I need alot of help. First of all, I know nothing about carbs and distributors. I have a 72 Lark, with a 350 in it. I stuck on a TA intake, headers and exhaust system and I replaced the old 750cfm carb with one that was built for a 401 riv. The car pings, diesels, and idles too high. Not a great combo.... So my questions are... what to do and where and how to start? Im not a complete tool, but my GN knowledge isnt helping much here.... I only have a standard timing lite from Sears... oh and Im on a college student (IE wife's paying) allowance.
Well first of all check the IAC and the MAF sensor...... oh wait wrong engine.:grin: The pinging is caused by the timing being advanced too far. Try setting at 12-14*. Try running the car with the vacumn advance plugged and see what happens. The run on can be from a very high idle or by advanced timing as well. Set timing first and then adjust mixture scres and idle speed until the proper RPM is obtained. It is good to have a reliable tach and a vacumn guage to tune.
Chris thanks for the info. Unfortunately my car did not have a timing indicator on it, so I bought one from TA. Since its an odd bolt size, I had to eye-ball it for the moment. For the moment its running alot better, still diesels a little due to the idle being too high, I started playing with the mixture screws and that seems to have helped a little. I drove the car with the vac advance unplugged and she is running better... since im on a tight budget, should I get a vac guage or a hand held vac tester? Im also going to try and score a tach so I can really tune this sucker. Will update when I have more...and Ill ask more questions then too! :eek2:
A vacumn guage may be the best $20 you will ever spend. After you get it dialed in spend another $10 and get a recurve kit for the distributor. But not the Mr. Gasket as the springs are way to stiff. Put the medium springs in and you should get around 32-34* of total timing. Good luck
Here's what I'll do with a new engine. Assume it's WAY out of tune, and I'm assuming that your distributor cap, rotor, wires, and plugs are ok, and the point gap is set right. Make sure all this stuff is good, or you're only wasting time. A dwell meter is the most accurate way to set the points. Look for a deal on one of these at a local pawn shop. ;^) ------------------------- I'd start with the idle speed, if it's too high, it makes it real hard to set anything else accurately. (One thing to watch for is that the carb is truly on the idle curcuit at idle, and that the throttle plates aren't open to the point that it's into the part-throttle circuit. To check this, start the engine, look down into the carb bores, you shouldn't see anything "wet" or any fuel on the top of the throttle plates. If you do, you'll have to back the throttle screw out while tinkering with the idle mix screws. Be patient, it can be a pain.) That being OK, I like to tune by ear first, then confirm with a timing light. Get the idle speed as low as you can, then tinker with the idle mix screws, you want them as far in as you can get them without the idle dropping off. A vacuum gauge is great for this, you want the most vacuum you can get. But a good ear works just as well. Then move the distributor (vacuum advance disconnected and plugged) either way until you get the fastet and smoothest idle. Go back to the carb idle mix screws, changes in timing change the idle mix. If you need to change the idle mix screws more than one turn, then go back to the timing, then back to the carb. When you've got it all set up for the best, smoothest idle, hook the vacuum advance back up and go drive the car. If you get pinging under heavy load, then back off the ignition timing a bit until it goes away. Once you've got the timing set, go back to the carb, double-check the idle mix screws (shouldn't need to move them much at all), and then turn them in a quarter to half turn each (if you've got a tach, you want a 25rpm drop for each screw, 50rpm total.) This is called the "lean-drop" method, and will get you the best power/mileage. The go look for a Honda to feed your Buick for lunch!!!:Brow: If you've got a timing light, I think you'll be end up somewhere between 8-14 degrees advance on the ignition, depending on fuel quality, etc, etc. More than 14 degrees can kill power, but it'll likely ping and knock before then. Hope this helps! James ps: and then you'll get to start tinkering with the carb jets, rods, etc, etc, etc. It's a never-ending quest for more, but that's what makes it all so much fun!
Im still having some problems. I didnt get a vac gauge (will tomorrow) but my idle is really high once the car warms up. With both idle/mix screws fully in, and the idle screw not making contact with hte linkage, the idle is still over 1000 rpms in park once warmed up. I have a TA intake, and the accompanying choke. When I change positions (two holes on the linkage for the choke) the idle shoots up from there. Also when you mentioned about the carb being wet, were you referring to the secondaries or the primaries? The secondaries look dry as well as the primaries... but it isnt as easy to confirm. The timing as of right now is about 8degrees. Im not sure exactly because it was eyeballed... (not sure if the timing tab bolt holes are unusual sizes (not 1/4 standard thread) or if they are mucked up. Lastly, the dwell i havent set, as Im trying to get a meter. Could the dwell being off be a source for some of the troubles? Should I consider replacing the points or points and condensor... and should I get the set that comes together? Thanks in advance, Kevin
Did you do this? Did you over lock this one? Did you use a new gasket when you replaced the carb? Lars
Your choke coil may be too rich. Try looking to see if the choke cam is engaged when the car is warm. If it is, then bend the linkage so that it just falls off the cam when warm. I had to do this with my car numerous times to get the linkage right.
