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Discussion Starter #1 (Edited)
hoping to discuss the physical differences between the 75 and 155 heads, but hoping to avoid a continuation of the 155 vs 75, which is better? my opinion, it's a matter of choice. the first 4 photos show the front cover bolt holes in the base of the head, you can not change a 75 head with a 155 as simple as changing a head and gasket on a nord, the ts motor will probably need to come out to address the differences in the bolt pattern.

the first 2 photos show the holes on the exhaust side thru which the bolt is passed from the bottom up. The 75 head is scrap and the 155 has the surface done.

the second set shows this area from the side, note that there is no metal into which you can drill and tap,

the 3rd set show the heads with a nord gasket, bolt patterm for front cover up into head is the same on the nord as the 155.

this is my first 155 head, so don't expect a-z instructions, rather this is checking the differences and adjustments and changes to be made to fit it as a replacement for the 75 head, hopefully I'll be able to upload scanned pages from the parts book that show the water pump and plumbing, and the ignition system. this head was purchased from a fellow board member, and arrived as he had acquired it, some port work done, nothing in the combustion chamber, not sure of valve angles, this head is not a priority so this will be slow.
 

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Discussion Starter #3
there is still the coolant passages and other items that can be dicussed, if you have anything to contribute please do, if you have general Questions or areas you would like to see in more detail just ask.
 

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Excellent pictures. If the second one is the 155 head (surface clean) then it looks like there is enough aluminum to drill for a new hole.

Something else just came to mind (and I am digging my memory here). There was a discussion about the 75TS head on the Nord engine with the engine cover from the 75. It was agreed that the Nord head gasket could be used by cutting off that piece of the gasket and repositioning it. Could it be that the Spica engine cover could go on the 75TS block with the 155TS head and work? In other words, are those two holes at the front of the 155 like the Nord and not like the 75? I doubt it is that easy, but I have to ask.
 
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Discussion Starter #5
I think the tab cutting was to use a nord gasket with a 75 motor, I don't see why a Bosch frt cover wouldn't fit, I know a spica one will, test fit at least.
The drawback would be for the ts builder that want's to retain the TS sensor for the crank trigger, which attaches to the TS front cover.
 
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Discussion Starter #6
Front covers

that a nord type front cover will bolt right up means that carbed engines can fit a more "correct" looking euro frt cover and single row 105 pully. But builders who want to retain the oil level sensor or the front mounted sensor need to use the 75 frt. cover,but as Iachella pointed out there is enough metal to drill and tap, it appears that the head was cast with the intent to use either hole. the photos show the head drilled and tapped for a 75 frt. cover 30mm c/c and 20 mm deep. The 2nd with the new bolt in place, 3 and 4 show the oil level sensor fitting on the intake side. And the front mounted sensor, needed for stock ECU or aftermarket mototronic compatiable engine management systems.
 

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So drilling and tapping a new hole in the 155 head is the first obstacle that is manageable. What is the next issue? You mentioned the water passages. I know they exit the rear. Can that be piped around to the radiator with rubber? Is the main problem the clearance to the firewall to fit the outlet piece?
 

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You mentioned the water passages. I know they exit the rear. Can that be piped around to the radiator with rubber? Is the main problem the clearance to the firewall to fit the outlet piece?
one of the best solutions is Jim Steck's but probably only with intake side water collecting , you will need inline separate stand alone thermostate body :)
 

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Discussion Starter #9
very impressive, but do we need to flow that volume of water thru a street motor? how about a log manifold below the intake manifold, 3 pipes to those plugs, a fitting on the back for the heater and a large section on the front braced off the distrubutor pedestal ( not being used) with a fitting below for the traditional bypass hose and a plate top angled and drilled to accept a euro "O" ring style thermostat and a bleed valve? the 155 has a very different water pump, the 75 front cover allows the use of the nord style pump, has the passage to the block, in thru the bottom, and out thru the top, bleed valve at highest point. Will the 3 outlet manifold not allow sufficent flow? I will try tomorrow to post the parts diagrams of the 155 plumbing, and photos of the opening in the back, which I was thinking could just be covered wih a plate. The 75 head has a large plug at this same end. I will also try to post a quick drawing.
 
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Discussion Starter #10 (Edited)
forget the pedastal, it looks like there are enough mounting points at that area of the head to bracket the "tank" section, unless I am missing something this can use stock heater, rad, and bypass hoses, as well as stock thermo and temp sensor and bleed valve.
 

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What is the problem with the water, exactly?? I don't follow why this contraption is needed. I thought that there was no room for the rear exit of water when the head is placed logitudinally.

Can the problem be stated first?

Thanks
 
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Discussion Starter #12
I don't know if there is a problem, the 155 has the thermo at the rear of the head, BUT that setup is for a FWD not the RWD 75 or 105, the head passages are the same, it's just that the external plumbing is different, no coolant passages thru head, each builder will come up with their own solution, I will post some photos of a mock-up installed on a 155 head and 75 block setup, simple and retains the stock "euro" hose setup, everything hand fits, but need to connect it all together and add mounting points, But not before tomorrow, other things that come first. A question for the members outside the USA where 155's can be owned, Do the heater hoses route direct to and from the radiator? Can't tell from the parts diagrams.
 

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So where is the water flowing in these 7 (???) tubes. I still don't see what it is doing. You say :
the head passages are the same
then you say:
no coolant passages thru head
this is not making sense to me. What can and what can't the water do as compared to the 75 and Nord head?
 
