1966 GTO Convertible - Engine plan - Pontiac GTO Forum
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post #1 of 8 (permalink) Old 10-21-2013, 07:05 PM Thread Starter
 
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1966 GTO Convertible - Engine plan

I am new and need your counsel and advice. I have a 1966 GTO Convertible (see attached) which I love. The car is all original (save for the color change in 90's to Red) and numbers matching. The GTO has the original 389 4bbl (head and block casting all match) and a 3speed Heavy Duty Transmission. In fact, the PHS build documents show the car is in same spec as when built -except for the color change.

As the engine is original high compression 389, running on pump gas is less then ideal - these were designed to run 100+ octane. So here is the question. The engine is running fine, but starting to show wear - Should I:
1. Rebuild - have the engine rebuilt by reputable Pontiac engine builder. I can retain the same heads and change the pistons which would make it street pump friendly and retain all the originality. The GTO is not a tri-Power/4speed, but original and unmolested.

2. Rebuild original engine and upgrade to tri-power/4 speed. Would be fun/fast, but not original. Does this matter to anyone else but me?

3. Put original engine in storage and install new crate engine? This has been suggested by several friends, but I'm not sure.

Sure the car is not the optimal build (tri-power/4speed), but the 4bbl and 3speed HD trans are original and offer lots of fun to drive.

Thanks - I appreciate the advice.
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post #2 of 8 (permalink) Old 10-22-2013, 09:28 AM
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Not too many 3 speed GTOs out there, I might be inclined to keep it.
As far as the engine goes, as long as you keep the original parts (for resale down the road), do what you want.
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post #3 of 8 (permalink) Old 10-22-2013, 01:26 PM Thread Starter
 
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Thanks. The 3Speed is a heavy duty Dearborn M13 on floor Console. Rare - not sure that means more value, but unique. Love your '65. Beautiful.
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post #4 of 8 (permalink) Old 10-22-2013, 04:54 PM
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100% original is best for resale value, if you care about that at all. In the mean time, go as crazy as your taste and budget will allow.

If you want to stay with the 389, have it streetable on pump gas, then option 1 is great (I'd also add a good set of forged rods). It preserves the original appearance but makes the car drivable.


If you've got the funds and the inclination, and want to step up (perhaps significantly) in power, then a plug and play crate motor is a good solution. For me, the top two builders in the country are 1) Jim Lehart at Central Virginia Machine and 2) Butler Performance (in that order).

If you've got the skills and the inclination, it's also fun to roll your own starting with a good 400 block and turning it into a 461 stroker.

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post #5 of 8 (permalink) Old 10-22-2013, 06:40 PM
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Helped a friend do exactly what you're thinking. Put a set of Ross dished pistons in the 389, ran a Comp Cams XE268 cam, and a 4bbl. The car screams and runs on 87-89 octane. Win-win. It was a cheap build and has held up for the past 5 years/10,000 miles without a whimper. And, it's the original stuff. Dearborn 3 speed: a LOT of GTO's had this trans when new. It's actually stronger than the 4 speed Muncie. With the torque of a Pontiac, a 4 speed is really not needed, except for the bragging rights. You can shelve the 3 speed and bolt the 4 speed right in, without doing any mods worth worrying about. It's done all the time. What was the original color of your car??
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post #6 of 8 (permalink) Old 10-26-2013, 01:10 PM Thread Starter
 
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Original color was Blue Charcoal. Now Montero Red.
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post #7 of 8 (permalink) Old 10-26-2013, 03:01 PM
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Aaaaaaaccccckkkkkk!!!!!
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post #8 of 8 (permalink) Old 10-27-2013, 03:57 PM
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Quote:
Originally Posted by richde View Post
Original color was Blue Charcoal. Now Montero Red.
Car is beautiful but must have been a stunner in Blue Charcoal. Love the big inch Cragars too!

As for the trans I say put in a Tremec TKO 500 and put your 3 spd knob on the stick. No one will know unless they climb under the car or hear you shift 4 times .
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