blocking of heat crossover port

[HeavyFuel]

I read that blocking the heat crossover in the intake manifold increases perfomance, if the car is not driven too much in the cold weather. 

Can someone explain the fundimentals involved in this?

[craigandlynda]

the heat crossover passageway allows the manifold to warm up some, facilitating winter operation...blocking it off may help summer performance, by keeping fuel a little cooler, but doesn't help driveability...i've done it, but would\n't really bother doing it again on a street car.

[Charger-Bodie]

Is the car going to have headers or manifolds? How wild of an engine?

[firefighter3931]

Can someone explain the fundimentals involved in this?

Basicly, all you are doing is blocking off the heat crossover with a new intake manifold "turkey pan" gasket. This keeps the intake and carb running cooler thus making more power. The added benefit is reduced opportunity for vapor lock....which is a problem for the current gasoline formulations. Todays fuel is designed for high pressure fuel injection and when it's introduced into a low pressure environment (carburator) the problems will start. There's more to it than that but that's the short version without getting too technical. 

Personally, i won't run any carburated engine unless the heat crossover is blocked off. I also like the heat insulating carb base gaskets. Anything you can do to reduce/prevent conductive & radiant heat to the fuel system is a step in the right direction. 

If you look at the current crop of aftermarket aluminum heads....none of them have a heat crossover provision. There's a reason for that. 



Ron

[craigandlynda]

Can someone explain the fundimentals involved in this?

Basicly, all you are doing is blocking off the heat crossover with a new intake manifold "turkey pan" gasket. This keeps the intake and carb running cooler thus making more power. The added benefit is reduced opportunity for vapor lock....which is a problem for the current gasoline formulations. Todays fuel is designed for high pressure fuel injection and when it's introduced into a low pressure environment (carburator) the problems will start. There's more to it than that but that's the short version without getting too technical. 

Personally, i won't run any carburated engine unless the heat crossover is blocked off. I also like the heat insulating carb base gaskets. Anything you can do to reduce/prevent conductive & radiant heat to the fuel system is a step in the right direction. 

If you look at the current crop of aftermarket aluminum heads....none of them have a heat crossover provision. There's a reason for that. 



Ron

curious, Ron....do you run any of those vehicles in below zero conditions?

[metallicareload99]

curious, Ron....do you run any of those vehicles in below zero conditions?

I can't speak for Ron, but this past winter I've started my Charger, 440, Street Dominator, cross over blocked off (Fel Pro 1215 Intake gasket/Valley tray), on several occasions in single digit temperatures.  Maybe even sub zero once or twice, but I couldn't say with absolute certainty.  It was never all that hard to start except for the one time I flooded it.  My advice is to take care not to flood the engine and give it a decent amount of time to warm up, although most people probably don't drive em in such cold
 

[Ghoste]

I've started and driven mine many times in freezing temps with the heat crossover blocked.  It's true, you can't just fire it up and take off like you can in the modern efi cars that have spooiled us all.  It has to be started with love and respect for old technology and then allowed to warm up before moving but when I take the Charger I'm not rushing to work or the hospital or anyhwere like that anyway so letting it warm up is a good thing.  It maybe adds two to three minutes to my start to pull out of the driveway time over the summer cruise.

[Musicman]

The only place I can see cold weather having any affect at all, is on engines which utilize a thermal choke system.... and that's no big deal either if your letting your engine warm up in the yard before driving.

[firefighter3931]

curious, Ron....do you run any of those vehicles in below zero conditions?

I can't speak for Ron, but this past winter I've started my Charger, 440, Street Dominator, cross over blocked off (Fel Pro 1215 Intake gasket/Valley tray), on several occasions in single digit temperatures.  Maybe even sub zero once or twice, but I couldn't say with absolute certainty.  It was never all that hard to start except for the one time I flooded it.  My advice is to take care not to flood the engine and give it a decent amount of time to warm up, although most people probably don't drive em in such cold
 

while i don't drive a hotrod in the winter i will start them up periodically. It just takes a little finesse to feather the throttle and once warmed up it will settle into a nice idle.

I'm more concerned with performance during the spring/summer/fall.



Ron

[craigandlynda]

no doubt it helps performance in mild or warm weather. when its cold, like REALLY cold (up here in northern minnesota, near canadian border, where we see days on end of 20-40 below sometimes) i have two dodge trucks, and that heat crossover is key to being able to get moving in the morning and off to work...the other necessity is a block heater, or the oil gets like glue. I've seen mobil 1 synthetic dribble out looking more like honey than oil at 40 below...also, we block off radiators with cardboard much of the winter...c'mon up and visit sometime, and we can hammer nails with frozen bananas. or, as we do when we celebrate newyears, throw pans of boiling water up in the air, and watch it snow coming down....

[firefighter3931]

Craig, you don't have to tell me about snow and cold....i live north of you in the Great White North.     Last winter we had a total accumulation of 15+ feet and temps dipped into the -40c range frequently. Not exactly hotrod weather though. 

If you're winter driving a 440 in -30 temps i can see your point about the heat crossover....no arguements there. 




Ron


PS. Check out this thread for some cool snow pix.....yes it got worse and we had more of the white crap. 

http://www.dodgecharger.com/forum/index.php?topic=41117.msg452951#msg452951

[craigandlynda]

nice pics! we live in Ely MN, lived in Embarrass, MN for five years...yep this last winter was a doozie...coldest we ever had here was feb 2 1996...(groundhog's day) 64 below...and the local merchants were have the "winter gear challenge" where they build snow huts and camp out overnite...most of them quit and went home!here's what one of my friends uses to plow his way out...

[Just 6T9 CHGR]

Screw all this technical mumbo-jumbo!   Bottom line.....

Blocking the crossover keeps the paint from burning off your freshly painted intake!

Nuff said!

[histoy]

Does someone have the Fel Pro number for a 383 engine intake gasket/valley pan with a blocked off heat crossover?

[Ghoste]

1214

[histoy]

Thanks Ghoste!

[Chatt69chgr]

Ron makes a good point about the carb base heat insulating gaskets and the current fuel problems.  I have heard that some of the gasoline companies don't put alcohol in their gas.  Costs maybe 25 cents more per gallon.  Might be good to use this in cars or small engines like weed eaters that don't get run much to save the carburetor from being internally corroded.

[HeavyFuel]

Can someone explain the fundimentals involved in this?

Basicly, all you are doing is blocking off the heat crossover with a new intake manifold "turkey pan" gasket. This keeps the intake and carb running cooler thus making more power. The added benefit is reduced opportunity for vapor lock....which is a problem for the current gasoline formulations. Todays fuel is designed for high pressure fuel injection and when it's introduced into a low pressure environment (carburator) the problems will start. There's more to it than that but that's the short version without getting too technical. 

Personally, i won't run any carburated engine unless the heat crossover is blocked off. I also like the heat insulating carb base gaskets. Anything you can do to reduce/prevent conductive & radiant heat to the fuel system is a step in the right direction. 

If you look at the current crop of aftermarket aluminum heads....none of them have a heat crossover provision. There's a reason for that. 



Ron

Regarding a stock engine/intake/carb setup, how is sufficient manifold heat achieved in order to accomplish complete fuel atomization if the crossover is blocked?

I'm asking because of a stumbling problem at quick throttle (I'm currently running the block-off), and after reworking my distributor a few times, the engine temp is up a little, and my stumble is much better. 

Could be the distro work is working better, but it could be the hotter intake.   

My temps (according to the factory gauge on the dash) have gone from 180* to about 190-195*.