Exhaust manifold crossover

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moparkrazed

moparkrazed

Moparkrazed
Joined
Oct 5, 2007
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Location
Columbia, South Carolina
Hey guys just installed an eddy 4 bbl intake. Got everything on and realized my intake gasket didn’t have the exhaust crossover plate. Is that ok to leave open or do I need to remove everything and get the block off then reinstall?
 
With an electric choke you don't need the crossover heat so it would be better to block the crossover.
 
If you're interested in any kind of performance, block the cross over. If you're more interested in emissions and your choke, leave the cross over open.

The only negative impact blocking the exhaust cross over in the intake has is a longer warm up time and more emissions when the engine is cold.
 
RustyRatRod said:
If you're interested in any kind of performance, block the cross over. If you're more interested in emissions and your choke, leave the cross over open.

The only negative impact blocking the exhaust cross over in the intake has is a longer warm up time and more emissions when the engine is cold.
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Awesome! I’m not really looking for performance, it’s just a fun drive around town car with the kids. As long as it runs don’t sound like crap I’m good with it. It still has a 7 1/4 rear in it so I can’t hammer it too hard. I noticed small amount of smoke coming from the crossover and didn’t know it would hurt anything. Still need to adjust the carb. Just threw it on out the box.
 
moparkrazed said:
Awesome! I’m not really looking for performance, it’s just a fun drive around town car with the kids. As long as it runs don’t sound like crap I’m good with it. It still has a 7 1/4 rear in it so I can’t hammer it too hard. I noticed small amount of smoke coming from the crossover and didn’t know it would hurt anything. Still need to adjust the carb. Just threw it on out the box.
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It will be fine either way, really. I always generally block them. People go ballistic tellin me how bad they'll run blah blah blah. Not every auto maker designed engines with exhaust cross overs. So there's "THAT". lol If you leave it open, I recommend using one of those THICK insulator carburetor mounting gaskets.....maybe even one with a heat shield made onto it. That will help keep the heat off the carburetor.
 
RustyRatRod said:
It will be fine either way, really. I always generally block them. People go ballistic tellin me how bad they'll run blah blah blah. Not every auto maker designed engines with exhaust cross overs. So there's "THAT". lol If you leave it open, I recommend using one of those THICK insulator carburetor mounting gaskets.....maybe even one with a heat shield made onto it. That will help keep the heat off the carburetor.
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That’s a relief, that intake kicked my butt yesterday and reallllly didn’t want to do that thing again. Good news is I have skinny carb gasket, metal plate, thick rubbery plastic feeling carb gasket, then the carb itself. I feel better about running it as is now. Idles and sounds good, it’s responsive when I press the throttle, but the smoke haze had me worried. Thanks for the feed back as always rust and Murray. Sure is good to have good guys to bounce things off of.
 
cudamark said:
What's an exhaust crossover plate?
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I may be using the wrong term for it. But it’s basically a piece of metal (usually on the intake manifold gasket). I’ve seen some vids where they block it off with a price of metal. Plugs the hole in the intake side of the head. Not sure if all makes sense. If not I’ll take a pic of the part I’m talking about when I go out this evening to fire it off and make sure my thermostat housing isn’t leaking.
 
Back in the day I blocked the crossover on a Mopar small block with "Liquid Steel" which I guess was a kind of epoxy. When I later dissembled the motor I found the "filler" had started to break up and the passage was partially open again.
 
Oh, so you mean an intake gasket without a hole in the crossover section. I figure if the manifold was designed and built with an open crossover, it should probably remain open....at least for the street.
 
dibbons said:
Back in the day I blocked the crossover on a Mopar small block with "Liquid Steel" which I guess was a kind of epoxy. When I later dissembled the motor I found the "filler" had started to break up and the passage was partially open again.
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Man that’s crazy. Makes sense tho. I saw a guy said he used a beer can haha.
 
cudamark said:
Oh, so you mean an intake gasket without a hole in the crossover section. I figure if the manifold was designed and built with an open crossover, it should probably remain open....at least for the street.
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Yeah that’s it. The one I took had it blocked the eddy gaskets didn’t and my intake goes below it so it’s completely open. I saw some white smoke but I think it’s from not having the carb adjusted yet. We will see tomorrow when I adjust but sounds like it’s fine leaving open.
 
cudamark said:
Oh, so you mean an intake gasket without a hole in the crossover section. I figure if the manifold was designed and built with an open crossover, it should probably remain open....at least for the street.
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So you run everything on your car according to the factory service manual?
 
RustyRatRod said:
So you run everything on your car according to the factory service manual?
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No, that might not even be possible these days. I do try to keep things as stock as I reasonably can on some of my vehicles. The car companies spent a lot of time and money designing them and most things work together better that way. Naturally, there are some improvements that can be made in some areas, and in the case of my race car, lots of things are different than stock.
 
cudamark said:
No, that might not even be possible these days. I do try to keep things as stock as I reasonably can on some of my vehicles. The car companies spent a lot of time and money designing them and most things work together better that way. Naturally, there are some improvements that can be made in some areas, and in the case of my race car, lots of things are different than stock.
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Stock works good sometimes. But for the cross over, unless you live in a really cold climate, the positive effect on performance totally outweighs the cold drive-ability benefits.
 
Most of the small blocks that I mess with the passage you are talking about is plugged solid with carbon buildup anyway.
 
volaredon said:
Most of the small blocks that I mess with the passage you are talking about is plugged solid with carbon buildup anyway.
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Mine is a new motor with 700 miles on it. So everything is fairly clean on it. If it were gummed up I probably wouldn’t have ever noticed haha. I was just excited to be “done” with the intake lol. When I saw it I was like crap… I really hope I don’t have to re do all my work.
 
Does the heat riser on the exhaust work or is it blocked open?
 
moparkrazed said:
it does not work anymore I don’t believe.
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Just make sure it's open and stays that way. I would pull the intake and block the ports. You don't need hot exhaust running through that aluminum intake. Some will go through the intake even if the heat riser is open.
 
toolmanmike said:
Just make sure it's open and stays that way. I would pull the intake and block the ports. You don't need hot exhaust running through that aluminum intake. Some will go through the intake even if the heat riser is open.
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It’s actually over the intake. The intake sits so low that the hole is just above the intake itself.
 
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