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Discussion Starter #14
the water in the 155 head can not flow out of the engine thru the intake manifold. in the nord and 75 the pump pushes coolant thru a loop along the exhaust side bathing the liners, the coolant is pumped up to the top of the engine thru the cylinder head and out thru the intake manifold. The nord manifolds have the "log" above the intake tracts. The top outlets may be necessary if the 3 intake side plugs are lower than the tops of the coolant cavities in the cylinder head, and the air can not be bleed out. in the photo with the 7 outlets, the coolant is running out of the tube near the dist. pedestal to the radiator. Not shown is the thermo assy. The manifold that I am making a mockup of will allow the use of the stock thermo etc, but the top tube connecting to the rear of the lower log may be a part of it. I would like to use the stock hoses and thermo housing. I will post the photos of the composite mockup tomorrow. Hopefully someone will be able to confirm that the top oulets are or are not required. I'm betting they are. or more correctly I am not betting $$$ that they are not.
 

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So why does it have to come out the intake manifold? Can't it just come out the back of the head where it was designed to and wrap around to the front and into the radiator via thermostat and bypass hose back to water pump?

If the 155 car with the FWD block doesn't have water going through the intake manifold, why do we have to? I'm still missing something here and I don't know what it is. :confused:

Thanks,
 
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Discussion Starter #16
Grainy photo, but it does show the rear opening. Coolant does not have to pass thru the intake manifold, I want coolant to pass thru the highest point of the cylinder head cavity. Air must be removed, filling a cavity from the bottom will push the air to the highest point of the cavity, if the upper flow passage is lower than the roof of this cavity, air will be trapped. If you look into the intake cam galley of a nord head you will clearly see 4 "tubes' cast into the head, 2 in the center and 1 at each end. they rise up out of the center cavity and pass horizontaly to the intake manifold, which contains the "high point". The 75 ts head is similar, but not as obvious. and the design of the intake maifold contains the "high point".

The 155 head does not pass into the intake manifold, the question is. Is this outlet at the rear of the head sufficent, if so whatever is bolted into place must be an open box that does not lower the high point of this opening, I do not want to bolt up a plate with a fitting in the center. It would seem that the Alfa design teams thinks this opening is sufficent. I have not seen on the head or in the parts diagrams any other higher point. I might be missing something.

Rather than install fittings down the side and fabricate a plate/box for the rear, Its easier to put fittings in the top of the head and run to the back to a vertical "tee" upper to new bleed point, lower down and over to intake side and pipe to direct coolant to front and remote thermostat. Temp sensor in rear of head.
Running down the center of the head is easier Than running off the 3 side outlets that ARE lower than the cavity. I like the retro pre-war/1900 look of the Steck motor, but my fitment will have a more industrial look to it.

My decision to use the top fittings is in part, that it is easier, and also a result of "unscientic testing" I set the head upside down on a flat surface. Raised the rear and poured 1 cup of water into the cavity. and set the head down to level. Let it set for awhile to allow the excess water to run out, and then raised the front of the head, allowing for some amount of water clinging to the metal, I still had enough water run out to question that the rear outlet will clear all air pockets. running thru the top of the cavity insures that the air pockets are purged. I think the 7 outlets may be more a solution to wanting large volume flow, and not that the top 4 will not do the job.

Keep in mind that this is really nothing more than looking the head over, not looking under the hood of a 155 and the postings are just, well, lets's see, hmmm, maybe, maybe not. I will post the photos of the mock up manifold I WON'T be using.(thats why its done in cheap composite:D) and what I wil be using. Right now, off for the holiday
 

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if the upper flow passage is lower than the roof of this cavity, air will be trapped
So why not drill and tap the top for bleed screws instead of a bunch of extra tubes?

I guess what I'm trying to figure out is did this head have problems in it's original car, the 155 FWD car? If not, why do we have to do something different?

It was situated 90 deg differenly, so the path to the radiator is farther away now on the 75 block, sure.

What about this scenario: Make a housing for the back of the head with a 90 bend (don't worry about the firewall for now, just the concept), come out from behind the engine and go the length of the engine to the front. Make a boss near the back, either on the housing, or on the tube near the back, for the banjo fitting for the heater under the dash. Attatch an inline thermostat near the front, like the 75, and pipe to the upper radiator and bypass to the water pump. Tap the top of the head in a couple of spots for a few bleed screws, like the Nord ones (Spica brass ones, I'm familiar with) or something else available.

Are there any conceptual problems with this? It seems to get the water back to the radiator as the original design, AND provide more bleed places for trapped air, something that the original car didn't have, so I really am not sure this is all that necessary, but could be added.

I hope some European or Asian residents can chime in on what this head was doing with the water in it's original car. Was it tilted dramatically to avoid air pockets? Did it have some other ways to bleed the air?

I'm still not convinced that there is anything wrong with the water flow, since I haven't heard anything wrong with the 155 car.
 
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Discussion Starter #19
6 of 1 or 1/2 dozen of the other comes to mind, there is probably no problem coming out the back other than space, heater hose, vacumn hose, and linkage are all back there. by blocking off this hole in the rear of the head and using it only as a mount for the lower "tee" this setup doesn't take up any more space than the heater hose it replaces. final installation will be neater and more elegant looking than this, with all new pcs. and the large pipe going forward on the intake side will not have the extra fitting, and will be placed last, after all intake, braces, linkage and mount have been fitted, the tube is probably the easiest of those items to relocate. this uses the 75 remote thermostat mounted in front, bleed in rear, but neither the 75 or the 105 temp sensor fit the opening in the rear of the head, or any of the 3 plugged outlets on the side of the head. simply add an adaptor to the rear hole?

This is basically the setup I will be using, each builder/owner builds to their needs and desires, and each setup is a little different. I prefer this because it is, for me, the simplest and easiest to do.
 

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Discussion Starter #20
another option?

1 3/4" extended back off head.. alum plate 1/4" gasket matched to rear outlet, box is 1 1/2 x 1 1/2 x 3, large lower outlet for return to thermo. small upper inlet for heater hose, bleed on top.
 

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