L78 396/375 HP Long Block CKO Stamping

**SuperNovaSS** · #1 04-14-2006, 08:28 PM

This is a L78 CKO stamped long block. The numbers are as follows: Block casting: 3999290 Dated E2471. Pad stamp: TO928CKO. Heads: 3964291 Dated E171(both).
This block is .040 over(actually .020 over its original 402 size) with no machine work required. There is a very nice sleeve in #5 that is virtually undetectable. The crank is very nice and does not need any machine work. The rods are 3/8" dimple with very nice Keith Black pistons. The heads look very good and have no porting or other mods. The pushrods and balancer are also included. I would install new bearings in this engine and run it. This engine spent most, if not all, of its life in a fresh water jet boat. The 71 date indicates that this engine was destined to be used as a warranty replacement in a Camaro or Nova L78 375HP and a manual trans. Perfect replacement for your non original engine L78. I can post pictures if anyone is interested. $3000.

Jason

budnate · #2 04-15-2006, 08:24 AM

**SuperNovaSS** · #3 04-27-2006, 03:25 AM

Nobody? OK, $2750. Otherwise I'll have to toss it in something

.

CamarosRus · #4 04-27-2006, 05:54 AM

You are saying/implying that this engine was assembled Sept 28,1971 using a 290 Block cast on May 24,1971. Alan Colvin says was this casting # was meant for 1972 240HP 402's.

Would somebody with more knowledge than I, please explain how this above engine received a 1970 CKO(L-78)deck code, for a NON 854 Block assembled more than a year after the LAST 1970 L-78 Camaro, Nova or Chevelle would have been built.

Just seeking education.......

**WILMASBOYL78** · #5 04-27-2006, 08:22 AM

Chuck, let me try to help...you are correct that the 854 block was used in the L78 in 70..it was also used in L34 motors(2 bolt). The 290 casting started sometime during 1971 and was made in both 2 bolt and 4 bolt. My 70 Fathom Blue L78 has a CE warranty motor dated E2572. They probably made these blocks long enough to satisfy any warranty or over the counter demands. The block is listed in the Mortec website for both 2 bolt and 4 bolt(70-72). I realize that the Colvin notes say that the only block to get 4 bolt mains in 71 was the LS-6 but I think that refers to assembly line installed units. These motors exist and are not that uncommon.

wilma

CamarosRus · #6 04-27-2006, 07:37 PM

Tom, I agree with your comments......I just dont understand how or why a replacement engine assembled one year+ after the car run ended would still be stamped as a CKO and not as a CE ????
Also, isnt it unusual (but not impossible) for the block to not have been assembled/machined until four months after casting.
I have not seen near as many CKO/Big Blocks as you, but those I have inspected had cast/assy dates with in weeks.
Thanks for the ongoing L-78 education.........

**WILMASBOYL78** · #7 04-28-2006, 03:29 AM

Chuck, this is an interesting topic and deserves some further investigation. When you consider how many 396 cars were made in 70...there must be some reasoning behind the number of warranty motors or extras that were made for potential use. I would guess there are others on this site that may have more to contribute to the subject. I will review casting dates and assembly dates on some of my 70 cars to see how they stack up. Hopefully others will share their thoughts.

wilma

CamarosRus · #8 04-28-2006, 01:05 PM

I will bring this subject to the 70 Camaro L-78 enthusiasts at www.nastyz28.com

**THNDER** · #9 04-29-2006, 09:07 AM

Chuck, remember Nils in New Jersy who purchased an L78 Camaro back around Xmas? He had the original engine in it. The cast date was J 18 69 . The engine code stamped on the block was T0407CKO. This engine was final assembled 6 months after the block was cast. Now I am not saying I know why the 71 block has a CKO stamping, but I have seen some pretty scattered assembly dates, compared to casting dates. I figure that the L78 was still not a very common engine, there fore they cast a lot of blocks at one time, and used them as needed. Make sense? Just a guess on my part, but seems logical. Mike

**JRSully** · #10 04-29-2006, 03:52 PM

My original 70 L78 Nova engine was cast A-28-70 and built April 24, I have seen another 70 L78 Nova block that was untouched and was cast early Feb 70 and built last day of April, these long spreads are definitely in existence.SULLY