Bought the car when I was 25 in 2006 and it was a basket case, having not run in a decade or two I'm told. I rebuilt the engine, trans, carb. Put in all new engine support systems cooling, fuel, wiring. I redid all the suspension, steering, brakes with new hardware and bushings, etc. Drive it for a summer then took it all back apart for body work in 2008. Spent 9 years replacing rusty sheet metal in between having 3 kids and moving many times. I've spent more in towing costs than actually buying the original car. I've towed that car with me to 4 rental houses and 3 purchased across four cities and two states. When we moved up to the Bay Area from San Diego the car was just a shell so that was a busy time trying to get the frame, wheels, engine, trans back in. Got it running again during covid after 12 years. The past year I've spent redoing all the interior and getting the exterior trim all shined up and installed. I've done everything myself except the exterior paint I took it to Maaco for that
17 years later and it's finally done. Many hours spent on this site learning from you all and I want to thank you for that. This place is wonderful.
Looks very nice. I like the color but I am very partial to blue. Looks to me like your not finished after all. You are missing the two rubber seals in the door jamb where your window rolls up in the back area.
I've been driving it when I can. Have to pull the van and truck out to park on street to get the Firebird out of the garage. I took it to a car show and that was a blast. It's a trip to drive after all these years. Also the first carbureted car I've ever driven so getting used to starting it. It has a hesitation when leaving a stop and doesn't start or idle as well as I'd like but it's pretty good. So there are some things to work on
What carburetor is on it? Rochester? 2 or 4 barrel? Hesitation/ hard start sounds like an accelerator pump. With engine off, take off the air cleaner and work the throttle while looking down into the throat. You should see two big squirts of fuel each time you work the throttle. If not, pump time. Has the carb ever been rebuilt? Resist the temptation to replace it with something else. The best carb is the one that came from the factory. But they get dirty and parts wear out. Learn to rebuild it and be the envy of all your friends!
It has a 4 barrel quadrajet 7029262 I got off ebay years ago and rebuilt with the help of Cliff's book How to Rebuild and Modify Rochester Quadrajet Carburetors. This car was a basket case when I got it. It had a 326 engine with 400 heads, no intake and no carb. Headers attached to the engine and a chrome exhaust tip screwed to the bottom of the rear end with nothing in between. Intake bolts were in the center of the V under an inch of grime. One good thing is someone replaced the 2spd power glide with a TH400. Rear end is stock 2.93 gears.
So I've done everything. Got a 400 engine off some guy out in the desert. Bought a stock intake and close enough carb off ebay. Rebuilt the engine, rebuilt the trans, rebuilt the carb. HEI ignition from summit. New everything over the years. My first time doing all this btw, I just would get a book on how to rebuilt TH400 then go through it for example.
Anyhow so on the carb this was originally from a 428 bonneville. My engine is bored over 0.060 so not far off on the displacement. I basically rebuilt it stock with a few mods from Cliff's recipe #1 in his book. Over the weekend I re-read the book. The accelerator pump works there are the two jets of fuel squirting in as you mention.
Since posting I've improved things by decreasing the vacuum advance and lowering the idle. Found I had vacuum advance turned up for some reason so I turned that down and moved up my starting advance to 15 so there's not such a sharp drop off in timing when I tip in. Lowering the idle I did to try putting the throttle plates in a better position relative to the idle transfer slots. The timing helped the most. It has improved but not completely better
I have a few more things to try. Cliff mentions a tip in procedure to help diagnose or setup the off-idle region which is the issue so I'll try that. This carb has an idle bleed adjustment at the top that I've never messed with so I'll try that. I have a spare pair of jets I was thinking of drilling one size larger to try richening up. Haven't tried ported or no vacuum advance so that's an option.
Acceleration is fine if I stomp on the pedal. The hesitation is only in a certain spot a little off idle if I slowly press into the pedal, like gradually driving away from a stoplight.
