The Stovebolt Site Forums The Shop Area Engine Shop water heated intake on 261

I'm working on a chevy 261. Does anyone have some ideas or pictures that show how to tie the(2)water lines for a water heated intake into the thermostat housing/heater return line?
Also, does a Fenton exhaust manifold require the rings where it meets the head like the stock set-up?

The exhaust manifold doesn't use rings. Only the intake manifold does.

tom langdons website has the proper routing of the water.

Water heated intakes were a mistake when manufacturers tried it, and aftermarket stuff isn't any better. The most need for heating the intake comes during cold start and warmup situations- - - -when the water is cold! "D'OH" as Homer Simpson would say! The exhaust gets hot immediately!
Jerry

I agree with Jerry. When I installed my Fentons on my 261 I had the same logic. I plumbed in plate using the exhaust lines and have never had an issue.

I have the water setup for tom. It works perfect and heats up fairly quickly. No leaks, no issues and looks nice installed. My intake is aluminum and was used with the stock exhaust prior to me obtaining it. The aluminum had some major deposits on it and took some time to chip it all out. Changed over to fenton headers so my first layout was to plumb the fentons into the bottom of the intake via exhaust gases. After doing that and reading and talking to others i was kinda steered into going with water due to the aluminum intake and the exhaust combination.

On a cold day i just need to wait a few extra min to let the intake heat up correctly.....no big deal.

Different strokes- - - - - -etc.! If somebody as big as Ford dropped water heating on their 3.8L V6 and went back to exhaust heat, I'm sure their engineers would be happy to hire some hotrodder to show them how to make it work!
Jerry

I have used both water-heated dual-carb intake manifolds and exhaust-heated dual-carb intake manifolds.

First: the Clifford and the Offenhauser intake manifold supposedly allow coolant transfer from end-to-end of the intake manifold. Fenton intakes do not allow end-to-end circulation.

The Offenhauser intake is designed to direct the flow coolant from one side to the other - the Clifford intake directs coolant to both sides at the same time. In order for the Offenhauser intake to direct coolant properly, a special bottom plate is needed, and a proper gasket must seal across the middle of the bottom of the manifold. So, except for properly plumbed/sealed Offenhauser intakes, only simple heat transfer takes place at the center base, even though there is an inflow and and an outflow port/line hose for coolant.

The exhaust heat plate/tube set-up (one or two tubes) is quicker in heating, and also only works by heat transfer to the base (not by circulation from end-to-end of the intake manifold).

Plumbing with coolant adds an extra concern regarding coolant leak.

Heating with exhaust air is less expensive, less complicated, and has no risk of damage if a leak occurs (if you get a coolant leak, you must deal with it immediately.

As William of Ockham might have wondered: why not use the simpler (and in this case, safer) solution - exhaust heat?

As William of Ockham might have wondered: why not use the simpler (and in this case, safer) solution - exhaust heat?

because liquid cooled and heated things are way cooler!

Because water heat is nearly self-regulating, and is far easier to adjust.

Unless you can draw the water directly from the block (where the water would be hot almost instantly), you will be missing out on the biggest benefit of manifold heat, which takes place during initial start up. It all has to do with preventing atomized air/fuel from coming out of suspension when it contacts the cold intake manifold. Until the thermostat opens, there won't be any hot water coming through the heater hoses (if that is the source of your hot-water-intake-heater).
I don't know what the benefit is for continuous heating of the intake manifold once the entire engine reaches operating temperature.
Carl

The guys who invented the heat riser valve probably knew exactly what they were doing when they put the thermostatic spring on it. Manifold heat is neither necessary nor desirable after warmup. It leads to detonation and engine damage, and loss of power due to an overheated intake mixture. Whether you heat the manifold with water or exhaust gas after the first 5 minutes of engine operation, you're on a fool's mission. The most effective method of manifold heating is with a vacuum motor operating an exhaust gas heat riser valve and a coolant temperature sensing vacuum control like the late 1980's GM vehicles used. The bimetal spring on the original-equipment stovebolt heat riser is the next best option.
Jerry

This topic has been discussed many times. 100's of guys have found that an aluminum aftermarket intake may need water heating full time to run properly at lowers speeds. The typical complaint is hesitation due to lack of fuel vaporization because of a cold intake manifold.The aluminum doesn't retain heat like cast iron.
If you have a proper functioning heat riser on a stock cast iron intake, try and place you hand on the intake just below the carb after a half hour. The darn intake is hotter than hell despite the heat riser being fully open.it might even be hotter than a water heated intake..

Guys, guys, look, I already did the research on this, and I'm acutely aware that there are various views, including conflicting views, about WHETHER to use water to heat the dual carb aluminum intake...I get that. Having done all that due diligence, I came to my decision to do it, to try it. What my question was: HOW to do it, what is a good way to plumb those lines into the existing hose/water ports on a chevy 261 which has (2) ports to the stock water pump,one of which just loops back into the housing, below the thermostat,
I've seen alot of 261's with a short by-pass line there...which I never really understood the purpose for. There is another port just above the thermostat that goes TO the heater. I really do appreciate all the helpful comments.

The coolant going to the manifold needs to come from the cylinder head before it gets to the thermostat. Either drill and tap the head for a fitting somewhere near the thermostat housing or fabricate an aluminum spacer plate to space the stat housing forward about 3/4" and take the coolant from there. The return line needs to go into the top of the water pump, same as the heater hose return. Not a good choice, but it's the best option of a bunch of poor ones.
Jerry

You make good points Fast truck. I didn't take into account that the intake is aluminum. That is a game changer. All of the original designs are irrelevant once you go to an aluminum intake. I still, however believe that hot water to the intake immediately upon start up would be very helpful.
Carl

Langdon sells a spacer plate as described by Jerry. I used that plate on one of my dual carb engines.

I think the lower thermostat housing on some GMC six engines have a threaded hole on the manifold side (for a temp sender, maybe)? That lower housing would be a good choice if coolant heat is used.

I do know I drove my truck with the original intake/exhaust for probably 20 years with a non-functioning heat valve. (I didn't even know it existed) Not a problem even at 10 below zero. The aluminum intake on the other hand ran OK till the outside air temp got down to around 40° or so then it needed heat. With out it the intake was very cold, but with heat, (I used water) it makes all the difference in the world. It starts well, idles well, there is a bit of hesitation till it gets up to temp, but that is probably me needing to do some fine tuning on the carburetors as much as anything else. You won't get INSTANT heat no matter which way you heat it. The exhaust would be quicker, but at least on my truck, it runs just fine with water heat. And I will never have to worry about OVERheating the intake. It is all up to you. Both ways have been used, there are pros and cons to each method.

Fleetliner, I used the two ports from that shot bypass hose to heat my manifold. That's to allow coolant to circulate through the block when the thermostat is closed. I used tubing to plum it up. Could E mail you pictures if you want. It works great.
Running a 261 with fenton exhaust and aluminum intake with TBI system that I made from junk astro van.

on my 235 with a clifford intake I just ran both hoses down under the motor and I used 2 90 degree elbows on the intake to put the hoses on and clamp down and then,i just cable tied them together