1973 Pontiac Grand Prix

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Hey all, this is my 1st post!

My friend has '73 Pontiac Grand Prix with the 400 V8. I am basically a noob when it comes to carbuerated vehicles so please be gentle with the responses. He's looking to get some performance out of the vehicle. He needs a carbuerator since the one he has is pretty gunked up and he just wants a better performing carb. He doesn't want to do anything to the block (i.e. pistons,cams,head work or anything thing like that). But I figured that the bolt on items such as intake/exhaust manifolds, carb and whatever else. But basically what bolt-on items would be good for him? But more importantly, what would be the best carb to use?

posted by  Gaffney982

A carb, an intake and a nice set of headers would be good. For the carb., go with Holley. Try to get a Double Pumper. It doesnt have to be anything really high-flow, just a 650cfm or so.

Any Edelbrock intake will be good, so you shouldnt have a problem there.

When looking at a set of headers, the best choice would proabably be a set or Hooker Super-Competitions. Hedman Headers are good too.

posted by  SlipKnoT

Or, if you want better performance and better fuel mileage for less money, just go back to the original style quadrajet. They flow 780 CFM yet have smaller primary bores for partial throttle where you spend most of your time driving. Make sure the car has a good tune-up on it. If it hasn't already been converted over to HEI, do it. It's all factory parts, can be done for less than $100 and is dead simple to do. It'll also give you better driveability, better mileage and probably a little more performance. Then stop. Unless you want to open up the engine and begin spending major coin, leave it the way it is. The VIN Y 400 is a low compression smog engine that doesn't respond well to bolt ons. Better to start saving money for a 455 that's been built right.

Alternately, you could take the other advice and waste your time and money. Your choice, have fun.

posted by  vwhobo

I,m in agreement with orfice, I will reiterate how good a good q-jet can be, and these days you can get a factory rebuilt unit very reasonably, also I will add make sure your vacuum advance in the distributor is functioning, the vacuum canisters are bad for sticking due top a leaky diaphram(hope i spelled that right) and that will hold your timing back, also if make sure the power lead to your coil when using hei, has been upgraded to 12 guage wire from the fuse block, point ignitions typically have resistor wire to reduce voltage and wont adequately power an hei coil. I've seen this many times,

One last note. the rear end gears in most of these cars was very high to combat what we then thought was HIGH fuel prices, often 2:29 or 2:56 gears, these won't perform very well in such a heavy car unless your pushing like 500 lbs torque, (insert caddy engine here) I would consider a gear switch to something a little lower perhaps a 3:32 or so to help fool your car into thinking it has more power, Have FUN

posted by  bobcat7

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