[Dragncar]

Originally Posted by geeteeohguy

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.

[carbking]

Originally Posted by hurryinhoosier62

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!

Jon.

[SRR]

Originally Posted by b-man

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.

[goatwgn]

Originally Posted by b-man

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.

I agree, wholeheartedly on this approach. Literally, the best combination for your car would be a 9.0 to 1 compression 455, with an 068 cam, 1968-71 Q jet intake and carb, HEI ignition, cast iron manifolds, TH400 with a 3.08 rear end. Build, close the hood, pile on the miles.

[David Jones]

Call Len Williams for a mild 455.

[Ponchy]

Originally Posted by Tomaso

Hi Guys,
Newbie here. As my first post I mentioned I had just purchased a 66 Pontiac Bonneville. It currently has a 389. I would like a beefier engine. What would be the best route to take? I heard some 389s were good motors.
Should I:

Keep the 389 and get a stroker kit?
Or aim for a 400/455 with a stroker kit?


Mike

No replacement for displacement....but I would go with a newer big journal motor, rather than stroking out an older, smaller engine.
You not only benefit from having a lot of the work already done for you, when you get the motor, you also benefit from newer technology. Lessons learned since your current engine was designed/built.
My vote: 455.

Ponchy

[77 TRASHCAN]

Does the original/current engine run? Run well or well enough to drive?

My advice, from personal experience, is to never completely disable a vehicle, unless it’s in need.
A driver 389 is a good engine, but search out a 455 like mentioned above. Like post 44

[Tomaso]

Originally Posted by 77 TRASHCAN

Does the original/current engine run? Run well or well enough to drive?

My advice, from personal experience, is to never completely disable a vehicle, unless it’s in need.
A driver 389 is a good engine, but search out a 455 like mentioned above.

I don’t know what to do now?
The 389 does run, but needs tune up, oil change, etc. But runs good... and sounds good (better when I get headers and dual exhaust).
But I would really like the torque...

Butler said it’s doable with a 389 to get the torque I want with the stroker kit and heads I was looking at?

But majority on here I still saying go for the 455...

[b-man]

Drive and enjoy the current 389, tune it up and do the basic maintenance.

Any exhaust system components you purchase will transfer directly to your new, more powerful 455 engine. A good free flowing 2.5” dual exhaust is all you need, headers are optional and are often more trouble than they’re worth.

Keep the 389 around as a spare after you install your new engine, that is if you have a decent place to store it. It’s always nice to be able to drive your classic while getting another power plant put together, that way you don’t lose interest and can still have fun with your car.

Keep it simple and let the cubic inches do the work, a completely stock 455 with a mild camshaft upgrade makes for a trouble-free reliable engine with enough grunt to propel your big Pontiac into the low-14s or high-13s in the 1/4 mile. The 455 really doesn’t care which rear end gears are behind it, tall highway gears work fine when backed by a torque monster 455.

[goatman1970]

If you want to spend a few bucks and make some unreal power, contact Don Johnston at DCI Motorsports in Akron, OH. His aluminum Ram Air V heads can be had for $3500 (bare) - $5000 (assembled), you'll need his headers and intake as well:
https://www.dcimotorsports.com/produ...ir-five-heads/

The minimum power you'll get with his RAV heads on a 455, naturally-aspirated on pump gas, is 650HP, that's un-ported as-cast 380 CFM per head (for comparison, Edlebrock's aluminum D-ports flow 260 CFM as-cast). He has available options for much more (800HP+). But as others have said, when you get into this power range, the whole drive train should be upgraded to handle that power: transmission, driveshaft, rear end.

[Stuart]

Some of you guys are a little over the top...remember this is a 1966 Bonneville street cruiser, not some all out race car.

[carbking]

Originally Posted by Stuart

Some of you guys are a little over the top...remember this is a 1966 Bonneville street cruiser, not some all out race car.

X2 on this.

