Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Opinions on 400 SB - daily driver AND crawler.

Discussion in 'Rocky Mountain Region' started by BadDog, Mar 29, 2003.

  1. BadDog

    BadDog SOL Staff Member Super Moderator Author

    Joined:
    Feb 24, 2001
    Posts:
    7,777
    Likes Received:
    11
    Location:
    Phoenix, AZ
    So, my son is building a 77 K5.

    400 SB
    TH350
    NP203 (part time)
    D44/C12 with 3.73
    No doors, no top, cut dramatically

    The 400 is believed to be mostly stock with indeterminate miles. Hooker headers and duals seems to be the only mod. My question is this. What do you think about the 400 SB in Phoenix heat? I'm leaning toward selling it and getting a 350. I'm afraid the heating problems due to the siamesed cylinders will get the better of it here. What do you think?

    <FORM METHOD=POST ACTION="http://coloradok5.com/forums/dopoll.php"><INPUT TYPE=HIDDEN NAME="pollname" VALUE="1049004973BadDog">


    400 or 350?
    <input type="radio" name="option" value="1" />Keep the 400, heat shouldnt be that much of a problem.
    <input type="radio" name="option" value="2" />The 400 will not live, sell it and get a 350
    <INPUT TYPE=Submit NAME=Submit VALUE="Submit vote" class="buttons"></form>

    Let me know what you think. If there are specific mods that will help it survive, let me know...
     
  2. azblazor

    azblazor 1/2 ton status Premium Member

    Joined:
    May 5, 2001
    Posts:
    1,953
    Likes Received:
    0
    Location:
    Arizona, Phoenix area
    I ran a 400SB in a 4x4 Suburban for way more than 300K miles, we traded for a 400SB reman from 5 star ONLY because both starter bolt holes messed up - 1 cracked out and then the other bolt broke off and I didn't want to mess with it. We ran it for another 50K and now it is TBI'ed with a 700R4. We hauled trailers ALL the time with it and 6 kids, camping, scouts, skiing. Its still going strong (oldest son's truck now). It ran hard and did not overheat with dual air and full loads.
     
  3. Hossbaby50

    Hossbaby50 3/4 ton status

    Joined:
    Sep 1, 2001
    Posts:
    8,972
    Likes Received:
    0
    Location:
    Peoria, AZ
    I say run it. Worst case just put a good 4 core radiator, good highflow pump and a 180 stat in it. I don't think it is worth swapping motors over. Also you could add/upgrade to electic fans. Don't fix it if its not broken right, thats what everybody tells me. (I don't listen all the time, but thats another story /forums/images/graemlins/grin.gif)
     
  4. Lazydog

    Lazydog 1/2 ton status

    Joined:
    Apr 17, 2002
    Posts:
    129
    Likes Received:
    0
    Location:
    Phoenix, Arizona
    Hey Baddog, If you decide to build a 350 I have one to trade for the 400?
     
  5. weisel

    weisel 1/2 ton status

    Joined:
    Feb 22, 2001
    Posts:
    491
    Likes Received:
    0
    Location:
    Laveen, AZ
    I had a 400 in my blazer and never had a problem with it overheating AT ALL. I ran in the summer heat, and towed a few times. All I would say is make sure you have a 4 core radiator.
     
  6. marv_springer

    marv_springer 1/2 ton status

    Joined:
    Aug 3, 2001
    Posts:
    2,781
    Likes Received:
    0
    Location:
    Mesa, Arizona
    Well.... I gotta be different!

    Mine came w/ a 400. I tried to run it for a couple of years and ultimately swapped in a 350. I prefer the 350 except those applications where max power output is wanted. With the "double" gearing options that are available today - for what we do - the additional torque of a 400 is not really an advantage. The 400 will run warmer, and I recall changing valve cover gaskets yearly cuz they got brittle in the middle and started leaking (just an indicator of higher temp in the middle of the head). 'Sides, I always say if you need the power (or torque) of a 400, you really need a 454!/forums/images/graemlins/thumb.gif

    That said, I would not throw away a perfectly good running 400. But, I've found that there is a good crowd of people who love 400's, so you never have trouble loosing the parts!/forums/images/graemlins/grin.gif

    Marv
     
  7. FWP

    FWP CRS

    Joined:
    Oct 11, 2000
    Posts:
    3,845
    Likes Received:
    3
    Location:
    Prescott Valley, AZ
    I think Marv hit the nail on the head- Parts..... How common is a 400 as compared to the 350 /forums/images/graemlins/wink.gif? I can't speak to the heat issue, so I'm not voting in your poll.
     
