[Zooguy]

I picked up a 1966 Pontiac Star Chief executive I believe it has a 389 with a two barrel carburetor I'm asking people on Facebook but I get a wide variety of answers and I'm not sure I can trust it so I'm asking here if I could get a little bit of help identifying exactly what engine I have. And if it's going to be usable for the build I want to accomplish with the car.

I would like to know:
Cubic inches
Compression ratio
Crankshaft Main diameter
Rotating assembly materials

This car is going to wind up getting a 8-71 Roots blower hanging out of the hood but before I stack it on top of this Pontiac motor I need to know if it will be able to handle a little bit of boost or if I need to assemble this 454 Big block Chevy I have in the garage.

I'm not trying to build a huge horsepower cuz this is just going to be a fun cruiser but having this information will help me decide which power plant I'm going with.

[quick67bird]

http://www.wallaceracing.com/boresizes.htm

Lots of other great information on that site.

[Stuart]

From the Wallace Racing site: a 1966 YD code engine is a 389, rated at 290hp, with 10.5:1 compression.
A 389 has 3.75" stroke, 3" main bearings, 2.25" rod bearings.

[Dragncar]

That block will not do for a roots blower build IMO. 1966 389s had overheating problems due to this cyl walls. Its the reason 67 400s have thick cylinder walls.
But please, find another 400-455 PONTIAC block. Keep a BBC out of that thing.

[25stevem]

389 blocks do not have thin cylinder walls!

There the same basic block as a 421 which is bored .030” over from the 389.

If your not looking for a big power increase then why are you dropping a 8-71 blower on it when a 6-71 will serve you better because it’s shorter which makes fitting the Dizzy back there easier and it’s lighter also.

I first ran a .030” over 389 when I got the 6-71 blower and I had no overheating, nor hot running issues with it .
My 70 had no A/C and already was fitted with a 4 row radiator when I got it.

On my 70 with only a 6-71 I had to install load leveler
Shocks in the front to get the ride height up to close to normal even though I had 15” tires on the front of the car.

I found that the 6-71 and the two carbs added 90 lbs to the nose of the car.

I hate to say it, but unless your ok with spending like 5 to 6K to build up the 389 to handle even just 8 psi of boost then your better off using the BBC in your B body car.

[Dragncar]

Originally Posted by 25stevem

389 blocks do not have thin cylinder walls!

There the same basic block as a 421 which is bored .030” over from the 389.

If your not looking for a big power increase then why are you dropping a 8-71 blower on it when a 6-71 will serve you better because it’s shorter which makes fitting the Dizzy back there easier and it’s lighter also.

I first ran a .030” over 389 when I got the 6-71 blower and I had no overheating, nor hot running issues with it .
My 70 had no A/C and already was fitted with a 4 row radiator when I got it.

On my 70 with only a 6-71 I had to install load leveler
Shocks in the front to get the ride height up to close to normal even though I had 15” tires on the front of the car.

I found that the 6-71 and the two carbs added 90 lbs to the nose of the car.

I hate to say it, but unless your ok with spending like 5 to 6K to build up the 389 to handle even just 8 psi of boost then your better off using the BBC in your B body car.

The 66 blocks were in fact thin. I got that from Dan Whitmore. He was a dealership mechanic back then and did a lot of work on the comebacks. The next year was the first year of the 400 and those blocks had extra thick cylinder walls. He did sonic tests on both to confirm it.
I grew up with a 66 Catalina station wagon. It finally died, from a cracked cylinder wall.
Bite your tong on that BBC stuff. he can do it, if he wants to ruin the car.

[25stevem]

In terms of if a B body and the original engine it came with , I offer this.
The 326 motor never came in a B body car, it was a 389 or you could order the 421.

If you ordered the 421 it had body emblems that said so.

[Zooguy]

I'm wanting to build a cruiser. So I want to make just enough boost to overcome the parasitic losses of the blower. The reason I want to do an 8-71 is because I believe I can reach the boost level needed to overcome the parasitic loss at a slower speed with the bigger blower which would in turn create less heat.

Getting close so it sounds like I might be better off just putting this big block Chevy in the car. It's already low compression and strong enough stock parts to handle a blower.

.... As far as ruining the car lol ... It's a good thing it's mine and not yours. Next year it getting back-halfed next February to fit some 31"-18.5" tires ...