Author Topic: Pontiac Engine Code Help 74 or 75  (Read 219 times)

Squamish Sasquatch

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Pontiac Engine Code Help 74 or 75
« on: September 27, 2017, 10:22:40 PM »
Pontiac 400 question. Casting code 481988 block code YT. Date stamp L064. But it also has a 2nd date stamp 75' by distributor pad. And has 5C-8 heads. So is this a 74' or 75' block? I can't find a 75 with YT code so I'm thinking it's 74 but it was built to sell in 75. Wondering because 74 has 225 hp and 75 rated at 185.
« Last Edit: September 27, 2017, 10:27:12 PM by Squamish Sasquatch »
1980 Trans Am, Pontiac 400, 3.08 Posi

firebirdparts

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Re: Pontiac Engine Code Help 74 or 75
« Reply #1 on: September 28, 2017, 07:24:24 PM »
Well, the difference in horsepower wasn't the blocks fault, ha ha.  But anyway it's a 75 block.  L is way too late for 74.  they had unfortunate 7.6:1 compression.

If you use wallace racing dot com, you will find that engine code with those heads and that year, no problem.
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poncho-mike

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Re: Pontiac Engine Code Help 74 or 75
« Reply #2 on: October 29, 2017, 07:35:38 PM »
L064 would be a December 6 1974 cast block, which would have been installed in a 75 car.  I had a 75 Formula 400, and I'm pretty sure it had a YT engine, and I know for sure it had 5C heads. 

The 1974 and older blocks were better, had thicker cylinder walls.  I've also read that the 74 and older cranks were better.  Still, the engine is suitable for a street build.

Re: Pontiac Engine Code Help 74 or 75
« Reply #2 on: October 29, 2017, 07:35:38 PM »
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