| Slant Six Forum https://www.slantsix.org/forum/ |
|
| Bad idle Holley 1920 https://www.slantsix.org/forum/viewtopic.php?t=40436 |
Page 1 of 2 |
| Author: | ESP47 [ Mon May 31, 2010 12:06 pm ] |
| Post subject: | Bad idle Holley 1920 |
I've got a Holley 1920 on a 67 Valiant and this idle is driving me crazy. I've tore the carburetor apart twice and everything looks to be in good working order. It came with the car so I have no idea if its a reman or not. I'm guessing it probably is. Anyway I'll start the car up and it'll idle at 700-750rpm in park for about 45 seconds and it sounds perfectly smooth. Then i'll hear a quick stumble. Then after a while it'll have 2 quick stumbles. Then 3, 4, 5 and so on. Eventually after 5 minutes or so it doesn't really want to idle in gear very well and will die out because it's running too rough. Then I'll turn it off, wait a little bit and when I fire it back up, it sounds great again and then starts the whole process over again. My timing is ok at 10* BTDC and the dwell is sitting fine at about 43* or so. Valves are newly adjusted and I've tried a couple different sets of spark plugs and wires since I have extras on hand. Vacuum reads a solid 20 as well. So what do you guys think the deal might be? Just one of those bad carbs that will never run right? |
|
| Author: | ceej [ Mon May 31, 2010 12:32 pm ] |
| Post subject: | |
What did you set your valves to? Loosen them up a couple thousandths from spec and see if the idle improves. Another way to do this is to loosen each valve until it just starts to make a loud "Tack," Measure the lash, then tighten it up a couple thousandths from that lash measurement. If it's lash related, this should solve the idle problem. It doesn't sound like a carburetor issue to me, but one never knows.  CJ |
|
| Author: | gato [ Mon May 31, 2010 1:30 pm ] |
| Post subject: | |
a fuel system that's just a little bit too slow? D~~~! |
|
| Author: | valiant1966 [ Mon May 31, 2010 2:07 pm ] |
| Post subject: | |
Almost sounds like a fuel supply problem. I guess you looked at: fuel pump float adjustment dirty gas line filter any kind of gas line obstruction Just some ideas. Sounds like you looked at other obvious possibilities. |
|
| Author: | SlantSixDan [ Mon May 31, 2010 2:42 pm ] |
| Post subject: | |
Fuel supply problems show up at high engine speed/load, not at idle. |
|
| Author: | Aggressive Ted [ Mon May 31, 2010 4:31 pm ] |
| Post subject: | |
ESP47, When was the last time you changed the condenser? It may be breaking down as it warms up. What voltage do you see at the coil at idle? |
|
| Author: | valiant1966 [ Mon May 31, 2010 5:01 pm ] |
| Post subject: | |
Quote:
Fuel supply problems show up at high engine speed/load, not at idle.
Actually, that's not true. An engine at idle can starve for fuel as well as an engine at speed. Ever have your gas tank go empty while sitting still?And it certainly causes problems. |
|
| Author: | ESP47 [ Mon May 31, 2010 8:03 pm ] |
| Post subject: | |
I adjusted the valves to the loosest spec the book allowed and gave them a nice loose slip fit where they sound a little tappy but not bad at all. I'll check the condenser since I think I have another one laying around. The car had not ran for a year and a half before I got it. I cleaned out the fuel tank and changed the fuel filter but I guess it's a possibility that there was still crud in the line that made its way up to the filter. I also changed the fuel line from the pump to the filter. But yeah it's fine while I'm at speed, just hesitates after a while at idle. |
|
| Author: | SlantSixDan [ Mon May 31, 2010 8:11 pm ] |
| Post subject: | |
Quote: Quote:
Fuel supply problems show up at high engine speed/load, not at idle.
Actually, that's not true.Poor idle with good running above idle is usually in the carburetor, not the fuel supply. |
|
| Author: | Fopar [ Mon May 31, 2010 8:27 pm ] |
| Post subject: | |
Try changing the fuel filter, might have a lot of crud in it. 
|
|
| Author: | MI6 [ Tue Jun 01, 2010 1:19 pm ] |
| Post subject: | |
1. Has anything been done to the car since it last ran correctly? 2. Have you done anything to the choke or choke pull off? I'm having similar problems with my 71, however I did the electric choke upgrade on mine so I'm pretty sure that's where my problem lies. If you're sure the choke is not the problem I'd take the metering block off and put a straight edge on it just to make sure it's reasonably flat. If it isn't, fuel can leak past it and cause driveability issues. |
|
| Author: | ESP47 [ Tue Jun 01, 2010 1:54 pm ] |
| Post subject: | |
MI6, I bought the motor a few months ago and haven't had it running correctly yet, so to speak. I heard it run in the other car for 10 minutes or so and everything was good as well was the compression check. This is a curb idle problem and doesn't really have anything to do with the choke. Besides it's not really cold enough right now where I'm at to warrant a choke. I'll check the metering block as well as everything else suggested next weekend when I get some time to wrench on it. Thanks guys. |
|
| Author: | 4x4jimbo [ Thu Jun 03, 2010 10:07 am ] |
| Post subject: | bad carb |
hey i was reading about your carb problem i have the same problem in my slant 6 in my van but i found that the ballast resistors still heat up even afetr i've changed them 3 times, you could have an ignition problem so to speak |
|
| Author: | SlantSixDan [ Thu Jun 03, 2010 11:39 am ] |
| Post subject: | |
The ballast resistor is supposed to heat up. That's what resistors do when we run electricity through them.
|
|
| Author: | 4x4jimbo [ Fri Jun 04, 2010 9:57 am ] |
| Post subject: | ballast |
i understand but iv had 2 catch fire this is the problem im haveing it runs for about 20 minutes stalls and wont start for a good 10 but the few times it started right bak up my resistors cought on fire nuthing big but the coil in the middle burned up ....by the way sweet beard u look like a jolly felo |
|
| Page 1 of 2 | All times are UTC-08:00 |
| Powered by phpBB® Forum Software © phpBB Limited https://www.phpbb.com/ |
|