Hey-oh!

I'm a bit stumped about my head gasket replacement.

I have a '76 F100 4WD. Seller said it has a 360 but he was a bit of an idiot and admitted he didn't really know if it was a 390 or 360. It's never mattered much up til now. The stock sheet says it was built with a 360 but that doesn't mean much as I'm not sure that the numbers match or if this was ever rebuilt. Here is my problem:

I have bought a gasket kit from Napa (a felpro set). The Napa folks are usually really knowledgable and helpful with this old wonky rig. However, this head gasket issue has them a bit stumped and they cannot seem to locate the part I need.

The problem is that the 360/390 sets are not cut to allow for water flow at both ends of the head. Here is my block:



And here is the old gasket along side the replacement:



You can see the bottom (front) of the gasket is cut for water flow but the top (rear) is not.

When I spoke with the sales guy he said it's likely hat the motor is from some other year isn't really a '76. That is likely as the block is stamped D4TE. I understand that that means the engine is from '74. There is a 105 / 5J18 stamped there as well but I'm not sure what those numbers indicate.

Part of the kicker is that this gasket wet is not returnable since I opened it. Which sucks because I'm not sure how much of it will be usable. Still, I really would like to know what the heck I'm running here so I can get the proper parts from now on.

The Napa guys said to being in the old gasket & they can try and look it all up that way. Okay. I can do that, but what to you all think?

 

I had the same problem a while back when I pulled my heads. I used the gaskets I had but the engine ran hotter and would over heat from time to time...
Anybody have partnumbers on the headgaskets with watter jackets cut for bolth the front and rear???

 

when I pulled the old gaskets I was careful just in case I had an emergency and needed to use them for reference. I'd hate to use these single cut gaskets- but the whole "two water jacket" thing has me stumped. The new single-cut are paper with metal rings and the old/pulled gaskets are all metal and in fine shape. Just dirty & ugly.

 

The head gaskets should be labeled either "up" or "front" but regardless you want the gaskets coolant passages to the rear of the head/block and NOT the front or you'll have over heating issues, if installed correctly FE head gaskets will always stick out at the outer front corners of the heads and block, if they're on backwards the gasket won't be visible here.

 

Looks like the PO cut his own coolant passages on the old gaskets. Probably why he was selling it 'eh?

With open passages in the front he engine just flows coolant straight thru the block and the heads will just sit there and cook.

The gaskets should be labeled FRONT and the front passages should be BLOCKED to allow coolant to flow thru the cylinder head and out the intake.

Since you have the block out of the truck the easy way to tell a 360 from a 390 is too look at the rear crank flange. 390 will have a square notch, a 360 will have a half-moon shape.

Josh

 

This is a stupid question: but, with the from passage closed won't water flow through the head up to where the front hole is in the head and sit on the gasket where it is closed in the front? If so, won't the gasket there just get sopped and disintegrate?

I'm a bit funny on the way the water flows through here I guess.

 

The coolant flows from the bottom radiator hose thru the water pump and into the engine block on both sides.

From there the coolant is pushed to the back and then up to the cylinder heads where it is then pushed to the front and then both sides combine in the intake manifold then go out the thermostat housing and then to the radiator.

If the passage is OPEN at the front the coolant just goes from the pump to the front of the block and then goes right back out the thermostat housing. The cylinder head and pretty much the entire back of the block will be overheating and steaming, even though the temp sensor will say everything is cool.

Josh

 

That help! It makes sense, but compounds my second question:

This papery gasket... as the water lows to the front of the heads it will flow out the front water jacket opening in the head, correct? There is a corresponding front water jacket opening in the front of the block. With the papery gasket as the only in between these openings won't the water just saturate the gasket and cause it to dissolve (eventually) and eventually open up the front water passage while also releasing partially dissolved paper into the cooling system?

May sound like a stupid question... I'm just trying to understand this and I'm stumped as to why there are water jacket openings in the front of both the block and the head if they are not meant to be open?

 

As long as you keep your coolant fresh i wouldn't worry about it "dissolving" through the blocked water passages on the head gaskets, old coolant on the other hand becomes very acidic and corrosive so just keep it changed when it needs it and you'll be fine, while Fel-Pro head gaskets are ok i personally would of went with a set of Victor-Reinz "Nitro-seal" head gaskets, Napa use to carry them but you can still get them at Carquest.