1973 Rebuild

[Matthew Abate]

My Mikuni 44PHH carburetors are in.

This. Took. Some. Work.

They are fitted to a Mikuni short-runner intake manifold, which sounds all well and good until you try to fit it along side a 240z thermostat housing, which fouls the manifold. I had to switch back to the ZX housing. It doesn’t interfere with the manifold installation, but it’s cover sure does. Also, the water inlet for the coolant fouls the front carb and the throttle linkage.

I want to retain a functioning heater, so I need that water pipe to work. I tried a bunch of stainless adapters, which were all much too big, but was saved by this little brass guy from Home Depot (a 90° 1/4 npt M to 1/4 npt F street / adapter). I still had to drill it out to increase the flow, as well as tap both the adapter and the thermostat housing and cut down the water inlet pipe to ensure a high rate of flow through the whole junction.

I also replaced the thin black carburetor gaskets that came on them with VW carburetor base gaskets by EMPI from JBugs California Pacific. I was a little bummed to find out that they are white and not the grey in the photos, but I am pleased with how thick they are. That extra few millimeters helped push the carburetors away from the thermostat housing and gave me some much needed clearance.

The gaskets are the perfect thickness for want I needed when it came to making clearance, but they aren’t an exact fit for the PHH carbs. They’re meant for VW solexes (so downdraft) and the bases are different, which meant I needed to trim them to no be sticking out a mile.

They also needed to be opened up from 40mm to 44mm to not interfere with the airflow.

On the left is one with the outline of the gaskets that came with the carburetors drawn in pencil. On the right is a trimmed gasket before final cleanup. In the next photo you can see that the holes are now the same size as the phenolic. They are slightly bigger than the carburetors and manifold, which I think is fine. If I have trouble I’ll make something from scratch that is custom to each port.

The last photo just shows that they don’t stick out a mile anymore, even though I could probably trim them further.

For the thermostat cover, I took a gamble on a NOS one for L20Bs and JDM C210 Skylines for $20 on Amayama. It looks like it uses the same gasket as the ZX, so hopefully it will fit. It looks just like the three-bolt ZX cover, except it doesn’t have the two extra bosses on the rear end, which hopefully means it won’t hit anything. We will find out when it arrives.

Now on to the goodies: the carburetors are 44mm Mikuni PHH side drafts (I explained in an earlier post how I got them). They are on the previously mentioned Mikuni short intake manifold, held on with OEM manifold washers and copper flange nuts on the bottom and SS flange bits on top, and wearing 50mm Kameari velocity stacks.

Next I plan to fit the heat shield and solve the water pipe routing problem. I have air filters but don’t expect to mount them until the brake and clutch master cylinders are in and the fuel routing is worked out.

Edited November 7, 2023 by Matthew Abate

[gundee]

5 hours ago, Matthew Abate said:

My Mikuni 44PHH carburetors are in.

This. Took. Some. Work.

They are fitted to a Mikuni short-runner intake manifold, which sounds all well and good until you try to fit it along side a 240z thermostat housing, which fouls the manifold. I had to switch back to the ZX housing. It doesn’t interfere with the manifold installation, but it’s cover sure does. Also, the water inlet for the coolant fouls the front carb and the throttle linkage.

I want to retain a functioning heater, so I need that water pipe to work. I tried a bunch of stainless adapters, which were all much too big, but was saved by this little brass guy from Home Depot (a 90° 1/4 npt M to 1/4 npt F street / adapter). I still had to drill it out to increase the flow, as well as tap both the adapter and the thermostat housing and cut down the water inlet pipe to ensure a high rate of flow through the whole junction.

I also replaced the thin black carburetor gaskets that came on them with VW carburetor base gaskets by EMPI from JBugs California Pacific. I was a little bummed to find out that they are white and not the grey in the photos, but I am pleased with how thick they are. That extra few millimeters helped push the carburetors away from the thermostat housing and gave me some much needed clearance.

The gaskets are the perfect thickness for want I needed when it came to making clearance, but they aren’t an exact fit for the PHH carbs. They’re meant for VW solexes (so downdraft) and the bases are different, which meant I needed to trim them to no be sticking out a mile.

They also needed to be opened up from 40mm to 44mm to not interfere with the airflow.

On the left is one with the outline of the gaskets that came with the carburetors drawn in pencil. On the right is a trimmed gasket before final cleanup. In the next photo you can see that the holes are now the same size as the phenolic. They are slightly bigger than the carburetors and manifold, which I think is fine. If I have trouble I’ll make something from scratch that is custom to each port.

The last photo just shows that they don’t stick out a mile anymore, even though I could probably trim them further.

For the thermostat cover, I took a gamble on a NOS one for L20Bs and JDM C210 Skylines for $20 on Amayama. It looks like it uses the same gasket as the ZX, so hopefully it will fit. It looks just like the three-bolt ZX cover, except it doesn’t have the two extra bosses on the rear end, which hopefully means it won’t hit anything. We will find out when it arrives.

