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| Hesitation https://slantsix.org/forum/viewtopic.php?t=23063 |
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| Author: | 61 V200 [ Sun May 06, 2007 11:09 am ] |
| Post subject: | Hesitation |
Stock 170, Holley 1920, orange box. About 10 BTDC I finally got my timing dialed in using a piston stop. When I put my foot into it anywhere in the range of 35 to about 50 mph it hesitates before it takes off. It's kinda like it is taking a big "gulp" before it wants to roll. Could this be my carb? Thanks for the responses |
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| Author: | SlantSixDan [ Sun May 06, 2007 3:31 pm ] |
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Which direction does the inlet hole or snount on your air cleaner face? If it is facing front, try turning it 90° clockwise so it faces the valve cover/passenger side of the car. Yes, this sounds silly, but there was a TSB released for '60-'61 cars with this type of air cleaner giving that exact symptom with this fix...and if that's the problem, the fix actually works! |
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| Author: | 61 V200 [ Tue May 08, 2007 10:38 am ] |
| Post subject: | |
My air cleaner is from a 225. No snorkle. It sucks.......from the bottom. My pump shot is set to the earliest possible "hole". Dan stated in another thread that the orange box has been crap for the last few years. Could that be an issue in this scenario? |
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| Author: | SlantSixDan [ Tue May 08, 2007 11:06 am ] |
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35-50 mph hesitation in the absence of the snorkel type air cleaner issue makes me wonder if your carb's power valve ("economizer") is working correctly. See threads: Here and Here |
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| Author: | Aggressive Ted [ Tue May 08, 2007 6:37 pm ] |
| Post subject: | |
I had a similar problem with my 1920 Holley. Our local carb shop gave me a few pointers that really solved the problem. My economizer circuit was not working properly. The plastic plunger arm had deformed so that the vacuum plunger was not hitting the arm squarely. He sold me a new plastic plunger that fits on the economizer body and several different thickness gaskets to tune how quickly and how much the vacuum plunger travels before engaging. I am using the thinest gasket at the moment for instant response. He mentioned that in alot of rebuild kits the bottom gasket is too thick, so they used to JB weld a washer on the end of the vacuum plunger to get a little more instantaneous reaction. He also punched the whole a little larger for the accelerate pump shot. He mentioned that sometimes the gaskets cover too much of the hole. Boy was he right on! If I am at a light and barely touch the throttle the engine jumps. It only takes on pump on cold start ups now. On hills the at speed the economizer circuit kicks in about 6 pounds on the vacuum gauge and the car takes off. With a #60 jet it really takes off, with a #58 it is a little gentler but still accelerates quickly. Hope this helps! |
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| Author: | dart63 [ Tue May 08, 2007 7:35 pm ] |
| Post subject: | |
Are you running a high performance distrubutor that came with the orange box in a kit?? That distributor has some vacuum advance characteristics that may not be good on a daily driver........just a thought. I run this set-up in my 63 Dart also with a Holley 1920 and I can tell the difference however I only drive her occasionally and it's not enough to bother me. |
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| Author: | Doc [ Wed May 09, 2007 9:06 am ] |
| Post subject: | |
Yes, take a look at the distributors advance curve and vacuum advance functionallity before "going after" the carb as the problem. One quick test is to turn the initial timing advance way up and see if the hesitation is reduced or eliminated. If giving the engine more initial advance helps, it is most likely a distributor advance issue. DD |
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| Author: | KBB_of_TMC [ Thu May 10, 2007 10:56 am ] |
| Post subject: | |
I had a similar problem that haunted me a long time, until I happened to notice the coil had leaked out 1/2 its insulating oil - so it was sometimes arcing internally. A new coil fixed the problem. |
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| Author: | 61 V200 [ Thu May 10, 2007 11:28 am ] |
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dart 63 Quote: Are you running a high performance distrubutor that came with the orange box in a kit?? That distributor has some vacuum advance characteristics that may not be good on a daily driver........just a thought.
When I converted to Elect. Ign I couldn't find a kit for my stock dist. I ended up with a new dist. when I got the orange box.DOC Quote: One quick test is to turn the initial timing advance way up and see if the hesitation is reduced or eliminated. If giving the engine more initial advance helps, it is most likely a distributor advance issue.
I'm guessing you all are on the mark as it had less hesitation before I got the timing dialed in. I was probably running 15-20 BTDC and now at 10. I will advance it and test that theory. So what I am getting from this is that the curve is too " aggressive" (for lack of a better term) for my stock 170. The only project I have on the bench is a 2 bbl BBD and Dutra's duals. Is this enough to wake up my 170 and allow it to take advantage of the orange box dist.? Or are we suggesting cam/head? Lastly, I have read D. Idiots many posts on advance curves but have yet to find a source to educate myself on this subject. Any links or references would be greatly appreciated. |
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| Author: | Doc [ Thu May 10, 2007 11:47 am ] |
| Post subject: | |
My bet is that the distributor advance is to slow for your 170. The curve needs to be reset to allow more initial and keep the total in the 30-34 degree range. (170) Have you tested the vacuum advance pod, is it working correctly? Is it an adjustable VA pod? Doug D. |
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