That can maybe be fixed by trying a different metering rod. Try finding Doug Roe's Rochester book. It really gets deep into the theory and what practical modifications really work. All the other Q-jet books are fine, but I found them more performance orientated. Roe's book concentrates more on stock carbs and their problems. Jet changes affect the entire rpm band. But metering rod changes affect idle, off idle, and part throttle. I have taken rods and jets from dozens of carbs and I can tell just by eyeballing them what to expect when I use one. Roe's book breaks them down by part number and gives specs about each one. So if you have a metering rod that is a little too fat [lean] where off idle or mid-range occurs, changing to a rod that is thinner [richer] at that point will solve the problem. The other thing to be aware of is that plenty can happen to a carb after 55 years or so. Many changes may have occurred. The Pontiac carb pages can be found at this site: Carb pages Look up your carb number and see what rods and jets were installed for the application. That is why I always say the carb that came on the car is the absolute best one and should never be changed. Here is an example of what info is on those carb pages. You should have # 45 rods and # 72 jets. EDIT: Don't drill jets!
So I figured out the issue with the tip-in hesitation, or maybe more like I figured out how to make it go away. I unplugged the vacuum advance and it's gone. I think that timing step change when going off idle was too abrupt for the engine. Maybe something is wrong with the vac advance or it needs tuning or something, but for now I'll just leave it unplugged.
On to the next thing, which is why the engine runs rough like its missing a cylinder at idle. I've changed plugs, wires. Done compression test. checked for vacuum leaks and can't find any. Last night I pulled the intake off to inspect the gasket and it looks fine. Maybe a carb issue. Will check again after I re-assemble
There's also a vibration when I got up in speed so I'll take it to the shop and have them re-balance the tires.
I did get that doug roe carb book. Haven't read through it yet so maybe that's a good next step
I finally have my issues fixed thanks to being laid off and without a job for a month haha.
The car forever has had a really hard time starting when hot. Sometimes wouldn't crank at all. I put in a high torque starter, larger battery, and larger battery cables and that's fixed.
There were a number of driveability issues. It would take a long time to start. It had a vibration when accelerating onto the freeway. It idle'd rough. The engine would box down and nearly die when accelerating away from a stop. From a cold start it would usually die and need to be restarted again.
I found quite a few issues when I took apart everything. I pulled off the intake and rebuilt the carb again. I had originally done that in like 2006 with the help of Cliff Ruggles book. Well I bought the Doug Roe book and have been just reading those over and over the past few weeks.
Here are the issues I found: -distributor vacuum advance canister was leaking -carb accelerator pump was not working at all since the seal had fallen off -accelerator pump check ball was not sealing well -main fuel metering rods were stuck in the full lean position! There's a little metal twisty thing that holds them to the hanger which was bent and being pushed down by the air horn when bolted together. This pushed the jets fully down all the time. I think the vibration I felt was actually knock due to being lean -the throttle body plate was missing holes drilled for fixed idle air bypass because that was a mismatched part I got from a local carb shop many years ago since my original throttle body had stripped out idle screw threads -the choke pull-off vacuum diaphram was leaking -hot idle compensator was leaking open all the time I think
I rebuilt the carb and fixed all those things. Had to get parts from a few sources to get through it. Finished assembly yesterday and just got back from driving and it's all better!
The car actually drives with confidence which is new. I bet someone other than me could even start and drive it, lol. Pretty easy to squeel those tires now
Well done. The Q-jet is a great carb. You can take a 'close enough' carb and make it work for what you have. The Roe book makes a point of checking everything else before tearing into the carb. Someone once said, 'Most carb problems are ignition related'. I am partial to ported vacuum for my vacuum advance. The old high compression engines, and radical cammed engines that have a hard time idling, can benefit from using full manifold vacuum. But dead stock low compression engines usually run best with factory timing and ported vacuum. There is a unique ported vacuum valve that 301 engines used. It is hooked to both manifold and ported vacuum. When the engine starts, it gives around 10° advance immediately, then as rpm rises, it adds more ported vacuum advance. I used it on my 1977 Trans Am 400, and the engine ran much better with that device. It looks like this:301 vacuum valve
