for a little background, the car is a 1986 Z28. TPI fueled 383, griffin 2 row radiator, derale 4000 cfm dual fan w/shroud, 160* t-stat, air dam is in place, radiator sealed agaisnt core support and open area between rad and grille filled in so air can only enter radiator. im running a high volume water pump, and i had heard from someone a while ago it can cause an engine to run hot by the coolant not staying in the rad long enough. my car will stay at 170 idling with both fans on when its 90* out. however, when cruising down the highway (75 mph, 2k rpms) with the fans off, it will run about 200-210* it cools off if i switch the fans on while driving. when i got home, i felt the tanks on the rad, and the cool side wasnt all that much cooler than the hot side, maybe only 30* i was thinking before it was a fueling issue, but there is no signs on of it running lean, especially at high rpms. should i go with a standard volume water pump?

 

Put a 180 or even 190 stat in first. The 160 isn't doing you any favors, as it's most likely staying open once the coolant gets too hot. Then at that point, yes, the high volume pump will be racing the coolant through the system.

 

i did have a 180* in it. it used to run hotter, about 225* with ambient around 85*

 

i looked up the pump im running, its clockwise rotation. i was thinking of ordering a standard volume. counterclockwise is for serp belt setups, right?

 

Right, reverse rotaton is for a stock serpentine setup. Have you fiddled with your ignition timing moving it one direction or the other to see if that makes a difference in temperature?

 

i set the base timing at 12*, the rest is up to the computer. i think its around 40* total advance at 4k rpm. ive thought of it, but havent tried it

 

You still running a knock sensor?

 

yes. it was desensitized, but still there. i dont hear any pinging or knocking going on, however it does on rare occacsion burp back into the intake, and thats only when its cold and in open loop.

also, can a short water pump be used with spaces to fit where a long belongs? finding a standard volume aluminum w/p under $100 is rather difficult

 

Make sure the flange on the short pump is dual drilled, short pump application uses a smaller diameter pulley bolt pattern. One thing though is using a spacer will put more stress on the pump bearing.

 

40 degrees is a decent amount of advance. I'm 16 base and 35 at full advance at 3K (msd billet stand alone w/ 6AL box) any more than that at my altitude even with 100 octane unleaded it will afterrun and run hot. If you do not have air in the system, then I would agree with 69 and that you are moving coolant too fast through the system and it is not allowing it radiate heat as it should. I put a mechanical back up gauge on during the first few miles after break in and it always ran anywhere from 10-20 degrees cooler than the sending unit gauge.....After about 500 miles on the motor it runs 180 or cooler on the move, but creeps to the 200 mark (not good when its 105+ with Al heads). I will say the first 500 miles it ran hotter than now....