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Discussion Starter #1
I am looking at A 4 bolt main on a 1962 pontiac block could someone help me out on block ID maybe 421 casting #538181
 

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# 538181 was the casting number for the following 3 engines: 1961 389, 1961 421, and a 1962 SD. IF the date code is for a '62 block, (at the distributor hole) it's a 421 SD. Pretty exiting stuff. Keep us posted. Is it for SALE?
 

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If it is a 4 bolt main and has a transfer lug it is a 61 or 62 421SD, the 389 will be a 2 bolt main and does not have a transfer lug. I believe they did not use letter codes in 61 and only used the casting number. Here is more 421 information with 62 letter codes, the letter code is on the front of the block, passenger's side just below the head;



389 and 400 blocks without transfer lug;



The 326, 350, 421, 428 and 455 blocks all have the transfer lug (except for the 1973 455SD);

 

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Discussion Starter #4
Thanks for info the motor also comes with tri power setup belived to be stock with motor picking up next week will know more
 

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Good deal. No matte what it is, ANY 4 bolt main '61-'62 block is a score. They are super strong, and have much more nickel and reinforcements than the later blocks. Only disadvantage is the trans mounted starter. I'm betting it's a 421 SD.....I can feel it!
 

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Discussion Starter #6
It is know in my possession head 538177 front passanger side block 861p top below 8110 their is also a E by itself at distrib k11 0 2 block 538181 help
 

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It is know in my possession head 538177 front passanger side block 861p top below 8110 their is also a E by itself at distrib k11 0 2 block 538181 help
The 538177 head (1.88/1.60, 69 cc) was used on the standard 389 and 421 for both 61 and 62.

The SD heads for 61 and 62 was 540306 (1.92/1.66 68 cc).
In 62 the 405hp head was 544127 (2.02/1.76 68 cc)

Is there a transfer lug on the block?
 

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389 block

4.06250" bore, 3.7500" stroke & 3.000" main bearing diameter,

421 block

4.09375" bore, 4.0000" stroke & 3.250" main bearing diameter,


3/32 is equal to .09375, could also be a 389 with a .030 bore.
 

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Discussion Starter #11
I am putting it on a stand this weekend it seams the next thing to check is diameter of main bearing get back when I got info
 

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Discussion Starter #12
Put motor on stand main bearing 3 inches so am i looking at a 389 and did all 1962 389 have 4 bolt mains if not what makes this different
 

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I've found a website that states the 61 & 62 421 did not have a transfer lug, the production numbers for that engine are very low, probably less than 200.

Those wanting even more power ordered the 425-A Trophy V8 engines, which differed from lesser 389s by their four-bolt main caps,lower block reinforcing ribs, and longer duration cam. The single four barrel was rated at 333 bhp while the Tri-Power version carried a 348 bhp rating. For the truly obssessed, 16 Grand Prixs were built with Pontiac's 421 Super Duty engines, rated at a staggering 370 bhp. Only one is known to survive today. Also, a rumored 75 cars were built with non-Super Duty 421 engines rated at 320 bhp.
 

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I read an article in a Pontiac magazine back in the '80's that featured an original 4 speed, 421 powered '62 GP owned by a mail man. He saw it on his route and bought it for $150. It was a black car with a parchment interior....even had the console. I'm still haunted by the thought of it. Sounds like you scored a great early high performance block, even if it is a 389. Most of us here would be all over it!
 

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Discussion Starter #17
Ok Got the straight info on engine built nov.1961 Code M4 -425A HO 348HP Manual Trans Found TRI Power is 1964 perfect for my 64 gto Its been fun
 

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Also, be advised that your engine would be very valuable and desireable to the '61 guys. There is a tiny but intense world of Pontiac guys who are into the '61 Bubbletop Venturas that were the drag car of the day. Most of these are being restored with 4 speeds, 3.64 posi's, and 389 engines. To have a real '61 348 HP engine for a '61 Ventura, Catalina or Bonneville is not a bad thing. You could probably trade it for a numbers correct '64 GTO engine straight across, or maybe come out ahead. Good score!!
 

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Mickey, I just thought of something: the '61 block you have does not have a starter mount. The starter mounted to the trans bell housing in those years. You will need an adaptor plate to make it work, or, better yet, to trade it for a numbers motor for your '64. Good luck!
 
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