Main Caps

[ric1969]

  Did all 1969 small blocks 302/350 have nodular iron caps ...

[z28z11]

"Most" high performance engines used nodular main caps (which for small blocks in '69 meant 4 bolt main blocks). 4 bolts were used for the higher performance units primarily for strength and warranty considerations  - although I have seen the occasional lower horsepower (meaning below 300) blocks with 4 bolt mains and nodular main caps. The letter "N" cast into the cap denotes nodular construction.

Never seen a two bolt in '69 or later usage with a nodular cap - '67 and '68 two bolts used them for the Z engines, and L48/L79's as far as I know. Considering GM, there could always be the occasional slip during engine assembly with an HP block making it into the less-than-H-Perf assembly applications.

Regards,
Steve

[ric1969]

 Thanks Steve , so for 69' LM1/L65 350 are 2 bolt and 4 bolt std main caps but some got 4 bolt nodular main caps ?

[z28z11]

I personally know of one locally, February car, non-SS with a 3956618 four bolt nodular main cap original block on board - car was destined to become a stock class racer, engine was removed and disassembled and ultimately sold - I was amazed to see the Feb dated block, four bolt mains and nodular to boot, was not marked as an L48. All dates aligned with the car, owner/racer was unaware of the significance of the casting code. To me. it proved that sometimes things got a little mixed up on the production/assembly lines.

Regards,
Steve

[ric1969]

 Thanks for the info Steve very interesting , i have three 69'bare blocks with 4 bolt nodular main caps but they been decked. Does anyone out there have a original 69' low hp 350 with 4 bolt nodular main caps   

[Stingr69]

I just built a '70 350/300 HP base Corvette engine that had 4 bolt nodular caps.  I understand this was the way they were built that year. 

Don't know when they went to 2 bolt mains.

[KurtS]

And I have a 69 L48 block with 2-bolt mains. I was surprised....

[ric1969]

 Anything to do with what options it came with transmission and rear axle ..

[z28z11]

One other application that sometimes used nodular mains - truck applications. Plenty of 3970010 blocks around with 4 bolt mains, and a moderate amount of 2 bolts, including 3932386 blocks and 3956618 blocks (both of which were listed as 327 and 350 casting numbers). All three casting numbers were used in '69, high and low performance. No evidence that any of the two bolt varieties were ever equipped with nodular mains after 1968 (when the four bolts were issued in '69).

As an afterthought, there was one other 4 bolt 350 block used in '69 - the 3932388 block. I have the L48 version of that one in my Pace Car -
if I remember correctly, there was an example or two of this block showing up in '69 Z's. Fairly scarce number -

All of these show in the CRG Drivetrain Decode - CBTN explains the numbers and applications as well. 

Regards,
Steve

[KurtS]

388 blocks were common. The scarce part is the 388's assembled at Flint.

My 2 bolt L48 block had a TH400 behind it...

[ko-lek-tor]

And I have a 69 L48 block with 2-bolt mains. I was surprised....

Kurt, is that a Camaro L48? I have read about, and personally owned a 2 bolt main L48. The 2 bolt variety of L48 came in full size Chevys. In my case, I pulled the engine out of an Impala. Heads were 041. Everything exact to my Camaro’s L48, except 2 bolt main.

[z28z11]

388 blocks were common. The scarce part is the 388's assembled at Flint.

My 2 bolt L48 block had a TH400 behind it...

I don't disagree - my HB code L48 388 block is a Tonawanda graduate. For some reason, I've seen and heard of several of these showing up in Z11's, any specualtions ? Maybe the transition period from 3956618's to 3970010 blocks ?

Steve

[z28z11]

An example of a 3932388 four bolt block w/ nodular mains - unfortunately the block was decked, we'll never know what it was out of or intended to be. Currently there are 2 or 3 HB coded L48 3932388 blocks on eBay, all with 2482 nodular 4 bolt main caps on board. There are also several 2 bolt versions listed -

https://www.ebay.com/itm/353066712849?hash=item52346a7f11%3Ag%3AYJcAAOSwmaBerQNs&LH_ItemCondition=4

Over the years, i've seen relatively few of these compared to 386's, 010's or 6618's. CBTN mentions they were fairly unknown as far as heritage was concerned -

Steve

[KurtS]

Kurt, is that a Camaro L48? I have read about, and personally owned a 2 bolt main L48. The 2 bolt variety of L48 came in full size Chevys. In my case, I pulled the engine out of an Impala. Heads were 041. Everything exact to my Camaro’s L48, except 2 bolt main.

Out of an Impala, with 186 heads!

[KurtS]

Over the years, i've seen relatively few of these compared to 386's, 010's or 6618's. CBTN mentions they were fairly unknown as far as heritage was concerned -

CBTN put out some bad info on 388 blocks. http://www.camaros.org/drivetrain.shtml#BlockCast
The 3932388 block is sometimes noted as being 'rare', but it actually was commonly used in mid-69 production. It was cast and used mainly at Tonawanda. The 3956618 block was also used in mid-69 production.