Talk:General Motors 90° V6 engine

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Grand Prix[edit]

Regarding the LB4 incarnation of the 90-Degree V6, my copy of the Standard Catalog of American Cars (3rd Edition) lists this motor as a $200 option on the 1987 Pontiac Grand Prix, listed as RPO Code LB4, VIN Z and available throughout the range of Grand Prix models except the 2+2 Aero Coupe. There are a few discrepancies, however: while described as "Optional V-6 (with three speed automatic)", which would lead me to believe the only motor/tranny combo available was LB4/THM200C, the "Technical" specifications give a separate axle ratio for the LB4 with THM200C (2.29:1 / 2.73:1 optional), and LB4 with THM200-R4 (2.41:1 / 3.08:1 optional). The engine specs are listed as simply "140HP @ 4200rpm" and "TBI/EFI", which doesn't match any LB4 on this list. No torque ratings or compression ratio are given. Those figures do not match any other LB1/LB4 specified on this list, so it's either a misprint or there is something about this motor unique to the Grand Prix (exhaust routing/size, I'd imagine).

I searched to verify this was not just a "planned" optional motor and I was able to find a handful of 4.3l V6 Grand Prix', however to add to the confusion I also found several 1986 4.3l Grand Prix'. lists a 1227137 ECU for 1986 and a 1227746 ECU for 1987.

All of this data would lead me to the conclusion that the LB4 4.3l V6 was a very late '86 addition to the option list on the Grand Prix and continued through the end of Pontiac G-Body production in the spring of 1987. The specific motor was most likely the exact one found in the Monte Carlo in '86 & '87, due to the use of the same ECU for those years. I'm still not sure what to make of the disparity (and lack of info) on power output, however. Considering only about 17,000 RWD Grand Prix' rolled off the assembly line in '87, and the LB4's status as a "mid-range" option, this would make this choice of drivetrain extremely rare. Also of note, this was the only EFI motor available in any A/G-Body Grand Prix during it's entire production run.

I'm leaving this info here so hopefully someone will insert it into the article in a slightly more tidy manner than I've laid out here, and also as a way to solicit info on the specifications of the '86-'87 LB4 option for the Grand Prix. I would do it myself, but I'm not yet that adept at Wikipedia style-guidelines and don't want to screw up a very nice article with what is, essentially, fairly trivial information. Nymetropolitans (talk) 08:47, 30 April 2009 (UTC)

Grand Prix Update[edit]

When I was researching for this article, I had noted the same issues you have. At the time I meant to do more research to find out the specifics of the Grand Prix and the 4.3L engine, but hadn't had the time.

My experience with the Standard Catalog is there are often minor mistakes, especially with the small horsepower variations that sometimes occur year to year. I find the most reliable sources are usually the brochures, however, I have not been able to find any for the 1986-87 Grand Prix.

That said, I did check the EPA fuel economy ratings for the 1986-87 Grand Prix and it lists the car available with the 3.8L 3spd, 4.3L 3spd, 4.3L 4spd, and 5.0L 4spd for both 1986 and 1987. It be my conclusion that the Grand Prix did have the 4.3L as an option for 1986 and 1987 model year and was available with both the TH200 and TH200-4R. It would also be my guess that the horsepower ratings were the same as the Monte Carlo and the El Camino (140 in 1986, 145 in 1987). I will update the page to include this info, unless someone can show a reliable source to show otherwise.

Caprice 96 (talk) 15:51, 13 May 2009 (UTC)

Hot Rod article - The 3/4 350 - Factual Error Noted[edit]

When the 4.3/262 was introduced in 1985, GM redesigned the valve cover surface where the bolt bosses were eliminated and the valve cover fastened with 3 center bolts. The Hot Rod article has an error where 1987 4.3s were introduced with the centerbolt cylinder heads; has pictures to prove this where no 4.3/262 was produced with perimeter valve covers.

Center bolted rocker covers were introduced on the Small Block Chevrolet in 1987 - which is demmed correct BASED on the 4.3's centerbolt pattern. There are no production 4.3s that are manufactured with perimeter valve covers; only aftermarket cylinder heads will have the perimeter bolt pattern or a hybrid perimeter/centerbolt design.

Wrong year for introduction of Vortec 4.3L[edit]

The 4.3L Vortec was introduced in 1992, not 1996. I've owned and worked on several 93/94 blazers and jimmys with Vortec 4.3Ls. —Preceding unsigned comment added by (talk) 15:53, 29 September 2009 (UTC)

GM Performance - rare splayed-valve heads[edit]

These are so bizarre and rare I wonder if they're worth mentioning. There are also more common 18-degree heads available from GM as well. Pics on my blog. Toneron2 (talk) 18:27, 27 January 2010 (UTC)

Add info on splayed/canted valve heads?[edit] — Preceding unsigned comment added by Toneron2 (talkcontribs) 01:43, 3 December 2015 (UTC)

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