Intake manifold design ~vs~ Intake air temp.

Having hundreds of miles of SnowWheeling just outside the bay door during that time of year, I find myself with question that I have never seen the answer to.
When the outside air temp drops to say -30°F (or lower) would the selection of a non-isolated manifold be a better choice?
We have never iced the Carb BUT we are still running non isolated intake manifolds (Performer RPM/Weiand Stealth/Torker II, etc). Next years build will be topped with the M-9424-G429 and I wonder if I’ll run into icing issues. I have toyed with fabricating a water heated plenum, which could be turned off while running the high desert in the summer time.
Figured I would just ask and see if there are any other Snow Runners that can give some input.

Thanks!

very interesting subject , cant wait to hear what the experts will say

Years ago, my only car had to do everything. It had a tunnel ram and had to go to work and everywhere else I wished to go, in the winter around here at an average of 20 degrees F; sometimes colder or warmer.
It used to ice up something terrible until I used some 302-V8 4 barrel water heated spacers under the 4 barrel carbs.
I don't know where you can still find them, (they were all over the place in the late 60's early 70's), however. some kind of way to water heat the mixture at the plenum would certainly work.

rmcomprandy wrote:Years ago, my only car had to do everything. It had a tunnel ram and had to go to work and everywhere else I wished to go, in the winter around here at an average of 20 degrees F; sometimes colder or warmer.
It used to ice up something terrible until I used some 302-V8 4 barrel water heated spacers under the 4 barrel carbs.
I don't know where you can still find them, (they were all over the place in the late 60's early 70's), however. some kind of way to water heat the mixture at the plenum would certainly work.

You beat me to it. A bunch of FEs also had those spacers with a heater hose running to 'em. Think 352/390 Galaxies...

dfree383 wrote:You have to have moisture to ice........ The air gets pretty dry when it gets that cold out.

True, but if a fella stores his rig inside, maybe even equipped with some heat, then he'll have some snow melting on the floor, raising the humidity level inside and then the still cold fuel tank will draw this moisture into it via the vent...causing condensation to collect inside the fuel tank. This will produce the conditions for making ice INSIDE the fuel system when the rig is let back out into the cold environment.

If a fella can control the above condition, by keeping the environment dry or by using a dry-gas additive to adsorb the condensate (such as a bottle of 99% iso-propyl alcohol, not 70% rubbing alcohol), then a fella needs to concern themselves with the fuel simply dropping out of the vapor phase and into droplets (fuel condensation) in the intake runners due to the air/fuel charge being too cold. Remember that the pressure inside the intake is less than the pressure outside the engine so the fuel will condensate out quicker than you may think.

The method described by RMComprandy & Cletus to use a coolant-heated spacer on top of the intake does work fine at pre-heating the fuel/air charge as it enters the intake. Using an inline coolant heater installed in the lower radiator hose will assist in starting out with warm coolant flow and easier starting.

A fella could also pre-heat the incoming air via some ducting & shielding from around a exhaust manifold/header. The warm intake air charge when mixed with the fuel should keep the fuel vapor in suspension, rather than condensating or dropping out.

StickBBF

So, it sounds like there "could be" a problem but that the addition of a heat source be it heating the intake air or heating the manifold or heating a spacer would likely take care of it.
I think I will fab sheet metal panels that would enclose the manifold and could be removed in the summer time. Another other thing I think I will do is add the ability to measure the IAT in the plenum.
The issue of the condensation in the tank has concerned me (any of the "E" Fuels are bad about this) mainly because if that condensate reached the Fuel Bowl and then freezes, or is in any of the various fuel circuits and freezes and thereby cracks the Carb casting, could be expensive... Needless to say a Block Heater is a necessity as is circulating the coolant.
I have killed 3 temperature gauges over the past 6 years the are dead after a few days of sitting in the cold. Switching to electric gauges for all temperatures seems to solve the issue

Has anyone compared IAT between isolated and non intake manifolds at more "normal" ambient temperatures?

Thanks for the replies

BBF4xFord wrote:So, it sounds like there "could be" a problem but that the addition of a heat source be it heating the intake air or heating the manifold or heating a spacer would likely take care of it.
I think I will fab sheet metal panels that would enclose the manifold and could be removed in the summer time. Another other thing I think I will do is add the ability to measure the IAT in the plenum.
The issue of the condensation in the tank has concerned me (any of the "E" Fuels are bad about this) mainly because if that condensate reached the Fuel Bowl and then freezes, or is in any of the various fuel circuits and freezes and thereby cracks the Carb casting, could be expensive... Needless to say a Block Heater is a necessity as is circulating the coolant.
I have killed 3 temperature gauges over the past 6 years the are dead after a few days of sitting in the cold. Switching to electric gauges for all temperatures seems to solve the issue

Has anyone compared IAT between isolated and non intake manifolds at more "normal" ambient temperatures?

Thanks for the replies

Are you considering enclosing the intake or an exhaust manifold?

If you have a block heater that circulates the coolant, then if you had a coolant-warmed carb spacer, your carb would likely stay warm enough to not freeze even if water got into the fuel bowl(s).

Back in the day, fuel filters were comprised of a small petrol screen at the top and below it was a clear glass "sediment bowl". The nice thing about those ol' sediment bowls was the fact that you could see if there was any water (or crud) getting into the fuel...as there was a visible separation of the water (bottom) and fuel (top) of the clear glass bowl. If the periodic inspection of the sediment bowl revealed any water (or crud), it could easily be removed, emptied, wiped out and replaced in a matter of a couple minutes. Maybe you need something like that in your system?

Regarding IAT differences between the two types of intake manifolds -- I'd guess that it would vary greatly largely depending on whether or not the vehicle was moving or not, at what speed (5mph vs. 75mph), whether or not the ambient air temps were 60*F or 99*F outside, etc.

StickBBF

StickBBF wrote:Are you considering enclosing the intake or an exhaust manifold?

I will enclose the intake, and I will fab attachment points for stove when I build the new headers, so the answer is both

StickBBF wrote:If you have a block heater that circulates the coolant, then if you had a coolant-warmed carb spacer, your carb would likely stay warm enough to not freeze even if water got into the fuel bowl(s).

That is what I'm thinking and fine when I can plug in... doing multi-day runs brings the bug in that plan.

StickBBF wrote:Back in the day, fuel filters were comprised of a small petrol screen at the top and below it was a clear glass "sediment bowl". The nice thing about those ol' sediment bowls was the fact that you could see if there was any water (or crud) getting into the fuel...as there was a visible separation of the water (bottom) and fuel (top) of the clear glass bowl. If the periodic inspection of the sediment bowl revealed any water (or crud), it could easily be removed, emptied, wiped out and replaced in a matter of a couple minutes. Maybe you need something like that in your system?

I remember those and have considered a Racor filter at the tank outlet

StickBBF wrote:Regarding IAT differences between the two types of intake manifolds -- I'd guess that it would vary greatly largely depending on whether or not the vehicle was moving or not, at what speed (5mph vs. 75mph), whether or not the ambient air temps were 60*F or 99*F outside, etc.

StickBBF

Make it easy: On an "Air Standard Day".

Thanks!