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1972 Motor Swap

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by rudycentral, Aug 29, 2004.

  1. rudycentral

    rudycentral Registered Member

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    Picked up a 72 in Nebraska last weekend, Motor is ok, but growing tired and leaky. I can't park in the drive until it stops per the wife./forums/images/graemlins/rolleyes.gif
    I have a 72 motor I built 10 years ago it has about 1K miles on it. I started the disasembly for inspection yesterday. Looks like I will need the heads cleaned up as some surface rust has come into the intake side. The exhasut was caked with carbon.
    Anyone done a motor swap on the early years Blazer? Can one provide any expiences/gotchyas? I will probably be doing this myself, mabe my brother or 1 other friend will come by when I need some extra hands.
    Webpage: Truck homepage
    Any help is good help, thanks!
     
  2. arq

    arq 1/2 ton status

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    make sure your engine hoist is big enough. take the hood off, make the change easier. take all the accessories off most importatly the distributor. I've done a few engine changes on my own on my 72. the most difficult part is the transmission-engine alignment. but that's it.

    ARQ.
     
  3. ljbear

    ljbear Registered Member

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    I'll second what "arq" said, make sure the hoist is large enough. Some may not lift high enough to clear the radiator support. The last thing you want to find out when the engine is hanging 4 feet in the air. You might consider pulling the front clip off, pretty easy and makes access to the engine a breeze.
     
  4. jakeslim

    jakeslim 1/2 ton status

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    I'm in mid-swap right now on my 69. It was close getting the old motor out, lift barely cleared it and
    needed a little push. I pulled the hood and oh yeah, make sure you disconnect the clutch equalizer from the motor, or you'll
    break it off like I did /forums/images/graemlins/doah.gif
     
  5. bigmike72

    bigmike72 Registered Member

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    I had the motor 4 feet in the air before I realized I wouldn't have enough room to clear the radiator support. I thought that I could take the wheels off and drop the front of the truck but looking at the engine in the air, I needed more than 2 feet /forums/images/graemlins/smile.gif Regardless, I'd pull the front clip or at least the radiator support first next time. It also makes it much much easier to get the engine back in and everything hooked up if the radiator support is out of the way...especially if the truck is lifted.

    Other gotcha's and lessons learned:
    -Make sure the throttle cable you have is going to work with your new carb if you are replacing the carb.
    -At least on my truck, that motor isn't coming out unless you remove the engine cross member.
    -It is a b*tch to get the engine back in with a manual transmission. The hard part is getting the transmission input shaft into the engine's pilot bearing (or bushing). If you can get the transmission to bellhousing bolts started then you can carefully pull the engine onto the tranny.
    -Make sure that your accessory mounts are going to work with the new engine. I replaced a short water pump engine with a long water pump engine and had to get new brackets (I was putting in a brank spanking new ZZ383 from GM, so didn't want to use the old water pump).
    -Keep a pad of paper near by, as you find things that you need then write them down. This way you can keep working on other things and only get cleaned up once to go to the store /forums/images/graemlins/smile.gif It also beats trying to remember everything you need at the end of a long/sweaty/dirty day.
    -Air tools, everything goes better with an air ratchet.
    -A patient wife and kids.
    -Lots and lots of beer for your aching back.
    -Tunes, I recommend KLOS 95.5 if you are in So-Cal. Lots of classic rock and few commercials.
     
  6. rudycentral

    rudycentral Registered Member

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    Thanks all for your input. Just to follow up some on your suggestions:
    1. I will remove hood and pull the front clip off. Looks pretty easy and the radiator mount has been replaced and should come off relativly easy.
    2. Throttle cable, check...
    3. Remove distributor, check...
    4. I have a TH350 in the truck now. I have a built TH400 in the garage with an ear that snapped off on the last car it was in. I supposed I could get that fixed, but the first gear is taller than the TH350, and theroretically it should be able to handle all the torque a 355 CID moter can push. The TH400 would need some mods to go 4x4, and I am short on cash for now. If they are cheap though, maybe...
    5. Motor originally came out of a 72 Chevelle. The truck has a long water pump, and I have a new long one that was laying around.
    6. Pad of paper for lame brain, check!
    7. My honey got me air tools 2 years ago for Christmas for all my car stuff, God bless her heart!
    8. Wife is patient as long as there is progress and she can help. Kid is 6mo old...
    9. Tunes - did you see the shot of the bed of the truck? Not an issue.

