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| Carter BBS jetting and pinging... https://slantsix.org/forum/viewtopic.php?t=43378 |
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| Author: | Josh P [ Tue Jan 25, 2011 9:59 pm ] |
| Post subject: | Carter BBS jetting and pinging... |
For a while my '66 Dart has had what I assume is a slight ping caused by a lean condition. It only happens at high RPM at WOT while ascending an incline. And for a while I suspected that was because the throttle shafts were worn. For the record, I'm not positive that its a lean condition, or any kind of vacuum leak. I have tried various timing adjustments, higher octane gas, and a few other things, so a lean ping is my best guess. So today, I was flipping through the FSM and noticed the Carter BBS I have on my '66 Dart with automatic transmission and no A/C didn't come with a BBS, it came with a Holley 1920. It lists the BBS being used for the 170, and I'm wondering if the lean ping (if there is one) is being caused by the carb being jetted too lean for the 225? And if so, can somebody tell me what the correct jet should be and where I can get it? Also, other ideas of the ping are appreciated. I did check for vacuum leaks but didn't find any (haven't tried the throttle shaft yet, but will do that tomorrow). Also, if it is just the throttle shaft bushings, anybody know of a shop that would rebush the carb same day (its my daily driver and I don't have a spare carb) somewhere north of Seattle, WA? |
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| Author: | emsvitil [ Tue Jan 25, 2011 10:04 pm ] |
| Post subject: | |
BBSs and BBDs have jets and rods that are hard to come by....... You could raise the fuel float level a slight amount which will enrichen the mixture a slight amount... Or back off the timing a little. |
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| Author: | Josh P [ Tue Jan 25, 2011 11:55 pm ] |
| Post subject: | |
Quote: You could raise the fuel float level a slight amount which will enrichen the mixture a slight amount...
I did think about raising the float level, but I think its already slightly (1/32-1/16) higher than spec. I guess I could recheck it...Or back off the timing a little. As for the timing, I've backed it off a lot (nearly 10°) and it doesn't seem to have any effect (other than poor economy and poorer performance). |
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| Author: | emsvitil [ Wed Jan 26, 2011 12:15 am ] |
| Post subject: | |
Disconnect the vacuum advance and see what happens. (plug it on carb) Somebody here had a weird problem with the air cleaner. It was too restrictive, and at WOT there was vacuum instead of 0. This would advance the spark with the vacuum advance can. If disconnecting the vacuum advance fixes it, get a vacuum gauge to see what's going on (or temporarily remove air cleaner) |
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| Author: | wjajr [ Wed Jan 26, 2011 4:44 am ] |
| Post subject: | |
At WOT, a throttle shaft vacuum leak would not be seen by the engine. Too much air passing through carburetor for it to contribute enough additional air. Sloppy throttle shafts do make a difference at idle and small throttle openings, when throttle plates are closed or mostly closed. Ed has a plausible theory where a restricted, and or dirty air cleaner is allowing enough vacuum to develop which will run up vacuum advance component of timing. This is opposite of what needs to happen under WOT. Engine requires a retarding of timing under hard acceleration. |
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| Author: | Aggressive Ted [ Wed Jan 26, 2011 10:12 am ] |
| Post subject: | |
Josh P, Go to Lynnwood to Joe's Carbs for rebushing, parts for yours or a 1920. One of the best rebuilders around with lots of hard to find parts. Look up their address in the Slanted Network. They are on Hiway 99 just north of 196th. |
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| Author: | Josh P [ Wed Jan 26, 2011 12:11 pm ] |
| Post subject: | |
Quote: Somebody here had a weird problem with the air cleaner. It was too restrictive, and at WOT there was vacuum instead of 0.
That is interesting... I do have the normal air cleaner housing (which is mostly closed except for the area where the top meets the bottom and a small hole).Quote: If disconnecting the vacuum advance fixes it, get a vacuum gauge to see what's going on (or temporarily remove air cleaner)
I think I'll hook up my vacuum gauge in a bit and see what happens. Or are you thinking it should be done while the engine is under some kind of load?
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| Author: | wjajr [ Wed Jan 26, 2011 5:58 pm ] |
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Get a good length of vacuum hose, 6 or more feet in length, fish it from under hood through side wing vent window, and set the vacuum gage on your dash board, than go for a ride. Take a clip board with you and record some information; listing rpm, throttle position, up hill, down hill etc. and related vacuum readings. I do this all the time when tuning my Holley. |
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