[wittsend]

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Crazyman,

Retarding the timing will reduce low end power and increase top end power. That is the opposite of what you describe. So, it sounds like your cam is already retarded. Is it possible that you are off a tooth? Some of those marks can get confusing with a three way timing gear.

Installed correctly the new chain and sprockets would advance the timing (assumimg the keyways are cut/installed correctly) back to normal over a worn set. Thus, with no other changes you should have more bottom end than top end. I would check the timing marks before you make alteration with offset keys. Something just doesn't seem right.
Tom

This post has been edited by wittsend: 25 December 2008 - 12:38 AM

[TWX]

Just because you installed it at 0° doesn't mean that this is what it's at. Remember, imperfect machining in the keyway on the crank, the keyway on the cam, the keyways on the two gears, and on the keys themselves might mean that you're a degree or two off. When I degreed my new cam back when I originally installed it in a stock engine with an Edelbrock aftermarket timing chain set I found that 0° was actually about 1.5° advanced (if I remember correctly). Being that it's a heavy car and that I drive it on the street this seemed good because it put power in lower RPM but didn't totally gut the higher end either. When I assembled my new engine and used the cam again (literally only about 2000 miles use in the old engine) I again degreed it with the timing chain and now aftermarket crankshaft, and again it was about 1.5° off.

You need to figure out if it's really at 0° or if it's off.

[blacksea7]

Hey, these guys are right.. but there's one more possibility... you became accustomed to the performance of the slacked chain and now, if the timing is where it belongs, you're now experiencing the factory specs... but personally, I'd think something is a tooth off... or machining... all of which are a possibility...........

[TWX]

Regardless, I'm afraid that you're going to have to take it apart. I know that stinks, but I can't think of another way to do any real checking.

[ImperialCrown]

If the distributor was adjusted while it had a worn chain, it will now be out of adjustment. Although base ignition timing is taken from the crank sensor (not adjustable), the distributor setting will control your fuel injector timing (adjustable). These engines also had auxillary shaft bronze bushing wear issues (the vertical one that runs the distributor/oil pump off of the camshaft). With the distributor out, you should not be able to 'rock' the shaft-driven gear back and forth where it mates with the cam drive gear. These can cause driveability concerns.

[MOPEkid]

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crazyman, on Dec 26 2008, 12:31 AM, said:

I verified the setting of the dots when I originally set it up. It's cool. However, it's a timing set designed for an LA, not a magnum. And thanks, for the insight. I feel that blacksea is right on the money. I was used to the setting that 230,xxx miles gave me, and now I'm at stock. I have all the parts in hand now. I am just waiting for a good day with the proper know how. Aside from starting it with the cover off. It used to idle at 400 rpm according to the in dash tach. After the swap, it idles at 700 rpm. That's the only way I can decide what it likes.

However, unless I install the balancer and alternator, the computer might possibly idle it up due to the low voltage.

Before the chain swap, 400 rpm was dead smooth, and the thing was rock solid powerful. Now, at 700 rpm, it has a slight burble to it.

By the "setting of the dots" do you mean you just made sure the dots were lined up, or did you use a dial indicator and degree wheel and actually degree the cam to the crank? I think it may be your injector timing as well as retarded cam timing; have you noticed any increase in top-end power? These things may not even be off by much, but the computer is also probably making things worse because of its incorrect readings.

[wittsend]

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Last summer I replaced the timing chain/gears on my LA 318. I did degree in the cam and found it to be 1 degree negative. The keyway only offered +/- 2 degrees so it is now plus 1 degree using the plus 2 slot. That said I was still "iffy" that I got it right based on the "marks." So, I double (and I think triple) checked. I say this so you know that even though I confirmed the correct setting with a dial indicator, the marks did not seem "correct." I had the radiator out, one eye closed and a straight edge and if I hadn't degreed it in I would have thought something was wrong.

I don't have anything to offer regarding the difference between an LA and a Magnum chain set. You might want to search vendors and see if they use the same part number. Also, the suggested 10 degrees advanced built into the gear set seems a bit suspect. They have cams ground to a well..., basic set of rules AND they have keyways to make adjustments. So, while it might be true, I'm incline to think that it is not.

Tom

[318a833o/d]

my LA318 t-chain was slapping the sides of the cover when I changed it last yr to double roller-expected big performance improvement because it was stretch-retarded ~ 10 degrees but no, if anything the performance probably went down a bit. was really hard to eyeball dots-had to use a plumline. Was considering retarding it a notch or two but don't want to possibly make it worse, plus all available data is for hi rpm race motors and may not apply to where I want torque performance: in the under 2000rpm range. let us know what you learn re the new setting.

[TWX]

Cool. Glad it worked out right. Hopefully you'll see as good mileage numbers as you saw before...

[kzooman83]

So, just to clarify, as I might be rebuilding a magnum 5.2 in the relatively near future; the engine performs the best with the cam actually retarded 4 degrees? Is that 4 crankshaft degrees or 4 camshaft degrees? (degrees at the crank are double the degrees at the cam)