a challenge for all the Nailhead Guru's....

I have a '64 Riv that I am stripping for parts. It has a dual quad set up but I don't think any of it is factory to this car.

The numbers on the front of the block are what have me perplexed. Maybe someone out there can figure it out....
Btw, the cylinders measure 4.31

 

The "4I" suggests it's an overbored 1962 401.
Happy for others to confirm/deny.

 

can you overbore a 401 to a 425?

 

I have heard from in person and read on the net that the 401 and 425 were that same casting for certain years, not sure what year(s) and not sure how true? GL



Derek

 

It's my understanding that the 401 and 425 are and have always been different blocks.

I'm wondering if the engine was replaced by a dealership and the original serial number was stamped on the passenger side to have continuity?

 

As stated above the letter "I" denotes the donor car was a 62 model.

 

I read that they are the same blocks and the only difference was a machining tab on the back near the bellhousing that indicated wether it be bored 401 or 425. Apparently the tab would trigger a switch and send to the 425 boring machine.
Cheers

 

For a thorough discussion of boring a 401/425 nailhead, click on the links below and the links within the second thread attached:

http://www.v8buick.com/showthread.php?242261-Another-block-inspection&highlight=boring+401+to+425

http://www.v8buick.com/showthread.php?216193-Boring-a-401&highlight=boring+401+to+425

 

6I8008335
6 = Series 4600/Invicta
I = 1962
8 = built at Arlington, TX
008335 = sequential number, range for Arlington in 1962 was 001001 to 019915

Serial number (VIN) is 9 digits for 1954-1964.

4I 168192 (only 8 digits)
4I = 1962 401 V8
168192 = sequential number

 

I get that's what the numbers indicate however it is bolted to a TH400 (i know, crank can be changed) and the cylinder bores are a 4.31 and I don't believe you can bore out a 401 to that spec. I know there are "rumors" that it can be done but I don't buy it.

I now have the engine out. Is there anywhere else I can look for ID?

 

How about this for an ID, the 425 Nailhead's first year was 1964 so if that is for sure a 1962 engine then it had to be a 401 or smaller to start. Must of been a really good block with minimum core shift for it to now be a 425. :TU:






Derek

 

Pretty sure I saw posts here at V8buick showing or otherwise identifying the thicker blocks.

It isn't really unreasonable to see blocks with very different water jacket cores, esp. knowing a few years in advance that they are producing them.
All of these blocks are being made well ahead of the assembly line and when sales figures exceed projections, sometimes the foundries use whatever core boxes are ready during a pour.

Elsewhere on the net was a detailed story from a former foundry employee outlining the procedures...it explained the many myths surrounding casting the identifying features, as well as the core boxes being staged in a disorganized fashion, and the fact that all of the markings face inwards (!).
In the middle of a pour, they use whatever they have to use to make it through.

I have 2 400 sbc blocks that are supposed to be thin that are actually thicker than the bowtie blocks.

If you simply look the block over visually, poke around with a drill bit or gauge pin, and maybe sonic test the block, you will see what's what.

 

Not that it matters here, but the 425 was introduced in the latter half of the 63 model year which would have been in the 63 calendar year.

 

So that would mean they were introduced before July of '63 because after that they were building the '64 lineup. If that is true then I stand corrected. I always thought the 425 was only made for three model years, '64, '65, '66 with '66 being the last year of the Nailhead platform. Perhaps the 425 engines were made ahead of time and they made it a dealer option for the last months of the '63 lineup?

Either way if the OP's block is a '62 it can't be a 425.



Derek

 

Yes some 63 models were sold with 425 engines.

 

Cool, good to know. It was a long time ago so hard to remember, because that was before I was born. :laugh:



Derek

 

They even made some Super Wildcat (2 x4s) powered cars in the 63 model year.

 

I would imagine that a '63 car with a factory numbers matching 425 would be worth more $$$, probably quite rare by now?





Derek

 

Here is a discussion about some-- one that was once located in Winston Salem, NC.

http://www.v8buick.com/showthread.p...ard-Cruise&highlight=63+winston+salem+wildcat

 

So did they introduce the 425 in the Wildcat before any other car got one until '64? Or was the 425 available in other cars in the late '63 lineup? Great info, thanks!



Derek