HEMI Tech - Cooling Systems

Why not block off the fronts and plumb return lines from rear of the head? Another thought is that you could D&T the 'side' of the front port. Yes, more fab time involved.

 

Just stumbled onto this thread. I ran into this issue WAY back when I first got my '52 331 for my '36v Willys coupe. First thing I wanted of course is a 4bbl carb. Actually I wanted a Holley 3bbl carb do bought one in '64 in college when I could not afford it. No-go for an early 331 except for couple dozen wet 4bbl manifolds made in '54 before the Factory converted the 331 to crossover like its big 354/393 brothers. Virtually impossible to find one of those for less than the national debt. Also, had zero room for a conventional water pump in the Willys so I cut the pump off the cast front cover and just used the timing chain CI cover.
Here is how I converted a 354 intake manifold to a 'wet' one to use on the 331. I brazed a couple water pipe stubs into the manifold that were connected to a thermostat housing I welded up;

Here is the holy grail for 331 lovers. A 331 wet 4bbl manifold. REALLY hard to come by.


My solution; get a 354 4bbl manifold which are extremely common and cheap.


I bored the carb inlet holes for my too-big 3bbl.




The main mod to the manifold is to drill out the blocked off water passages and braze on pipe stubs. This allows use of a thermostat off the manifold instead of a crossover.


My home-made thermos housing. Might be able to use a Hot Heads one?


Next step was to adapt a stainless steel 4" centrifugal chemical pump to the engine. I machined a front cover in aluminum and a new shaft and made a 1/4" steel mounting bracket to mount it like an alternator. I first used the impeller that came with the pump but it was WAY too efficient and produced too much volume and pressure and blew off hoses. I then adapted a 'flapper' impeller from a junk yard pump which works fine.

Here is my centrifugal water pump adaptation.

That setup ran great for a decade or two but then I started being unhappy with the tiny valves and ports on my 331 heads. There has been some discussion about truck heads in this thread which perked my interest. I have been a big fan of truck heads for as long time. First they are 'undesirable' so you can get a set for not much more than scrap metal price. Second they have the biggest valves and ports the factory put into hemis, and have hardened seats. A great feature that drag racers should love is, since they use water for manifold heating, they don't have Siamesed center exhaust ports that must be welded to make headers happy. and most importantly, they are 'dry' so fit my 331's design.
They are very easy to convert to hot rod use. Here are the steps
1. Weld the manifold crossover holes closed a bit so they don't stick above the manifold.
2. Replace the fat sodium filled valve stems by installing new Hot Heads valve guides. Good idea on any 70 yr old engine.
3. Drill out the index pin holes (an H bit I as I remember?) to fit the old 331 pins.
4. Cut off those ugly lugs on the corners of the head. Plenty of meat to do that.

Shorten the tall crossover ports to fit a passenger manifold.


Early 331 vs. truck exhaust ports. ‘Nuff said!!


No need to weld the hole joining the two interior ports.


Cut off the lugs.


Drill out the locator pin holes.

 

Actually all NYer Deluxe & Imperials had the 4 bl engine & the standard NYer was supposed to have the 2 bl engine, but few '54 2 bl engines seem to be reported in NYers.

 

I’ve got one of those 54 4bbl manifolds holding down a shelf. Id think I’d give it up to pay the national dept off.
They’d probably scrap it

 

31 Vicky, that's a really good point about using two thermostats. My goal for this engine swap is to retain the stock wheel base and minimize firewall modifications. Another option to think about is making a cross over for the rear of the heads, teeing off of it and running a single stainless tube forward between intake manifold and and lifter valley cover. This tube would connect to a thermostat housings that would sit just behind the riser. A single return hose to the radiator would be used. This option would short circuit a "pump to return water path" and provide more even cross flow block cooling. A rear cross over is certainly going to take up more space than thin blocking plates but maybe with some creative machining a low profile one can be made.

 

73RR, Sorry Gary I didn't see your post before posting my last comment. I agree, if I run a front cross over it will be drilled and tapped from the side of the machined block so that it's aligned with the riser.

 

Willys36, how much did your pump reduce engine OAL ?

 

If a chevy water pump is used, mechanical freeze plugs are a must. I have blown out 2 freeze plugs on 2 different hemis. It is always the center passenger side for some reason. Now i will hear someone that has "way more knowledge than me" say, well you dont know how to put stock freeze plugs in correctly. My response is with a stock 180 hp engine with a slush box behind it, stock freeze plugs are fine. If you build a nice engine with more than twice the hp and add a chevy water pump and it revs way more, yes a stock freeze plug will blow out. Bob Walker will attest to this as he will not sell stock freeze plugs. So take my advise, its free info.

 

Fortunately my hemi came with hot heads copper mechanical freeze plugs.

 

Gets rid of fan and pump nose so probably saves 5" or so. Sticks out as far as alternator and AC compressor.

 

What's a "freeze plug"?

 

I have been told that will not work.

The computer flow model says otherwise, as long as you drill two holes in the block deck.

