HI . recently i put a new cam & solid lifters in my 1963 roadster 327 /340 hp. along with crane steel rollers set to specs .012 int.& .018 exh. it has the correct vac. can . has great vac. at ideal set about 750 RPMS. the cam is a speed pro ( CS-113R )SET @ 8 degrees. the car still wants to run after i shut it off ? should i advance it a coulple or retard it a couple ? PLUGS ARE GOOD , wires are good , it has a pertronix ign. works good . & 40,000 coil new. correct 8" balancer & timing cover .....THANKS IN ADV. NCRS MEMBER
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Re: ENGINE C2 327/340
Later year cars with air would activate the air-compressor to produce a drag on the engine when turned off. You could not worry about it and just have it in gear and begin letting out the clutch enough to see the rpms drop and turn off the ignition. In my opinion alot better that letting an engine try to run after turning off the key. -
Re: ENGINE C2 327/340
Set the lash at .008" inlet, .016" exhaust. If you want the full details on how to set lash and why I quoted the above specs, e-mail me and I will send you the valve lash instruction document.
The original vacuum can is NOT FUNCTIONALLY CORRECT FOR THIS ENGINE; '63 was the first year Chevrolet installed vacuum advance on Duntov cam engines and they just didn't get it right! The OE vacuum can needs 15-16" to pull to the stop, but the engine only pulls about 12" @ 900. You have so little total idle advance that the combustion chamber surfaces are getting hot due to too little advance and this is probably causing the runon.
A proper vacuum can is the one installed on '64-up SHP/FI engines which provides 16 degrees advance at 8". The NOS Delco part number ends with "236" and a visually identical can is available at NAPA under part number VC1810 and is stamped "B28". If you can find a new Delco 236 can it may also be stamped "B28" since Delco no longer manufacturs this part. They buy it from Dana Controls who is also the manufacturer of the NAPA/Echlin VC1810. Since 8" is less than idle vacuum the vacuum can will be "locked" at full advance at idle.
Initial OE recommended timing for the '63 L-76 is 10 degrees. The OE distributor provides 24 centrifugal. Depending on the engine and fuel quality you may be able to run up to 16 degrees, and I consider 14 to be optimum as long as the engine doesn't detonate. This combined with 16 degrees vacuum advance will provide 30 degrees TOTAL idle timing, which is what the engine needs at idle.
When setting initial timing, VERIFY that the centrifugal advance has not started by watching to see that the advance does not start for at least 200 revs higher than the speed at which you set the initial timing. It's best to set the initial at below 700 where the engine barely runs to be sure that the centrifugal has not started.
DukeComment
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Re: ENGINE C2 327/340
If all those things are wrong with Ricks engine, they would have also been wrong on a new 63 340 HP car but they didn't run on after the key was turned off. Wonder what's different on Ricks car? I've owned a few 340 HP cars over the years with correct 201 advance units and my cars didn't run on. 62 and earlier didn't have a vacuum advance unit at all and they didn't run on either. Could it be there's another problem?Comment
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Re: ENGINE C2 327/340
The combination of only 8 degrees initial and insufficient vacuum advance could cause runon. Insufficient total idle advance means the throttle has to be opened farther for a given idle speed and this can contribute to runon.
My engine had poor idle quality and stability until I installed a 236 vacuum can circa 1966, I also installed the '64 SHP/FI weights and springs.
This conbination really improved performance - good stable idle and the improved low end torque with the quicker centrifugal advance really helped being as how my car has a CR gearbox and 3.08 axle.
For ten bucks it's worth installing a VC1810 vacuum can to get the ignition map dialed in to something suitable to the engine's vacuum characteristic.
If it still runs on then we'll go to plan B.
DukeComment
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Re: ENGINE C2 327/340
Yes, but if that's the case, wouldn't it be a lot easier to just recommend setting the initial timing higher instead of changing to a non stock vacuum advance unit? These cars didn't require 25 deg or more total adv at idle to shut off when they were new so there should be no reason why it should be changed now. I would think that recommending any modification from original would be an absolute last resort. I would first test by setting the timing around 14 deg initial, then see if the problem goes away. I suspect it won't but at least one "possible" would be eliminated and at no cost or great amount of work but most of all, the car won't have a Wal-Mart vacuum advance unit on it.
One thing that I'm a little confused on is Ricks statement about 8 degrees. He mentions this in the same sentence as the cam specs and I have to wonder if he's refering to the cam timing instead of ignition timing. If cam, that could explain this problem with run on. At 8 deg advanced, that motor would have a LOT of cyl pressure at idle. Any thoughts on that?
These 340 HP cars ran VERY well when new so I would have to disagree with any modifications of any kind unless absolutely necessary.Comment
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Re: ENGINE C2 327/340
THANKS FOR ALL THE RESPONSES . THE CAR HAS THE VC-1810 CAN . IGNITION TIMING IS SET AT 8 DEGREE'S... I'LL BUMP IT UP TO 10 or 12 DEGREE'S AND SEE WHAT HAPPENS AS FAR AS VAVLE ADJ. I"LL LEAVE AT SPECS RECOMMENDED BY CAM PROVIDER...THANKS RICKComment
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