1987 Looper v4 140 RPM only 4000

[nymack66]

Thanks a million guys , Boat ran like it should , Low and behold it was the damm lower unit it was a v6 all along , New v4 lower unit runs like a rabbit , No stalls etc , I am running a new Aluminum prop 13 x 19 , I am only hitting 4,900 RPM at WOT , (increase by 1000 from V6 unit) While I am very please I may downsize to a SS prop I have 13 3/4 x 17 this hopefully push me over the 5k RPM at WOT ,
However an important issue pop up , I install a new Temp sender and gauge for the first time (no previous benchmarks) I notice at WOT the temp jumps to 180 degrees and pulling back to under 4 k rpm instantly drops it to 140 degrees. New T-Stats and water pump , Strong water discharge (not as strong as the v6 ) just my observation. I am wondering if it might be the impeller since I use the one from inventory , I am not sure how old it is but a visual on it looks good.
Note I have double sender on this block this is starboard side , I will connect the port side and observe the readings on it tomorrow.
Bottom line is I am very happy with the progress on this engine at this point. I am almost there I can smell it.
If any one on this site needs that V6 lower unit I will trade it for a V4 or something just let me know. I have a new spare cdi engine harness also.