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| Bad pcv valve??? https://slantsix.org/forum/viewtopic.php?t=41856 |
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| Author: | thedeputy [ Sat Sep 11, 2010 9:25 am ] |
| Post subject: | Bad pcv valve??? |
Hi gang, I've been adjusting the BBD on my 225 super six today, and it runs pretty good. Only problem is that it doesn't run very constant at idle, and sometimes stalls when coming to a sudden stop. I noticed a light whissteling/sucking sound coming from the pcv valve. As soon as I took the pcv hose from the carb, and kept the nipple shut with my finger, the whissteling/sucking sound stopt, and the engine ran perfectly. I could balance a nickel on it so to say. Do I need a new pcv valve? And what kind does it need to be? I now have the original metal one. Or can I just cap off the nipple on the carb? Thanks, Antoon |
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| Author: | ceej [ Sat Sep 11, 2010 11:13 am ] |
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You will likely need to change the PCV to a one that is appropriate for the BBD you have mounted. Removal of the PCV isn't a good idea. The PCV flows air through the engine to sweep out contaminants. Without sweep air, your oil will get dirty very quickly, and wear will be accelerated. Keeping clean also minimizes pressure in the crank case, which helps your rings to seal effectively. There are other methods for doing this without a PCV. There are exhaust evacuator systems and vacuum pumps can be used to provide flow as well. These are generally used in racing applications and are very expensive in comparison. Hope that helps! Look into a later model valve cover that you can install a Standard V165 PCV in. That should work for the BBD. I'm sure folks running the BBD will have suggestions that will work well for your application, and you should key off what works well for them. CJ |
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| Author: | rustyfords [ Sat Sep 11, 2010 1:49 pm ] |
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yeah...definitely don't eliminate the pcv. PCV stands for Positive Crankcase Ventilation and it does just that....it ventilates the crankcase. Fortunately, they're dirt cheap and available at most parts houses. Be sure to get a new grommet for where it plugs into the valve cover. |
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| Author: | olafla [ Sat Sep 11, 2010 6:21 pm ] |
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Hi Antoon, when you close the vacuum nipple on your carburetor with the finger, you increase the vacuum felt by the carb, and then your engine runs great. That indicates that something is not correctly adjusted, and/or that you have very low vacuum at idle. Do you have access to a vacuum gauge to measure the vacuum at idle, with and without the PCV-valve connected? Do you have any EGR-stuff connected? Have you adjusted the valve lash? When using a strobe light to check the ignition on my '77 Aspen Super Six, it fluctuates some degrees at idle, have you done any adjustments to the ignition, is it stock? Stalling at sudden stops (traffic lights) is very often related to faulty choke pulloff adjustment, you should definitely double check the components and settings. Quote: Try a NAPA Echlin 2-9207 (you can also get a new grommet at NAPA, Balkamp number 6301051 ). That's a plastic-body valve, the same style Chrysler used from '71 to date, but I've never had one whistle or squeak for me. If you want a metal-housing valve, use ACDelco # CV761C. You can get the CV761C and a new Dorman grommet 42064 (or Airtex 2P1007) at RockAuto. Check your PCV hose and carb base gasket as well as your crankcase breather cap and its grommet to make sure none of those is the source of the squeak via a vacuum leak.
Have you followed the carb links in the FAQ? Read through the adjustment procedures again, and double check your settings.Without hijacking this thread, but asking because it is related: I asked the forum once already without getting any response, have anyone seen any source for data on pcv-valves for different engines? I have searched but not found any, are they maybe regulated or described in official papers on emission? Olaf. |
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| Author: | rustyfords [ Sat Sep 11, 2010 7:33 pm ] |
| Post subject: | |
I'm using the metal-housing valve, ACDelco # CV761C..got it at NAPA. |
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| Author: | thedeputy [ Sun Sep 12, 2010 12:18 am ] |
| Post subject: | |
My vacuum at idle is ok at 16 inch. I haven't checked if it improves when holding the nipple shut. Another thing I noticed, is that I have about 5 inch vacuum at the ported nipple for the distributor, and I can't get it any lower, even though the throttle blades are fully closed. At least the idle screw isn't touching the adjustment point. The egr is closed off So it's best if I look for a pcv that should go with the BBD super six set up. I checked rock auto, and they list a V165 for a 79 aspen with the super six. Should be the one to order? There are no partsstores here in the netherlands who have that kind of stuff, so I have to order it over the internet. But what's different about the valve cover, and can't I use my 68 valve cover? Antoon |
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| Author: | ceej [ Sun Sep 12, 2010 8:15 am ] |
| Post subject: | |
Good idle vacuum should be in the 19+ inch range unless your carrying a lot of cam. If you have 5" at the distributor ported vacuum fitting @ Idle, you have a problem. Is this a slant six BBD, or a V8 BBD? If the latter, some mods need to be done to get the butterfly closed to an appropriate setting. CJ |
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| Author: | thedeputy [ Sun Sep 12, 2010 10:42 am ] |
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It's a v8 BBD, at least I think, because I had to change the choke bracket to a 90 degree angle as described in the super six swap in the tech area. The throttle blades however don't have holes in them. I noticed that the blades aren't fully shut when I close it manually. When I hold it against the light, you can clearly see light coming around the edge of the blades, so I guess that's where my 5" vacuum leak is coming from. I've got an incomplete BBD that came on the original supersix intake. Can I change the throttle body from that high top carb, to the low top I have? What other mods do I need to do to make the V8 carb work on the super six? Antoon |
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| Author: | thedeputy [ Tue Sep 14, 2010 10:58 am ] |
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bump What changes do I need to make to get the butterflies to close, or is it just better to get a new carb? How much play is allowable on the throttle shaft? Antoon |
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