68 Firebird help needed

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Luckysg14

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I have searched and asked around everywhere but a online forum and I really hope someone can offer assistance. I have a 68 Firebird with a unconfirmed T-400 tranny. The engine that came with the car turned out to be a 1970 350 engine. I have completely rebuilt the engine and everything added back on is brand new. My car starts and idles like it should be a beast but when I push on the gas I have no power! It will go and drive at a snails pace considering what is under the hood. I really need to know if anyone could suggest possible problems that I had missed.. Thanks!
 
Do you have the transmission kickdown switch on the gas pedal connected? What did you set the initial timing for? Assuming the distributor has a mechanical advance mechanism, did you check to see if it is not sticking? Do you have a vacuum advance connected? What make and model carburetor do you have?
 
Luckysg14 said:
.... I have a 68 Firebird with a unconfirmed T-400 tranny. ....
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This sentence intrigues me. What do you mean by unconfirmed? Are you unsure that it is a T-400 or are you questioning the condition of the tranny?

If you suspect the tranny is causing undue drag on the engine you can always take it to a good tranny shop for a service. They should be able to confirm what tranny it is and what condition it is in.

Of course, if this is not an issue then, nevarmind. :)
 
Melsg5 - All great questions that I will have to find out. I did some research and for sure will be checking to see if the vacuum advance is connected this weekend. Thats what I originally thought it could be. I will check the carb too but know nothing about a kick down switch.

Thanks for the article info. Being that I am 6 months pregnant I will have to try and get my husband to get under the car and help me figure it out. ;) Or figure out a way to get a picture of it.


Kelvar - I said unconfirmed because I bought the car with the whole engine unassembled and was told by the seller it was a T-400. I didn't have it checked but it looked in great shape to my untrained eye. I have had it at multiple shops for this same problem and none said there was anything wrong with the trans. Although I still assume I got ripped off because I am a girl. It operates with no problems though but having it looked at by a transmission shop could be another solution if it comes down to it.

92 Sunbird- In all gears there is no good performance.
 
if you didnt assemble and install the engine yourself why isnt the shop that did the work looking into the issue? What are the multiple shops telling you about the lack of power? If you really have a Turbo Hydramatic 400 it requires a kickdown switch mounted and adjusted correctly on the gas pedal in order to get the transmssion to downshift. It also reguires a vacuum line going to the modulator on the passenger side of the transmission.
 
melsg5 said:
if you didnt assemble and install the engine yourself why isnt the shop that did the work looking into the issue? What are the multiple shops telling you about the lack of power? If you really have a Turbo Hydramatic 400 it requires a kickdown switch mounted and adjusted correctly on the gas pedal in order to get the transmssion to downshift. It also reguires a vacuum line going to the modulator on the passenger side of the transmission.
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I installed it with help from an neighbor down the street. I will definitely look into that and do some research about my Transmission but start with verifying the vacuum. Thanks for all of your suggestions!
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Luckysg14 said:
... Although I still assume I got ripped off because I am a girl. ....
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I hate when people do this! As the proud father of three grown daughters, this makes my blood boil! :mad:

... ok, got to cool off now ...

Don't let those schmucks get the best of you and take care of that little Mini-Me you got cookin! :)
 
The vacuum advance is only for improved gas mileage when cruising it will not effect power output when you put the gas pedal to the floor. What did you set the intial timing to? Verify the transmission you have by the pan shape. Find out what carburetor you have?
 
You know, the other questions we haven't asked yet are the engine specs at time of rebuild. If you've stayed with stock specs then barring any problems during the break in period, your problems should be solved with proper tuning.

In other words, the cam should work well with the heads, intake and carburetor (unless the carb needs a rebuild). If you've installed a competition cam, it's important that the intake, carb and heads match the performance curve or you'll not be happy with the results and tuning may not make much difference.

Just a few more thoughts.
 
ok who put the 350 together? cam timing could be off one tooth.

the base timing should be set at 10* to 12* with the vacume advance hose unhooked and pluged off. with the hose hooked back up 32*to 36* total timing depending on what heads you have.

by the way what are the numbers/letters on the center exhaust port of the head? if it has the wrong heads it can hurt performance!!

good luck with both of your baby's.
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are you sure there isn't a very high stall torque converter installed?

That would kill all low rpm performance
 
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