I have been chasing the cause of my 440 overheating problem here.....(https://board.moparts.org/ubbthreads/ubbthreads.php/topics/2509662/1.html)

.....and for a couple reasons, I've convinced myself that it had to be the head gaskets. I've been through all the normal stuff (180 t-stat, no t-stat, radiator check, installed spring in lower radiator hose, new coolant, new water pump, checked engine timing, new coolant temp sensor, different temp gauges (2), installed clutched fan (had a fixed fan when I got it), etc and nothing has helped. Also, the upper radiator hose barely has any coolant flowing through it; my survivor 69 Charger with completely original 383 has much more pressure in the upper radiator hose.

I pulled the heads this morning and the saw a couple things. 7 or 8 pistons were kissed at one time or another.....but anyway, the cooling slots seemed suspect. They look way too small. What do you think-could this be the source of my problems? And does anyone have pictures of what the slots would look like? I've read that they were much wider on the original head gaskets. If anyone has modified the slots, does anyone have any pictures? Thanks

What you have is standard on many replacement head gaskets, look else where for the heating problem
Are you absolutely sure your motor is running hot? If not verify the temp reading with another known good gauge or a hand held infra red gun or a heating and air conditioning pocket thermometer

Before you get into modding head gaskets, check the cylinder walls for obvious cracks, have the heads mag'd, now's the time for a valve job/guides/seals as long as the heads check out first, you might have a cracked head/clogged cooling ports?

Keep in mind some slots/holes are reduced in size to reduce water flow so the water can effectively absorb the heat and transfer it to another point/time, sometimes water traveling at too high a velocity can not absorb or transfer heat effectively, you have to pick your "battles" when it comes to modifying various components of the cooling system, but I'd eliminate the mechanical properties of the heads as long as you have them off, same goes for the decks/cylinders

I've swapped 3 different sets of gauge clusters in the car and they all read the same. I also bought an infrared temp gun and it shows that the block is heating up. The radiator is only showing about 170 degrees but the block climbs to 210 or more just at idle. Because of this and the low upper hose pressure, it seemed likely that the cooling ports were too restrictive.

That is not how heat transfer works.


What the various sizes actually do is redirected unneeded flow to areas where it is needed. It balances the flow thru the engine so that all parts get proper cooling. Like anything else water flow will take the path of least resistance and if that path is not where all that cooling is needed other areas suffer.

Early gaskets had wider slots, .250 wide, same length on 67 and down, .940 long and .455 wide for fel pros before 72, .118 wide now. It is my opinion that the late thin slot gasket works well with hourglass cooling hole blocks, not so well with round hole blocks. I don't know why you can't just drill a hole in the block where the head hole lines up, an hourglass block would line up there,and expose the whole slot,how could that not work? Motorhomes have the bottom 8 holes drilled in block and head, and hourglass in their blocks and they cool. I have made my slots .250 with no issue. I put peanut plug heads on a 400 with hourglass, left slots stock, used the gasket you have there and drilled the 8 .250 holes in the block, it ran dead cold with a stock 3 core.

Just did a little research, inlet in a 70 440 block is .985 square inches, outlet at rear is .785 square inches, you should be able to increase slots up to about .180 total square inches and be safe, keep block full and pressurized before coolant goes in in head. 6 .250 slots with .040 gasket is only .075 sq inches, 6 .455 slots is .108, should be no problem. I dont think even the 2 lower triangles in the early 440-3 engines fully lined up, just an edge to keep block full. I guess you could try making things bigger,I dont have one here or a triangle gasket to compare. I would stay under that .180 sq in total. Radius squared x 3.1416 for holes. Would be interesting to see if it changes. It appears the pistons are .060 over, could be a problem, thin block.

Do you have the history of the motor, has it been rebuilt bored ECT?

have any core plugs been removed from the block to check for rust/sludge blocked coolant passages ?

The engine was rebuilt about 12 years ago but has very few miles due to the overheating. The guy I bought it from had done nothing with it in the 10 years he owned it. The previous guy (two owner ago) had it rebuilt. I know very little other then this:
1. there is a receipt for a purple shaft 509 cam
2. There is a receipt for building and balancing the bottom end
3. The pistons are labeled as .060 over

I rebuilt a 1973 CA cop car 440 motor years ago that had heating problems from day one, it was bored .060 over also

70b5, shoot me an e-mail, will send you some pics of a 1970 block, never milled, you can see where the large slots were when new, they measure .375 wide by .815 long, also have an original head gasket that matches this, and a set of original hemi head gaskets that also slot match.

P4876071 hemi head gaskets also have this large slot, current felpro 4.50 bore gasket, so it used to be bigger, hemis never revised? Hemi slots line up on this 440, so that location must be the same

The following pics are from 4406bbl. The first picture is of the deck surface of a 1970 block with the imprint of the original gasket on it. 4406bbl can clarify since the are his pics. Interesting for sure...











And then mine again

First is a 1970 440 6bbl engine I took apart, I was the first one there. Threw head gaskets away, never even thought about the slots, never had an issue. Funny thing is this block is going to be decked monday, glad I looked. Have one other 1970 known from a 6bbl car and it had wide slot gaskets too.

Second is 4.50 hemi gasket big slot, matches 440 block

Third is an original mccord steel hemi gasket, matches 440.

Last is a perfect circle gasket kit from 1969, not sure on head gasket brand.

It appears hemis were never revised, bigblocks were.

My understanding is the top holes are only to let the air escape.....

I don't buy that for a minute. The upper holes are for water flow. There doesn't need to be as much there because it's the exhaust ports where the heat is.

When we were kids my brother and I built a 400 Pontiac. Smart me, I said "let's put forged pistons in". That engine overheated from Day 1. We talked to the machinist. What is piston to wall clearance? 0.001" to 0.0015". He didn't understand the forged pistons needed more room. It took more than 10,000 miles for the overheating to subside. That's what you call "wearing in" a piston!

As long as you've got the head off get the cylinder wall thickness measured. It may be that you have too thin cylinder walls after the 0.060" overbore.

R.

Here is my factory original head gasket to my 1969 383 Roadrunner. It is part number #2863225. In the photo below, the original head gasket is sitting on top of the new Mopar head gasket #3614824. The coolant slots are/were the same on both gaskets;

0.892" Long

0.121" Wide

To round out the original cooling system to my 69 Roadrunner, the original #2863225 head gasket was ran with an original 053 22" inch two-core radiator with fixed seven blade fan and no fan shroud. I've never had the car in running forum but I can't imagine this set-up in of itself was ever a problem back on day one causing a warranty nightmare for Chrysler. In fact I've heard people with this same set-up say they run fine. I can't imagine it's your head gaskets that are the source of your problem. Have you had a chance to look into the other items we talked about in your other thread?

Keep in mind the infrared temp gun is measuring the surface temp of whatever you're measuring. Coolant flowing below the surface will be a different temp.

CompSyn, could you shoot a picture of the other side of the original gasket at the slot?