I've owned my Riv for 9, soon to be 10 years.
I had the 425 rebuilt to specs, new int, new headliner, exhaust, brakes.
In summer I drive it often.
Back in 66, many cars were built to run on hi tech, you have to know what your car was built to run off. I found out the hard way by racing a new Trans Am; blew an piston from using regular gas.
Now she's rebuilt 425 nail head duals, she's HOTT, I'm in parades often. She gets her due, they don't make em like that anymore, so be easy with her, she'll give you all you need and some.
I love mine more than words can say. I have an 60 Olds 371, 65 Cat 389 conv, nothing beats that RIVIERA 425, THAT MY HONEY.
PEACE, HAPPY HOLIDAYS TO ALL, regardless of the car.
Just happen to come across this site again after a year, and I'm still very proud of my 1966 Riv. Yes, GM did the best for their classic cars. Today you can't find that type of craftsmanship. I've rebuilt the entire car, just changed the color to medal flake blue. It doesn't matter sun light or not; she shines better than the new ones. If you're ever in AK, you'll see her, she's known as DBL SIX. She's bad to da bone.
I bought a 66 Riv 4 years ago, and have not even heard it run yet (having children - twins - can slow a project down).
Anyway, reading these posts makes me dream of the one day I'll hear that nailhead roar. It's rebuilt and in place, just need to rebuild the carb, paint and tires. $$$$$ positive that it'll run this summer, and need new tires by fall.
My Buick loving friend... (I am one myself, also recently acquiring a 66) it would be in your best interest to immediately join the ROA... Rivieras Owners Association. I am the Regional Coordinator for the State of KY. You will find a wealth of info and people that specialize in every area of expertise involving your 66. My phone number is 270-779-1641 if you ever need anything. Just google ROA and you can go from there. Thanks, Andy.