Since you state the 389 runs, and runs well; why not do the tune-up, and drive and enjoy the car for six months. During this time you can determine if you NEED more torque, or if you are happy with the way the car drives. During this time you can do a cost study on the costs of replacing the 389 with a 455 (and replacing the automatic transmission that the 455 may destroy); as well as look for bargains on these parts.

When you do a conversion such as this, there are always issues you didn't think of, and no one mentioned. As an example, when I put long branch factory headers on a 1974 GTO, I found they would not clear the steering box; even though two well-meaning friends had assured me they had done the same thing. Turns out I had power steering and they didn't. The manual steering box was easy, but it required a different drop link, which took a year and a half and $180. to find.

It just might be that you will be happy with the existing engine, and thereby save several thousand dollars. And possibly some headaches!

Jon.

[Ponchy]

Tomaso,

Listen to b-man.
He speaks the truth.
Headers are a money pit. New exhaust PIPES and muffler with the cast manifolds will do you just fine.
Build your heavyweight Bonneville as a slick street cruiser and let the big engine speak when you need it to.
4-bbl., dual exhaust, HEI...maybe 1.65 rockers. It would do that setup just fine.
If you can get the 455 now, make the change.
If you have to search one out, do the maintenance on the 389 and drive it until you can locate a suitable 455....and who knows, maybe by that time, you'll find you're actually quite happy with the 389 as is (like carbking said).
Either way, you got a nice ride. Enjoy it. -b

Ponchy

[Tomaso]

Originally Posted by Ponchy

Tomaso,

Listen to b-man.
He speaks the truth.
Headers are a money pit. New exhaust PIPES and muffler with the cast manifolds will do you just fine.
Build your heavyweight Bonneville as a slick street cruiser and let the big engine speak when you need it to.
4-bbl., dual exhaust, HEI...maybe 1.65 rockers. It would do that setup just fine.
If you can get the 455 now, make the change.
If you have to search one out, do the maintenance on the 389 and drive it until you can locate a suitable 455....and who knows, maybe by that time, you'll find you're actually quite happy with the 389 as is (like carbking said).
Either way, you got a nice ride. Enjoy it. -b

Ponchy

Thanks guys! I added the links given to my favourites for future use.
My mechanic just called, and said the car needs brake lines, and fuel lines, and for engine just needs an oil change, filter, and spark plugs...
I will just get dual exhaust for now, and drive it the way it is until I can source a 455. But won’t be in a big rush for it...

Thanks!

[carbking]

Enjoy!

Jon

[b-man]

Link to a mild 455 I used as a daily driver some years back, it always started with a flick of the key and never left me stranded.

https://forums.maxperformanceinc.com...22&postcount=4

The Tri-Power setup and HO exhaust manifolds could have been replaced with a much less expensive common iron Quadrajet intake and carb along with standard log exhaust manifolds with little to no performance loss.

[hurryinhoosier62]

Originally Posted by Dragncar

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.

Huh? Studebaker had a 289 as well as Ford, but I’m aware of only one 389.

[Ponchy]

AMC did have a 390. Could be an older six cylinder engines, too.
Some of those old hulks got pretty big.
GMC had an inline 6 that displaced 503 cu.in., so if he's looking at the brown Motor's Manual, which would be for commercial vehicles, then it could be that's what he's remembering.

----------------------------------------

b-man,

Looks like a winning combination.
Dead simple, stone reliable, and it still made power.....Pontiac Power! =)

[64speed]

My car had to come apart because of body and frame damage but if it wasn’t for that I would still be cruising my little 326 2 barrel and having a grand old time. My cars been torn down 2 1/2 years now. I am making good progress on my limited budget but I wish I could drive it. My freshen up turned into a frame off

[carbking]

Originally Posted by hurryinhoosier62

Huh? Studebaker had a 289 as well as Ford, but I’m aware of only one 389.

The 1916 Pilot model 55 had a 389 CID engine, and used a Zenith carburetor

Jon