have just done head gaskets and am trying to set the idle on the 350.have a bad stumble i cant shift from idle set at 600 to 1000 rpm i have to give 2 or 3 very lite pumps so as not to stall. From 1000 rpm up it pulls like a school boy. So far if i hook up vacuum gauge i get a reading if 15 adjusting the idle jets screws has no effect on vacuum. also the recommended 650 idle seems to hi and i can idle down the road at 20mph. checked for vacuum leaks with carb cleaner,ok. Do i need to pull the carb and blow out the idle circuit with carb cleaner and air ?
Have you checked the accelerator pump? Mine went bad and had the same symptons you are describing, make sure the pump is ok. By the way do they put ethanol in the gas ? That can cause problems too.
I am having accelerator pump sticking issues with my '62 Buick (401 Rottenchester 2bbl) as well. Same symptoms.
pump still seems to give a big squirt. stock cam. havent touched timing ,no points in this 1 so not sure how it could have changed, always pulled hard with 2bb l so im thinking its the carb, very little response from the idle jets when trying to tune it makes me think blocked idle circuit . What idle do you guys use 650 seems really high to me but then i'm used to working on harleys lol. Better order a kit for the carb. as always shipping will be twice the cost of kit
By the way do they put ethanol in the gas ? That can cause problems too.[/QUOTE] Good point Gary there is an upgraded pump for that isn't there?
15 inches of vacuum seems a little low. Could just be late timing. Try this- with the vacuum gauge connected, try slowly covering up the carburetor air horn with your hand. Slowly choke the carb of air. As you do this, look at the vacuum gauge and see of the reading goes up. Also note if the rpm goes up as well. I think you may hav a vacuum leak. if the car DOESNT have a leak, the engine should stall or try to as you cover the air horn with your hand
just set timing at 12. need to mark balancer at 30 in daylight (old eyes) Adjusted idle jets in park got to 20, drop to 15 in drive. Noticed a lot of play in pump linkage so gave it a tweak, seams better will test drive tomorrow can't be bother moving 4 cars to get out of driveway at 1 am
So your vacuum got to 20" in Park? Dropped to 15" in drive? Seems like a big drop, but OK. Make sure your timing doesn't over advance at higher RPM. You can't run any initial timing you want without checking the total timing. Make sure you use light springs in the distributor when you check the total, light enough to get all the mechanical advance in at lower RPM.
just been rechecking . timing set as per http://www.buicks.net/shop/tuneup.html . Tested vacuum advance by no vacuum to connection ,check with timing light then conect 20 vacuum from manifold port, test with light no change. Tells me vacuum advance not working correct? So i think that 1 of these is in order http://www.taperformance.com/proddetail.asp?prod=TA_690B/C/R
I like spending money on parts as much as the next guy but you know you can buy a replacement vac advance for less than 20 bucks right?
Almost seems like your idling with the throttle blade angle up into or past the off-idle transfer slots. If so, you don't want that. The symptom is a big drop going into gear, and a huge off-idle flat spot. I generally don't run direct manifold vacuum on the vac adv can unless the spring curve has a wide enough range necessitating it. Example; some distributors have enough curve in them that if you set initial @ 6*, max will be 36*. If I know I need more initial, but the same total, I might leave it there for easy starting, then the direct vac will pull it up 10*(?) more once running to have a better idle. This way I don't have to limit total timing, which is time consuming...drill & tap, limit screws, welding, etc. Also, if your having probs tuning idle using the screws, it's a good sign that your using transfer slot fuel, rendering tuning ability with the screws useless. They might be, in fact, closed off. I can't quite see whats going on without you holding your computer up to the car for me to look, but I would verify this first before continuing. As far as striping a timing mark, the easiest way I've found is to rob my wife's flexible sewing tape, wrap it around the dampner using the cm side, then go 10%. 10% of 360* is 36*. Stamp a line there so your factory timing cover marks become useful for reading total timing and vac adv added. cm's are easy to read, ex. 56 cm circumference would equate to 5.6 @ 36*. Mark the dampner @ 5.6cm (or wherever) for easy simple reading. I could be totally wrong, but I ALWAYS check this first before proceeding. Good luck.:grin:
Unless your 40 year old car has the original distributor it left the factory with, stock timing specs are useless. Measure your total timing and go from there. Your initial timing will be limited by the amount of mechanical timing in whatever distributor happens to be installed in your engine, and the total timing you wish to run. You can use the vacuum advance to increase your timing at idle. It will go away at wide open throttle though, so it won't add to your total. Replacement vacuum advance units are readily available for about 10.00 or less (www.rockauto.com) Read the power timing thread, http://www.v8buick.com/showthread.php?63475-Power-Timing-your-Buick-V8 30* of timing is 1.75", 34* is 2" on your balancer.
Larry you cleaver man you. marked balancer as per your advice allin is 32,10 at idle and no more flat spot . Also put in lighter springs on the advance so all in around 2700. Had a play with a buddy with a camed cheby 350 couldnt get him off my door so need to work on some traction so i can get the jump on him. Thank you again larry for your wisdom
