Hemi Heat Tubes - how to block off/remove

[Mopsquad]

Hi All!

I'm in the process of converting the 426 to EFI and being a newbie, I never noticed the heat tubes attached to the intake manifold before.  I removed the intake manifold to install the new EFI intake and I had to unbolt the existing heat tubes.

So what should I do with them? I can cap them off and leave in place or, I can attempt to remove them from the exhaust.

What are your thoughts?

(pic is the two tubes at the time of assembly, the engine is currently in the car)

[Chryco Psycho]

The EFI wuill adapt to intake air temp so it doesn't require the heat tubes + I doubt you are driving the car in below freezing temps , the heat tubes help atomize the fuel & keep it suspended in the air while inside the intake , with injectors at the inlet of the head this will not help & will lower performance with a hot intake .
So the short answer is yes remove the tubes & plug the holes at the exhaust manifolds .

[Mopsquad]

The EFI wuill adapt to intake air temp so it doesn't require the heat tubes + I doubt you are driving the car in below freezing temps , the heat tubes help atomize the fuel & keep it suspended in the air while inside the intake , with injectors at the inlet of the head this will not help & will lower performance with a hot intake .
So the short answer is yes remove the tubes & plug the holes at the exhaust manifolds .

Thank you for the reply.  Yes, the EFI will self adjust to temp.  I guess I was asking for the sake of giving a stealth EFI look, can I leave them attached to the exhaust?  It would also save me the hassle of working down in that cramped area.  I heard there is a flapper door or something like that down low.  Will it default to staying open?

Thank you

[Chryco Psycho]

I would wire the flapper open or remove the plate from the shaft so it cannot restrict flow ,
i would also block the heat tubes in some way that is easy to remove if needed later .

[RUNCHARGER]

If you want to leave the tubes in place for the restored look you can cut some aluminum sheet pieces the size of the gaskets to sandwich between the manifold and gaskets to block them, wire the flapper open if it is still functional.

[Mopsquad]

If you want to leave the tubes in place for the restored look you can cut some aluminum sheet pieces the size of the gaskets to sandwich between the manifold and gaskets to block them, wire the flapper open if it is still functional.

Thx.

The new EFI intake doesn't have a provision for the heat tubes.  They would be blocked off by separate plates and gaskets and just hangout behind the intake manifold.

I'll see if I can check out the flapper. Not sure where and how it works.

[RUNCHARGER]

Ah: You might have to remove the tubes then. I usually build a plate for the one and install it with a gasket. The other one will need a plug of some sort made if you can't find a frost plug that will fit. I did it twice and the repro H-pipes had the nub welded on for the tube to slip on to, however they weren't drilled out so no action was needed.

[GY3R/T]

      Heat tubes attached to nothing behind intake wouldn't look stealthy and frankly would look odd. I would remove tubes and block at exaust manifold and exaust pipe. If you're just street driving, i would leave baffle alone ( if it operates freely ) They sell blockoff plates and gaskets if you don't want to fabricate.    If that's your car and motor in the pic, I don't see an exahaust baffle assembly.

[Mopsquad]

Thx for the feedback.  I'll see if I can get at the tube origins at the exhaust.  Probably the best idea to remove and then sell them.

Yes, that is my engine in the pic.  I'll investigate what the flapper assembly looks like and see if I have one installed.

[Flatdad]

Thin gage, might only be 20gage (.036") still seals fine with a gasket.

[Mopsquad]

Thin gage, might only be 20gage (.036") still seals fine with a gasket.

Thanks, I might make one or just purchase a block off kit from a Mopar parts house.

[Mopsquad]

Next question regarding blocking off the exhaust.  How do I cap the part that has a heat tube/clamp bracket attached to the exhaust? The parts houses have the plate for exhaust manifold but no mention of the other tubes attachment.

   

[GY3R/T]

As runcharger stated;  Find a plug...( oil or freeze ) that fits inside exhaust provision. Clamp or tac weld.

[RUNCHARGER]

I suppose a simple nut and bolt with flat washers could work as well.

[Mopsquad]

As runcharger stated;  Find a plug...( oil or freeze ) that fits inside exhaust provision. Clamp or tac weld.

Thx everyone!  I'll pull the tubes and see what size of flange has to plugged. 

OAN. this dual EFI conversion definitely involves a lot of ingenuity.  Just working out routing out the throttle linkage.  TG, the shaker height is perfect.