Which engine do I have? 91 Firebird Formula. VIN indicates 350. Catalyst sticker on underneath side of hood indicates 350. Hood scoop badge says 5.0 L fuel injection. Seller says it has 305. It still has exhaust manifolds so I suspect the engine has not been removed.looking for casting number but can't get it

30

Asked by Lmasseyutility Aug 16, 2015 at 05:13 PM about the 1991 Pontiac Firebird Formula

Question type: Maintenance & Repair

5 Answers

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The hood has 2 stickers that contradict each other. Decal says 5.0, catalyst sticker says 5.7

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8th VIN character would be an 8 for the 350, E for a TB 305, and F for a TPI 305. While you are checking, the 5th digit should be a W for either a Formula or Trans Am. If it is an S, it started life as a base Firebird and someone has done some parts swapping. I agree with Jim, it is unlikely that someone would bother to swap the catalyst decal and a base Firebird could only be bought with a 305 TB V8 or a V6.

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Agreed. VIN states 5.7 as does catalyst sticker. It still has exhaust manifolds which leads me to think that the engine has never been pulled. I'm assuming that the previous owner stating that it is a 305 came from his use of the hood badge's 5.0L FI, as it has two other sources stating it is the 5.7 (L98 ?) (unfortunately, the console options stickers are missing). I guess this weekend I will have to get to the casting stamp on the block to truly know, but I'm anticipating finding that it is a 5.7. Otherwise, 2 factory size indicators that an owner can't alter are incorrect and a decorative sticker that could have been added by an owner is correct. Thanks guys

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