Now on to the goodies: the carburetors are 44mm Mikuni PHH side drafts (I explained in an earlier post how I got them). They are on the previously mentioned Mikuni short intake manifold, held on with OEM manifold washers and copper flange nuts on the bottom and SS flange bits on top, and wearing 50mm Kameari velocity stacks.

Next I plan to fit the heat shield and solve the water pipe routing problem. I have air filters but don’t expect to mount them until the brake and clutch master cylinders are in and the fuel routing is worked out.

Also have Mikuni set up. Had to trim the manifold some to clear the thermostat housing. 

Pretty common on these.

I am not a fan of your choice of head studs. Some of those are too short for my liking.

Same with the Mikuni studs. Just too short IMO.

[HusseinHolland]

Nice Work all over!

 

Question - are those engine/trans gussets a 280ZX thing? I don't recall seeing them on my 75 280Z. This would be the only RWD car I've owned that doesn't have bracing for the lower bell housing. 

[Matthew Abate]

38 minutes ago, gundee said:

Also have Mikuni set up. Had to trim the manifold some to clear the thermostat housing. 

Pretty common on these.

I am not a fan of your choice of head studs. Some of those are too short for my liking.

Same with the Mikuni studs. Just too short IMO.

The Mikuni studs can’t be much longer because they will hit the manifold when it’s tightened down. I might be able to add 5mm but not more.

same story with the carburetor studs.

7 minutes ago, HusseinHolland said:

Nice Work all over!

 

Question - are those engine/trans gussets a 280ZX thing? I don't recall seeing them on my 75 280Z. This would be the only RWD car I've owned that doesn't have bracing for the lower bell housing. 

Thanks. Yeah, they are a ZX thing. They were also used on some L20 configurations.

Edited November 7, 2023 by Matthew Abate

[Zed Head]

The F54 block has the holes for the gussets.  The N42 block does not.  In case you were thinking about a retrofit.

[HusseinHolland]

4 minutes ago, Zed Head said:

The F54 block has the holes for the gussets.  The N42 block does not.  In case you were thinking about a retrofit.

You read my mind 🤪 I was looking back through pics I took whilst working underneath -  I see that the block casting has no flat in that area on my motor.

[Matthew Abate]

Kameari makes a gusset that uses the oil pan bolts to accomplish the same thing. I’m not sure it works without their aluminum oil pan, though, which is thicker.

[HusseinHolland]

12 hours ago, Matthew Abate said:

I want to retain a functioning heater, so I need that water pipe to work. I tried a bunch of stainless adapters, which were all much too big, but was saved by this little brass guy from Home Depot (a 90° 1/4 npt M to 1/4 npt F street / adapter). I still had to drill it out to increase the flow, as well as tap both the adapter and the thermostat housing and cut down the water inlet pipe to ensure a high rate of flow through the whole junction.

 

Isn't the water pipe fitting pointing directly into the path of the #1 runner? Or is that just optics? I saw you are making an SS tube to traverse the motor, it will use a short section of hose to attach here? 

[Matthew Abate]

It’s forward of the runner, but it may still give me problems. I’m going to try to get the tube to work, but it’s going to take some experimenting with different hoses to do it. I may still end up doing something different with that whole setup.

Regarding the studs, I think I’m going to figure out an optimal length after I get all of the plumbing worked out. I will have to pull the carbs off when I route my AC lines anyway. I have 45mm studs on there now, and I’m nearly certain 50mm will hit, so I’ll have to machine the 50mm ones down to make them work.

All of this probably explains why you don’t see this manifold much.

[HusseinHolland]

1 hour ago, Matthew Abate said:

It’s forward of the runner, but it may still give me problems. I’m going to try to get the tube to work, but it’s going to take some experimenting with different hoses to do it. I may still end up doing something different with that whole setup.

Regarding the studs, I think I’m going to figure out an optimal length after I get all of the plumbing worked out. I will have to pull the carbs off when I route my AC lines anyway. I have 45mm studs on there now, and I’m nearly certain 50mm will hit, so I’ll have to machine the 50mm ones down to make them work.

All of this probably explains why you don’t see this manifold much.

Have you considered running it around the front of the motor? My 280Z heater pipe is on that side T/stat port comes out the front, goes to a branch by the alternator - I'm not familiar with versions like yours on the manifold side.

[Matthew Abate]

I hadn’t because of the belts for the alternator and compressor. I will take a look at that though. I’m also thinking about whether it could go under the headers instead of cramming them in between the headers and the carbs. It might actually be cooler if I get it low enough.

[dutchzcarguy]

Looks good but i hope that stripe just above the middle of the picture in the lip of the coolant/thermostatholder isn't a crack? 🙊