#1  
Old 06-06-2022, 08:58 PM
Zooguy Zooguy is offline
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Default Roots blown 66 Star Chief

All right so I have a 1966 Pontiac Star Chief executive that will be getting a Roots blower. This is not going to be a race car it is just going to be a fun spirited cruiser. Being that it will see lots of Miles I'm assuming bigger is better so I'm looking for an 871 Roots blower to go on the vehicle so I don't have to spin it as fast as a 671 to get the desired boost levels. I'm wanting to create just enough boost to overcome the parasitic losses from the blower. Again this is a cruiser not a race car!!!

So here's where I need some help it would be easiest to use the motor that's already in the car it has a 389 with a two barrel carburetor. However I'm learning not all 389s were created equal. I could be mistaken but I've been told my motor has 10.5 to 1 compression which isn't ideal for boosted applications but if I keep good fuel in it I'm sure it would be okay.

I would prefer to use the 389 because it's already in the car. I also have a mark 4 big block Chevy torn apart in the garage that would be perfect for a boosted application. But that would make a lot more work to keep power steering air conditioning etc.
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  #2  
Old 06-06-2022, 09:00 PM
Zooguy Zooguy is offline
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My history is with nitrous racing builds but I'm wanting to do a family cruise right now it'll be my first boosted application I'm just looking for some advice on if this motor would be a good fit or if I should put the big box Chevy under the hood.

  #3  
Old 06-08-2022, 11:02 PM
Scott Roberts Scott Roberts is offline
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Quote:
Originally Posted by Zooguy View Post
All right so I have a 1966 Pontiac Star Chief executive that will be getting a Roots blower. This is not going to be a race car it is just going to be a fun spirited cruiser. Being that it will see lots of Miles I'm assuming bigger is better so I'm looking for an 871 Roots blower to go on the vehicle so I don't have to spin it as fast as a 671 to get the desired boost levels. I'm wanting to create just enough boost to overcome the parasitic losses from the blower. Again this is a cruiser not a race car!!!

So here's where I need some help it would be easiest to use the motor that's already in the car it has a 389 with a two barrel carburetor. However I'm learning not all 389s were created equal. I could be mistaken but I've been told my motor has 10.5 to 1 compression which isn't ideal for boosted applications but if I keep good fuel in it I'm sure it would be okay.

I would prefer to use the 389 because it's already in the car. I also have a mark 4 big block Chevy torn apart in the garage that would be perfect for a boosted application. But that would make a lot more work to keep power steering air conditioning etc.
Are u just trying to strap a blower to the engine u have with no work or are u planing on going through it to make it blower ready?

  #4  
Old 06-08-2022, 11:57 PM
Zooguy Zooguy is offline
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I'm still learning about the 389 and Pontiac motors in general. I've been building Chevy engines for a long time so this is the completely new platform with lots of similarities. I would probably put a different camshaft in it upgrade to some hydraulic roller lifters. I haven't done very much research into the different cylinder head options available out there. But if there's another stock cylinder head I could put on to mine that would lower the compression ratio I'm sure that would help me out. I don't really want to dig into the short block changing out piston rods to a shorter option and or pistons ... If I'm going to do that much work I might as well do it to the 454 big block Chevy I already have torn apart.

So the short answer is yes I want to just drop a blower onto the 389 ... but I know the motor won't last very long at all if I were to do that.

So I'm trying to learn all the different options I have out there to see if I can make it live without having to do a complete rebuild and overhaul of the motor.

  #5  
Old 06-09-2022, 10:07 AM
rustedgoat rustedgoat is offline
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You can easily lower the compression by swapping heads. But rest of the engine still has to be good shape.

