5.3L Engine Rebuild Home

862 heads with broken exhaust bolts
Figure 1

Figure 1.. The teardown of the engine begins. The exhaust manifolds were removed and the discovery of broken manifold bolts was a little surprising. After some research, it seems this is not that uncommon. Four bolts were found broken. As you can see, these are 862 truck heads. A pair of 243/799 heads were located for a reasonable price, and the 862 heads will not be used in this build. The 862 heads have small intake and exhaust ports. For cathedral port heads, research shows the 243/799 heads have the best flow of all factory stock cathedral port heads. If you want to use the 862 heads, you can get them here: Remanufactured Cylinder Heads cast 862.

862 bolt removal with vice grips
Figure 2

The broken bolts were removed by clamping on to them with vice grips and turning them out. This turned out to be unnecessary as we did not use these heads in the final build, but we had not made that decision yet at the time.

Used 799 heads from Ebay
Figure 3

Figure 3. The new heads after they are refurbished will add nicely to the power output of the engine. The part number for the head is 12629058. This set was purchased from Ebay. However, you can buy a remanufactured set a this link: Remanufactured Cylinder Heads Cast 799/243. We are not going to use the stock springs, so opted not to get a remanufactured set, and will have them machined locally.

Gen IV Powdered Metal Connecting Rods
Figure 4

Figure 4. Parts acquisition has also begun with a set of 12649190 Gen IV Floating Pin Connecting Rods. While these rods are not as good as aftermarket rods, they are better than the original gen III rods that came with the engine.


Disclaimer: The information provided here is how I did it. I strongly urge you to do your own research and make sure you do it right. No claim is made that the information provided is the only way it should be done, or that you should follow my work without verifying for yourself that it is correct. You are free to do as you choose with the information shared here, but you do so at your own risk.

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