you very well could have other issues going on, do a compression and leak down test and let us know what you find. a video of the issue might help as well.

if you can hear the knocking at idle using a mechanics stethoscope or a long screw driver might help figure out where the knock is coming from.

 

OK. It'll be a little while till I can get my hands on a compression tester (like a week) so I'm gonna decomission her for now so I don't destroy my engine any more than it is

I will see about a video, maybe sometime tomorrow. It's dark out now and very very cold

 

Is it possible that my knocking could be caused by oil that's too thin? I doubt it, but it's worth asking. I put 5w-20 in so that it could turn over in the cold temperatures better

 

Sorry I just now figured out you replied to this. My email has been wacky the last week. It sounds like you have other issues other than carbon deposits but at least you have it a good cleaning!

I'm not sure how much black soot your seeing when you start it but when tuned right your really shouldn't see that. If you look at your tail pipe or pipes they should be a tan color kinda like what you want to see on a spark plug. I'm wondering if you have more carb issues than anything. If it's knocking and loss of power it could be drowning in fuel. However a compression test and a leak down really is the right way start now.

 

Also I don't see the oil being the issue. I would prob run 10w 30 or 10w 40. The 20 weight might be a little light for that engine since -10c really isn't that cold. Do you know how much oil pressure you have? I run 15w 40 in my 390 and its fine. I don't drive it everyday but it sits outside and still started the other day when it was 0 deg Farenheit here.

 

Yeah, I should have a compression tester on tuesday. I also took the time today to spray carb cleaner all around the intake manifold to check for a vacuum leak... no change in RPM, so I think it's fine.

 

Mine probably would too, but I bought the thinner oil cause it was having trouble turning over. turned out it was just a dead battery.

 

Ok, so I got some solid data on my compression test. It was done Dry and with engine cold cause I didn't have time to let it warm up. They are as follows. 1 (155psi) 2 (152psi) 3 (165psi) 4 (160psi) 5 (170psi) 6 (160psi)

 

You're gonna have to define "knock" first. Every one so far has assumed its a spark knock, that might not be the case. Pull every plug and note the condition. You're also need to locate where the knock is coming from.

 

Right when this issue started, I pulled the plugs to try a compression test but had the wrong adapter. The electrode of all the plugs was white, and further down there was some carbon buildup, but where the spark jumped and on the tab all the way to the base of the threads was white on all plugs. Pulled the plugs for the test today and all but cylinder 1 and 6 were black all over. 1 and 6 were still white. I did seafoam the truck and attempted to drive it pretty leadfooted, so the seafoam may have caused the carbon buildup on the plugs. Don't know.

As far as knocking or weird noises, the sounds change with engine temperature.

Cold, just started, about 2-5 minutes: Sounds like a diesel at idle, idles really slow, but fairly consistently. Give it a bit of gas, and it struggles to pick up. starts missing pretty bad, and has very little power. still sounds diesel like. Once RPM's get up to a certain point, power is pretty good, sound is better, seems ok. If you floor it in this state, it may pick up and go (and sound like marbles) and then drop out to idle, and then go and jump around, or it may just altogether die

Warmed up: idle sounds mostly normal, idle speed is normal, smooth idle, gas response is OK, not great, better power at low end, but if floored, will still do the missing thing till it gets to that certain RPM (I don't have a tach, so no clue what it is. If I had to guess, around 2000)

So the two sounds are Diesel sound at idle only, mostly when cold, and a lot of marbles rattling around in engine when it's under load at low RPM's, nothing really at high RPM's

 

White indicates a lean mixture, running too hot. It definitely sounds like pre ignition. Retard your timing and look into jetting up on your carb. This is gonna be rough because it sounds like multiple problems. If you can set your timing to factory with a light that would be a good start. Use 91-92 octane fuel, factory set your curb idle on the carb again. Replace the spark plugs and take it on a road test. That should consist of warming it up to operating temp, and then take it for a cruise where you have a steady mph at around 45-55, a hill and bring her back and check plugs. Note the condition. Now take it on a hard drive of stops and hard acceleration. Bring it back and note the plug condition. We're looking for a tan color as good mixture. From there we can adjust jetting and the timing further.

 

Ok, well in regards to retarding it, the diesel sound gets worse and worse the more I retard it. Would it be a good idea for me to clean the carb? I haven't done that yet.

 

Never hurts to have a clean fuel delivery system. Go ahead and do that. Get a timing light and set the timing again. You need that to be right before we can go any farther. Get back to me, this all sounds like some tuning issues.

 

Timing is right at 6 BTDC unless the harmonic balancer/crankshaft pulley slipped

 

Carbon buildup is the most likely cause. All that buildup can pre ignite in the cylinder before the spark. This is bad because you could detonate your piston. Pin point which cylinder/cylinders knock.