The Ford Barn - View Single Post - What is Engine 'Break-in'??

PotvinV8 · 03-05-2021, 01:29 AM

Modern engines and modern engine builds using modern components (IE roller cams, roller rockers, etc) don't suffer from the same issues as hydraulic or solid flat tappet cam setups. Incorrect break-in of a flat tappet cam is a notorious cause of flattened lobes. I've done it and have seen it done many, many times.

I worked in a machine shop with a cam grinder who had 50 years under his belt and he told every customer the same thing, break in the cam. Vary the rpm for 10-15 mins, don't let it idle. Keep the oil pressure up and the lifters spinning (flat tappet cam lobes are ground with a ramp to force the lifters to spin to prevent them from wearing a flat spot in them). The dyno shop we use does the same thing and they test motors day in and day out. They wouldn't waste 20 mins of dyno time if it wasn't necessary.

Now, how that concerns a Model A? If I was swapping in a new cam, I'd break it in. Rings, new pistons, etc. Probably not.

03-05-2021, 01:29 AM	#12
PotvinV8 Senior Member Join Date: Jul 2018 Location: Los Angeles Posts: 114	Re: What is Engine 'Break-in'?? Modern engines and modern engine builds using modern components (IE roller cams, roller rockers, etc) don't suffer from the same issues as hydraulic or solid flat tappet cam setups. Incorrect break-in of a flat tappet cam is a notorious cause of flattened lobes. I've done it and have seen it done many, many times. I worked in a machine shop with a cam grinder who had 50 years under his belt and he told every customer the same thing, break in the cam. Vary the rpm for 10-15 mins, don't let it idle. Keep the oil pressure up and the lifters spinning (flat tappet cam lobes are ground with a ramp to force the lifters to spin to prevent them from wearing a flat spot in them). The dyno shop we use does the same thing and they test motors day in and day out. They wouldn't waste 20 mins of dyno time if it wasn't necessary. Now, how that concerns a Model A? If I was swapping in a new cam, I'd break it in. Rings, new pistons, etc. Probably not.