Adding MAT to 350 TBI $0D/7247

[EagleMark]

I guess that makes it a good thing to play with, so it can be helpful to the whole community!

I'm trying to find the patch for $61 that expands that table. It is IAT but from factory only has like 4 entries in warm areas, expanded covers from cold to hot. I'd like to add IAT to my kids $OE conversion on his IH engine.

[907 Chevy]

I think it would be beneficial to add an mat sensor,however I'll add to what others have said earlier in the thread and say that most of your issues would be alleviated by going back to a stock air cleaner setup with a heat riser off your headers.
I'm having the exact same issues with my engine running a single plane manifold...crappy cold start idling,throttle icing,low idle,and atrocious fuel economy in cold weather.
With ambient temps around 0d F down to around -15d F during a recent cold snap,fuel economy was down to around 5 mpg. When ambient temps increased to around 30d F average,fuel economy improved by almost 3 mpg. A 60% improvement from just an increase in ambient air temps and the throttle icing issues went away as well.
I'm guessing when I find a stock air cleaner setup,fuel economy and driveability in general will improve greatly. As I said before,it would be beneficial to add an mat sensor,but in this instance,you're trying to tune around what amounts to a mechanical issue. My 0.02 cents

[woody80z28]

Do you know of anyone who has made a heat pipe work with headers? I'm open to trying that out for a winter solution, but my heat pipe was already gone on my truck and my parts truck...so I'm a little in the dark on what I'd have to fabricate.

Anyone have pics of a stock thermac or one made to work with headers?

[EagleMark]

Just find a stock GM air cleaner for your car/truck and grab the cold air tube too! Then look at Summit Racing for the part to clamp on headers for hot air.

[PJG1173]

I would imagine you could just wrap a sheet of aluminum around a couple primarys with some sort of bung to attach the heat tube to.

[EagleMark]

That's basically what they sell...

[93V8S10]

When I had this on my truck, I just made my own, wasn't hard to do. Unfortunately, I don't have any pictures. Doesn't have to be fancy, unless you want it to be, it would work even if you just stuffed the heat pipe in between a couple of tubes.

[gregs78cam]

I have thought about making a heatshield to go around the headers similar to the new LS exhaust system, it wouldn't be hard to then duct it up the air filter.

[woody80z28]

This is about the best I've found...which is nothing special from what I can see. It will only take air off one tube...will it be enough to actually do anything?

http://www.summitracing.com/parts/HED-24510/

[EagleMark]

Yes! It will! Done that been there!

I have also seen shields made like Greg described which get heat from 2 to 4 cylinders. Don't know if they were made or aftermarket. More heat more better, the valve will just close or half close sooner. More heat more better at highway speeds to as air blowing by headers is not only cooling air coming in it is blowing it by the hot air intake tube.

When I used one like you pictured I pointed it back, so air from fan or air at highway speed blew hot air in tube instead of, like being striaght up fan air or highway air would blow hot air past it.

You will notice a difference in how engine runs when cold within 1 minute of starting a cold engine. Think about how long you could hold your hand on a header tube when engine was started...

For summer time you can just block it off? But I have checked mine and it is always closed when warm. Pretty slick the new ones are with no vacuum hoses or thermac valve in air cleaner needed. But they still work well, just more stuff. If you look at older chevy trucks you will see they have one with vacuum hoses and thermac valve inside air cleaner. Newer, like my 1987 and 1990 Chevy trucks had the new flapper with thermac valve built in (no vacuum hoses).

[woody80z28]

Ok. I have two stock air cleaner housings so one of them should still have a good thermac on it. I'll have to modify my TBi studs a little to make it work, but that should be easy. Or wasn't there a single stud lid for early TBI trucks? That would be even better.

[907 Chevy]

EagleMark is right on the money. I just tracked down a stock aircleaner and installed it yesterday. Driveability is much better and the engine warms up much faster. I don't have a pipe attached to a header tube right now so I just have the heat riser tube sitting on top of a header tube. It'll have to work for the time being.
It'll be a couple weeks before I'll see if any fuel economy gains were realized as a result,but the swap has already proved worthwhile for me.

It's my understanding that the thermac valve is basically just a thermostat,is it not? It seems that its designed to keep a constant temperature of air entering the engine by either taking in warmer air off the manifold or cooler air off the fender to add to the mix depending on the temp of air flowing over the temperature sensing element.

If so,it seems running a stock setup would make tuning VE much more predictable and easier by keeping a constant temp(density) of air entering the manifold.

I'm pretty positive that if I put an 02 sensor in every header primary and watched the AFR values while the engine idled on a cold day without any sort of air preheater,I'd see wildly fluctuating AFR values between cylinders as a result of poor vaporization,fuel falling out of suspension,and fuel puddling in the intake.
Before adding the stock intake my truck smelled uber rich at cold start idle and even warm idle. I think the reason was that there was raw fuel literally running into the cylinders and getting blown out the exhaust. If anything,most of the cylinders were probably running lean as a result.

[EagleMark]

That's how it works. Where your at has a lot to do with how well it works too! I had a 1228746 $61 system on a Scout. It is from a Caprice and the Camaro of those years used it too. It was basically a 1227747 with IAT and you could see temps changing. I watched the valve and it was closed at cold start, open when hot in summer and you could see it in the middle sometimes too blending cold and warm air!

Glad someone listens to me and tried it!

[woody80z28]

So, I've been super busy lately and haven't even had a chance to do the MAT or heat riser on the truck yet. I have noticed as ambient temps have increased that the truck runs much better! It's an animal now...the throttle response is much more crisp! So by this fall you can bet that I'll have this done for when colder weather arrives. I've always assumed colder air was always better (magazines will brainwash you of this)...but in this application that is definitely wrong.

[jameslleary]

I was under the same impression, until I started reading about the projects that Smokey Yunik was doing.