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Technical Heat crossover in iron intake

Discussion in 'The Hokey Ass Message Board' started by Fabulous50's, Apr 20, 2021.

  1. Fabulous50's
    Joined: Nov 18, 2017
    Posts: 344

    Fabulous50's
    Member
    from Maine

    What is the consensus about heat crossovers? I removed the butterfly on the passenger side manifold, and now that I have the engine out, is it worth filling in the crossover ports? Or will this result in a cold blooded engine?

    The idea of exhaust moving through my intake and heating things up just seems wrong......

    This is obviously a summer car and the coldest air it will ever see will be 25F I'd suspect. 16189635323832090594340196048868.jpg
     
  2. oldiron 440
    Joined: Dec 12, 2018
    Posts: 2,402

    oldiron 440
    Member

    I have been plugging crossovers for 35 years, it's automatic with me. Plug it and don't even give a thought. It's just that more heat that will not boil the fuel.
     
  3. Jack E/NJ
    Joined: Mar 5, 2011
    Posts: 675

    Jack E/NJ
    Member
    from NJ

    >>>I removed the butterfly on the passenger side manifold>>>

    I'm with you. That's all I did cuz it didn't move anymore and the spring was shot. I don't like the x-over either. But mainly because it discolors the intake especially if painted. But I didn't block it except on my flathead. 8^) Jack E/NJ
     
    Fabulous50's likes this.
  4. jaracer
    Joined: Oct 4, 2008
    Posts: 1,221

    jaracer
    Member

    If you do this on an older Chrysler product, 318, 360, 440, you need to change to an electric or manual choke. On these engines the choke stove is in the intake manifold and without the crossover and the damper valve, the choke will never come off.

    I still have a damper and open crossover on the 312 in my T-Bird even though the carb now has an electric choke. Old Fords are pretty cold blooded without it.
     
    klleetrucking likes this.

  5. lippy
    Joined: Sep 27, 2006
    Posts: 5,669

    lippy
    Member
    from Ks

    I use to wad aluminum foil up and jam it tight into the crossover ports in the heads on irrigation engines. They were on natural gas. 413 chryslers. Lippy
     
  6. oldiron 440
    Joined: Dec 12, 2018
    Posts: 2,402

    oldiron 440
    Member

    This and a plug made of carefully trimmed sheetmetal. I've even filled the first 2" of the crossover with allmetal then a plug.
     
    Fabulous50's likes this.
  7. Fabulous50's
    Joined: Nov 18, 2017
    Posts: 344

    Fabulous50's
    Member
    from Maine

    I was just going to cut a piece of 316 stainless sheetmetal to fit inside the gasket and a bit or high temp silicone.
     
  8. saltflats
    Joined: Aug 14, 2007
    Posts: 10,929

    saltflats
    Member
    from Missouri

    It will make it cold natured and change the exhaust sound. ;)
     
  9. oldiron 440
    Joined: Dec 12, 2018
    Posts: 2,402

    oldiron 440
    Member

    Like my ex wife. :)
     
    BJR and 57Custom300 like this.
  10. I've found MoPars are pretty sensitive about plugging the cross over in the winter, especially the small blocks. This said, I block off the crossover for my Pontiac engine in my 34. Had it in stop and go traffic over 100 degrees with ethanol fuel and it never faltered but it's cranky in cold weather...so am I.
     
    Desoto291Hemi likes this.
  11. I wouldn't do it. It rarely gets as cold here as it does there and FEs tend to be cold-blooded as it is. It was pretty common to find a heated carb spacer on them, Ford added extra heat at the carb. I blocked the heat riser exactly once, never again...

    You can pitch the spring-loaded valve though.
     
  12. The picture looks like an FE manifold. Do not block the crossover, especially if you are using an Autolite 4100 Carburetor.
     
  13. Fabulous50's
    Joined: Nov 18, 2017
    Posts: 344

    Fabulous50's
    Member
    from Maine

    Yes, FE 352. Running an Autolite carb, has electric choke. It was an absolutely fantastic running setup, I just don't want to disturb that.
     
  14. I seriously regretted NOT blocking the crossover on a 350 Chevy. The fuel in the carb would boil so easily, because of the crappy gas. And I live in Texas, where it's hot way more often then it's cold.
     
  15. I had a 64 Galaxie once with a 352 and a 4100. Had a spacer plate beneath the carb with the heater hose circuit going through it. I disconnected it and the car did not like it in the winter. The FE manifold is so large that it dissipates heat well, and I never had a fuel boiling issue. If it was a small block my answer would be different.
     
  16. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,330

    sunbeam
    Member

    The heat riser valve does not stay closed very long. Fire up your car and watch it. There is a reason the long ram Chryslers setup got removed. My first pickup had a 235 that the heat riser was stuck open below 50 deg. on a damp day the carb would ice up and quit.
     
  17. speedshifter
    Joined: Mar 3, 2008
    Posts: 279

    speedshifter
    Member

    I would not block off the heat riser passage. With the butter fly valve removed the passage will run much cooler. I feel this is a good compromise. Also if the engine is in a car without a hood the intake & carb will run cooler. With passage plugged the engine will take longer to warm up increasing carbon build up. & engine wear. Greg
     
  18. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 3,513

    2OLD2FAST
    Member
    from illinois

    Cold fuel does not atomize nearly as well as warm fuel .
     
  19. jimmy six
    Joined: Mar 21, 2006
    Posts: 9,982

    jimmy six
    ALLIANCE MEMBER

    Ford Y-block have 2 different intake gaskets. The truck one had a stainless insert that leaves about a 1/2” hole in the crossover and works great. I’ve removed the flapper exhaust valve and installed a spacer. I also use a 3/8” thick phenolic spacer under the carb. Runs great and doesn’t boil fuel.
     
  20. lostone
    Joined: Oct 13, 2013
    Posts: 1,790

    lostone
    Member
    from kansas

    On my performance pontiac motors I always just put a thin piece of stainless sheet metal between the gasket and intake side and called it good. The gasket didn't care if it sealed to a solid piece of metal or an open port on the intake.

    They were cold blooded but once warmed up ran fine.

    Also ran 20-50 valvoline race oil in them for years, 20 years in one motor and never had any problems but had more people than I can count tell me this was a big no-no....
     

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