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    Results 1 to 13 of 13
    1. #1
      Join Date
      Oct 2012
      Posts
      219
      Country Flag: United States

      400 SBC questions

      After reading up on my 406 based on the 400 SBC instead of the 350 block I'm starting to think it may have been built incorrectly. It forces coolant into the oil system and under the intake is getting pressurized to the point it is bubbling oil out the back of the intake.



      Now what would happen if you put the wrong heads on a 400? I know there were steam vents in the 400 block not on the other SBC mills. Would this mistake cause the problems I'm seeing?


    2. #2
      Join Date
      Mar 2011
      Location
      Ca
      Posts
      336
      Country Flag: United States
      wrong heads, or gaskets, or combo of both could cause that problem. i'd run a compression check and a coolant system pressure test to see whats going on.

    3. #3
      Join Date
      Jun 2012
      Location
      South Lyon, MI
      Posts
      1,217
      Country Flag: United States
      The steam holes make some difference, but the lack of them will not cause the symptoms you are describing.

      I agree, looks like a head gasket problem.

    4. #4
      Join Date
      Oct 2012
      Posts
      219
      Country Flag: United States
      Thanks guys. It gets worse too as I now have a knock and a spark plug that looks like this.....


      I walked away from the car and wont go back for some time.

    5. #5
      Join Date
      Mar 2007
      Location
      Cincinnati, OH
      Posts
      331
      Country Flag: United States
      It can get frustrating and this hobby can test patience of steel. But I have a SB 408 myself in my first gen and it is a beast if setup properly. Looks like something might have come loose in the bottom end or a valve has let go. Heads need to come off to diagnose. Car mechanics is not for the faint of heart my friend....been there did that and I have a performance boat. B-O-A-T = Bring Out Another Thousand!
      Jim S.
      67 RS
      "driver "

    6. #6
      Join Date
      Oct 2012
      Posts
      219
      Country Flag: United States
      My biggest problem is living in a condo with an HOA that is foaming at the bit to fine me $250 every time I pop my hood for more than a few minutes.

    7. #7
      Join Date
      Mar 2007
      Location
      Cincinnati, OH
      Posts
      331
      Country Flag: United States
      Quote Originally Posted by Thephranc View Post
      My biggest problem is living in a condo with an HOA that is foaming at the bit to fine me $250 every time I pop my hood for more than a few minutes.
      You might think about getting a self storage unit that will fit a car. If it has a light you can run an extension cord under the hood for a trouble light and go to town. Sounds like with your HOA you'd be money ahead...
      Jim S.
      67 RS
      "driver "

    8. #8
      Join Date
      Jun 2012
      Location
      South Lyon, MI
      Posts
      1,217
      Country Flag: United States
      Quote Originally Posted by Quickboat View Post
      You might think about getting a self storage unit that will fit a car. If it has a light you can run an extension cord under the hood for a trouble light and go to town. Sounds like with your HOA you'd be money ahead...
      That's what I did when I lived in the dorms as a freshman in college.

      My cousin used to use the self-serve car wash bays late at night.

      You gotta get creative.

      Good luck.

    9. #9
      Join Date
      Mar 2011
      Location
      Ca
      Posts
      336
      Country Flag: United States
      its hard to tell in that pic, but it loos like you got contact on that plug, or you melted it, either way thats no good, time to recheck some clearances, be sure to look at your other plugs as well to make sure you don't have a bigger problem. if thats from contact you'll want to check your valves as well.

    10. #10
      Join Date
      Oct 2012
      Posts
      219
      Country Flag: United States
      The plug strap was actually blown off to the side. All compression knock no contact.

    11. #11
      Join Date
      Mar 2007
      Location
      Cincinnati, OH
      Posts
      331
      Country Flag: United States
      Compression alone cant do that. Maybe a rod cap is loose allowing contact.
      Jim S.
      67 RS
      "driver "

    12. #12
      Join Date
      Jul 2013
      Location
      St. George, UT
      Posts
      1,144
      Country Flag: United States
      I got my first 400 sbc when I was 16, it was in a 69 Malibu. The bonebrain that built it put camel hump heads on it but didn't have the steam holes drilled. It ran pretty warm, usually 200+, all the time no matter what I tried to cool it down. That's all it did however, it just ran hot.

      I might agree, your issue sounds like a head gasket or worse. Could be a chunk of it came off and tagged that plug electrode, bending it over. Worst case is that something bigger came apart. Doing a compression check / leak down test will narrow the search, but your plug is a good indicator something isn't kosher.

      No buddies with at least a driveway you can use? For a couple years I did all my work in a storage unit. I found that the tall light poles near the unit had 120 volt plugs hidden behind a small cap on the base so I would run an extension chord down to the unit. I did most of my work on Saturdays or after 5 so the landlords rarely saw me working. I also cleaned up everything real well so when they did see me working they didn't mind.

      Lots of people dog on 400s, but I've now run them in 5 different vehicles from my lifted 4x4 Suburban to my drag car to my daily driver wagon and a couple other vehicles. I have another fresh one going in my son's Nova. They're great motors when you build them around the way they like to work. If the bottom end is in good shape, I give 'em a thumbs up and hope it stays in your car.

      Hope you get yours worked out, best of luck.
      -Ben, Creative Director at Speedtech Performance
      We sell some really cool parts, build cool cars, and do cool concept renderings too!
      435-628-4300 www.speedtechperformance.com
      My Pumkinator build thread- https://www.pro-touring.com/showthre...ght=pumkinator

    13. #13
      Join Date
      Oct 2012
      Posts
      219
      Country Flag: United States
      Managed to get driver side head off and did it in under 5 min. Planning pays off! gasket was blown in several places. Layers were cracked in different places. I'm not very happy with the builder. No visible damage to pistons and valves but there maybe damage at the crank or wrist pin, I just can't tell yet.

      The one buddy I had who had a drive way passed away recently the others live in other states or places like me where HOAs rule like Pol Pot. But with starting a new company hobbies have taken a back seat for now.

      Before it popped this was a very nice motor. 400s seem to be easy top make power with and not have them be strung out on the edge.





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