Found it your self?! Looks like you solved this one your self, the changed position must be activating the "choke fast idle" setting on the carb, maybe this adjustment is so "off" (aktualy on/engaged) that it overrides the "normal" idle adjustment!o No: or did i get somthing wrong here?:spank: " dwell be the reason," dont think so. "the set that comes together?" newer wrong to change worn parts. both alernatives will work, just get good quality parts. Lars
Kevin, I'm with Smartin. I'll bet the fast idle cam (on passenger side of carb) is either stuck, or the choke is out of adjustment, holding it up on high idle. If it's the fast idle cam, it should die when you get it off of it, if the idle mix screws are still all the way in. I'd back them out 2 turns each, and then tune from there. Hope that's it!!! As far as the carb insides being wet, you look in the primary side to see if fuel is being pulled through the venturis, but you've verified yours are dry. If you don't know the history of the ignition parts, I'd replace them before you start tuning the carb. Show around for Blue Streak points and condenser, made by Standard Parts. They're MUCH better built, and don't cost that much more. Then charge ahead with the tuning fun! James
Thanks for the heads up. I guess for now, Ill disconnect the choke to get everything baselined, then work it from there. Also I used a new gasket when replacing the carb... and I cant find any vac. leaks.
Take the choke off for now and see what happens. Also if the mixture screws are turned all the way in the engine should die. If not you are no longer running on just the idle circuit. Also, what carb are you using? if it is a 455 Q-Jet than it has an idle air bypass circuit that may be causing you some grief on a 350.
Wow, it's great to know someone else out there is going through the same thing I am atleast. I just rebuilt my 67' 340 and have the same symptoms(dieseling,idles way high etc.) I cannot get the darn thing tuned for nothing. I am running a 650 cfm Edelbrock and when I turn the screws all the way in the car doesn't die like you were talking about Chris,what does this mean? And I have my choke set on the richest setting(as per Edelbrock website says to run the engine up to operating temp.,then loosen the choke to the leanest setting the turn in rich until the choke just begins to move then back off to the leanest setting before that point,which puts me at the richest setting there is) but the choke is still full open even at this setting and idles up high when you close it off even more. Sound right to you guys? I bought a timing light last night to check my timing tomorrow, Chilton's says my timing should be 21/2 BTDC, but can I go further than this because my car seems to run better with more advance. Also, I am missing the kickdown setup on my switch pitch 300, will this cause me problems with my car not wanting to stay running very well in gear, but idles way high in park?I thought it might have something to do with the high/low stall thing since it isn't hooked up at all. Ideas? It sucks having to idle the car way up to 1400-1500 rpm in park just to keep it running when you drop it in gear. Sorry to trow my problems in the mix, just seems like we have a lot of the same problems and the advice was sounding helpful to my application too.
I am using a 800cfm carb... it was for a 430, but I imagine it was originally slated for a 455. hmmm... is there anyway to avoid this grief created by the bigger q-jet?
Sorry Ron, I know nothing about the Eddy carbs, but I can tell you for sure that you are on the primary circuit if the screws are bottomed out and it still runs. Check for an air leak somewhere if you are sure the throttle blades are closed. Air has to be getting in from somewhere to cause fuel to drip from the sqiurters. As mentioned before lose the choke until you get the carb tuned right. You can run as much timing as your combo will allow you to without knock. Get the carb figured out and I am prettty sure your high idle problems will be fixed. You also need a vacumn gauge. I can't strees enough how this is good tool for tuning a carb and a decent one cost under $20. Good luck Nivek, if you have a decent size cam then the 800 is fine but a little large for stock cam and heads. Also, I think the dual plane intake makes a difference as well. I had no idle problems when using the cast iron stocker.
Taking the choke out of the equation is probably a good idea, but I think the key thing to look for is the fast idle cam on the passenger side of the carb, and make sure it's not holding the idle up high. On the pass. side, look at the end of the throttle shaft, there should be the fast idle screw. It only comes into play when the choke linkages pull the fast idle cam up, then the screw bottoms on the steps of the cam. There's a weight on the end of the cam, to pull it down and out of commission when the engine warms up, so the idle drops off. I've seen them get gummed up, then the weight isn't enough to pull them down again, keeping the idle too high. Make sure the weight is DOWN, and the fast idle screw isn't hitting it. James:Smarty:
