an angle, below the surface at the rear cam bearing. In effect you'll be connecting the 2 feed holes in the rear cam bearing hole, but under the surface. This allows you to use the proper (1955-1963) cam bearings but with the newer cams without any rear grooving or flat on the cam for the 265's. We just did 2 (265's) blocks and used the CS274 cams. Thanks, Gary in N.Y.