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Thought I would share my experience, maybe someone has done this already. I have been a long time ROP member, but am finding more info and traffic here now.
Replacing my Edelbrock 3711 (SBO Performer EGR) with the Edelbrock 2711 (SBO Performer Non-EGR). Needed to eliminate that EGR boss for a couple of reasons.
At any rate, was struggling to find a fitting to replace the heater valve fitting at the Passenger side rear of the manifold. I knew I would not replace with another Heater Valve. I had seen some standard heater hose fittings, but I would have to use a brass reducer in the manifold to make them work. A steel factory style, non-ac heater hose fitting would work, but is kind of expensive. I happened upon this at Summit, fits exactly as needed!
Made in USA, billet aluminum, no reducer fitting needed, and fits the standard hose size. Made for a clean, low profile install. 7 bucks. I went with Anodized Black to offset the Gold engine paint. A lot cheaper than the factory style, non-ac steel hose fittings sold through a few resto places. Anyone updating to an Edelbrock intake, or want to clean up their engine bay, this looks like an inexpensive solution.
Nice find. Be aware that there needs to be a restrictor in the fitting or else the heater core will balloon and burst at higher RPM. Did that more than once over the years before I figured this out. The factory parts (hose nipple for non-AC and vacuum control valve for AC) have a 1/4" hole in the fitting.
I used the same fitting on my 2711 , I bought the blue anodised one.
Certainly does look better than the heater control valve sticking out of the intake.
One heater core ballooned and leaked after the first 5000 RPM pull.
The core expanded. The heater core tubes are wide, flat, and thin. With too much coolant flow the tubes sort of inflate and try to become round, which causes them to split at the edge.
I had the same thing happen right after a track day, kind of ballooned. My radiator guy thought it had frozen but no way that ever happened. I welded a washer onto the manifold fitting to reduce it down to appx a 1/4” opening as I learned from Olds forum. Never a problem since.
I so far have been lucky, probably jinxed myself. I just used a hardware store 3/4" hose barb and have done a few 5000 rpm runs in my 70. It is probably the 7 psi rad cap I run, at 13 to16 psi my old cars want to leak somewhere.
I put a similar brass hose hose fitting in my new eddy 3711. I have a high flow water pump as well. Now I am a little concerned I may blow the heater core based on previous comments. Not that my rev's ever get to 5000 rpm... never know though. . The old fitting I took out was pretty corroded. Almost need a flow control in the heater hose to reduce the flow or get the right fitting.
After comments here I think I will just put a cup plug with a 1/4" hole in the heater hose with a clamp to hold it in place. Any reason that wouldn't work?
One heater core ballooned and leaked after the first 5000 RPM pull.
The core expanded. The heater core tubes are wide, flat, and thin. With too much coolant flow the tubes sort of inflate and try to become round, which causes them to split at the edge.
Thanks for the info Kenneth, I'm surprised hearing of this.
The reason being, I worked in a rad shop back in the early 80's after school, Saturdays and summer vacations. Did many re cored rads and heater cores. These were the the original copper core single tube inlet/outet with the 1" X .1875 thin tube style you mentioned, a little hard water build up back in the day caused the expansion.
I know the heater cores had larger tube separation in the mid 70's , they were changed to .250 in which eliminated this at higher RPM's.
In fact,
We tested the new heater cores at 40PSI after complete, yet they could handle 60PSI before expansion began. The tank was the first expand over 60PSI.
If guys are running high flow water pumps and T-stats, I don't think, downsizing to 1/4 restriction would be a good idea to restrict the flow like the old days.
I recall one heater core that I bought from Summit in the mid 90s made a roaring noise during normal driving that changed with engine speed. Then of course it blew out after some 5000 RPM pulls.
I have a edelbrock 2711 intake and cannot find the fitting I need to work on the rear left (looking at car from the front) heater hose. The actual size of the hole is 1 inch. I need an adapter or something that will work or do I have a defective part? HELP!
