Old 11-08-2019, 04:41 PM
Dragncar Dragncar is offline
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Join Date: Mar 2004
Location: Humbolt County California
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Originally Posted by geeteeohguy View Post
Len Williams Engines has a good reputation for turn-key 455's at a reasonable cost. I have not used his services, but others here have. I personally would keep the 389, and would keep it smooth and stock-ish. The car is a full size luxury car, not a racer. It should have nice manners. I have run 389's, 400's, and 428's.....I like 389's because it just 'sounds' right, and is a proprietary Pontiac engines size, like 421. Good luck whatever you choose. A big, bread-and-butter 455 would be really nice in your car as well, and do it with less fuss than a smaller engine.
There is another 389, I looked it up in my dad Motors manuals where I was a kid. Don't remember the brand but I think it was a "off" brand like AMC or something.
Now 421 is, I have it as my race car number at our track.

Old 11-08-2019, 05:30 PM
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carbking carbking is offline
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Join Date: May 2000
Location: Eldon, Missouri 65026
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Originally Posted by hurryinhoosier62 View Post
On the street, you’ll be much happier with reproduction long branch cast iron manifolds from RARE. You’ll give up a little top end power but you’ll lose all the headaches of headers. It’s amazing how efficient Pontiac designed those manifold to be, and they are comparably priced to quality headers($569 a set).
Plus, you will be able to converse with the lady sitting in the front seat beside you!


"Good carburetion is fuelish hot air".

"The most expensive carburetor is the wrong one given to you by your neighbor".

If you truly believe that "one size fits all" try walking a mile in your spouse's shoes!

Owner of The Carburetor Shop, LLC (of Missouri).
Old 11-08-2019, 07:41 PM
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SRR SRR is offline
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Join Date: Sep 2005
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Originally Posted by b-man View Post
Go with the 455 for the best street engine if torque is what you’re after.

A bone stock 455 will make you smile, and will be less expensive than a hotrodded 389.

Both engines are great and have their place, but on the street cubic inches gets the job done without the need for ported heads and big cams.

Another thing to be aware of is 1966 389 blocks are not known for their strength and are also known for having very thin cylinder walls, I would avoid building a hot engine using that block.

A big Bonne needs a big engine, you won’t be sorry going with a mild 455. In later years (1969 for example) the 428 became the standard Bonneville power plant while all the other big Pontiacs came with the 400.
Big cars like 455 engines...makes them act like "A" bodies.

“Nothing in the world can take the place of persistence. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. The slogan Press On! has solved and always will solve the problems of the human race.”
― Calvin Coolidge

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