loud rattle

[dan68toro]

When my 68 Toro is stopped at light idleing, I hear a tick sound every other second....Then last week on the interstate I hit the gas hard to pass a truck and I hear a very loud rattle( scared me silly) wondering if the two might be related or not. Anyone have any ideas what the noises could be?

Thanks

[pfloro]

Hello dan68toro:

The two noises don't seem to be related (IMHO)...

First the rattle during hard acceleration: this is probably pinging due to an insufficient octane rating of the gasoline. Are you running premium (92 or 93 octane)? The engine in your '68 has a compression ratio of about 10:1. These high performance engines need high octane fuel which burns more slowly and evenly. If you are running premium, the base timing might be too far advanced or the advance mechanisms within the distributor might not be working properly. Lastly, if the car has been used mostly for low speed driving & the engine has lots of miles under it's belt since the last rebuild (perhaps it's never been rebuilt), there may be carbon deposits within the cylinders. I have a suggestion regarding carbon buildup but don't want to rattle on!

The rhythmic ticking may be a collapsed valve lifter or something amiss in the valve train. Do you hear this ticking from the moment the car is started (cold engine)? Does the noise stop if you slowly raise the engine speed while in neutral?

Keep us posted...

Paul