I believe the valve on both engines are interference fit with the piston crowns, so you may suffer damage if the chain breaks. The M103 has a single roller chain and rarely breaks. The biggest issue with the 8 cyl is the chain rails breaking. The tach will tell you nothing, other than the average rpm for the engine
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.