Hello all, I have a 46 1 1/2 ton dump with a stock flat head V8, I made some headers to replace the original manifolds that were rusted out and cracked. As far as I know that is the only modification. What I am wondering is what is a safe RPM to rev this engine to? I don't have a tach hooked up yet but this engine seems to be revving pretty high at 45 MPH.
I have ran it up to 55 MPH but the engine seems to be screaming but it seems to just keep revving the more gas I give it. So I was hoping some one could suggest a safe RPM limit? Thanks, Dan

 

In my corner if it sound's like it's overreving .. it probably is.. you can get a rpm gauge cheep and know for sure,, any idea what gearing you have?? my 54 has 5.13 gearing .. so it is screaming at 55 mph.. so I just don't go on the highway..

 

at 55 you are screaming! does'nt mean you reached your limit. (but you ARE close) keep in mind these heavier trucks usually had a larger fan, which will scream at higher rpm,s

 

at 55 you are knocking on 3000 rpm. as long as you have good oil pressure and not running hot I would not consider it detrimental to the engine, just annoying. Depending on what I am pulling I can usually hit 50 mph in 4 high with the 8.11:5.83 rear axle. according to my tach that is 2600 rpm and I hold that for 30 miles at a time on some trips. If I am pulling one of my smaller tractors I run around 2800-3000 rpm. at 55 mph. I was able to pull a 56 ford 600 series tractor on a 25 ft lowboy gooseneck at 55 mph at 2000rpm in OD. of course in south LA we have no hills and it was not real windy. The wind is a killer on topend lol