How many 1966 Bonneville's were built with the 421 three two barrel option?


Asked by Nov 09, 2012 at 06:14 AM about the 1966 Pontiac Bonneville

Question type: General

When I was a kid, my parents owned a 1966 Bonneville coupe with a 421 and three two barrel carbs. The car was not a 2+2, but looked very much the stock Bonneville with all of the trim and highly optioned. The 421 emblems on the lower part of the front fenders was the only hint of what this sleeper had in store under the hood. The car was burgundy outside with white seats, and black carpet. It had a bench seat,  PS, PB, TH400 trans, AM radio, and factory air. The wheels were the base steel 14 inch with wheel covers, and used an H78-14 tire. The car came with factory color matched fender skirts. How many of these Bonnevilles were equiped this way? Thanks in advance.

25 Answers

135,401 Bonnevilles were built in 1966 I could not find figures for that engine

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If you sweet talk the person behind the counter at a dealer they may be able to find out, but the odds of finding another one like it are extremely slim.


In those days one could order strange combonations of options on cars. My uncle was an engineer for Chevrolet, and I remember him special ordering a 1966 Caprice four door sedan with a 396 SS and a powerglide two speed automatic. Maybe the 66 Bonneville, 421, three duces was a one off special order car using a 2+2 power train in a Bonneville body? I have never seen another one, and no one seems to have stats on the car. Too bad the car sucumbed to rust, wear and tear, and was junked in the mid 80's.

Actually the three- 2bbl carb manifold and the three 2-bbl carbs were quite was called Tri-Power, the middle carburetor being the only one used until you stomped on it, it was adjustable too, you could set when you wanted the other carbs to kick in by a little slide-lock on the throttle cable--my '64 GTO 389 I had set to kick in at a very low throttle, gas was all of 38 cents a gallon, I whined and beyotched when it hit 45 cents-- and I just loved cruising at 55 then kicking those other 4 barrels in to action, THAT is where that GTO would scream and GO-- Not so much a 0-60 car, but 60-100, no peers.

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The tri power set up was common on GTO's with the 389 engine. The 421 was not available in a GTO. There were some tri power 421's in the 2+2's, a B body car based on the Catalina. I have seen a couple of tri power 421's in Gran Prix's also. The 421 was a common engine in the Bonneville, however I have never seen another tri power one besides the one my parents owned. They purchased it brand new in 66, so we know it was factory built and not a modified car. I am really beginning to regret that it was not saved. The engine had a problem in that it kept blowing rear main seals. We pulled the engine and sent it to a machine shop for a complete rebuild, only to have it blow a rear main seal again within a few months. That and the rust did the car in.


unfortunately, there is NO exact can search the internet for ball park figures, but nothing exact, compliments of your friends at the Mecum Auto Auctions....

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Today is June 27, 2013 and a 66 bonneville coupe 421 is on eBay! It is in Arizona and needs a major restoration, wish I could buy it. Thanks for confirming 421 badges are in the right place for that car, nice! Growing up we had a 66 bonneville wagon with 8 lugs!

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That ebay Bonneville is basically the same car as my parents car, except their car was solid burgundy with no vinyl top. The three 421 badges are in the same places on both cars. Too bad that car is such poor condition, but it does appear to be original.


Yeah But a stripped down YH 421SD block, complete motor w/o carbs was recently at an autofair on a trailer with a price tag of $5000.00!! Bet the burgandy bomber was fast! I had a 65 2+2 that was a project I never got to put a wrench on, sold it in Queens NY around 1990: Light Blue metalic, Super dark Midnight blue interior, 4-speed w/ bucket seats. 421 with single 4 barrel motor (needed a rebuild) but this car had Power Windows! Pretty sure that was rare in a 2+2 Coupe! Locally I have a line on a 66 GP (great tail lights) and a standard 66 catalina with original 421 badges but the 2 barrel carb makes me think it had a motor swap. Junkers though. Take Care.


For a large car, the 66 Bonnie was scary fast... 13.8 in the quarter. Ultimately my folk's car was junked. For some reason the engine developed a severe rear main seal leak at 40K miles. Dad pulled the engine and had it rebuilt by a local machine shop. When he reinstalled the engine he got aggravated with trying to get it to run correctly. I was at the age where I was getting interested in cars. My auto shop buddies and I finished installing the engine, and I learned how to tune a tri-power. The car ran like a clock for the next few years, but was beginning to rust out. Than the rear main seal failed again. The car had 120K miles on it at that time. We discussed restoring it, but ended up stashing in our hay barn for later. A couple of years later, more rust, some mouse damage, and the car went to the wrecking yard. It was crushed a year later. I imagine that most of those cars had a similar end.