  8. smp

    smp 1/2 ton status

    Joined:
    Jul 5, 2000
    Posts:
    708
    Likes Received:
    0
    Location:
    Florida
    I don't think parts are any issue considering the use the same parts. I have a 400 in my Blazer for 3 years now driving and wheeling it and i've had no problems with it i like the extra power i get out of it. I also just bought a 78 suburban with a 400 in it and it runs like a raped ape /forums/images/graemlins/laugh.gif Our mechanic has a 400 in his 76 Blazer and has no problems with his either out here in the desert sun. You will want to make sure your cooling system is in good condition. And i still think there better than a 383 stroker. /forums/images/graemlins/shocked.gif
     
  9. FWP

    FWP CRS

    Joined:
    Oct 11, 2000
    Posts:
    3,845
    Likes Received:
    3
    Location:
    Prescott Valley, AZ
    Shane- They use the same parts? I didn't know that, I thought they were different, shows me what I know /forums/images/graemlins/blush.gif
     
  10. BadDog

    BadDog SOL Staff Member Super Moderator Author

    Joined:
    Feb 24, 2001
    Posts:
    7,777
    Likes Received:
    11
    Location:
    Phoenix, AZ
    Actually, the blocks and heads are different.

    The blocks have siamesed cylinders so that they can be bored beyond what a 350 can handle. This prevents coolant from effectively circulating in the block. This, in turn, causes steam to form around the upper cylinder area of the block which, if not addressed would damage the cylinders. So, the block and head have extra matching holes to vent the steam and allow coolant to reach the tops of the cylinders (which the steam would otherwise prevent). This obviously requires a head gasket with matching holes as well, though most all have them.

    This mostly addressed the problem. However, it is a fact that the cylinders do still see considerably higher temps than other small blocks. After a rebuild, you’ll often see discoloration in vertical patches where the cylinders meet. If you don’t keep your coolant in good shape, corrosion can easily stop up the steam holes. Fully/Mostly blocked holes lead to engine death fairly quickly. Another common problem is cracks (usually in the heads) around the steam holes.

    And of course, there is the difference in the crank, flex plate, and damper due to the unusual externally balanced nature of the 400 SB...
     
  11. BadDog

    BadDog SOL Staff Member Super Moderator Author

    Joined:
    Feb 24, 2001
    Posts:
    7,777
    Likes Received:
    11
    Location:
    Phoenix, AZ
    Oh, one more thing. Some cams won't work in a 400 SB due to lobe contact with the crank counter weights...
     
  12. azblazor

    azblazor 1/2 ton status Premium Member

    Joined:
    May 5, 2001
    Posts:
    1,953
    Likes Received:
    0
    Location:
    Arizona, Phoenix area
    Russ,
    Sounds like you already had your mind made up before you posted this poll. /forums/images/graemlins/smile.gif
     
  13. BadDog

    BadDog SOL Staff Member Super Moderator Author

    Joined:
    Feb 24, 2001
    Posts:
    7,777
    Likes Received:
    11
    Location:
    Phoenix, AZ
    No, not really. All those things are just the facts (at least as I know it). However, these things are possible anywhere. Back in AL, I would probably run the thing as long as it's in good shape. But that's highs around 100 (with 90%+ humidity, sheesh) and higher speed trails (dirt, mud, hill climbs, etc.) I'm just wondering if it's enough worse out here to make me say "no way!"

    Seems the general consensus is that it's doable even here and on the rocks. I’ve never been out with you, but it sounds like you’ve used one thoroughly. I’ve been out with Shane and if it lives with him I have no doubt it will work for my son. /forums/images/graemlins/laugh.gif We will probably set it up and get it running as is. See how the engine really is. If it's bad, no doubt, 350 time... If it's good, run it. Maybe sell/trade it if the right opportunity comes along but not go out of the way to dump it...
     
  14. mplogic

    mplogic 1/2 ton status

    Joined:
    May 7, 2002
    Posts:
    263
    Likes Received:
    0
    Location:
    Phoenix, AZ
    Yea, add one for the "keep it" side. Especially since I just went through all the trouble of swapping my ok 350 for a 400. /forums/images/graemlins/smile.gif Overheating shouldn't be a problem with the massive frontal area on our trucks. A 400 in a F-body car might be a different story though. The only problem I encountered (knock on wood) was the increased cost of 400 pistons, rods, etc. which can be a good deal more than a 350, but then again the 350 is about the most common engine in the US and the cost difference is comparable with building a stroker. Also according to our machinist the majority of the 400 heads do tend to crack, but any SBC heads will work they just need to be drilled for the steam holes. There's just something cool about having the biggest small block chevy ever made. /forums/images/graemlins/thumb.gif
     
  15. Mreetz

    Mreetz 1/2 ton status

    Joined:
    Jun 26, 2001
    Posts:
    1,282
    Likes Received:
    0
    Location:
    Subs of Denver, Colorado
    I have a 400 block and new crank for sale in Denver!! Gettin ready swap a 406, rebuilt 400, for my 305 this summer. Lookin forward to that one!!
     

Share This Page