I was told that if i ran my new engine with my open shorty headers that i could cause valve damage. Why is this is it even true? Does it maybe have something to do with back pressure and the valves being heated up then cooled so rapidly? Basically what i wanted to know was could i run the eng in the driveway to set timing and tune the carb without hooking up my PITA exhaust. Any help/insight would be greatly appreciated. Thanks -Bob

 

when i first broke in my 400 i ran it with just the headers and a y-pipe. i never had any problems with it. i would imagine that you would warp a valve with just the shorties and nothing else

 

It's an old wives tale. How many times have people run with open headers and warped/cracked a valve? None.

 

When we got my motor together and finished , and after I got back from the hospital (starter fell on my pinky finger and smashed it, 6 stiches) We ran the motor with no exhaust.

 

When I put my motor into my green car I ran it open headered to the muffler shop. damaging valves is not a concern with open headers. when I race I have a cutout that opens right after the ypipe.. basically open headers. no problems with valve damage after 3 years of racing.