I have a edelbrock 2711 intake and cannot find the fitting I need to work on the rear left (looking at car from the front) heater hose. The actual size of the hole is 1 inch. I need an adapter or something that will work or do I have a defective part? HELP!
That would be 3/4" NPT. The hose barb size is 5/8". NAPA sells a restrictor fitting that works.
The aftermarket intakes are made with a "universal" sized port so they can be used by any year vehicle. The early Olds engines had a 1/2" port and the later engines had a 3/4" port. So depending upon your hose nipple or heater valve, you may need a 3/4" to 1/2" reducer bushing.
What Joe posted above is a good choice for a straight nipple, but if you need a heater valve, one of these may be needed:
The factory restrictor fitting is to slow down the flow through the hearted core ..that’s it. it’s meant to allow the fan to have better heat transfer across the heater core.
it doesn’t reduce the pressure…the max pressure the core will see is right after the engine is shut off ..the heat soak and pressure will rise.
The whole cooling system is under the same pressure, including the heater core. whatever the rad cap relieves at, that’s what the heater core will see. a fitting without a restriction, will not balloon the heater core.
Last edited by CANADIANOLDS; Jul 28, 2024 at 02:35 PM.
Mine did. No doubt about it. The one that ballooned failed right after a trip to the track and it was a “new” copper/bass part that had only been in car 3-5 years. Welded a washer in fitting as a restrictor and no problem 20 years and counting. When I showed my radiator guy the ballooned piece, he said it must have froze, but I can say unequivocally that it never came close to freezing.
Also note post #17 has information that is contradictory to the laws of both physics and thermodynamics.
Considering that automotive A/C systems work by forcing high pressure refrigerant through an orifice. The pressure drop causes the refrigerant to expand and cool.
They are easy to install, just apply Teflon tape or paste to the external threads of it and your hose barb. Finger tighten the bushing either into the intake NPT hole or onto the barb fitting. Use a wrench on the fitting and it will tighten itself into the intake.
As I said before, I had the same ballooning failures due to no restrictor.
Also note post #17 has information that is contradictory to the laws of both physics and thermodynamics.
you haven’t got a clue what you’re talking about. I’m a refrigeration mechanic and have my boiler license. The restrictor does nothing more than slow the flow for proper heat transfer. it’s time over area for heat transfer. Same as a rad
Wow, a post on the interwebs with no source or backup as proof. Yeah, I'm convinced. EVERYTHING on the interwebs is true, after all.
do you know what you just posted is a post on the interwebs with no proof or technical info? 😂😂😂
you haven’t offered anything here so far as to the reason why the factory fitting has a smaller diameter hole than the hose or heater core in and out? let’s hear what you think.
I once flushed out a heater core with my garden hose..that’s 40 to 45 psi with waaaay more flow than any Olds water pump would ever move. then I tested it for leaks by blocking the outlet and put full hose pressure to it.
Without a pressure differential between one end of a pipe and the other, fluid will not flow. Thus, a cooling system that is the same pressure throughout cannot be flowing fluid. It is the localized pressure differential (created by the pump) that gets the fluid flowing. Thus, localized pressure in a system with flowing fluid may be quite different depending on flow, pressure and restrictions at any given point. A heater core is a substantial restriction in the system, thus is it not hard to create pressures much higher at its inlet than the radiator cap limiter (which is on the suction side of the pump, thus the lowest pressure point in the system).
Think of the cooling system as an electrical circuit. The pump (battery) generates a pressure differential (voltage) across the system (load circuit). Adding a restrictor in the intake manifold fitting that feeds the heater core is like adding a resistor in series with a light-bulb (heater core) that reduces the flow (current) through the heater core. Less coolant flow through the heater core results in less pressure differential between the inlet and outlet (which also goes to the suction side of the pump). I suspect that this restrictor also forces more fluid flow through the passenger side head since there is less flow through the heater core bypassing that critical section of the cooling system.
Just to stick a pin in this once and for all, physics proves that an orifice causes a pressure drop. The amount of drop can be calculated using formulas available here and here.
