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| Carb trouble https://slantsix.org/forum/viewtopic.php?t=44887 |
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| Author: | Nongan [ Sun May 08, 2011 11:42 pm ] |
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Just a suggestion if you have vaccum advance make sure you are on a ported vacuum on the carb or else your advance would be on all the time |
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| Author: | Ross [ Mon May 09, 2011 6:47 am ] |
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It is on a ported spark tube I made sure of it. |
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| Author: | Ross [ Mon May 09, 2011 11:51 am ] |
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Ok took the carb of again and emptied out the fuel. Blew out every hole in and outside of the carb. I did notice that there is fuel leaking aroun the throttle shaft when I spray starting fluid to prime it (after putting carb back on). Did tighten the intake manifold bolts down, a few were a little loose. |
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| Author: | Reed [ Mon May 09, 2011 2:17 pm ] |
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Throttle shaft leaks will cause idle problems due to vacuum leaks. |
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| Author: | Ross [ Mon May 09, 2011 3:22 pm ] |
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Ok that makes sense. Well I took the throttle body off the other 1945 I got from pick n pull. It runs now! Still doesn't run the best but it runs and pulls it's own weight so I'm happy. It idles at 1100 and still hesitates when giving it throttle but as long as she runs and will get me place I'm happy. Till I get a 2bbl. DO they make 1-2bbl addapters? |
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| Author: | Reed [ Mon May 09, 2011 3:47 pm ] |
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Quote: Ok that makes sense. Well I took the throttle body off the other 1945 I got from pick n pull. It runs now! Still doesn't run the best but it runs and pulls it's own weight so I'm happy. It idles at 1100 and still hesitates when giving it throttle but as long as she runs and will get me place I'm happy. Till I get a 2bbl. DO they make 1-2bbl addapters?
(1) You should set the idle to the correct idle speed. Turn the idle speed screw out until the engine idles around 750 RPM in park, then double check your base timing.(2) hesitation on acceleration is usually either a vacuum leak or an accelerator pump problem. (3) There are one barrel to two barrel adaptors, but they are not worth spending your money on. If I were you, I would skip the two barrel conversion and save up for a good condition used or a new-old-stock Holley 1920 carburetor (preferably an Economiser version). |
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| Author: | Ross [ Mon May 09, 2011 3:54 pm ] |
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Well the reason I asked my dad has a 2bbl that was rebuilt. Would it just be better to get a super six manifold? If I turn the idle down it has no power and won't pull it's weight. I just got my brother from school. I had to baby the clutch going from a stop and it had no power at low rpm. Also when I give it a lot of throttle I hear this loud sucking noise and it hesitates, it also stumbles then the rpms shoot up. |
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| Author: | 4speed [ Mon May 09, 2011 4:16 pm ] |
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Are you running with out the air filter on right now? |
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| Author: | Reed [ Mon May 09, 2011 4:42 pm ] |
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Quote: Well the reason I asked my dad has a 2bbl that was rebuilt. Would it just be better to get a super six manifold? If I turn the idle down it has no power and won't pull it's weight. I just got my brother from school. I had to baby the clutch going from a stop and it had no power at low rpm. Also when I give it a lot of throttle I hear this loud sucking noise and it hesitates, it also stumbles then the rpms shoot up.
These are classic symptoms of three problems-(1) idle mixture is too lean. The motor will not run smoothly at lower idle speeds, so, to compensate, the owner increases the curb idle speed. (2) Increasing the curb idle speed beyond factory specifications can create several problems. First, the throttle is opened so far that the port for the distributor vacuum advance is uncovered and the vacuum advance is operating at base idle. To compensate for the advanced timing, overall timing is retarded, hurting performance and economy. Second, the throttle can be opened so far at idle that the transfer slots in the carburetor are uncovered, leading to the carb operating on the transfer circuit at idle rather than the main idle circuit. This can lead to leaning out the idle mixture circuit too much and can also lead to bogging on acceleration since the carb is already running rich and it gets more fuel squirted down the intake by the accelerator pump. (3) The accelerator pump shot could also not be functioning properly leading to a lean condition on acceleration and hesitation on acceleration. Since your hesitation on acceleration could be caused by the fuel mixture being too lean or too rich, you need to get everything set back to factory specifications before you go modifying anything. The answer to all these problems is to set the curb idle speed and curb idle timing to factory specifications and not to mess with them to mask another problem. Disconnect and plug the vacuum advance line at the distributor. Start the truck and let it warm up. Screw the curb idle mixture screw in until it lightly seats, then back it out 2.5 turns. Start the motor and set your curb idle speed to 750 RPM. Now check your timing and make sure it is at 10-12 BTDC. If the timing is off and adjusting it changes the idle RPM, reset the idle RPM and recheck the timing. If the timing is on and the idle RPM is on but the motor runs rough, turn the mixture screw out 1/2 turn at a time until the motor runs smooth, then turn it out 1/2 more turn. now recheck the curb idle speed and timing. Once all is done and set to factory specs, reconnect the distributor vacuum advance hose. There is no one correct setting for the curb idle screw. 2 1/2 turns out is just a ballpark guess as to where you should start. I have had carbs run good with the mixture screws set anywhere from 1 1/4 turns out to 3 1/2 turns out. There is an excellent manual and training video for the Holley 1945 in THIS THREAD. Some day, you might want to switch to a two barrel carb. However, I believe you should get all the bugs worked out of what you have now before you do a carburetor swap. Swapping carburetors adds a whole bunch more potential problems to troubleshoot. I recommend you make the most of what you have before you change anything else. |
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| Author: | Ross [ Mon May 09, 2011 6:01 pm ] |
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Dang you expanded that much better than the manual does. Thanks reed. I'll go do that. And 4speed I was adjusting the mixture screw with air cleaner on. |
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| Author: | 4speed [ Mon May 09, 2011 6:51 pm ] |
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I was asking if you were driving around without the air cleaner on when you heard the "sucking" sound. |
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| Author: | Reed [ Mon May 09, 2011 6:55 pm ] |
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I believe the "sucking sound" he is referring to is the "brouummfff" noise a carb makes as the motor bogs down due to being too rich or too lean. A noise I am VERY familiar with myself. Try driving a van with the doghouse off and air cleaner removed while you fine tune the carb. Lean backfires through the carb are exciting! 
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| Author: | Ross [ Mon May 09, 2011 7:17 pm ] |
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Haha explained^ dang auto correct. I'm on my iPod. So I just did everything. Idle set to 600rpm. Timing at 12*. high idle about 1500. Mixture needed 3.25 turns. Idles good. Accelerator pump isnt working dangit. I put the throttle on from the other carb and com to find out that one was leanburn and doesn't have a ported spark tube, mine did. So it always advanced. But at idle it still idles fairly good. But thank you guys so much! I didn't think I'd be able to get her running again. |
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| Author: | Ross [ Mon May 09, 2011 7:20 pm ] |
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Oh and also I wanst driving it just revving it. With and without the air cleaner on. It still does it adjusted too. |
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| Author: | Chuck [ Tue May 10, 2011 8:21 am ] |
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FYI, I always started with the idle air screw 1.5 turns out. Seems closer to the correct position on the cars I have (early 60's). |
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