68 firebird cabriolet

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  #1  
Old 10-04-02, 05:43 PM
hvac4u's Avatar
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68 firebird cabriolet

gonna change the motor. currently 350/350 hp double hump heads, muncie 4 speed. any suggestions? want a new motor, should i get it for local parts house?
 
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  #2  
Old 10-04-02, 06:21 PM
knuckles
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Cabriolet? Do you mean convertible?

As for the engine...You say you have 'double hump' heads, which would indicate a Chevy engine. Nothing wrong with a Chevy, but it doesn't belong in a classic Firebird IMHO. Sell your existing engine & trans and replace it with a 326/350/400/455 Pontiac engine and TH 400 trans (if automatic). Manual transmission cars can keep the trans, but a BOP bolt pattern bell housing will be needed. Lots of other small parts will need to be changed too, but you'll have something worthwhile when you're done.
 
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Old 10-05-02, 07:28 AM
Joe_F
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I agree with Knuckles and being a Pontiac person, go 400 or better. If the vehicle was originally a 400, put one back. With the right adapters, any 400 from 67 to 79 will fit.

You will pay decent bucks for a 400 Pontiac motor though, as the cores have not been made since 1978 and are pretty scarce. I know, I have 2 of 'em .

One "advantage" of Chevy power. It's as common as dog poo and cheap horsepower. Barring that, it doesn't belong in a Poncho not so originally equipped from the factory that way.

(There were Canadian Pontiacs that were Chevy products in disguise in the 60's and were Chevy powered...also the 250 straight six in some applications was a Chevy engine).

If you send your VIN # to Pontiac Historical Services (www.phs-online.com), they will tell you all you need to know about your car. You can then find out what engine it had originally and try to find a close match to that.

The value of the car has significantly dropped if the original #s matching engine is gone in such a case though. But, it will make a nice driver.
 
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Old 10-07-02, 05:48 PM
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great advice

got my hands on a 400, which is what was original. just so happens local junk yard needs a/c work, will work for free for a day, but even with materials cost, i came out like a bandit! cabriolet is what the convertibles were called that year, has new top, $1200 paint, chromed, has been at rod run in pigeon forge 3 past years.
 
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Old 10-07-02, 07:40 PM
Joe_F
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Thumbs up

Sounds like a plan. Take your time going through it all and replace all questionable parts or you'll do it twice.

Depending on the year of the 400, different adapters/mounts will be required.

High Performance Pontiac magazine did a writeup on this about 6 months ago. Order the reprint. Well worth the fee for the parts sources and information.
 
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