C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette
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Old Oct 24, 2014 | 12:25 PM
  #1  
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From: deland fl
Default Vacuum advance

Hi guys..
I'm in the process of replacing the vac advance on my 75 and tried to find a VC1838 per Lars' papers. I can't locate one but have been sold a VC204 which I'm told is a direct replacement. However, when I check the VC204 on the Standardbrand.com website it says "it will not fit my vehicle". Anybody have any suggestions about what I need to do ?
TIA !
Larry
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Old Oct 24, 2014 | 01:42 PM
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Neither one is a direct replacement for the one that came on your vehicle from the factory, you are making a modification, they are for a Buick, which is why they list it that way.

Last edited by MelWff; Oct 24, 2014 at 01:45 PM.
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Old Oct 25, 2014 | 11:28 AM
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From: deland fl
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I guess my question should have been does the VC204 have a starts @ "HG of 7-9 and Max adv (distr. degrees @" HG) 7@10-12 like the VC1838 ? If not, what are the specs for the VC204?
Thanks
Larry
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Old Oct 25, 2014 | 01:02 PM
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From: charlotte north carolina
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The Rockauto web site has some specs if you click on the "details" or "info" (can't remember what they call it) when the item is displayed. I just got a B26 and B28 can from them.
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Old Oct 25, 2014 | 02:57 PM
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From: deland fl
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I did install the VC204 this morning and checked it out with timing light and vac gage. For those of you that need to know, it starts at 7 to 7.5 inches mercury and is all in at 12 inches of mercury. It gives me a total of 15 degrees at the crank. I set my 75 at 14 deg initial with no vac. With vac reconnected, I had 29 degrees. I ended up with 34 degrees @ 3000 RPM with no vac and 48 degrees at 3000 RPM with vac reconnected. It runs great. Now if I could just get rid of the smoke problem. Smokes bad at idle, have already replaced valve stem seals once. Any advice on valve stem seals ?
Larry
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