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Blueprint 383 Stroker Blown Head Gasket Diagnosis

Discussion in 'General GM Truck Discussions' started by Black-Chev-K, Apr 24, 2019.

  1. Black-Chev-K

    Black-Chev-KNew Member

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    I've got a Blueprint 3830CTC1 (w/Edelbrock carb & cast iron heads) (405 HP, 440 torque) in an 86 Chevy K-series pickup with 5300 miles on the engine. Truck has an automatic transmission with 35 inch tires and 4.56 gears. Engine has always run good, especially the top end - even though it is anything but aerodynamic. In November, after warming up, I pulled slowly out of the garage and heard a loud pop. ...couldn't imagine what it was, so I got out and looked around the truck and didn't notice anything abnormal. When driving down the road, there was a notable loss of power to the point I knew something was wrong. In running a compression check (see attached), I found cylinders 4 & 6 to have almost nothing. ...took the head off the passenger side and found a huge chunk blown out of the head gasket between those 2 cylinders. Head bolts were pretty loose. See attached pictures of head gasket and top of block on the passenger side. In talking to Blueprint engines and showing them, they think that it was a detonation issue; they said it was timing and those cylinders were running too hot. I always run the highest octane available when fueling. I took head gasket and pictures to local shop where I have a trusted mechanic for many years. From looking at the gasket and its seal that doesn't appear completely compressed, he thought the head was never torqued down. Others that have seen it thought the same thing. Blueprint said that it is completely normal for the head bolts to be loose after a blown head gasket, but I'm getting varying opinions on this. Straight edge seems to indicate head and top of block surface are good. My main concern is to try to understand what happened in order to determine if I can put things back together and have everything be OK. Blueprint said to reuse existing head bolts, install new head gasket, & reconnect distributor without the vacuum advance connected, and everything should be good. Would you use any gasket sealer or locktite to prevent the head bolts from backing out? Any ideas, thoughts, takes...?

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  2. 7mopar

    7moparWell-Known Member

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    I think Blueprint Engines is blowing smoke out their a**s to save themselves. Before put it back together check the bolt threads in the block to make sure they will except proper bolt torque. If not your just wasting time and money. Check the piston top for pitting caused by detonation. If pistons look ok and bolts can be torqued it should be ok to put back together if surfaces are ok.
     
  3. Black-Chev-K

    Black-Chev-KNew Member

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    Thanks for the reply! I have already checked those bolt threads and they are fine. I've also been told that these type gaskets are known for having head bolts back out over time; should there have been something applied to the threads of the head bolts to hold them in better? I can't imagine having to re-torque the head at periodic intervals just to keep things tight...
     
  4. 7mopar

    7moparWell-Known Member

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    I have never had a problem with that type gasket and all cast iron. With good bolts and block treads there should be no need for thread locker on head bolts. Torque cold and check when hot there should be no need to check again. You may want to check bolt lengths to eliminate the possibility of bolt stretch.
     
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    • 65 sporty

      65 sportyWell-Known Member

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      Any time I have seen this, the head has been warped. All small block chevys need sealer on the head bolts because they go into the water jacket. That looks like a fel-pro permatorque head gasket, doesn't need re torquing.
       
    • 7mopar

      7moparWell-Known Member

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      Is that for the new LS style blocks? Have rebuilt many older small blocks none with open bolt holes.
       
    • 65 sporty

      65 sportyWell-Known Member

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      No LS engines have blind holes, on the SBC all 17 go into the water jacket. Felpro now sells bolts with sealer already applied.
       
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