So the Berlinetta I'm about to get has a 305 V8. She likely was cared for most of her life up until some air force kid abandoned her on a base near by since 2019. Since she was discovered in 2023, she's had a piston slap or a rod knock upon start up but the sound goes away after the engine gets up to temp. She's drivable as is, has been since she was found. Not sure if the exhaust leak will make a difference. What's the most cost effective but effective solution without rebuilding the engine?

 

If it's piston slap, which it sounds like it MAY be, since it goes away when it warms up (usually a rod knock gets worse as the oil warms/thins) I'd just learn to ignore it. 305's (cast piston engines) don't typically have piston slap, though. Is it a valve train "tick"?

You mentioned exhaust leak also....

I think I'd start by identifying the source of the noise.

 

Zackly.

Leave the engine alone. Fix "the" exhaust leeeeek. You may well find that doing so fixes the other too.

 

Can confirm it is rod knock but the sound does go away with heat. Possible temporary solution would be using thicker oil since 5w-30 is in there now, as well as some oil additives like Restore's 8 cylinder formula. There definitely is additional ticking sounds due to a manifold leak, but that will come later. I'll keep tabs on things as I go.