I have a 63 Catalina with a 389 roch. 2 bbl. It had the exhaust replaced in 89 by the PO and it is rusted and leaking. I'm wanting to go dual exhaust would 3in be too big? I am wanting them dumped at the rear axle and was priced 250 that seems high what do y'all think. The carb choke is not working and I think the carb needs to be rebuilt it is pretty hard to get the car to start and idle at first, it wants to die no matter how much I pump the gas. It will do that the first 2/3 times I try and start it which makes me have to work the gas pedal for a few minutes before it will idle. I have tried to adjust the idle screws and they are adjusting it a little and I have gotten it a lot better than it was but its still got a pretty good shake to it as it idles. As far as I know the engine is stock, I have a Holley 6379 I would like to put on but with all the adjustments it takes since it has a slim Jim I am hesitant to remove the old carb to even see if the Holley will work. Does anyone have experience with these old 389s and where I could find a manifold adapter for the carb if I needed one? One last question I have is the stance on the car could be improved with raising the rear a bit, I know getting the rear leafs re-arched is one way to do it but is that the easiest/best way to do it?
Car has coil springs on all 4 corners. Carb can be a little tricky as most of those trans works off of throttle pressure. Linkage has to be correct or it won't shift like it should. Shop manual would help Slim Jim not the best trans. 4 spd hydro better if you ca find one or get adapter set up from Wilcap to put later trans in.
With my wives 64 catalina i have had best result by changing jets four size bigger 64 to 68 and slightly enlarget the idle emulsion tube restrictions.It is now much smoother and more powerfull. This with original 2jet and slimjim combo. I blame todays gasoline.
2'' head & tailpipes to the rear bumper work very well on 389 Pontiacs. Under the axle will suck fumes inside the car at highway speed, plus drumming your ears numb. A factory 4 bbl intake & the AFB it came with are what you need, and will hook up to the slim jim as is - don't screw around with "adaptor" shit on Pontiacs. A nice, thorough tuneup will fix most of the ailments you describe. Always a good idea to replace the timing chain & cam gear on these engines. Why not lower it - raising that car won't do anyone any favors ... As mentioned above, the Jetaway 4 speed from a Star Chief or Bonneville is a much better setup, but unless you buy a complete parts car, piecing the parts is a hassle.
If all you are wanting to do is get it running, the Rochester 2-GC carburetor is one of the very finest 2-barrel carbs ever made. And virtually bullet-proof. Easy to rebuild, AND engineered for your engine - fix it! While you are in the carb, open up the idle tubes by 0.002 inch. And you might also open the main jets 0.001 inch. If it is more power you wish, then reread the post above by 302GMC. Jon.
Nothing to add really. Doesn't look like the car needs to go up to me - looks good as is, maybe just some wheelcovers or shiny wheels if they are in the budget. Love the '63 Pontiacs. My only criticism is I wish the Catalina & Bonneville had the same taillight treatment as the Grand Prix. Have fun with it! Gotta56forme/Scott
It sounds like you're more interested in making it a driver than a racer, which is good if you're going to stick with the Slim Jim for the time being. In this case rebuild the 2 barrel that's on it as already mentioned above. It's a pretty straight forward job but take your time and do it right. Check CarbKing's site for some really solid info and help. If you don't have a shop manual for the car, be sure to take plenty of pictures of all the carb linkage. Especially any linkage connected to the transmission. As far as the hard starting is concerned, you might want to concentrate on getting the automatic choke working properly. This might require a new choke thermostat and vacuum break and doing some extra adjustments. It might also involve pulling the intake and clearing out the carbon in the heat crossover passage that runs under the carb base and connects the ports on each cylinder head. You might also need to repair or replace the heat riser valve. It's a bit of extra work but when you can get in the car, press and release the accelerator pedal and set the choke, hit the key and it fires up and runs smooth at high idle, it will feel like you just rebuilt the engine. If some of this sounds like it's beyond your skill level at least put a manual choke on it, adjust it properly and start learning when and how to use it.
Thanks for all the replies I do have a shop manual and I will look into rebuilding the 2bbl. I don't have a problem keep the roch. on there I just had the Holley sitting around. As far as a manual choke I'd rather not do that at this point and time. Should I switch the jets out? The car gets driven about 50-75 miles a week and runs good after it gets past the bad start up.
I had a 63 Bonneville convertible in about 65. Put a 421 cam in it, tripower off a 64 GTO, and converted it to stick shift. Loved that car and for a big car, it would haul. As the others have suggested, just rebuild your carb. If you can score a four barrel intake, then consider adding the bigger carb. But those 389's run great regardless of how mild or wild you build em. 3 inch exhaust is WAY too big. 2, maybe 2 1/4 max is about right. Don
My rear main seal is leaking so I'm debating on taking the engine out for a freshening up when I take it to get a trunk pan put in and the trunk lip replaced. If I go that route I'm going to get the block tapped for starter holes so I can bolt a different trans up.
Believe it or not, I actually happen to have a 4bbl manifold and REBUILT AFB carb numbers matching off my old 62 Bonneville that I sold off last year. NB that I am in Australia, so PM me if you want to experience the eye-watering freight and tax costs us Aussies have to go through to get our hands on such straight forward options...
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