    Ok, now for some more questions.
    1. What does the TH400 car trans (major shift kit, and reverse manual valve body) need to fit the 4x4 duty?
    2. I have a few stall converters around for the Beauty. Stock, 2300 RPM, and something like 3200 RPM. The 2300/TH400 ran great in my 72 Nova 10 years ago.
    3. Engine is 10 years old and has not run in 9 years. Looks good inside - took the intake off to check out the heads. Called a shop and they said, "lube the cam, pour some oil in each intake cylnder and prime the oil pump/berings. Sounds logical. Should I risk taking the heads off for further inspection. There were no leaks last time it was running. Motor is 355CID, heads have 76cc chambers. Pistons are Keith Black Hypereutetic, all was balanced and heads were decked. Compression has been estimated to be 10.25:1. Cam is sweetly torquey, total Lift is .465, .488 and 224/234 @.050 duration. Barely runs on 94 octane. Torque is good from about 2250 to about 7000.
    4. I have 3 carbs to choose from. A 600CFM square bore holley which got me 18MPG in the Nova. A 750 Holly 4010 vaccuume secondays - could not get this thing working for the life of me... and the quadrajunk in on the current engine.
    5. The front seal at the balancer is shot and has (rustproofed) sprayed oil under the whole underside of the vehicle. Any reccomendations for removing this, or should I leave it as a nice protective coating? I am afraid that the paint will come with it. Kinda thick in some spots.

    I will have some better pics when I get back from vacation, the wife went ahead of me and has the digital camera.

    Thanks again - I love this place!
     
  7. 1979jimmy350

    1979jimmy350 1/2 ton status

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    you would need to change the output shafts on the THM 400 to be able to use it as a 4x4 tranny this requires the whole trans to be taken apart
     
  8. bigmike72

    bigmike72 Registered Member

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    [ QUOTE ]

    Ok, now for some more questions.
    3. Engine is 10 years old and has not run in 9 years. Looks good inside - took the intake off to check out the heads. Called a shop and they said, "lube the cam, pour some oil in each intake cylnder and prime the oil pump/berings. Sounds logical. Should I risk taking the heads off for further inspection.


    [/ QUOTE ]

    9 years is a long time to have an engine sitting without running lubricant through it. I'd lube it up as suggested then see if you can turn the crank with a breaker bar (and wrench of course) first. If you can't then I'd think twice about trying to start it, the piston rings could have developed a nice rust-bond with the cylinder walls. I had this happen on an Toyota 22RE here in California that only had the head off for 3 months, a couple squirts of oil and it was ready to go (preceded by some panicky moments) If you can turn it and decide to start it then I would run it for 30-50 miles then change the oil (and inspect it for cr*p as well) and then do the same again at 500 miles. Basically, I would follow the same procedure as breaking in a new high performance engine. Better an ounce of prevention than a seized engine.
     
  9. rudycentral

    rudycentral Registered Member

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    Thanks Bigmike for your suggestions! I am able to turn the motor over by hand and have primed and done so before every winter and sometime between spring and summer most years. It rolls over very nicely. I was just worried about the rust flakes from the intake, but it that will just blow through and/or get caught in the oil than I am good with that. Today I am starting the cleanup of my old engine.
    I will have pics while in process. Lookout for more posts.
     
  10. R72K5

    R72K5 Banned

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    if you can get the two rad support cushion mounting nuts to give loose then id personally remove the entire front clip assembly its not hard doesnt take very long if not real rusty, most are rusted bad though, so some heat will be required probably, all you have to do is remove the cowl panel and disconnect radiator hoses and trans lines and a/c lines and the brace across driver side innerfender that boxes in the steering column shaft, unplug wiring at firewall backside of fuse panel, leave it all intact on the clip
    then you wont have to lift engine very much at all, 72 older anyways
    73 up you just lift slightly and rmeove the block brackets and then pull forward just as easily as 72 older


    what trans you got ?
    3 and 4 speed a little more fun than auto equipped, when pulling anwyays

    oil pan gasket get one that i think fel pro makes, the one piece one, its a good one fixes leaking oil pan issues on sbc engines, remember 80-up changed oil stick to pass side though, so make sure what you think you have is really what you have, run the stamping suffix code pass side top front deck surface
     

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