ok i have 464 miles on my new 355, i have been told that at 500 i can put the hammer down, but i have also been told that i should wait until 1k, now what all do you guys think, she is running great right now with the only problems being a dam exhaust leak which is getting fixed with headman long tube headers and dual 40series flowmasters. thanks for any info.

 

the "break-in" period of an engine is largely a myth these days. all professional engine builders i know just run it for about 20 minutes once they have it put together, change the oil and it's good to go.

Personally i just take it fairly easy on an engine for the first few hundred miles. At the point you're at, i'd say if it's working fine now it's going to be working the same for a much longer time. Unless something drastic happens.

 

i go 30 minutes at 1000 to 2500 rpm idle varying the engine speed. might let it cool down once, asll with 30w dino oil. change oil and filter and get some street time on it, same deal running it up and down the rpm range from idle to around 4000. for another 30 to 60 minutes doing it with several heating and cooling cycles. after that's it's as broke in as it'll ever get. roller cams require much less break in.

 

Ok, to break in a flat tappet cam, you must run the engine at 2000-2500 rpms for 20 minutes. Then the recommended mileage before flooring it is 500 miles.

 

ok because i have the summit brand cam part number sum-11004 the heads are stock but with 1.94 valves, and ported/polished, edelbrock prefermore intake, edelbrock 600cfm carb electric choke, and beefed bottom end. so i guss ill wait until i go to my dyno on january 18th with my car club to give it full throttle. thanks for all the info.