Oy, I can't for the life of me, figure out where or why this is happening. :af: I've sprayed all vacuum locations many times to find a leak, in all possible places. I've rebuilt the carb, made sure all the passages were clean, and free of debris. I guess I'll start from the beginning. 67 Electra, with 72 455, mild cam- a little increase, but not big enough to change out the springs. stock trans, divorced choke. Carbs are 7027130 (DESTROYED) and 7042252 (REBUILT) distributor fully gone through and rebuilt. Timing is where it should be. The vacuum advance has been disconnected. The engine builder though that this was a good idea?? I also don't know the exact timing, but, it really has never been a problem. I never really had any problems with the carb in the 5 years Ive own this car. This is my daily driver, and has driven fine. Every other year, I would rebuild the carb with a new kit, and clean it like I should. It was an old carb, and had warpage of the airhorn, but that never stopped it from running. Ran like a champ, no bog, no hesitation, also, no transmission kick down. oh well.. more and more frequently, i would come to a stop light, and the rpms would go up and down, almost if it wanted to stall. It got to a point where I would have to hold my foot on the gas, and the brake to keep the engine running. Drives fine and accelerates just dandy, until I get to an idle situation. Rebuilt it one last time, and screwed up some air bleed holes, and that was the end of that airhorn/carb. SO, I checked online for a new carb, found one that was rebuilt some twenty years ago, or so, but was never used, and was still wrapped in shrink wrap and such. It was a clean looking carb. Put it on, and I should have done this before putting in on, as the float was stuck open. Carb flooded, and i tapped a bit and it freed up, and it took a while for all the gas to get to the right places, but it finally started up, and was sort of choppy actually. Took a while for it to clear up, but eventually, it did. ish.. drove around the city, and on the highway, with great response, and no bogging. ONLY when It came to idle, it got choppy, and from idle to transition to the main circuit, only then afterwards, it would smooth out. After a couple minutes, That also disappeared, and though it was in the clear. Then, I come to a stoplight, and the rpms drop significantly, and it stalls out. Thank god I'm close to home. I ONCE again, double pedal it back home, and take the carb off, and go in for a rebuild. I still have all the fresh parts from the last rebuild as they were still lying around from the destroyed carb. I check all the passages and find a disintegrated bug carcass in the passage leaving the accelerator pump cavity. All else is well, and clear. I slap everything back together, and to no avail, it still has the same issue. Heres what happens... Get in the car, turn the ignition to start, and crank the engine. First, I need a new flex plate... so i have to find the sweet spot where there are enough teeth to actually start the car. I rebuilt the motor 2 years ago, and somehow failed to replace the STOCK flex plate. Rookie mistake. Anyways, once the engine is warmed up, I turn the ignition and crank the engine. Vroom! It starts like a champ, no extensive cranking needed. Gets up to probably around 1000-1400, and then just drops to almost 400 and poops. Crank of the engine, it fires right back up, and then I give it gas to high 1000s, probably 2. at that point, it sounds fine, no coughing, or jumbling. I ease off the pedal down the scale, and as it gets closer and closer to 1000, it starts coughing, and being erratic. I have the mixture screws around 3 turns equally, and the idle screw turned in, sometime even more so than I've ever had it. It still will not run. It has the same symptoms as of the other carb. I can't find a leak for the life of me. New hose to the power booster, and the pcv valve is nice and loose, and it rattles around like it should when I check. Brakes brake nicely, so, theres no vacuum loss there. I redid the intake manifold gasket about 2 months ago, and it was fine. Checked all the torques of the bolts, and they are all at 55 lbs/in. Can't really do another vacuum leak test when the engine won't idle. I unfortunately don't have a vacuum gauge, as that would help a ton. ....But I need the car to run first. I was reading the Cliff Ruggles book, and short of rejetting and re metering and all that jazz, I don't know what would help. I just don't know what would do it. It sounds like a vacuum leak, because its happened with 2 carbs, BUT, it ran and idled for a while with the second carb on, and I thought I was good to go. Any suggestions? I was even considering getting an Edelbrock, but I won't. Quadrajets are so easy to teardown and rebuild, but yet, they are complex. Any suggestions would be much appreciated!! I just want to drive mah car!!!
