Stewart stage 3

[Belgian1979vette]

Ok, I have a new stewart stage 3 waterpump for my vette. I noticed that this pump has boses on the outlets where you can tap in connectors and have additional hoses to the side of the block. Is it worthwile to consider this mod and how difficult is it drilling in the cast iron block ? I'm a bit scared drilling the block.

 

[guru]

They arent for connecting to the side of the block. You run the lines to a coolant port you drill directly under and centered below the siamesed exhaust ports.

If you read their recommendations/tips/tricks/FAQ section they mention it.

http://www.stewartcomponents.com/tech_tips/Tech_Tips_5.htm

External Plumbing
Street-driven vehicles seldom need auxiliary plumbing or coolant lines. SBC race engines with aluminum cylinder heads usually require extensive external plumbing to address two design problems:

1. Aluminum heads have much smaller water jackets than cast-iron heads because the external dimensions are similar, but the ports are usually larger, the deck is thicker, and the material near the rocker stands is thicker, all leaving less area in the water jackets. This decreased internal area leaves less area in the water jackets.
2. The siamese center exhaust ports are a design compromise that presents additional problems when aluminum heads are used. The area near the center exhaust valves is thicker, thus allowing providing less surface area for cooling.

We recommend installing a pair of –10 AN lines that connect the rear of the aluminum cylinder heads to the thermostat housing crossover in the front. This step will help offset the smaller water jackets. A pair of -10AN lines connecting the pressure side of the water pump with the area in the center of the cylinder head (just below the exhaust ports) will offset the lack of surface area due to the extra material.

 

[redvetracr]

I run that setup but mine go to the head (not the block) and I use a -6 hose...cooling has never been a problem.
redvetracr

 

[Twin_Turbo]

Howard, is yours closed to the block or open? I think they recommend the -10 if you seal off the pump to block passages. Effectively you'll have a sort of reverse flow cooling, with the coolest coolant being introduced right at the siamesed ports where it gets hottest.

This pump can be sealed with little o ringed plugs, the plugs are retained by the set screws on the flange.

 

[Belgian1979vette]

Question is, would it be worth the trouble drilling the block for it ?

Also, is the top connection on the pump used for something ?

 

[redvetracr]

Howard, is yours closed to the block or open? I think they recommend the -10 if you seal off the pump to block passages. Effectively you'll have a sort of reverse flow cooling, with the coolest coolant being introduced right at the siamesed ports where it gets hottest.
]

open, same Mackay pump I have used for years, just drilled and tapped it for use with the 18* heads, I also have two -8 hoses on the intake from front to rear. With the 23* motors I used two -4 lines from the thermostat housing to the top of the head (intake side at the center).....There is some mention of modifying the heads (or drilling the block) in one of the Chevy Power books...probably a later edition.

 

[guru]

Can I see a pic of those -4 lines?

 

[Twin_Turbo]

Question is, would it be worth the trouble drilling the block for it ?

Also, is the top connection on the pump used for something ?

Yes, usually a recirculating setup (hose to front coolant crossover). You'll notice these pumps don't have the anti cavitation hole on the passenger side (block has to be tapped & plugged)

No sense in drilling the block, you don't need the additional coolant in the block, you'll only disrupt then coolant flow goes into block and then to the rear and up the head, then through the head back into front of manifold and out the thermostat....this is why there is a pulsing flow which is a part of the cooling issues.
See it like this, both sides of the block heat the coolant however they can't both "flow out" through the thermostat, as both streams make it there one will always have more "force" (heat related) to push it out, this side becomes dominant and the other side stagnates (well, slows down), because of that the stagnated side heats up because coolant flow is slowed down in the head, more heat energy is transferred into the coolant, pressure rises there and that side's pressure will get higher than the other side which flows and has a nice supply of cooler coolant. The hotter side now because of climbing pressure becomes dominant and flow stagnates in the other bank. This is an ongoing effect from L to R.
The solution there is one of those Y manifolds tapped into the front of the head and doing away with the manifold mounted stat.

 

[Belgian1979vette]

Sorry TT, I understand the pulsating part, but not why drilling the block would disrupt anything. I would assume it would improve cooling of the block.

 

[guru]

From what I have read, very little cooling actually happens in the block, most of the cooling is done in the heads.

 

[Twin_Turbo]

Sorry TT, I understand the pulsating part, but not why drilling the block would disrupt anything. I would assume it would improve cooling of the block.

Because you are distupting how the coolant flows to the rear and up the head. If you drill, drill the heads. We can specuylate on it but there have been many many guys who have tested/developed systems like that including good old smokey yunick, and if those guys say something I take it as gospel.