Hot Rods Heating your inline intake

I've read a pile of older threads here about the need to bring some type of heat (exhaust heat/hot water from the cooling system) to the aftermarket intake manifold of an inline engine. I understand the concept (maybe) but in doing some web searching I see that there may now be an electrical device to do this. I'm looking for input or discussion about how to use such a part. See pic.

I'm building a 181 GM 4 cyl and will need to fab my own intake. Nothing really available for these engines. Don't know why but there's not. Since its a 4 banger the intake runners will not be as long as a 6 would be but introducing heat still seems like good idea since the carb(s) sit away from the engine.

How would you go about this?

Thanks

 

Well, Clifford makes a 4 barrel intake for them and a side draft set up for Webber’s. Hill born injection is available as well.

Sometimes I see model A intakes used as the are close enough to use an adapter plate. I’ve also seen two people use an offy 3x1 intake for the Chevy 6 with the last 1/3 cut off and capped.

More to your question about heat.

the marine intake for these engines- oh yeah omc <- that might be a letter off- has a 2 carb intake the used. Have a water passage built it. It runs a hose from the thermostat housing into the intake and out the back. Like a heater hose.

The cars used exhaust heat with the exhaust manifold having a passage into the bottom of the intake. The intake has a hollow where that heat can go.

I have seen several plates that block that hole off when you use a header. Some have tapped it for water but most use an exhaust heat riser. More or less a metal tube that touches but does not enter a header primary and the. Let’s that heat rise into the intake chamber.

speedway carry’s these and most of the inline Chevy 6 places do as well.

that being said I’m leaving mine with no heat riser.

the runners are as short as an A or B 4 cylinder and I never see those with a heat riser system added.

it’s all so tight I figure the headers will damn near touch the intake. I’m not worried about the intake being to cold.

 

Follow up.

if I were going to build an intake and wanted it heated, which I had considered, I would do a log type intake for 2 carbs with an elbow to run into the head.

then attached to the log I would weld a smaller tube lengthwise with the ends tapped for fittings and run water threw it for heat.

 

I run mine with a gutted heat riser chamber and a thin stainless steel blocking plate. I do run my heater return hose zip tied to the intake manifold I Have driven in temps down to into the 20's and not experienced ant driveability issues. But on my Mopar flathead six, the stock intake and aftermarket dual intake are pretty close so heat transfer is probably pretty good not like with headers.

 

Problem solved, at least for me. Thanks for the heads up about Clifford. Didn’t realize they had anything. Just talked to them. Their intake is cast with a water jacket inside + fittings etc.. ordered one. Thanks again.


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The Cliffords work well. I've had one on my 302 Jimmy engine for a long time.

 

a couple more pics with added water heat

 

The purpose of a heated intake is really not so much about the intake. More so about the carb throttle plate area. In cold damp weather as the air fuel rushes past the throttle plates it can ice up and in general cause poor driveability. (I've never seen a throttle ice up and stick opened or closed). If your only driving your hot rod in warmer weather, you likely won't need to worry. As far as that electrical heater. IMO, I would HIGHLY recommend against that. First off is electrical heaters use quite a bit of electricity. Second and possibly of bigger consequence...is will that element turn red hot in an intake filled will air/fuel mixture? Kaboom!. Diesel engine use an electrical heater to help warm the air, but diesel fuel/air mixture tends to be far less explosive when it's not being compressed.

 

It don't get that cold in Snomish. I would not even bother.

I have spent my life trying to keep my intake charge cool. From a performance standpoint I belong to the cooler is denser and denser fires stronger. I live where it actually gets cold and don't run manifold heat if I can avoid it.

 

I've had two in-lines. The 235 used a Clifford intake and Fenton cast iron headers. I hooked copper exhaust heat tubes where they appeared were designed to go.


The second was a 230 for which I cast an aluminum, divided, equal length runner aluminum manifold. I designed in a chamber on the bottom under the carb plenum that was heated by water inside a bolt on 1/4" plate.

 

If you feel you need to warm up the carb bases bad enough, go to a local junkyard and spend some time shopping. There were several vehicles made with coolant heated carb risers. Fugly but they work.

 

Hi. My photo shows the dual 2 bbl Clifford with Webbers on my 235 engine. The front line follows AC hose to a tee at water pump and the rear line goes around rear of rocker cover and tee's into heater line there. Jimmie

 

The water style don't work well until the engine is warm But if you would add one of these with connections right before and after the carb plate it would heat up very fast. https://www.zoro.com/kats-circulating-tank-heater-1000w-120v-13100/i/G8730611/?msclkid=ca774e8bf2741941692f10962c03209f&utm_source=bing&utm_medium=cpc&utm_campaign=PLA_US_L1 Fans & HVAC Equipment&utm_term=4586200438774276&utm_content=All Products&gclid=CO7PoqK0g-cCFe2qxQIdBgAEpA&gclsrc=ds Sitting there pumping the accelerator to keep the engine running and washing the cylinder walls is an ring killer.

 

I heated my home made 250 intake using the stock exhaust manifold. There is a chamber under the main manifold tube where the heat can spread out under both carburetors. I ran the three carb intake without heat, it ran OK till it was time to start it when cold. It took a good 5 - 7 minutes of warm up before you could leave.

 

This is a two-sided coin. You are correct about a cool intake charge producing the most peak power, but for low power output it has issues with the fuel not vaporizing as good, making the engine run rougher and causing more unburned hydrocarbons and carbon monoxide in the exhausts. Probably also causes more fuel contamination in the engine oil too.

For a race engine the answer is simple, cooler is better. For a street driven engine... well, I think there are few street driven cars that spend more time on full throttle than cruising at regular speed or idling.

 

No offense but it would take an idiot to place a heater element into the air/fuel chambers of the intake.


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