I have a 66 Bonneville convertible, I bought this car from a guy who raced it.He took his motor out & I put the original 389 back in after I had it Bored out & done up. I too have a Tripower system which I haven't put on yet (breaking in the engine first) along with alluminum radiator & a bunch of other goodies like a March pulley system. I was able to buy a set of original bucket seats & center Console from Ebay along with matching door panels. The car runs strong! This car been a project for 9 years+ & its still a project. Point is; You can always find one & build it to your liking, but it will cost you time & money & a lot of searching, but it all pays off when your driving down the street tearing up the pavement.


Here's a pic of the interior


Top Down

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Our family car in 1968 was a 1964 Pontiac Bonneville 2 door HT. White with black interior, and an automatic. Under the hood was a 421 3x2. My Dad had a mechanic take the linkage off the front and rear carb so me and my brother wouldn't kill ourselves. I remember it had 421 emblems down on the front fender rockers. Seems to me they had a checkered flag behind the 421. The frame rusted out because of salt on the roads. The local Pontiac mechanic got word we were junking it and asked to buy the motor. Dad sold him the whole car for $200.00. I later saw the car crushed on a transport trailer heading for Pittsburgh. Tried to track down the motor years later with no luck. So, I can absolutely say there were 1964 factory Bonneville 421's with three deuces.


In 1966 Pontiac built 42,004 two door Bonneville's 2622 --- 421 Engines with tri-power were built in 1966 547 WH Engines 356 HP 4 speed Manual 984 YJ Engines 356 HP auto trans 9 YM Engines 376 HP auto trans 562 WJ Engines 376 HP 4 Speed manual 520 Yk Engines 376 HP auto trans I have a 1966 Bonneville 2 door. WH engine no a/c, no elect windows, bench seat. It has power steering I want to remove and go to Manual. Can't find a pitman arm! That's It Dick Malmgren

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Dick Malmgren, I have a Manual gearbox & pitman arm that I took off my Bonneville.

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Gvie me a call about steering gear and arm 360 593 9642 Tks DM


anybody know where I can find a posi rear end for a 1966 Pontiac Bonneville. three sevens or higher Tks Grooon

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I know of a couple complete 66 Grand Prix's one has an automatic with posi the other is a four speed car so it probably is a posi car also but these cars are complete and not for parts.


Attention if you are following this 421 string; I have located a complete original 421 HO YK 66 Grand Prix (auto car mentioned above). Car is rusty rusty but has Window sticker! Options are complete except wood wheel and maybe a Kleenex box lol! $2000.00 in options (price of a 6-cyl 66 Nova!) Strato Bench column shift Auto 421 GP. YK Engine runs appears to have all three original carbs and long exhaust manifolds! Numbers match NC car - expensive price and expensive restoration needed - but original paint and no major accident evidence. Has 421 badges on rocker trim like the 66 Bonnie. Maroon with Black. Please reply for details if you are / or know a buyer. Also sharing details for historical / research purposes too. Thanks

Hi I just brought a 66 bonneville with 389 gold on gold been a mopar man forever but love these cars.


Hello Mopar 66- Sounds like you got a nice Pontiac! I am pretty sure I love the 66 Pontiacs because when I was just a little kid our family car was a 1966 Bonneville Wagon with 8 lug wheels!!

My parents had a 66 9 passanger wagon with 421 with tri power and dual exhaust. The linkage was set to run on just the middle carb when he bought the car. I changed it so all of them worked. It wasn't much out of the hole. But from a 20 mph kick down it would smoke the plycrons even when shifting into second. Made a believer out of a 340 4 speed Swinger. Then you tell them it's stock. Finally broke an axle and dad sold the car. Wish I could find another one.


That is awesome! Not the car sold part but as we know time goes on. We had a 66 Bonneville wagon with 8 lugs too! Not a 421 or anything. But I recently found a 66 gp for sale with a ton of options. I helped sell the car - wish I could have bought it myself. 421 HO with auto on the column!

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