valvetrain noise under load (1 Viewer)

[runthejoules]

Been reading through some of the old threads but haven't found my answer yet. I've adjusted the valves a couple of times and everything is in spec... but when engine is hot and under load, I get some crazy valve clatter. Especially bad in long gears uphill or starting from a dead stop if you let it bog down a tiny bit. None of this happens in neutral or if I'm on flat road or going downhill. It does it a little bit when cold but not bad.

 

[Seth S]

That’s not valve clatter you are hearing but ignition pinging. It can easily be confused with clatter but it’s much worse(meaning it’s bad for the engine). Try running some high octane gas and see if it goes away. If it does then it’s confirmed. Are you still running all your smog equipment, factory carb, and stock curve on dizzy?

 

[BlackCat]

Been reading through some of the old threads but haven't found my answer yet. I've adjusted the valves a couple of times and everything is in spec... but when engine is hot and under load, I get some crazy valve clatter. Especially bad in long gears uphill or starting from a dead stop if you let it bog down a tiny bit. None of this happens in neutral or if I'm on flat road or going downhill. It does it a little bit when cold but not bad.

Are you sure it’s not pinging/detonating? What’s the timing at? Smogged or not?

edit: @Seth S beat me.

 

[runthejoules]

its desmogged with a weber 38 and timing slightly advanced

 

[1911]

its desmogged with a weber 38 and timing slightly advanced

Timing is too far advanced; back it off (retard it) until the pinging under load goes away.

 

[runthejoules]

whoops... ok I'll back it off. It was just running so rich with that weber. I need to rejet it I suppose.

thanks!

 

[joebattle1]

premium fuel fixed this for me.

 

[BlackCat]

whoops... ok I'll back it off. It was just running so rich with that weber. I need to rejet it I suppose.

thanks!

My truck will ping with the EGR disconnected at 7BTDC. So with yours advanced an no EGR, I’d Imagine it sounds like you have marbles in the motor under load.

 

[Seth S]

Pinging is a symptom of engine setup problem. High octane fuel is a bandaid but not a fix. You likely need to fix your carb jetting and get your distributor advance curve redone as the engine behaves differently without the EGR.

 

[John Staton]

Mine ran rich after the desmog and putting on a Weber 38. I had a lot of dieseling when shutting off the engine and it was idling way too high. Would also hesitate between gears if I didn't hit it just right. After opening up the jets a bit I was able to get my idle down to 650-700 and no more dieseling. Runs great.

 

[runthejoules]

it actually ran fine before I advanced the timing but I was trying to compensate for running so rich. The carb is pretty much leaned out as much as it will go so I guess I'll just have to run it rich until I can rejet (or just run high octane)

 

[4Cruisers]

It could also be that the mechanical advance stop pin bushing is no longer there, probably bits of it are sitting in the bottom of the distributor. Check this out:

Distributor stop pin bushing dimensions

Does anyone have a picture of, or preferably dimensions, for the stop pin bushing in the distributor that limits the mechanical advance? Mine is missing and I want to make a replacement. I assume the ID is approximately 4mm x 6mm high, I can only guess that the outside diameter is somewhere...

forum.ih8mud.com

 

[runthejoules]

good find... I agree, chances are high that that bushing isn't there anymore

 

[morganism]

Dizzy FAQ

 

[runthejoules]

backed off the mechanical advance and it runs great... no pings. Thanks smart people.

 

[Seth S]

Your pistons are writing songs about how good you are for them.