vortec heads and cooling issue
 

Anyone here running vortec heads with aftermarket intake and post 96 block? I've been having issues with my engine making some noises and I think I've narrow it down to possibly coolant spikes. It seems to be on the passenger side head. I am not running a coolant bypass, which I just recently read I should be using with my set up. I have a tstat that has several holes drilled in it to allow some flow. Just wondering if I should install the bypass as well. I recently switch to the holley stealth ram and have only noticed this issue since the changeover.

Re: vortec heads and cooling issue
 

Well, for anyone that may have the same problem. I did install the bypass between the water pump and the intake. It appears to have fixed my problems

Re: vortec heads and cooling issue
 

My motor runs at a cool 160-170 even on hot summer days. I can see the thermostat open at 195 like it's supposed to and it runs cool the rest of the time, and I dont ahve any sort of bypass at all.

Edit: I dont think my block is post 96... I'm pretty sure it's a TBI truck block. What's the difference in the later 1 pc RMS blocks?

Re: vortec heads and cooling issue
 

My HSR manual had this statement in it. I did not see it when I first installed the system. It pays to read I guess.
One reference I read stated:
"This manifold is primarily designed for
use on Vortec heads on pre-Vortec engine blocks. 1995 and earlier blocks have the thermostat bypass passage from the block directly to the water pump. Important: If you use this manifold on a 1996 and later Vortec engine (which doesn't have the bypass in the block), you must
run a coolant bypass line from the manifold to the 5/8" hose nipple on the passenger's side of the water pump. Route from 3/8NPT tapped hole in front of the manifold."
I never really noticed a problem with a carb and vortec heads. I put the HSR on and immediately noticed a problem. I shot the heads with a heat sensor gun and they were about 40 degrees different. Steam pockets were forming in the passenger side head. I run the bypass tstat and it still had the problem until I put the hose bypass in.:confused:

Re: vortec heads and cooling issue
 

I have had same problem(880 block and eq heads).Temperaturemeter spikes and then goes normal temp.After I changed waterpump and new thermostat problem was solved.I have two 5mm holes drilled to thermostat body.
Have you cheked that you have normal pressure at cooling system(no air in system)?

Re: vortec heads and cooling issue
 

I have a 74 Block, with Vortec 906 heads, standard water pump, no issues.........

Re: vortec heads and cooling issue
 

Can you post pic of your bypass?

I gearing up to do a L31 swap and have been looking at how to do a propper bypass.

Re: vortec heads and cooling issue
 

I've run the vortec's and an rpm airgap with no problems at all. mind you , car was 3.1 to 350 swap/70' block. valve guide wear convinced me to change heads back to corvette aluminum and performer. 11:1, great torque with 214 cam.