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.

350 engine parts for building a 400

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bajaviking, Jul 21, 2003.

  1. bajaviking

    bajaviking 1/2 ton status

    Joined:
    Apr 10, 2002
    Posts:
    752
    Likes Received:
    2
    Location:
    Baja
    A friend of mine has a 400 block that he will help me build, according to him I can use my intake, exhaust manifolds, distributor, cam and all the other accessories from my 350. All I need to do is have the 400 machined and buy pistons and piston rods and bearings for it. Is this correct, is the 400 a good choice for a Blazer. Also, this is my daily driver and I want a reliable engine with some good power, any suggestions on what pistons to use will be appreciated. Also, will my stock heads be OK?

    Sorry about all the questions /forums/images/graemlins/1zhelp.gif
     
  2. b454rat

    b454rat 1/2 ton status Premium Member

    Joined:
    Jan 21, 2003
    Posts:
    3,009
    Likes Received:
    7
    Location:
    Binghamton NY
    All external parts will interchange. The rotating assembly are the only non-interchangable parts. Your cam/lifters, timing gears, will all bolt on. A 400 is a good motor for any vehicle, has good low end torque, and built right can make some awesome power. If you are gonna rebuild it, get a set of 5.7" rods, off any small block chevy, and get the 400 pistons to match. The longer rods help the rod ratio, and flattens the torque, instead of peaking at a certain RPM. I built a 406 that way, and it made a ton of torque, kept pulling till I ran out of highway. If the stock heads are 882 or 993, they will be good heads for a mild motor. I have a couple friends with 406 with the long rods, and they both run strong, mid 11s strong.
     
  3. bigblock44k5

    bigblock44k5 1/2 ton status

    Joined:
    Jun 8, 2003
    Posts:
    396
    Likes Received:
    0
    Location:
    Hurlburt Field, FL
    It would be a good motor for your truck. Just make sure you have a good radiator. 400's naturally run on the warm side. If you are going to use your 350 heads make sure you drill out the steam holes or you willl definetly have problems overheating. Everything you have will fit on the 400, you could even use your crank if the 400 crank is shot. all you have to do is use bearing spacers. This would make the engine a 377. Which is basically a faster reving 400 due to the shorter stroke. You dont need anything to fancy as far as pistons go, unless your trying to get a lot of power out of it, going to use nitrous, or going to be reving the piss out of it. You could try Keith Black Hypereutectic pistons. They are good pistons for a reasonable price. As far as the cam, it would be a good idea to get a new cam and lifter set since it will already be apart. It's only $150 tops and will net you a lot of power if you choose wisely.
     
  4. SUBFAN

    SUBFAN 1/2 ton status

    Joined:
    Mar 23, 2003
    Posts:
    2,334
    Likes Received:
    0
    Location:
    Davenport, Ia
    While it is true that you can use 350 heads that have been 'drilled' the chamber volume is smaller and you could run into compression issues....

    The longer rods is a very good idea in these. Cheapest is the 5.7", better would be 6" IIRC Olds 350 rods are 6" and can be easily resized for the 400 crank. That way the expense is only in the piston. As with aluminum heads, you can run more compression with the longer rods, and not effect detonation as much....

    400's like to breath, and aftermarket larger heads are worth a look. Chevy Hi Performance has a 406 with Vortec heads and a cam with .050 duration of .230 intake and exhaust with .480 lift that puts out around 475 lb/ft torque at 2400rpm's.

    If this doesn't convince you, send me the short block, and watch the build up.... /forums/images/graemlins/thumb.gif
     
  5. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

    Joined:
    Aug 28, 2002
    Posts:
    9,095
    Likes Received:
    144
    Location:
    california
    In my opinion the 400 smallblock is the best motor for a truck because they deliver much more torque at lower rpm's than any other small block. I would recommend using a set of 400 heads with 76cc combustion chambers because they have the bigger 1.94 intake valves and 1.50 exaust valves which will flow pretty well for a mild buildup. make sure that block hasn't been bored over all ready because you can only go .030 over safely. I wouldn't use the 350 crank because it would defeat the purpose of the 400 with the shorter stroke. Don't think twice about buying a new cam because a lot of horsepower and throttle response can be gained with a bigger cam. I built a very nice 406 with the big valve cast iron heads, comp 268H cam, performer intake, 9.2:1 compression, headers,high voltage ignition, and an edelbrock q-jet(soon to be holley multi point injection).
    I'm pushing around 400hp with this combo and spent $4,700(w/ fuel injection)Thinking about a 4" stroke crank which would make a 434ci small block and outrageous torque /forums/images/graemlins/thumb.gif.Hope this gives you some extra ideas, good luck. /forums/images/graemlins/cool.gif

    85K5 3/4ton,14bolt,10bolt,9"lift,35"boggers,16.5x14welds,big horse 406/700r4 /forums/images/graemlins/k5.gif
     
  6. u2slow

    u2slow 1/2 ton status

    Joined:
    May 9, 2001
    Posts:
    2,217
    Likes Received:
    0
    Location:
    BC Canada
    [ QUOTE ]
    If you are going to use your 350 heads make sure you drill out the steam holes or you willl definetly have problems overheating.

    [/ QUOTE ]

    Many production 305/350 heads are prone to cracking after drilling steam holes. In the 80's especially, the castings became very light so they shouldn't be drilled.

    Yep, gotta have steam holes or the 400 will overheat.
     
  7. SUBFAN

    SUBFAN 1/2 ton status

    Joined:
    Mar 23, 2003
    Posts:
    2,334
    Likes Received:
    0
    Location:
    Davenport, Ia
    1. Go for 2.02 1.6" valves, the 1.94 x 1.50 is the small valve....

    2. A 400 can be bored to .040....

    3. I already suggested using the larger chamber heads....Larger aftermarket heads would be even better....

    4. If you can get a 400 block, then use it all, or sell it to someone that will, they are getting to hard to come by....

    5. If anyone has a 400 motor, please send me a PM /forums/images/graemlins/grin.gif
     
  8. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

    Joined:
    Aug 28, 2002
    Posts:
    9,095
    Likes Received:
    144
    Location:
    california
    [ QUOTE ]
    1. Go for 2.02 1.6" valves, the 1.94 x 1.50 is the small valve....

    2. A 400 can be bored to .040....



    [/ QUOTE ] Actually GM made many heads with the smaller 1.78 intake valves and even smaller exaust valves. They were on the smaller cubed V-8's including "light duty" blocks which are 2 bolt main blocks. My 400 2 bolt main block had the small valve heads. THe small heads have 72cc chambers and the "heavy duty" big heads are 76cc 1.94 intake,1.50 exaust valves. The heads you are thinking of are rare . Fuely heads or camel hump heads had the big 2.02 intake. Unfortunatly these heads shouldn't be used on the 400 because drilling out the steam holes is not all that of a good idea.Machine shops don't recommend boring a 400 bigger than .030 because the cylinder walls get to thin

    85k5 3/4ton 14bolt/10bolt,9"lift,35"boggers,16.5x14welds, big horse 406SBC/700r4 /forums/images/graemlins/k5.gif
     
  9. Mreetz

    Mreetz 1/2 ton status

    Joined:
    Jun 26, 2001
    Posts:
    1,282
    Likes Received:
    0
    Location:
    Subs of Denver, Colorado
    I have a brand new 400 crank I bought for a rebuild! 150.00
    /forums/images/graemlins/grin.gifI got another 400 that was already rebuilt instead.
     

Share This Page