Re: '73 f250 390 Highboy w/Blown Headgasket
Changing the head gasket on an FE engine or any engine for that mater is more intense than just lifting the head pull out the old and slip in the new...
****If you know someone or a reputable shop let them do it****...if your going to do it your self,
1)Rotate the engine to TDC (top dead center)
2)drain coolant from radiator and engine, so as to not get any coolant in the oil
2)pull all the wires off the spark plugs and unbolt the distributor clamp and pull the distributor out.
3)Unbolt the carbarator and likages and carefully pull it off the in take and set in a safe place as not to drop it or damage it in any way.
4)Unbolt the valve covers, both sides, (5 bolts) and under the valve cover is a rocker assembly. There are four bolts holding it down, unbolt them and carefully lift off the assembly. Keep the bolts in the assembly where they came out, remove oil drip rail pan. Next caefully and slowly pull out the pushrods, if they are tugging to come out twist them so you don't pull the lifter out of the socket.
5)Pull off any wiring and vacuum hoses and lay them aside. Label them if your not sure where they connect back too.
6)Remove radiator hose then unbolt the intake and remove it from the engine. If it's a cast iron intake you might need another person to help you remove it. Remove valley pan.
7)Unbolt the exhaust manifolds from the the heads. You can now proceed to unbolting the heads from the block. There are five(5) bolts where the rocker assembly were removed and five(5) where the exhaust were bolted to. These bolts are torqued so you may have to exhert some strength to lessen them. After they are loosed and removed the head is ready to be removed. They are heavy and cunbersome so get help! After they are removed you can pull the gasket off and clean the area of any residual gasket material. If there is any coolant dispersment when the head was removed and now laying on the pistons, with clean paper towels wipe up all the residual coolant, if this occurs, make sure you drain the oil!
8)Clean all gasket surfaces so that there is only metal showing. If you have a local machine shop take the heads there and ask them to see that the heads are not warpped. You can do this yourself by placing a long steel ruler on the head, straight and twice diaganaly and if there are no gaps to where you can see light through (between the head and the ruler) then the head is fine. You can have the machine shop do a light resurface just for peace of mind.
9)Buy a head gasket kit that has all the gaskets for the top of the engine. Now you are ready to assemble the engine. Place the head gaskets on the block, the gasket will be stampped wich side is to the front of the engine.
*note- the coolant flows from the water pump through the block and up to the head from the long hole at the back, so make sure that the gasket is set so that the water opening is toward the back and is free to flow coolant through.
Make sure that the dowel rings are in place so that the head is lined up corectly. Now you are ready to torque the head, you will do this in three stages, and in a sequence that starts from the center. see below:
7 3 1 5 9
8 4 2 6 10
Torque in the above sequence starting at 35ft lbs -then again at 75ft lbs -then fianlly to 110ft lbs. for the top row and 100ft lbs for the bottom row. this will be sufficient. Do the same procedure on the other head. Next bolt the exhaust manofold back to the head, make sure the gasket with the smooth side is to the heads and the corrigated metalic side is to the manifold tighten from the center outward. tighten until gasket starts to crush.
10)Replace valley pan and place intake gaskets on the heads, make sure the bump is facing upwards.
*note - If the head and the intake have different size ports always use the large port gasket.
There are either cork or rubber gaskets that rest on the front and rear edge of the block. A better solution then those narrow gaskets is to use "silicone" or "the right suff" place a ¬ľ" bead along the edge let it set up for about 15 -20 minutes then install the intake, being carfull that you place it one time as to keep the gasket in place and to let the front and rear have a solid seal.
Torque the intake to 25ft lbs, in the sequence below:
3 8 2 10 5
6 9 1 7 4
After you have turqued it once the intake wil settle, keeping your torque wrench at 25ft lbs., go over the same sequence again, making sure that the entire intake is torqured. Do this to ensure a good seal so that you don't leak any water or air. Instal the distributor so that the rotor falls into place where the number one(1) spark plug wire is facing. If not exactly sure,.... with the vacuum advance diaphram facing straight forward set the distributor in so that the rotor points toward the number 7 and 8 spark plug. You may have to line it up a couple of times before it falls into place, but having set the engine at TDC it should fall into place right where it came out. Next install the pushrods in the holes in the intake where they came out , make sure that they are seated in the lifter. Place oil drip rail pan in place and then install the rocker assembly. Make sure that the pushrods are lined up with its mating rocker. tighten the rocker assmbly evenly until it bottoms out onto the head. Torque to 45ft lbs from center outwards. install valve cover with new gasket and tighen untill a good seal is made. Reinstall the carb onto the intake, preferably with a new gasket. Tighten the four(4) bolts or nuts evenly around the carb, ¬Ĺ turn until tight. Hook up all electrical wires and vacuum hoses, fill radiator with coolant, and if needed new oil and filter.
Start engine retime the distributor to proper degrees, check for leakes, if all is OK, your done.