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By gentz - 15 Years Ago
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well i have tried it all, timing, carb, rebuilt it thought maybe the power valve, but still no go.. i still have this persistent hesitation only on off idle....i have tried advancing timing no go, richen up the card,no go....and my advance appears to be working fine...any tips..I am thinking a bad carb? or a distributor..
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By PWH42 - 15 Years Ago
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You don't say what kind of carb you have,but I'd guess a Holley.That stumble is almost a standard Holley feature.
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By PF Arcand - 15 Years Ago
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gentz: For a start, it would be helpful if you told us what make & model of carb...
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By Ted - 15 Years Ago
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What carb and if a Holley, what list number? What distributor? Electronic or points ignition? Ported or full vacuum to the distributor? Standard or automatic transmission? What’s the initial timing set on? Has the distributor curve been verified as working with a timing light? Were both the mechanical and vacuum ignition advance mechanisms verified as working independently of each other? Like the other forum members have requested, more information is needed. This can be the result of multiple causes and all be intertwined.
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By Timbo from Mempho - 15 Years Ago
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Have you checked the dwell. Sometimes it's the simplest things. I usually set point gap with a dime but if I don't have one I use 2 nickels!!
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By aussiebill - 15 Years Ago
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Timbo from Mempho (5/6/2010)
Have you checked the dwell. Sometimes it's the simplest things. I usually set point gap with a dime but if I don't have one I use 2 nickels!!Timbo, is that your 2 cents worth? 
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By Y block Billy - 15 Years Ago
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I used to set mine with a book of matches but now have to use a Bic lighter. All kidding aside, point gap/dwell and spark plug gap make a world of difference and when changed then you normally have to adjust timing and carb to match.
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By gentz - 15 Years Ago
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ok its stock 62 292, the original 2 bbl, the original distributor with accel pointless kit...
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By pegleg - 15 Years Ago
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I would suspect the accelerator pump in this case. Try seeing if the pump is working by manipulating throttle with the engine and ignition off. You should be able to see two fuel streams in the carb when you open the throttle, (obviously you'll need to remove the air cleaner first). DON'T try this with it running, unless you need your eyebrows burnt off. This is a common problem with today's gasoline and the ethenol in it.
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By DANIEL TINDER - 15 Years Ago
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[quote]Y block Billy (5/6/2010)
All kidding aside, point gap/dwell and spark plug gap make a world of difference and when changed then you normally have to adjust timing and carb to match.
Interesting. I have noticed since installing dual points (more dwell) last month, I have a slight hesitation. As pump-cup was new last fall, and no gas stabilizer was used (unless alcohol ruined already), I likely need to play with the idle settings. Curious though, why more dwell might cause it?
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By BrianL - 15 Years Ago
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I'm also going through a similar symptoms, but my set up is different then your. I have a later dizzy converted to Pertronix II/Flamethrower coil, Demon Jr 525 carb. I stumble under light acceleration, but if I press the throttle further, it catches & runs smooth. BG Tech is advising me to try various timings between 10~14 degrees, adjust idle mixture for best vacuum, & dial in float levels. After that, next up would be the power valve. Plugs look fairly good with a light tan. Some of these may apply to you as well. cheers
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By mctim64 - 15 Years Ago
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BrianL (5/7/2010)
I'm also going through a similar symptoms, but my set up is different then your. I have a later dizzy converted to Pertronix II/Flamethrower coil, Demon Jr 525 carb. I stumble under light acceleration, but if I press the throttle further, it catches & runs smooth. BG Tech is advising me to try various timings between 10~14 degrees, adjust idle mixture for best vacuum, & dial in float levels. After that, next up would be the power valve. Plugs look fairly good with a light tan. Some of these may apply to you as well. cheers I don't think this will help Gentz but we put a 525 Demon jr. on Steve Johnson's (Ibuzzard) 292 and it had a slight off idle hesitation till we changed the main jets from 58s to 64s, then it was very smooth.
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By BrianL - 15 Years Ago
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Thats interesting. I have 58's in it now. But the plugs look real clean & a nice light tan
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By pegleg - 15 Years Ago
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Brian, With the Demon, or as Holley, you may need to play withthe power valve a bit to cure that stumble. Try using a power valve with a 1/2 or 1 inch HIGHER number and see what happens. Don't go nuts or you'll kill your gas mileage.
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By paul2748 - 15 Years Ago
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Daniel - you might try a little more distributor advance. With the distributor change, your timing my be a little off even if at factory spec.
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By DANIEL TINDER - 15 Years Ago
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Paul,
Since I've been running premium exclusively these days, I usually set the timing by ear (there seems to be a narrowing window between excessive exhaust popping due to retard, and too much advance for starting). As the dual points were new, it IS possible the rubbing blocks have settled in and retarded a bit. But, your post gives me the idea of advancing timing beyond starting limit with the engine running, and taking a test drive to see if the hesitation is affected (I'll just have to be careful to not kill the motor before coming home). Is it safe to assume, I wonder, that 12V cars can routinely get away with more initial advance since the extra starting power may overcome resulting hard-cranking?
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By DANIEL TINDER - 15 Years Ago
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Turns out timing is moot. Inspection reveals only a dribble from 6 mo. old accelerator pump cup (*!%$#!*). Blue cup material is obvious junk, and was stored dry (no Stabil) over the winter, so will finally try the premium black cup from CASCO I had put away. If IT stands up to alcohol, I will lay in a lifetime stock.
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