# 1966 389 rebuild advice



## DanMinninger (May 24, 2017)

Looking for some insight on rebuilding the 389 in my 66 GTO. The car is not numbers matching, but has a "period correct" 389 with 093 heads and tripower. Most of the projects in and around the car are done and I have turned my sights to the engine. Because it isn't numbers matching, I have no problems modifying the engine.
Right now I am leaning toward a forged crank, .30 overbore and a longer stroke. Most likely a 4.250. Both the .30 over and 4.250 will leave some room for another rebuild in the future. The car isn't a "trailer queen". I drive it and enjoy it when I do. I don't intent to ever race the car, but I like to leave some rubber behind at the occasional stop light or parking lot.
I need to keep the compression low for pump gas. 93 is what I usually run.
What are your opinions on the top half of the engine? I want to keep the tripower set up. Aluminum heads are expensive. Can I get some performance out of the 093 heads or should I just bite the bullet and replace them? Edelbrock or KRE?
What about cam and lifters? Most people seem to lean towards hydraulic roller.
Butler Performance is just over an hour away from me. Other than that, I can't seem to find anyone who has much experience with Pontiac engines in Southeast Tennessee. That bothers me because I love this car and.
Bottom line, I want a strong, reliable Pontiac engine in this GTO. When I open the hood I want it to look like a 66, but when I stomp on the gas I want more than the factory 360hp. Does that make sense? What combinations have you guys had good luck with?
Thanks for the input. Here is the current set up.


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## bigD (Jul 21, 2016)

"...When I open the hood I want it to look like a 66, but when I stomp on the gas I want more than the factory 360hp..."


Well, you'll have to decide exactly how much you want it to look like a '66. 

A stroker assembly & performance cam will not show when you open the hood. Outer changes will.


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## 1968gto421 (Mar 28, 2014)

Your best bet for the stroker kit is Butler Peformance, great quality-good price. True aluminum heads are pricey, best bet is to have your 093's ported and then a good valve job. Best known porter is SD Performance ( SD Performance- Pontiac Performance Specialists ). Butler does porting (https://butlerperformance.com/c-1234782-cylinder-heads-pontiac-cast-iron-cylinder-heads.html ) and guys on the PY forum recommend Marty Warden in Waxhaw, NC (704-624-3267 Warden Porting & Flow Testing).

Noted camshaft designer Harold Brookshire designed the UltraDyne and Bullet cams as well as the Lunati Voodoo cams (which are gentler on valve seats). Paul Cater, noted Pontiac engine builder Paul Carter (520-409-7236) highly recommends the Voodoo cams available in both hyd flat tappet and hyd roller. He is great to talk with and possibly can also do porting.

Here are the Lunati sites for both Flat Tappet and Hyd Roller cams:

Voodoo - Hydraulic Flat Tappet - Lunati Power

Voodoo - Hydraulic Roller - Lunati Power . Clicking on the cam will give you a description and specs on duration and lift.

I think your current tri-power will suffice fine for what you're planning.


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## DanMinninger (May 24, 2017)

Thanks for the replies. You're right about the aluminum heads being pricey. Especially since Pontiac options seem to be limited. Porting the heads and matching them to the intake seem like an economical alternative. When I say that I want it to look like a 66 I mean, tripower, chrome valve covers and Pontiac Blue metallic paint. Not exactly stock, but something you might see in the late 60's early 70's.
I will check with some of these guys about porting and valve options. Also, thanks for the Lunati Voodoo links.


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## VETKLLR (Nov 16, 2011)

Hey Dan, what did you end up doing? I am curious as I am in search of the exact same thing you wanted. A factory looking, dependable, HP machine that runs on pump gas and has decent street manners. When you pull up to cruise night, everyone knows, that does not sound stock. When leaving, it can unload the front suspension quicker than you can say 'Holy Shnikies'! Yeah, I know what you want, and so do I. I am also curious, did you stick with the headers or did you run some High Perf manifolds?


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