 

What is the freeze plug on the engine block?


If the coolant inside an engine freezes, it may cause the block to crack. Water expands as it freezes, and the pressure created by this expansion can cause cracks to form. Freeze plugs prevent this from happening by allowing the frozen water to expand out the plugs' passages.

 

Absolutely not.

They have never been, never will be for, and are not capable of protecting a block or heads from the initial expansion of freezing water.

Those are core plugs, for cleaning out casting sand. That is all. Nothing else.

The errant notion that they have anything to do with freezing is one of the most oft-repeated myths any sector that uses cast components with water jackets.

One can call a pig a duck, but death will come before the first quack is heard.

 

What holes? Where? How big?
I spent some time staring at blocks and heads and cannot see why the water flow would care if it went out the front or back of the head. The heads can mount on either side, and the face does not show any obvious differences as to water jacket/cooling passages. The return water would travel an additional 20" or so to get to a t-stat but that would only give off some heat. The only critical part would be ensuring that the return lines are adequate size.
I used a similar design on a blown 392 many years ago. I adapted the alum B&RB pump and brought water from the rear of the heads to the adapter blocks to feed the t-stat. The adapter blocks placed the oem P/S and alt brackets too close to the head to be able to use the front ports. Today I might D&T the 'side' of the front port boss and try a shorter/tidier connection. And yes, the t-stat had to be raised via a machined riser so that it was just above the highest point of the heads water jacket but nothing abnormal was found.
The biggest challenge was forming and routing the 3/4" hard lines under the manifold.

 

If you lay a head gasket down on the block, you will see that there are two holes in each gasket, towards the leading-edge of the block, that are not reflected by holes in the block deck.

The deck being solid here prevents coolant from taking the shortest route between the pump and crossover, by forcing more coolant towards the back of the block.

If you convert the early Hemi to cross-flow cooling, as in front-rear, rather than front-front, the areas adjacent to where these nonexistent holes are will get hotter than is ideal.

Drilling out those holes to the gasket hole diameter fixes the issue. I think it was about 3/16".

Typical gasket pattern:

These are symmetrical. They have the holes at both ends, as do the heads. I put red dots next to the holes:


Typical block deck:

Note that it does not have symmetrical holes, with the absence of them being at the leading edge of the deck:


Will it be a problem on a street engine? The flow/temp model indicated that would be a hotspot.

As you well know, these engines are not inexpensive to build, and even less inexpensive in the supercharged version.

I was not willing to roll-the-dice on not making the change. It was free, and can be reversed with a tap and a grub screw.


Stock crossover, with spacers, and a thermostat adapter plate so that Chevy-intended stuff and Chrysler stuff will get along.

 

Points well taken. I'll study a bit more on the block. Maybe it's good that I don't have the hi-tech computer modeling stuff...

 

I see exactly what you’re showing
But
The the right bank of the deck has those holes in the rear and not front. The left bank has no holes font and holes at rear.
So your idea is to flip flop with new holes and plug existing since your crossover is flipped to rear?
Or you want 8 holes.

 

I don't think your comment accurately reflects what you meant to say.

 

US drivers side of block has holes toward front but not rear. (Those holes in the deck gimpy is talking about)

US passenger side has holes toward the rear but not the front.
It’s opposite.

 

That's how I see it too.....

 

I didn't have any problem with OEM type, but I used a bit of JB Weld as sealer...

 

Here's the quote:
....... the right bank of the deck has those holes in the rear and not front. The left bank has no holes font and holes at rear.......

As I read it, it is saying there are no holes on either side of the front, and holes on both sides of the rear. Am I misreading it?

 

Good idea with stock freeze plugs. JB will help for sure

 

Looking at the block photo from gimpy, the driver side coolant holes are at the front of the deck,

The pass side deck has coolant holes at the rear but NOT in the front of the deck.
If you are looking at the deck surface (ignore left or right) the layout will be the same orientation with the two noted coolant holes on the left.
So, if you pull water from the front of the heads the flow, through either head, will be essentially the same as if pulling from the rear of the heads , just opposite.
Please correct me if I am mistaken.

 

@73RR

Yes, you are correct. And so am I.

However, if you read the @31Vicky with a hemi comment it says there ARE holes in the rear on BOTH banks, and NO holes in the front on BOTH banks.

Here is is again, verbatim. Read it carefully, draw it out, whatever. Then tell me whether it is right or wrong.

....... the right bank of the deck has those holes in the rear and not front. The left bank has no holes font and holes at rear.......

 

Aren't we just jousting windmills in worrying about these 1/4" holes? After all hemis have been successfully terrorizing the streets as-built for 70 or so years.

 

My 354 had missing holes in the front of both sides.

The picture that you see above is a 392, that I found on the internet.

Bottom line is, if you want to run water out of the backside of the heads, whatever holes are missing at the front need to get drilled.

 

This only applies to cross-flow cooling, with the crossover at the rear.

So no, this is not something that has been used on the streets since the 1970's.

I have only seen it done three times since the 1970's, and one time was me.