MY 1963 327 340 hp engine keeps running after i turn it off, car runs great until i turn off the key . I have the timing set at 12 degrees should i add or take out timing? it has the solid lifter cam valves are set at 12 & 18 hot . thanks all
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Re: ENGINE TIMING
lower the idle speed for startersBill Clupper #618 -
Re: ENGINE TIMING
There are a couple of issues to consider.
First the OE "201-15" vacuum advance control is not well suited to the vacuum characteristics of the Duntov cam. It will not provide full advance until about 15.5" Hg., yet the engine typically idles at only about 12". The result is insufficient total idle timing that can heat up the combustion chamber boundaries, which can lead to detonation and run-on. It can also cause idle instablility.
The technically correct VAC to use is the 8" type used on later SHP/FI engines. It is available at NAPA under part number VC1810 and is stamped "B28". This number can be cross referenced to other brands, but they are all made by Standard Motor Products and carry the same stamped ID.
If the engine will operate without detonation (and assuming that the original distributor is installed or equivalent, which provides 24 total degrees centrifugal advance), set the initial timing up to 14 degrees, and this should yield total idle timing of 14+16 +30, which is in the ballpark for a high overlap cam and should keep the engine cool.
Idle speed is somewhat subjective - set it to the lowest speed that yields acceptable idle quality. For me this is about 850-900 with the Duntov cam.
If the above fails, get in the habit of releasing the clutch as you turn off the key. Cars don't have cognitive systems to adapt to varying conditions - like different gasoline properties than 40 years ago - so we drivers have to make the adjustments in our technique, if required.
DukeComment
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Re: ENGINE TIMING
it has the VC 1810 can and the idle speed is 750 to 850 . so just adv. timing a couple of degrees..............THANKSComment
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Re: ENGINE TIMING
Given the VC1810 VAC a couple of degrees more initial timing probably will have little or no effect, but it's worth a try. Depending on operating conditions and available octane, s distributor with 24 degrees centrifugal should be set at 10-14 initial, and 14 is usually best if there is no significant detonation.
Also be sure that you set the initial timing at a speed below where the centrifugal starts. Otherwise your true initial will be less than you measure.
DukeComment
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Re: ENGINE TIMING
can you explain detanation in simple terms .............. thanksComment
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Re: ENGINE TIMING
Nancy, My 63 360 HP had the 201 Vac advance. Hi-dome pistons, 12-18 cam. Pure stock. I realize that this VA is not as good as the one that Duke recommended and you agree. But for judging it's a must. Anyhow higher octane fuel will correct the problem for sure. I can turn my off no matter how hot it is without any detonation. Reason is 100 LL fuel. If I were to use the 91 octane crap it would be another story. JohnComment
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Re: ENGINE TIMING
Nancy, Sorry for typos. I HAVE the 201 original VA so I don't get any deducts. I had another 63 driver that was originally a 340 HP car and no way could I ever turn the key off without denotation. I was using 93 octane at the time. Only way I could shut down was to put the car in first gear and let the clutch out and stall it out without ramming the garage door. So one day I put some 100 low lead aviation fuel in it and the problem was solved. Course now it's quite difficult to buy and not legal for street use. JohnComment
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Re: ENGINE TIMING
John,
You need to move down near me. I can drive up to the 100 LL pump and fill it up any time I want. Just put a tail number in the gas pump log book and drive away.
VerleComment
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Re: ENGINE TIMING
Verle, Thanks for the invite. Don't have a tail number though as my favorite tail flew the coop. Isn't that 100 LL the best fuel? Yes you hear pros and cons about it but I just listen and ignore the nays. My 63 runs so nice and smells good when doing so. LL smells sweet. Good for cleaning spots off the carpet also. JohnComment
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all this stuff abour avgas is made for high
altitude and will not run in cars is BS. i ran 100 LL in race cars and race bikes with no vapor locking problems after sunoco quit making 260 and before racing gas became available. 100 LL is equal to about 106 octane the way the rate auto fuel.Comment
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Re: ENGINE TIMING
The '63 FI system has a ported vacuum advance for some obscure reason, so it doesn't need an 8" VAC, however, my recommendation to '63 L-84 owners is to convert to full time vacuum advance and install an 8" VAC.
The VAC ID is not in the JG, but a judge can surely make the call based on system knowledge.
DukeComment
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Re: ENGINE TIMING
Detonation is "abnormal combustion". Rather than the flame front progressing across the combustion chamber in a smooth, and linear way, it progresses part way, then the remaining unburned charge "explodes" like a bomb.
This generates shock waves that you can hear as "knocking" or "pinging", and sounds somewhat like a metallic rattle. The detonation shock waves heat up the combustion chamber boundaries that can lead to preignition, which is the equivalent of advancing the spark, and this can make the detonation worse. It's this increase in heat transfer than can damage pistons and valves, but it usually takes at least sustained moderate detonation to cause damage.
Run-on after turning off the key is effectively preignition. A hot spot in the chamber is igniting the mixture in the absence of a spark, which indicates your combution chamber boundaries are very hot. Marginal octane rating can also contribute to run-on.
Detonation occurs under high load, especially at low revs, and is pretty tough to miss, although light detonation can be inaudible.
Another cure for run-on is a good Italian tuneup. Since these pre-emission engines run rich, they can build up carbon deposits from lots of idle and low load operation. They need to be run hard once in a while, which will dislodge some of the excess carbon buildup.
DukeComment
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GM solved the "run on"problem with a
solenoid that closed the carb butterflies to below idle speed setting when you shut off the ignitionComment
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63 vacuum advance
Duke, I find that most 63 car owners and some judges aren't aware of even the 201 VA as being original. They are aware of the 163 16 VA's that Chev sold as the replacements for an eon. I know you are not keen on the 201's but here is some trivia on them.
The real deal 63 201 vac. advance is what we call a two piece one. Means that the tube where the vacuum hose is attached is soldered on to the front of the can. Typical later style or replacement 201's are one piece in that area. Repros are SR's. The front of the can has a little different configuration also.
I have seen a lot of judges look for the correct ID advance though and lately I have noticed an improvement in the judging of them at the bigger shows I attend. But we are talking about show and you are talking about go. Yes a little weaker VA does the trick especially with the fuel available today. Gets you to full advance much quicker.
One thing to watch is that the 163 16's that are around listed as NOS are in fact reboxed B1's. Have found out that hard way they aren't worth crap. Spring is way too strong. JohnComment
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