I bought a C118 cam from Kenne-Bell and had it installed back in 1988. As I remember the cam info. was as folllows: intake 284/exhaust 304 with 490/490 lift. I am just getting the car back on the road after a few years and have it running O.K. now but want to set the timing according to the original specs. for this cam. Does anyone have any info. on this ? Thanks, Mario.
If I'm not mistaken, KB ground the small and big block cams with the same profile. Here's the info for the big block C118: I/E duration @ 0.050" valve lift: 228/246 Lobe center: 118 Lobe lift: 0.308"/0.308" Timing events at 0.050" valve lift: I open: 1 BTDC I close: 47 ABDC I centerline: 113 E open: 66 BBDC E close: 0 ATDC E centerline: 123 Overlap: 1 Devon
Why would he need cam info to set the ignition timing? I believe that he wanted the cam info to set the valve timing/degree the cam properly.
Hello again guys, I hope I am not starting a big confusion about what I am asking for. I don't do this all the time and perhaps I am not well versed in all the lingo. All I am asking is, when I set the timing with the timing light, do I use the stock setting from the tech. manual or does the timing have to be set differently since this is a non-stock cam and if so does anyone have the specs. for this particular cam. There is a double roller timing chain from Kenne-Bell on it with the three keyway setting on the sproket and that was already set properly when the cam was installed. Thanks again , Mario.
Mario, the only "correct" ignition timing curve for your engine and car combo has to be discovered by you through experimentation. It's all right here: http://www.v8buick.com/showthread.php?t=63475 These guidelines work for your small block as well. Devon
Mario, You are confusing ignition timing and valve timing. They are 2 different things. Ignition timing is the timing of the spark in relation to piston position. Valve timing is the timing of the opening and closing of the valves in relation to piston movement. Ignition timing can be varied by moving the distributor position, and modifying the mechanical advance and vacuum advance mechanisms in the distributor. Valve timing is adjustable when you install a cam and degree it using multiple key way crank gears. Read the thread that Devon linked for you. Your optimal ignition timing will depend on which distributor you have in the car. Set the total timing.
Thankyou guys for the information. I've read about it and have seen it done many times but for me, unless I do it myself and often it remains a mystery. I did get the answer though this morning from T/A Performance. They have a lot of the old Kenne-Bell literature and they said that my idle rpm, 800-850, is correct for that cam and that I should set initial timing between 10 & 12. Mario.
See, here is the thing. Without knowing which particular distributor you have, you cannot arbitrarily set your initial timing to whatever you want. The only time the engine runs at initial timing is at an idle. As soon as the engine climbs above idle, the timing will change. The mechanical advance and the vacuum advance will add timing above the initial advance. At some higher RPM, the mechanical timing will max out. The timing will then be equal to the initial + the mechanical + the vacuum advance. At wide open throttle, the timing will be equal to the initial + the mechanical. Distributors differ in the actual amount of mechanical advance built into them. This varies by year and engine. When you increase initial, you increase the total maximum timing. There is no getting away from this unless you modify the distributor. That is why I advocate setting the total timing. With a specific total timing, the initial will be whatever it will be depending on the distributor in the engine. You have no choice in this, UNLESS you modify the advance mechanisms. The reason I wrote that thread is because of the confusion I see evident when it comes to ignition timing basics. If you set the initial timing to 10-12, you may over advance at higher RPM's. The total timing needs to get checked. You can do this yourself if you read my thread and attempt it.
