80 Pontiac T/A 301 CID

Your friend is totally and completely full of SH*T!!!

The 265/301 was made to reduce weight and production cost but use existing tooling. It was designed and made by Pontiac and was GM's most advanced engine at the time(released in 1977) It used a thin wall cast block and siamese port intake which made it look different from a traditional Pontiac engine.

Unfortunately it was made with hardly any performance in mind and bean countered to the point that they aren't very reliable.

Ask him if there are "big block" and "small block" Pontiacs. If he says yes you know he's clueless because all pontiac blocks are the same size from 265 - 455.

301 was a Pontiac 400 with a cut down deck and short throw crank but they use the 400 rods with short skirt high pin pistons to prevent the piston from hitting the heads. It was designed in late '76 to compete in Trans Am competition with the Ford 302 in the Mustang and the Chevy 302s in the Camaros. T/A rules at the time mandated that the engine be produced by the same manufacturer as the body. They are a tough engine when built up. As far as the Ponchos go the engine line up was kind of strange a few years. They used their own 250,350,400,455 up until '77, Then they had the Buick 231, Pontiac 301, Chevy 305, An Olds and a Pontiac 350, the 400 was still Pontiac and the 403 was an Olds engine. Then they added the Pontiac 365 in '80 But dropped the big blocks. His engine should have either a YN code if it doesn't have a turbo, YL if it does, (If it has a XN or another code it is not the original engine).

They used their own 250,350,400,455 up until '77,

The Pontiac overhead cam inline-6 250 cu was dropped after the 1969 model year and replaced with a Chebbie 250 cu in 1970. The Chebbie was used in Firebirds until 1975.

It was a 265, based off the short deck 301 block.

Pontiac never had any big blocks. Just Pontiac blocks :-) Set a 326 block next to a 455 block and they're the same size.

His car does not have a turbo, so it should have the XN code. Can you tell me which digits in the VIN this would be? And if you say something like digits 5 and 6, is that starting from the left or right of the VIN? I would guess it's starting from the right, but I wanted to be sure.

Many thanks!!

Rick

Thanks a lot for your help, Dennis!!

Rick

The 5th letter in the VIN will note the engine. Y for 155HP 301 Pontiac and W for 140HP 301 Pontiac.

Engine codes for 140HP 301's are XT, XW, X3, X9, XN. Codes for 155HP 301's are, YN, and YR.

This code is located on the front of the engine on the passenger side just below the cylinder deck. Further down closer to the oil pan you will find the partial VIN which should match the VIN number on the dash.

The 403 Olds was a big block engine (not a Poncho engine but not a bad engine IF you knew how to mod it) The 250 in the 70 I had here was still the Pontiac OHC engine not the integral head Chevy. Guess it was a leftover one,still had the BOP pattern bellhousing. And yes the 365 was a typo sorry about that...

Guess again! The 403 was considered a small block Olds. Big blocks were

400, 425, 455.