Engine Clacking Bumping Clatter while driving uphill

[cillitbang]

Hello im Sven from austria,

I have the following problem, whenever I drive uphill(no matter how fast) and give more than 3/4 throttle the engine starts to clack strongly (sounds almost like a lack of lubrication but oil pressure is fine), at the beginning i thought that maybe a spark plug is not working, I have already replaced all 4, then I thought that I might lose compression, I then measured this, is very low but the same on all 4 cylinders, then I adjusted the valves because I thought that they might need adjustment, the noise (sounds something like mechanical bumping/clatter) comes even if I drive 70-75 Kilometers and then give full throttle shocks, I can reproduce this every time or at low speeds with even the smallest gradients (OIL is on MAX).

Did anyone already have that, or does anyone have an idea what I could check?

Best regards

Sven

[mdainsd]

Have you checked the timing? Sounds a lot like ignition knock. Or bad gasoline?

[YLG80]

Hi Sven
Have you tried to slightly reduce the ignition advance?
What is the color of the plugs?
If black, you might have carbon in the cylinders… causing knocking.
Yves

[cillitbang]

Hi mdaisn, the gasoline is fresh 95 octane.

Hello Yves,

i can try to set the ignition later,(i measured the ignition with a negative pressure device because with the stroboskop its not working for me) at the moment there is no popping or anything else to hear when its "idle", the colour of the plugs is bright grey, is there a way i can clean the cylinders withouth taking the head off?

Thanks for the answers

imperial greetings

Sven

[Wolfman]

A negative pressure device ??
Like a vacuum gauge ??
If you set the timing to maximum vacuum, there is a good chance the timing is too fast. Needs to be retarded a little.
Alternative to a strobe light.
Use a test light. Set the timing marks on the flywheel. Turn the ignition on. Put the test light on the distributor terminal the small wire from the coil connects to. Back the distributor off until the test light goes out. The points are now closed. Advance the distributor until the light just comes on. The points just opened and this is real close to where the timing should be.
Don't get bit.

[mdainsd]

Plugs should be tan to light brown. Grey indicates a too lean mixture, not good.

[dpcd67]

I set timing with a vacuum gauge and my ears. No lights.
And usually, just my ears. You can tell when it is too far advanced and knocking, like yours is. Back off the advance (rotate the distributor).

[conrod6]

Sounds like piston slap to me - this may be a UK term - don't know what our US cousins call it.

Barrie

[Donovan]

You cannot use the original timing marks to set the timing as the original marks for when ignition occurs is based on an Octane rating of ~65 (I cannot find the reference to this but pretty sure it near this number). Most regular gas is 87 today so the ignition point has to be retarded a bit more. If I remember, the original ignition point was something like 5 deg BTDC whereas it should be somewhere around 12 deg BTDC with the higher Octane gas commonly used today.
Donovan.

[W. Winget]

Have you ever oiled the mechanical advance weights under your ignition points plate?
If they do not move freely (they are under spring tension) then it will not advance as a load is placed on the engine and it will begin to misfire.
Couple of drops of light oil every few years is all it needs.
V/R W. Winget

[JAB]

I’ve used scoutilot’s (he’s on the gee too!) method successfully with my old jeeps; https://oldjeepcarbs.com/thread/29/time ... ming-light

The video at the end helps explain everything better too.

[17thAirborne]

Great Link. Thanks

[cillitbang]

Hi Wolfman,

yes a vacuum gauge, sorry for my bad description


Conrod6

yes this coud be a possible problem, i heard some videos online(the noise is very similar to me)

W.Winget

yes i oiled it a few kilometers ago

JAB

I did it that way(nice video i didnt know that this existed) i own/used the same devices as this gentlemen does
__________________________

I was very lucky because a friend of a friend of mine, own´s a fresh restored "new" complete engine and we are switching them right now, thank you all for your very good tipps and tricks

Imperial Greetings to you all

Sven