Having said that, I really doubt that the orifice is intended to protect the heater core from ballooning. I mean geeze, it's only 16 PSI. A far more likely reason for it's existence is to balance flow between the heater core circuit and the cylinder head. Coolant flow in an Olds motor runs backwards from the water pump in the block, up into the heads, and then forward in the heads to the intake crossover and thermostat. The heater core circuit actually allows coolant to bypass the RH head; reducing coolant flow to the head actually reduces the ability to cool the hottest part of the engine. The restriction in the nipple (or in the heater control valve) limits the amount of coolant that can bypass the RH head. This is the same fluid design as the restrictor in the outlet port of fuel pumps used on cars with fuel return, for exactly the same reason (otherwise the pressure to the carb would be reduced). And by the way, this is also why it's a really bad idea to simply loop the heater hose to bypass the core, or worse, go through the trouble to implement "four corner cooling" on an Olds motor. All that does is reduce the amount of coolant that flows through the heads, which are the hottest parts of the engine.
Last edited by joe_padavano; Aug 13, 2024 at 01:11 PM.
Just to stick a pin in this once and for all, physics proves that an orifice causes a pressure drop. The amount of drop can be calculated using formulas available here and here.
Having said that, I really doubt that the orifice is intended to protect the heater core from ballooning. I mean geeze, it's only 16 PSI. A far more likely reason for it's existence is to balance flow between the heater core circuit and the cylinder head. Coolant flow in an Olds motor runs backwards from the water pump in the block, up into the heads, and then forward in the heads to the intake crossover and thermostat. The heater core circuit actually allows coolant to bypass the RH head; reducing coolant flow to the head actually reduces the ability to cool the hottest part of the engine. The restriction in the nipple (or in the heater control valve) limits the amount of coolant that can bypass the RH head. This is the same fluid design as the restrictor in the outlet port of fuel pumps used on cars with fuel return, for exactly the same reason (otherwise the pressure to the carb would be reduced). And by the way, this is also why it's a really bad idea to simply loop the heater hose to bypass the core, or worse, go through the trouble to implement "four corner cooling" on an Olds motor. All that does is reduce the amount of coolant that flows through the heads, which are the hottest parts of the engine.
your first sentence is correct..the rest is hogwash.
some vehicles from the same manufacturer have a reducer fitting that feeds heater core and some dont.
GM , Ford , Chrysler etc, some have it and some don’t…even within the same year and car model.
yet they don’t have a different heater core part number…think about it.
the main reason is when testing was done, the temp drop across the heater core was not sufficient to provide the desired heat for the interior. So instead of designing a bunch of different heater cores, they used a reducer to slow down the flow to allow the coolant to stay in the core longer, that provides a higher temp drop..not pressure drop …which means more heat to the interior.
I'm sure the turbo guys will be thrilled to know that they will get improved intercooler performance via cooler intake temps at the manifold if they would just slow down the flow of fluid that is extracting the heat from the intake charge so that IT rises more in temperature between inlet and outlet.
the only thing we agree on is the reducer isn’t meant to reduce pressure.
the rest is bs and I’ll explain why. you said the heater core circuit allows the coolant to “bypass the right head” that’s not true…it allows some bleed off of coolant for the heater core, that’s all.
the majority of the coolant still passes through the head like normal…you twist things into a pretzel when there in no need. the heater core needs a feed from somewhere, the closest spot to the core is at that point.
how is that the same as a return line on a fuel pumps that’s main purpose is to prevent vapour lock by allowing fuel to recirculate back to the tank?
and if four corner cooling in an Olds is a no no, why did the NASCAR batten intake have four corner cooling returns and another in middle for a total of six back to the front by a log designed into the intake on the later versions? it’s because the water being pulled out the top of the head in three spots was better for even cooling than the factory coolant flow path…where the back cylinders ran way hotter
. The old fitting I took out was pretty corroded. Almost need a flow control in the heater hose to reduce the flow or get the right fitting.