You would be much better off if you would get a correct Buick 455 quadrajet for your car and start there. You had a Cadillac carb an now have an Olds carb. They just aren't calibrated correctly for your Buick. Every Quadrajet was built for a specific application and they usually don't swap around well in stock form without many modifications.
I have never heard of leaving the vac advance disconnected. Have you tried reconnecting it to see what happens?
Very true. I was looking at your website as well, Mark. The only thing I don't get is, that I've been running that oldsmobile carb for years. I might have to use your work!
How are you checking for a vacuum leak besides examining hoses and what not? Not sure how you can diagnose this type of issue without checking timing or vacuum. Does this car have points or electronic ignition?
I could connect it, but Ive been running it without being disconnected, and its ran like a champ. I don't think it will make any difference. I just don't see how after this long, it would be the vacuum advance, if it was doing fine for so long
I'll have to get a vacuum gauge and see what she reads when she fires up for the small second. It's an HEI system
Very true. I was looking at your website as well, Mark. The only thing I don't get is, that I've been running that oldsmobile carb for years. I might have to use your work!
You might have been lucky with the first one not being too different from stock. The second one though--who was the rebuilder or what brand was it? I used to be in the parts biz and we sold Tomco for a long time, but we chose to quit because it would take three tries to get one that would run even close to right, never mind being tuneable or really right. ( This was nearly 15 years ago). So unless it's something more accurate than a mass rebuilt unit, it already has one strike against it. Age after rebuild might be strike two....I'd suggest either building a proper Buick 455 carb (a known good core, not one a mass rebuilder did) or have one of the gurus do one for you. Patrick
Does it run well with the choke on when you first start it up? If so your describing a textbook example of a massive vacuum leak. With the choke off, try restricting the air flow to the carb with your cupped hand or a rag. as you choke out the carb, watch the vacuum gauge and see if it goes way up. Hell, you really don't even need a vacuum gauge if the leak is as big as I suspect. You'll hear it. The idle speed will go way up as you restrict the air
Some random thoughts from stuff I have read on this fourm, could you have a can or lifter problem, or a distributor problem? Have you taken off the dist cap and watch the rotor spin while cranking with no spark to see if it moves smoothly?
It was a rebuilt from Cardo. I'll have to speak to Mark. I guess you guys are right I think i got lucky with the 67 olds carb
I wish!!! The 67 olds carb I had on it, didn't have the choke setup on it, so I would just feather it and drive it. 72 caddy carb, the one time I did get to drive it, the choke worked fine, and then I released the choke cam, and the rpms dropped normally. Then, I drove it around the city.
A1 Cardone is good for other OEM parts, but I can't attest for their carbs. Most carbs from big reman houses are junk. All they will do is pass emissions tests. They will never run correctly for any particular engine. When rebuilding these carbs, did you ever pull the idle tubes out? These are not part of a standard carb kit. They are the brass tubes which are pressed into the carb float bowl assembly. Most idle problems are related to debris/blockage in this area. They can be pulled out with a sheet-rock screw, and new ones can be tapped in with a brass punch. Also, most parts in standard carb kits are not designed to work with ethanol in the fuel like today. They will dry up and/or swell, and never work correctly. You should check this shop for sourcing the correct parts for the carb: http://quadrajetparts.com/
welp, not that it matters anymore, but I went to start it up, and it ran and shifted into gear, and didn't stall. It ran like crap for a bit, and then it evened out. WOT was crap though, for obvious reasons. I've spoken with Mark from Quadrajet Power LLC, and have ordered a application specific carb. I've seen his work, and am extremely impressed. Thanks for all the help though!!:beer
Put the vacuum advance back in play as well. Running without it means that a richer mixture is required for completely combustion for "normal" driving. Engine builders and hobbyists who don't use them leave considerable power and engine efficiency on the table in the engines "normal" operating range. It's a load sensing device, and designed to add timing for light throttle driving. It will have ZERO negative effects anyplace else, contrary to what we often read about with these things.......FWIW......Cliff
