VC460 valvetrain noise?

[scottykify]

Hey guys, I just finished up building a VC460 and used all the parts that came with it, I also upgraded to champion 1.1 rockers. so I noticed a slight noise when turning the engine over by hand, it ONLY happened when the pushrods and rockers were installed and valve spring pressure is pushing against it. Almost like the noise is camshaft gear backlash and when the lifter is on the down side of the cam ramp it would make a tick noise.

So I figured it must just be normal, so I installed it in the cart and started it. The thing runs great with awesome throttle response but the valvetrain noise is horrible. Im just curious if others have noticed this with the stock cam that comes with the VC460?

I have since pulled the engine back out, tore it down and cannot find anything wrong with it, verified the noise is only there when the valve springs are pushing against the lifters. I would purchase another cam if I knew that would fix the issue.

Thanks

[chrisr32]

Did you use the cam that came with the vc460? If so, I had the same problem and when using the stock Predator 420 cam and/or aftermarket cam from NR racing it was fine.

[raydhd]

Any of the stamped steel lifters have a certain "ting" to them. With the 1.3 billet rocker arms from NRracing and the cast aluminum valve cover from smalltown speed I used this noise is very minimal. Can't say if doing just one or the other would have the same effect. The valve cover is like $60 compared to the $130 for the rocker arms.

[scottykify]

Originally Posted by chrisr32

Did you use the cam that came with the vc460? If so, I had the same problem and when using the stock Predator 420 cam and/or aftermarket cam from NR racing it was fine.

yes it was the cam that came with the vc460 which from my understanding is a stock "cheater" cam which is a stock core that has been welded and reground for more duration. Im going to post a video on youtube tomorrow showing the issue. Its more than a little ring noise that comes from a stamped lifter or flimsy valve cover. Its a pretty definite mechanical noise.

Which cam did you end up going with?

[raydhd]

I don't think they use a welded cam. They just start with a cam blank and grind it for more duration and I doubt VC has the ability to grind their own cams. With the simplicity of the whole system I wonder if it has something to do with the compression release assembly making this noise.

[chrisr32]

Here is what mine sounded like with the VC460 cam. I took out the spark plug during the video to make it easy to turn over by hand. Seems like others have had a similar issue with the cam that came with the kit.

When the stock 420 cam worked and did not make the same degree of valve train noise, I opted for the 390CAM-280-0211 Camshaft, (Approx .280 lift and 220 duration (at .050)) from NRracing along with the champion shaft mounted rocker arms. Since then I am now using the 1.3:1 roller rockers from NRracing.

[scottykify]

Here's a video I made of what Im hearing and seeing, I turned it over without valve springs at the end of the video so you can hear it both ways. and I did actually run the engine to see if it went away. Same train of thought maybe it was compression release doing something weird, or if I loaded the cam like it was intended at running rpm maybe the noise would go away. but it didnt go away it still knocked. I emailed Ivan to see what he thinks.

I admit I do not know how these are manufactured, but I know there are a couple other companies that buy stock cams, add material by welding them then regrind for more duration. They're called cheater cams for racing classes that require a stock lift and stock appearing cam.

https://www.youtube.com/watch?v=Fak4KFktnM4

[chrisr32]

Yea, at first I thought it was the compression release that may have been causing the problem and since the cam may be bad anyway I removed the compression release and same noise. If I ran the engine with an open header you would have never heard it, only when I was running the muffler. I put the VC460 cam in a 420 and it was quieter so it may be the VC460 block/crank that is part of the contributing to the overall valve train noise but the aftermarket cam seems fine in the VC460.

[raydhd]

I did measure the spring pressure on the compression releases on a stock cam 100 grams and a VC cam 125 grams. I seen the VC spring has more tension on it. But that doesn't seem to be the issue in your case since the sound is there on both the intake and exhaust strokes. But to me it sounds more like there is some issue with the rocker arms rather than the camshaft.

[scottykify]

It sure sounds like its coming from inside the engine. I've been brainstorming for a day or so now and here are my thoughts. The noise is very consistent on both valves at any rpm basically, and there is 1 click when the valve starts to close, and another click when it is actually closed. So in my mind the noise is possibly gear lash banging around from drive side of the teeth to driven side of the teeth as the spring pressure actually drives the cam. and then when the lifters are back on the base circle of the cam there is another click as the crank starts to drive the cam again. Or maybe its the thrust play since its a helical gear and the cam is moving axially banging on the front cover and the engine block. Hopefully Im explaining myself well enough to make sense.