VC460 valvetrain noise?

[scottykify]

ok, sorry for blowing up the forum so much today but I got somewhere finally. I didnt want to break the headgasket loose and pull out the piston anymore than really necessary. So what I did was drill out a washer to fit over the cam bearing journal and take up some slack. being careful when tightening the cover so I didnt break anything I pulled her over and no more noise! So with any luck Im going to purchase some proper thin shims and add them to each side of the cam until the noise is gone.

The case or cover is apparently mis-machined with too much thrust play in the cam and the helical gear would force the cam from one side to the other when the forces on the cam lobe from the lifters would switch direction going down the closing ramp. Makes perfect sense but sure is hard to find and measure in these engines! I asked Ivan if these shims were available yesterday, since this is what I originally assumed was the issue and he just thought I was just dumb and didnt know how the engines worked.

[scottykify]

Also with all my searching youtube and google I noticed ALOT of these VC460's sound pretty bad with this valvetrain noise. I cant wait to get it together and hopefully have a engine that sounds like a engine

[sliding]

This is what I know. I had a torque cam from Vegas carts in my engine and removed it because I couldn’t handle the valve train noise. I replaced it with a stock Honda cam. No more noise! I was building a performance G2 engine for a friends cart and was having a cam designed for that. So I sent the guy who grinds my cams the torque cam to see what specs it had. He said it was basically a cam grind that he would only use on an engine with hydraulic self adjusting lifters as it little to know tappet rams and would be extremely noisy. So this is why it is so loud in our engines and all the fixes suggested are only bandaids for a camshaft that is not designed for a flat tappet engine. I have the cam specs from his camdoctor program at home and can post them next week when I’m back if anybody wants.

[Shepard]

I have a thread below on a performance VRX460 Magnum engine I'm building as a side project. I dialed my cam end play and it was huge - .024 I used 5/8" muzzle brake shims to reduce the end play to .010. I would like to get it down to .004-5 end play but need more shims.
I set the end play on the crankshaft at .007 but the more studying I do the more I need to get tighter yet. I need to get it down to about .002.
All measuring was done on a clean block with a little oil to make things slide easy.


https://www.amazon.com/Barrel-Muzzle.../dp/B01FZLWG1Y

http://www.buggiesgonewild.com/clone...60-magnum.html

[Shepard]

I just watched your video 2 times and I noticed that it made the noise at TDC just as the magnet is under the Ignition coil. It does it on every revolution.
I think you need to pull the head and check for piston to head contact - turn your flywheel and watch when the noise happens and where the piston is at when the noise is heard. In your building did you check the piston for protrusion above the cylinder block? What type head gasket are you using? If your using the .020 metal head gasket make sure the hole in the center is a true 92mm in diameter.

[scottykify]

Hey Shepard thanks for the reply. I actually ran the engine and disassembled it, no signs of any contact on the piston or anywhere that I could see, I inspected the conrod, cam, case, piston, lifter slop, rocker arms, valve to valve guide. but if you watch the video and listen very close you can hear the same noise as EACH valve closes, even the valve closing from compression release makes a noise. Its so odd.

I ended up shimming the cam and using plasti-gage to measure the endplay, not ideal way to do it but it at least gave me an idea of where I was at. I put it back together with approximately .005 of end play in the cam. I could verify this by putting too many shims on the cam, removing the cover gasket and I could losely measure/see the gap between the case and cover. I ended up using .026 worth of shims.

So the weird thing here is that the engine was silent, sounding great turning over by hand. thinking its good to go I put it in the golf cart and started it, ran perfect, sounded good and quiet so I put all the accessories and wiring and whatnot back on. Did a oil change, valve adjustment, getting ready to go for a ride I gave it few rev's then the same noise came back! The noise is either going away or being drowned out as the rpm rises so I went for a rip anyway. and the engine runs awesome way better than a stockish 420. I used carbon steel 5/8 shims from Mcmaster carr on the end of the cam. So now I am waiting till I get some motivation back to tear it back apart to see if I can notice anything. Reaching engine mount bolts, aligning the belt drive, adjusting the start/generator, fighting the exhaust are the things I'm not looking forward to. I might have to build a temporary exhaust to test run this thing on the bench so I dont have to keep pulling it out.

If the next tear down does not reveal any issues then I think I will be ordering a different grind torque cam, from what sliding says he put these on a cam doctor and measured the actual lobe ramps and determined unsuitable for a solid flat tappet engine. "although that doesnt explain why it makes noise from the compression release" I have to try something here.

[Shepard]

Here's an old school idea but you need a modern tool, LOL. When I tracked problems in big diesel engines I used a really long screw driver - like as long as you can find. Carefully hold the screwdriver handle to your ear and touch the tip to the engine in various positions. You can hear different sounds in different places on the block. Maybe you can find the exact place the noise is coming from.

[raydhd]

OR you can buy a cheap Harbor freight mechanic's stethoscope. I use mine all the time for pin pointing noises.

[scottykify]

yep I have tried the old stethoscope already. The noise is coming from the case LOL

I really couldnt narrow it down to be honest, the noise is loudest when I touch the scope to the case pretty much anywhere.

[scottykify]

So I took the engine back out again, put about 40 minutes of run time on it cruising around the neighborhood before I took it out. Dissassembled the whole thing and no signs of damage or anything wrong. Shims are still in place and intact. Such a strange deal, I ordered some crankshaft shims so I can bring that within spec its currently about .020 endplay on the crank. Hoping that can take care of the noise, if not then Im just at a loss of ideas on what it could be. It sure sounds like steel on steel