I need a little help. When I put a timing light on my 455 it's rock steady up until I get to the 3,000 rpm range then it bounces around. Is this normal, or what can anybody tell me to do? I have checked the distributor gear and it still looks like new. I have all brand new MSD coil, distributor, cap, and wires. If anybody can help, I would appreciate it.
Check the advance bushing in your distributor, it prolly is either loose or worn. I see you have a new MSD distrib. but check it anyway, stranger things have happened.
I wanted to chime in here with a similar but different problem. My timing mark is all bouncy at idle to about 1000RPM's. And steadies out above that. I do not remember with motors doing this before, is it normal? Thanks...
Mike, Take a look at the weights and springs under the rotor. One may have broken and the weight may be flopping around. It goes to full travel as engine speed increases, and the mark gets steady. Or the springs are very light allowing alot of the mechanical advance in at idle, very suddenly.
Play in the timing chain will make the timing bounce around, usually at idle too though. I'd look at mechanical advance stuff first. John
Well I checked the advance stop and it's fine. I also looked at the springs which are light, but they are on with the weights and working. I also have a double roller chain from TA that doesn't have but 50 miles on it. Of course going to the track isn't exactly normal wear but shouldn't those things last longer than a couple years? I also tried checking the timing off the #6 cylinder just see if it could be a wire, but it jumps around the same there. I really appreciate the help, but it's still bouncing. ???
What kind of light are we talking about? Some timing lights will have a hard time dealing with the MSD (Multiple spark discharge). Right around 3000 RPM, is when the MSD starts to put out one long duration spark as opposed to multiple sparks below 3000. Might have something to do with it? How does the engine perform?
Jim, My timing light is a Craftsman, advance inductive light.? Is that my problem? I thought that was supposed to be a good light.
No, that's a good light. Do you have a HV/HP oil pump? Are you checking the timing when the motor is cold? The oil pump can sometimes cause a bit of timing fluctuation, especially if the it's pumping thick, cold oil.
Hey guys thanks for the great ideas. I don't have a high volume pump, and I am checking everything when its all warmed up. I run 10-30 oil. And the new MSD has perfect little round bushings that hold the weights on. But I will switch springs just to see what happens. I want all the timing to come in around 2500 but I'm gonna stick some stiffer ones in just to see if it changes anything. I'll let you know in a while.
Timing jumping @ 3000rpm reply Hi Wildcat4 One more thought that goes a little deeper. If your camshaft bumper in the timing gear cover is worn from years of use, check the end play of your camshaft, .006" is factory end play tolerance. If end play is excessive your timing will become unsteady. So, if all else fails, and you have a nothing else to do "pop the top" and dial indicate the lateral movment of your camshaft. Weekender
Okay, I think we found the problem. I changed springs and the bouncing timing mark is only down at low RPMs. I switched three different sets and the heaviest set I had stopped the fluxuation at high RPMs. Now my only problem is to get the advance to come in a little sooner. All my springs are new, so I would assume I don't need new ones. I just need more choices. Anyway, I'll be ready to go to the track on Friday. Thanks for all your help.
