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I have TPI 400 block in a car that it never belonged in. I have a 1993 Caprice wagon with a highly modded set up. It does not like city driving, gets to 200+ degrees too quick.
When I open the radiator cap, I noticed a strong push of water constantly coming out of the hose coming back from the heater core. I'm thinking if that much water is being diverted, and never goes though the block, no wonder it overheats. The water in the block apparently just sits there with little recycling from the pump.
I noticed a few posts about diverter valves here apparently restricting the flow (or maybe eliminating it) coming off from the throttle body hose. My system does not have one. I'm thinking the pump pushes it into the heater core via the throttle body hoses instead of through the engine block. ((YES the 400 has the correct head gaskets with the steam holes in it)..
So should there be restricter valve of some sort, and how would I get it to function from the heater A/C controls on the dash? Electric or vacuum?
The diverter valve keeps water from going TO the heater core straight to the radiator (or oil cooler if equiped). That does end up bypassing the heater core AND the radiator... since it just ends up in the suction side tank.
The intake fitting for the TB and heater is a restricted fitting. The wall is thick, leaving a smaller passage through it. You could disconnect the hose from the intake to see if your fitting is restricted or not.
It's just a hose directly from the TB, a plastic 90* bend and straight back to the core. No restrictions.
Unless I misunderstand the routing though the block to begin with, it seems there's a hell of a lot of water coming out of it that would be better served cooling the engine block and not simply returning to the radiator so soon.
You could be right that needs more restriction. Trace back further... Where does the water come from before it goes to the TB? THAT fitting at the intake manifold should be the restrictor.
The fitting should look like this... Except you want one like the second picture, left fitting and the smaller ID. Note the smaller Inner Diameter on the left.
never considered that area to look. Will do so, and thanks.
Next question of course becomes where to find a resticter like that?
I have a non restricted fitting on my old G20 with TPI. With my setup coolant flows from under the thermostat to the throttle body to the factory heater valve where it either routes it through the heater core then to the radiator or straight to the radiator. Coolant flow through a heater core is always subtantial regardless of engine rpm. I would look into something effecting your airflow or blockage inside the radiator core itself. A 400 is going to make more heat than a 350 and even my 305 needed a massive 454 core radiator to stay cool in summer pulling around a van with the a/c blasting.
Next question of course becomes where to find a resticter like that?
I used "npt 3/4 intake hose fitting restrictor"in Google, browsed the pictures and found these;
Although, I am not sure the difference between this and this. They're both 5/8" hose, 1/2 NPT and 1 1/2" length, for $6 or $7, respectively. Compared to a 3/4" hose fitting, the ID looks much smaller than just the 5/8-3/4 difference.
to Fast355: first, thanks for all the others times you helped answer my questions over the years.
I suspect I will also need to shroud the fans to make sure the system pulls as much air through the radiator as possible. It's on the "bucket list" of things to do before my wife kills me.
But i want to get some of that mis-used water through the block as well. For the cost of a simple fitting it's good "bang for the buck" money
to Fast355: first, thanks for all the others times you helped answer my questions over the years.
I suspect I will also need to shroud the fans to make sure the system pulls as much air through the radiator as possible. It's on the "bucket list" of things to do before my wife kills me.
But i want to get some of that mis-used water through the block as well. For the cost of a simple fitting it's good "bang for the buck" money
That water IS going through the block. You can actually put a ball valve in the heater hose and manually shut off the coolant flow during the summer months. Has always made a big difference in A/C temps for me to completely shut off the coolant flow to the heater core and a source of heat into the A/C box.
I found a simple solution to the restricter issue. I happened to have a stock manifold in the garage with a fitting still in it. I pulled it to see if it was the same size inside diameter. It was slightly smaller. I looked down the bore but it seemed even smaller.
The previous owner must have had a similar issue as a small rubber grommet had been stuffed into it. I plucked the old grommet out and stuffed in a new one. I put that fitting in place, and gave it a quick drive. Engine temps dropped about ten degrees on the expressway. Stoplight to stoplight temps still were higher than I wanted to see 205-210. I get worried at that point.
So I think the overall solution will be shrouding the two electric fans so at a stoplight they can actually pull more air through the radiator. Prior to this point, I still had a single stock water pump driven fan that was shrouded. When swapping to the dual electrics, that single fan shrouding became history. Sounds like history should repeat itself in the form of shrouding the duals as well.