Being that your going to be running very low boost not sure how important these are
timing controller
capable fuel system
free flowing exhaust

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  #6  
Old 06-10-2022, 08:43 AM
mgarblik mgarblik is offline
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Your opening post pretty well spells out your options. To be brief, IMO, there is no really easy way to take a 389 2BBL engine and plop a 8-71 blower on it and have a pump gas ready, reliable engine. On the other hand, fitting a BBC under the hood of a 66 full size Pontiac and having everything bolt up properly with AC and all the Pontiac accessories will be a challenge as well. Everything is just totally different. Don't know if it has any meaning to you or not, but your car with a BBC, will be almost completely ignored and shunned by the Pontiac faithful. Same as putting a Ford V-8 under the hood. One alternative you did not mention, was to possibly buy or trade for a 71 -74 400 Pontiac V-8 or a 71-76 Pontiac 455. That platform would give you low compression iron heads, compatible with the crap fuel we have and everything would bolt up and be OK for low boost application. A 66 389, even a 2bbl, may have some value to the owner of Tempest or full size from that era for a restoration. Something to think about. I just sold a 455 minus intake which would have been perfect for you with forged pistons for $1500.00. So that's about the typical cost here in the midwest. Good luck.

  #7  
Old 06-10-2022, 12:06 PM
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b-man b-man is offline
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The ‘66 389 is far from an ideal platform for a blown street cruiser.

Thin bores which are a known issue with the 1966 block castings and heads with press in studs and small high compression combustion chambers are not the best way to start out.

I think you’re underestimating the difficulty of making the accessory drives work with the blower drive belt setup, packaging everything in front of the engine and behind the radiator is not a slam dunk.

For the cost of just an 8-71 blower and everything needed to make it work on any Pontiac engine you could build a nice 400-based stroker or 455 with a much easier to manage and tune 4-barrel carb and have an easy 450 to 500 horsepower.

If you’re wanting to build a reliable street blower engine be prepared to crack open your wallet to the tune of 10 to 15 grand, and quite likely more than that. A nice naturally-aspirated Pontiac engine built off of a much more solid pre-‘75 400 or any year 455 instead of a 389 will be around half of that.

Learn more about Pontiac engines and make a solid plan before diving in, it’s not a simple thing to put a roots blower on a V8 of any kind and expect to drive it anywhere and everywhere.

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  #8  
Old 06-11-2022, 12:04 AM
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b-man b-man is offline
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Some interesting reading in this thread regarding the ‘66 389 blocks:

https://forums.maxperformanceinc.com...89#post5761716

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  #9  
Old 06-11-2022, 12:08 AM
Zooguy Zooguy is offline
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Quote:
Originally Posted by b-man View Post
The ‘66 389 is far from an ideal platform for a blown street cruiser.

Thin bores which are a known issue with the 1966 block castings and heads with press in studs and small high compression combustion chambers are not the best way to start out.

I think you’re underestimating the difficulty of making the accessory drives work with the blower drive belt setup, packaging everything in front of the engine and behind the radiator is not a slam dunk.

For the cost of just an 8-71 blower and everything needed to make it work on any Pontiac engine you could build a nice 400-based stroker or 455 with a much easier to manage and tune 4-barrel carb and have an easy 450 to 500 horsepower.

If you’re wanting to build a reliable street blower engine be prepared to crack open your wallet to the tune of 10 to 15 grand, and quite likely more than that. A nice naturally-aspirated Pontiac engine built off of a much more solid pre-‘75 400 or any year 455 instead of a 389 will be around half of that.

Learn more about Pontiac engines and make a solid plan before diving in, it’s not a simple thing to put a roots blower on a V8 of any kind and expect to drive it anywhere and everywhere.
... So would all of my accessories bolt up to a 400 or 455?

  #10  
Old 06-11-2022, 12:15 AM
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Pulley alignment would be an issue, the crankshaft balancers changed in 1968 pushing the bottom pulley forward.

Unfortunately throughout the years the accessory drives were redesigned a few times, you can mix and match some of the parts but it’s kind of a trial and error thing.

The best way would be to use the accessories off of the later 400 or 455.

No matter what adding a roots blower belt drive into the mix is going to be far from a bolt in deal, I really wouldn’t expect everything being kept in the stock location when it comes to the power steering, A/C compressor and alternator. You’ll have to get the blower drive in place first and work around it.

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