Cubby hole
Can someone explain this port please
- Thread starter Boduke
- Start date
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Lonewolf3165
Living the Dream!
That’s where your money gets sucked into. Blocking it off does no good. It has mystical powers.
Professor Fate
Push the button, Max...
Donny DartO
Well-Known Member
So now I understand the crossover port, but is it ok to block it off? And will a gasket just like in this picture do the job?
cudamark
Well-Known Member
The crossover allows exhaust to pass through to the other side when the heat riser is closed. It also heats the choke spring and keeps the carb from icing up under certain conditions. If you don't need those features, sure, block it off. A metal intake gasket will do the job.
And yes, remove the heat riser in the passenger exhaust manifold. We take the butterfly and shaft out, then weld the 2 steel sleeves shut to block the holes.
Now the exhaust will free flow out through the exhaust system, and there will be no hot gasses trying to push across the intake manifold ports with the block off gaskets installed.
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Dartfreak75
Restore it, Dont part it!
I've took apart several engines that have a little piece of metal rtved over the hole then the gasket over it. I personally do not block it off on a engine built for the street. A race engine is a different story. But if I was building a race engine I wouldn't be using factory cast heads.
Donny DartO
Well-Known Member
I have headers for it anyways. When you say weld the two sleeves, you must mean the ports on the heads, I tried to have a welder do that for me and he gave me a long explanation about the difficulty of welding cast iron. But I do have a MIG and I've seen some YouTube videos where they show it's been welded, should I just booger it up or is high risk for cracking?
No welding on the cast iron heads.
It is the factory cast iron exhaust manifolds that have the steel pivot sleeves in them, that can easily be welded shut with a wirefeed.
If you are using headers, problem solved > no heat riser.
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I timed my 56 Plymouth with a GTech not long after I got it. 277 poly, four barrel carb, dual exhaust, Powerflite trans and 200 gross horsepower. Ran 18.60. Now I didn't expect it to be fast, but I thought it shouldn't be THAT slow. So, pulled the right side exhaust pipe from the exhaust manifold and, sure enough, the heat riser valve was stuck completely shut. Took it out with some vice grips and a little cussing, left the shaft in. Now it ran 17.80.
Friend said, wow, that's a huge difference. I was kinda surprised it didn't make more difference than that, since with the closed valve, virtually all the right side exhaust (except what little sneaked by the closed valve) was forced into that one little heat riser passage and out the other side into the driver's side manifold. Probably would have made more difference with a more powerful motor.
RioGrandMan
Well-Known Member
Thanks for the info on this. I just pulled my intake off on my 66 B-cuda's 273 (for a 4-barrel swap) and found those passageways plugged with decades of carbon. Im not planning on pulling the heads off. Is anyone aware of a good way to clean this out, I was thinking, after I chip out what I can, to spray de-greaser in the upside-down 'U' passageway and then blow it out with compressed air, maybe, but I dont know where I would be sending that. and maybe something similar with the exhaust portion to try and blow it out the exhaust?
Also does anyone know what these small front and rear gaskets are? The gaskets I bought came without these.
Also does anyone know what these small front and rear gaskets are? The gaskets I bought came without these.
4eighteener
Well-Known Member
Does the 4 barrel manifold you are switching to have the heat crossover?
You can use the permatex ultra black in leue if the cork gaskets.
You can use the permatex ultra black in leue if the cork gaskets.
The upside down "U" isn't a passageway and doesn't connect to anything. Just there as a lightening hole.
The center hole connects to an exhaust port. On each side. You could just leave them plugged as they're there only to help driveability when cold. They cost power when the motor is hot.
The front and rear gaskets just seal the front and rear of the intake manifold to keep oil from escaping the lifter valley area. As suggested above, the ends can be sealed with rtv. But an intake gasket kit should include the end gaskets.
RioGrandMan
Well-Known Member
Thank you for the insight. After cleaning out the carbon I see my new intake allows for the exhaust but my gaskets do not and will seal it off so clear not so important.
Thanks
furrystump
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If you wash the engine again, make sure you get the water out of the passage that is shaped like a crescent. You don’t want it to freeze during the winter. It might crack the head. I can’t be sure, but believe that is what happened to this one.
The exhaust coming through the cross over will burn right through the gaskets in no time. So if you want the cross over blocked off, you need either use an intake manifold that does not have the cross over, or use intake gaskets witht he stainless block off plates.
Dartswinger70
Well-Known Member
someone always drops a carb flange nut in that hole...
What intake did you plan on using? You may need to remove those locator pins on the front and rear "china wall".
cudamark
Well-Known Member
clip and/or washer for the accelerator cable....
My Dad (passed away in January of 1984) dropped a machine screw down into the intake of the 440 in his 62 Dodge convertible. He thought just starting the motor and running it would blow it out the exhaust. It didn't. I pulled the driver's side head (can't remember how I figured out which one to remove), and the screw was imbedded in one of the OEM cast pistons. I pulled the screw out. The piston had screw thread marks in it, but otherwise seemed OK. Buttoned everything back up and ran it that way. The piston never failed.
Some time later he dropped an exhaust valve in his Hemi Charger. Then drove it five miles home. The valve head was imbedded in one of the pistons, and had knocked a hole in that head. Then he gave the car to me.
Some time later he dropped an exhaust valve in his Hemi Charger. Then drove it five miles home. The valve head was imbedded in one of the pistons, and had knocked a hole in that head. Then he gave the car to me.
RioGrandMan
Well-Known Member
Just look at the bottom of the intake in the pan rail area. If there's not a hole for the locator pins in that area, then you'll have to remove the locator pins. They're only there to keep the gasket from moving out of position when you install it. Just glue it to the block before dropping the intake on. Or you can do like some and just use rtv instead of a gasket. Personally, I prefer using the gasket.
By the way, that fitting you have for the hose from the intake to the water pump is too long. Reproduction fittings are available for a very modest cost. Two different sizes, depending on intake and what size bypass hose you run. Mopar Nipple 1" BYPASS for 1970 & Later 318/340/360! *See FITS & DETAILS Below! | eBay Mopar BYPASS Nipple Hose 3/4" on 1965-1974 Small Block! *ALL FITS DETAILS Below! | eBay
Early 273s used a smaller diameter bypass hose. Your intake probably uses the larger, later version. Most rebuilt cast iron water pumps today will take the screw-in fitting for the larger bypass hose, but will have a threaded adapter to run the smaller diameter fitting. If you're running the later aluminum water pump, the fitting is built in and it will require the larger bypass hose.
Here's what the correct fitting looks like.
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