NEED HELP, 78 Trans AM

I Have a 78 trans am, with a 455 motor in it, I have a th-350 trans, and a aftermarket 600 cfm edelbrock carb, my problem is my brake pedal wont go down all the way like it use to, (i think It may be the booster/master cyclinder) and in addition my trans is messed up, like when the car is cold it will shift as normal but within 5 minutes when it gets to 180 degrees, it wont get out of first and it over revs, Could all this have to do with a vacuum leak or what?

I Have a 78 trans am, with a 455 motor in it, I have a th-350 trans, and a aftermarket 600 cfm edelbrock carb, my problem is my brake pedal wont go down all the way like it use to, (i think It may be the booster/master cyclinder) and in addition my trans is messed up, like when the car is cold it will shift as normal but within 5 minutes when it gets to 180 degrees, it wont get out of first and it over revs, Could all this have to do with a vacuum leak or what?


you have mor than one problem first of all the 600 cfm carb is WAY to small for a 455, secondly a TH350 was never used behind a 455 because it won't be able to handle the torque. A Th400 was used from the factory behind those engines. Your tranny might already be a goner....as a matter of fact, it sounds like it is gone.

dont go throw that tranny away just yet, might just need a filter n new fluid, but thats a maybee, also check your radiator as the tranny fluild is cooled some what throuh the bottom of it, heat is bad on a tranny
as for the carb does it run good like it is now, if so leave it, a bigger carb can mean black smoke out the tailpipe
vaccum is used in the braking system and comes from the brake booster to the back of the carb, and big cam can cause vac loss that shows in the brakes

what you got is probsably fine just needs a lil work to maintain dont let someone crash your car
before they think, and say a buncha bull

dont go throw that tranny away just yet, might just need a filter n new fluid, but thats a maybee, also check your radiator as the tranny fluild is cooled some what throuh the bottom of it, heat is bad on a tranny
as for the carb does it run good like it is now, if so leave it, a bigger carb can mean black smoke out the tailpipe
vaccum is used in the braking system and comes from the brake booster to the back of the carb, and big cam can cause vac loss that shows in the brakes

what you got is probsably fine just needs a lil work to maintain dont let someone crash your car
before they think, and say a buncha bull



miamivice87 this person is obviously talking about himself, and as usual out of his behind. just a guy with an attitude problem that continously brings in bad behaviour into this forum and doesn't know jack about cars. go check original pontiac literature and you will find out what i say is the truth, as a matter of fact you can check everywhere and find that out. a bigger carb than yours gets black smoke out of the exhaust, never heard such a crap in my life. go and check what sat on top of a 455 and it wasn't a 600 cfm carb, I can assure you that. And as far as your trans is concerned. Sometimes one knocks off the vacuum hose at the distributor where the vacuum hose from the trans joins. If that has come off your tranny would do what you are saying. If everything is attached you will most likely need a tranny rebuild. And I can assure you that changing the fluid won't fix the problem. And if Pontiac thought a TH350 would work behind a 455 they would have delivered cars with that combo but they did not. The Th350 weighs less has a better ratio in terms of powerloss than the TH400 but it will not withstand the torque of a 455.

all im trying to do volkswreck is make sure you dont railroad this guy into wasting alot of extra money, the carb may be to small in some cases
but if it runs good at all how can you just say that
is it a pro dragster?
again it sounds alot like a rather large cam
ill even go so far to apologize for whatever i did to knot your pampers ok

all im trying to do volkswreck is make sure you dont railroad this guy into wasting alot of extra money, the carb may be to small in some cases
but if it runs good at all how can you just say that
is it a pro dragster?
again it sounds alot like a rather large cam
ill even go so far to apologize for whatever i did to knot your pampers ok


you always come up with the same arguments to big a cam, and vacuum. you do not even know the specs of the cams people are running. and no i do not assume he drives a pro dragster cause then he would need way more than the recommended 800 cfm carb, but certainly not a 600.and you can't fix broken trannys with a fluid change. you can't even adjust the band on a TH350 from the outside. If the vacuum line is still connected than he has a serious problem. and I do not advice people to do a messy fluid change if there is no use for it.waste the guys money and time on that...
how'd you feel somebody gives you that advice, you are soaked in tranny fluid and your car still won't work?

For the love of god, can't we all just get along. We have the same excellent taste in cars. Can't we share a mutual respect for each other?. Let this little scuffle die cause I don't wanna have to lock this thread. Thanks

John