455 olds

[snits]

I have a 455ci olds motor in my sleekcraft, 74' 19'. While checking the timing I found the timing mark moves around while using the timing light. Probably a worn timing chain. It will turn 4200 rpm in the water, but tends to dog out or feel like it is holding back. I have checked all the fuel system and electronic ingnition.

Has anyone experienced a timing chain causing a 455 to flatten out at high rpm. ?

I have good compression in all holes. But before I put a new timeing chain set in I though I would ask.

Snits

[sleekcrafter]

have you ran with a fuel pressure guage hooked up? Double check you plug gap, and timing. What carb are you running? and do you know that the TACH is accurate for sure. Thinks to check, before moving on.

[snits]

I did check spark gap. It was at .035, I regapped to .045. I may need to go more since it is a hfi system. It has a 750 or 850cfm Quadrajet carb, with a torker manifold.

When I timed the motor I used one of the new timing lights you can set your degree. I had it at 30 degrees advanced. When you watch the timing light on the harmonic balancer you see the mark moving around, not staying where you set it, even at idle.

It has a new fuel pump, (oem). I do have an electric pump I could install that may help it. The plugs tend to be white, running lean, so maybe it is a fuel problem. I act like it starves for fuel at wot.

snit 74 sleekcraft rebel

[OldSleekOlds]

The maximum rpm will be determined by the hp that the engine develops and the condition of the jet pump. While 4200 rpm doesn't sound like much, a Berkley pump with a "AA" impeller, all in good condition, will require about 280 hp to turn 4200 rpm.

The "wandering" spark advance is likely the result of wear. It could be the distributor, the camshaft floating front to back, and/or the timing chain and sprockets. The total advance can be as much as 36° running premium fuel. There is no guarantee you can run 36°, that's just the generally accepted max for a 455 Olds.

There are so many variables that can influence engine performance that I'm not going to try to second guess all the possibilities there.