Ahhh, it always has to be something it seems... I have a solid “stumble” when the 53’s running now/when it's warmed up... it's a smooth, "blub, blub, blub, blub, blub, blub, blub, blub...then a phleh phleh…phleh...blub, blub, blub, blub, etc. Like it suddenly misses real bad, then goes right back on track. If I let it sit long enough it will eventually kill, in an idle period of ten or fifteen minutes. It does this when sitting in neutral, in park, or at a stop light in drive. TIMING: [FONT="]It shouldn't be the timing I don’t think...I threw a vacuum gauge on it and it at the wiper port on the intake and it pulls 19hg(accounting for Minneapolis, MN 1,340 feet above sea level – I added 1hg) of vacuum. I turned both idle screws in until it stumbled big time, then backed them out until it smoothed out. Then I backed them out more to see if it would stumble going that way, but it didn't until they were turned out far enough to fall out... So back in they went, about two turns out from being seated. [/FONT] [FONT="] [/FONT] [FONT="]Then I disconnected the vacuum advance on the carb and set the timing "blob" on the crank pully exactly even with the timing pointer on the block wen standing in front of the car, exactly what the shop manual says. Tightened it up and then reconnected the vacuum advance and figure that's as good as it will get. Timing is set, unless there’s a different/better way to do it.[/FONT] [FONT="] [/FONT] [FONT="]I’m guessing it’s a carb issue, which beats a cooling issue any day of the week in my book… But gotta get it figured out.[/FONT] [FONT="] [/FONT] [FONT="]The engine has 600 miles on the rebuild, bored 30 over, and has the Pertronix electronic ignition, but totally restored as stock otherwise. Everything is brand new..fuel tank, fuel lines, fuel pump…did it all myself.[/FONT] [FONT="] [/FONT] [FONT="]http://www.youtube.com/watch?v=2WtaeubuG3I - Just watch the first 30 seconds you can see the drop in the vacuum gauge when it stumbles (thought you’d be able to hear it better, but can’t)[/FONT] [FONT="] [/FONT] http://www.youtube.com/watch?v=WpMc67cArnk - Still kind of hard to hear, but can make it out a little bit. [FONT="]Any ideas? Pulled a little crud into the carb somehow maybe? Dashpot?(Which I’m still not familiar with really)?[/FONT] [FONT="] [/FONT] [FONT="]Thanks guys…Just not sure where to start.[/FONT]
could be a little dirt in the carb picked up from the gas tank. I would take the carb apart and clean it.
could be a little dirt in the carb picked up from the gas tank. I would take the carb apart and clean it.
Some observations; great car and engine, congratulations on a job well done. You said 600 miles, how do the plugs look? Clean? sooty? Do you have motor oil with zinc in it to lube the valve train? Check to see if the carb is clean, because thats easy. The vacuum gauge shows what could be sticky valves. Try a can of Marvel oil in a tank of fresh gas. What kind of coil? I like the Pertronix, but I like to see them with a Pertronix coil too. Are the plug wires good? On a new motor thats all clean inside, its a great time to put in a PCV. Let us know.
Ole don, great stuff. Here we go... Thanks, first of all. : ) I appreciate it. As much as we all enjoy theses old beauties, they never seem to just finish themselves. Every plug has a golden brown to it, like a perfect toasted marshmallow at the campfire. I believe that means I'm operating in the correct range, and no deposits or anything on them.. The oil I put in at this oil change was Motorcraft Superduty 15W/40 for diesel engines...recommended to me on here by another HAMBer specifically for the "zinc" reason. Yep, Pertronix coil as well. I have the Pertronix "Igniter II" in the distrib. and the matched Pertronix Flame-Thrower II coil. I also bought the Pertronix plug wires (their universal set designed for the flatheads that keeps the 90 degree original factory look at the plug) and cut them and put them together myself, to keep it looking clean and neat. Doubt we'll do the PCV conversion, though I've thought long and hard about it. And I'll definitely take the carb off and give it a little run-through...see if I find anything out. Like you and vein said...could be a "little something" in the carb. I'm not running a fuel filter of any kind anywhere in the system, and I did notice a very small amount of flakey-like sediment in the bowl on the fuel pump, so it any of that did slip through the screen at the top of the gl*** bowl...might have made it to the carb. I really should get a paper filter for in there..
That "flakey" sediment is showing up on a regular basis in carbs it is a by-product of the ethanol in unleaded gas,it may help to add some lead subs***ute every 3rd tankful CD2 and STP both make the product,you may want to clean the gl*** bowl more often.
JeffB2, Excellent tips. I did not know that, nor would I have ever some up with that about the ethanol...Thanks for the info!!!! Now when we had the engine rebuilt we did put in hardened valve seats...is the additive still necessary(suggested as a viable solution) with having the hardened seats in it? You know even though the bowl is crystal clear and full of clean gas, I took it for granted that there was anything in it...I have never cleaned it out to be honest. SOOooooo, when I started this thread, I had just gotten it going after it sitting for a month and getting the new radiator in....well I've burned through about two tanks of gas since...and it hasn't done it since a little before the beginning of the most recent tank... Damn really? That bugs me that gas deteriorates that quickly... Could it have been just that? And now it's fine???? hmmmm....
Since you have harden exhaust seats you don't need to ad the lead solvent to your fuel . Yes the fuel will evaporate much more due to the ethanol. ONLY the newer cars can keep the fuel from evaporating due to they have close fuel systems in the cars now . SOOO...it doesn't pay to buy and store extra fuel when you find it at a cheaper price . Out a gallon on a plastic gas can and watch how fast it will be down to nothing in a couple weeks ! Jim
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