motor tune problem?

[jan alma]

i recently bougt a opel gtj from 1974 whith original 1.9 motor and solex carburator.
now i`m trying to tune the engine and i have a problem.

the motor is running bad in some cases.

this is when i drive at low speed (30mph) in the third gear and i accellerate, the engine starts to give a strange noise. it sounds like there is something ratteling in the engine. now when i consist in accelerating and the engine comes at higer RPM (above 3500) the ratteling sound almost stops.
when i start to drive and i accelerate normal/very slow, the sound is not present.
but if i accelerate quite fast, the rattling sound is heard in all gears.

had anyone an idea what might be the cause of this??

[baz]

sounds like your timing is out and it is causing pinking(per ignition of fuel)
check static timing first then check fuel mixture

[Jeff Pozorski]

It could also be the timing chain tensioner. This part is known to get weak over time causing the timing chain to rattle upon sudden acceleration or deceleration. Do a search on this site for solutions (some cheap and some not) for timing chain / tensioner / noise / rattle and you should get your answer.