360 budget build with 343 kit causing knock

[marsupilami]

Hi all,

I just finished rebuiling my stock 360 with the 343 kit. So far, all is fine. Really straight forward plug and play. Rick's thread was a great help! Thanks again Rick!

Only difference to his build were the heads. I have the 322502 heads with smaller volume. Did not think I would get detonation as I am running on Propane.

I was wrong.

At accelleration from low rpm up to medium speed, I hear a metallic pinging. When I swich over to petrol, this is stronger. On propane it is less, but still there.

I have forwarded my ignition to a point where I am at 0 degree. This is where the knocking stops. However, cant start the enginge there anymore.

I thought it would be the heads, so I took them off and changed them to the 63cc heads that I had from the old engine.



Today, I started the engine, but still there is knock. I feel that it makes no difference on pertol or propane now, but even at 5 degree BTC it is knocking.


I even changed the platinum spark plungs for Bosch WR9DC+ ones, but that makes it only slightly better. I have now ordered WR7DC ones to see if that is doing anything.

Dont know what to check next. I can exclude anything rattling, I checked the engine bay for loose lines, but could not find any. Does not add up that on petrol it is worse than on propane?

I am running W30 break in oil with zinc additive. The hydraulic lifters are still making some noise. Not much, but a bit louder than in the old engine with 10W40 in it.

Only extra I did, was adding an oil cooler for the TH400 tranny. Don't know if that could cause any of this noise? Had a bent line in the past, causing a similar noise.

Slowly runing out of ideas, I wanted to post this to see if any of you would have any idea where to look, what to check.

Other components that were already there:
-Ready to run MSD distributor (now with the weakest springs and purple stop bushing from the 8464 kit)
-Stock manifolds with smog bosses removed
-Stainless steel 3" exhaust
-Edelbrock 2131 performer intake

I had the 63cc heads milled by 0,15mm = 0,0059". Can that be the cause?

Any help and commets are welcome!

Robin

[SC/397]

It doesn't happen often but sometimes the vibration damper slips on the rubber so the timing reading might not be where you think it is. I doubt that this what the problem is but, I would double check it.
I would try the MSD distributor and make sure the vacuum advance is working.
The only thing that I can think of mechanically is that maybe that you got the timing set 1 tooth off. Difficult to check without taking the timing cover off to look.

[marsupilami]

Cylinder 1 was at top position and the timing mark was on TDC, I checked that.

[marsupilami]

Vac advance is working, now on manifold vacuum. Will try to play with that, maybe it gets better on ported vac?

[marsupilami]

Could I use the fuel pump opening to get a small camera in to check?

[rang-a-stang]

You could try! It might save you some time. It would have to be a pretty maneuverable camera and you may not get the view you want but it is worth trying, IMHO.

[babywag]

Could I use the fuel pump opening to get a small camera in to check?

unlikely you would be able to see timing mark with oil slinger installed.

[rocklaurence]

The lighter springs in the distributor to bring on the advance sooner would be my plan but it sounds like your doing that. Cooler plugs, running lean would cause higher combustion temps.

[marsupilami]

Thanks for your comments. I really dont think I put the chain in wrong, but can not be certain.


Just wanted to share this evenings test drive:


Changed manifold vac to ported vac.


Engine cold, running on pump gas: no ping at all! Not at cruising speed, nor WOT, nor accellerating from standstil.
Engine warmed up: pinging again. Not on high revs, but especially when accellerating from slow speed. Even ping at cruising speed and slowly accelerating.



However, the ported vac seems to have improved it slyghtly.


Checked timing:
initial: 15 degree
vac: 16 degree
total with hose hooked up at idle: around 30 or 31 degree.


Changed to propane
Changed initial to 8 degree (while running in idle)
total with hose hooked up: 24 degree


test drive 2: engine at operating temp: still some ping, but definetly less than the previous drive.


Am I on the right track to exclude any flex plate/tranny issues?
Can I still have the timing chain wrong?


Next thing I want to try tomorrow is to check if it starts well at 8 degree initial
Second is to swap the light springs for stronger ones. Am I wrong to think that I want the timing delayed to avoid knock?


Also, I should begetting the cooler plugs by mid this week, so I will check that when they come.


PLease let me know your opinion. All is better than taking the engine apart to check the chain...


I made some audio recording of the pinging this evening. I will check if I can get this uploaded somewhere.

[marsupilami]

Uploaded a video

Just a short video of the engine idling. I hear some valve rattling, but not too worried.
No ping here. If you feel something does not sound good here, please share.
The video is quite wobbly, I only wanted to record the sound.

https://youtu.be/mx6u3UAUhVE

[marsupilami]

Audio File 1

https://youtu.be/SSBzYzzmHvc

[marsupilami]

Audio File 2

https://youtu.be/F_o_J60lrJI

I hope you can hear the knocking/Pinging sound I am having issues with...

[SC/397]

I can't here well enough to tell anything but, my ears aren't what they used to be.
As far as the valve train noise - Can you adjust rocker arms? The normal specs are .020"/.040" lifter preload for hydraulic lifters.
You put in the lightest springs in the distributor. Should you put heavy springs in so that it doesn't advance as fast?

[MysticRob]

Not knowing your compression ratio but knowing your detonating when warm makes me think you need to go at least one step colder on your plugs, and maybe tighten up the gap.

That was kinda creepy watching the video not seeing your boy blink, then realizing it was a still picture.

[SC/397]

Did you actually measure the 63cc heads to see if they were indeed 63cc?
They vary and I wondering if they were less than that.