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71 LeMans Sport, '70 400/350
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Discussion Starter · #1 ·
Help needed for confirmation of dates and type on my 16 code heads.
Block is an XZ code with no. 9799914 which I believe to be a '70 full size bodied motor. Unfortunately I don't have any valuable history for this motor. Runs good though;)
 

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1971 GTO resto mod. Modified 428 HO, 4 sp (built by midwest muncie) Dana 60, 3.55 rear
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While the first letter looks like an " I " in your date code, it's a bit hard to tell.. But that would make the heads made on September 19 1969. I've found different sized valves stated from different sources.. Some say 1.96/1.66 and others say 2.11/1.77. Wallace racing came back with a 330 HP small valve code 16 heads.
 

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General rule is that cast dated parts (blocks, heads, water pumps, manifolds) use the letter I for the month of September.
Stamped dated parts (alternators, starters etc) skip the I and use J for September
 

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Don't overlook the big 70 on the distributor pad. Looks like the last number is a 9 and I'll take your word that the letter is an I which would make it a block produced for the 1970 model year. Anyway 1970 block and the XZ says its a 330 horsepower 400 out of a big car. The 16's would be stock to this engine and my source says 1.96/1.66 valves.
 

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71 LeMans Sport, '70 400/350
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Discussion Starter · #7 ·
Thanks for the replies confirming my thoughts, I did find some conflicting info on the various sources. The head "I" code isn't clear but I can't see what else it could be. The block is a '70 with N269 date. I'm making an assumption the heads are original to the block and the likelihood that they will be small valve as it's from a full size car. Guess I'll find out when the heads come off sometime.
 

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Are your SURE that's an "N" and not an "H"? H works out to be the 8th month, August. ("N" would work out to be the 14th month of the year). H269: August 26, 1969. Close enough to the date code on the heads for them to be original to that block. At any rate, it was cast in 1969 and late enough in the year for it to be for model year 70 because the foundry started casting parts for the next model year in or around June/July.

Bear
 

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71 LeMans Sport, '70 400/350
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Discussion Starter · #10 ·
Good call Bear, most likely an "H". Good to confirm the codings and know I have some decent parts to work with, from members here who are familiar with these motors. My first Pontiac V8, having only worked with a /6 OHC many years ago in a '68 Firebird.
 
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