Steve's 67.5 Stroker

[pebbles]

Smooth as silk, doesnt get any better than that.
Fun run yes.
Best wishes for the New Year.

[Gregs672000]

Awesome man, she looks great and it sounds like she performs well! Dave is a good guy who knows his stuff, glad you were able to get together. Did you ever install the wideband or do you not need it?

[S Allen]

Thanks Greg. I have not installed the wideband as yet but seat of the pants she runs strong. Dave is the man when it comes to mikuni's and a lot of other stuff as well.

Steve

[Pjackb]

So Steve a few questions
How does the car feel now in the middle of the powerband say 2500-4500 rpm Compared to the big SUs?
And how about on the highway say that your cruising at 55-65mph do you absolutely need to downshift to pass someone or can you just lug it?
obviously she has more power now but do you feel the Miks are better suited to your engine or is it just a different feel?

Thanks in advance
Jack

[S Allen]

She feels strong through all the gears. Punching it will get me around most times. The 240Z SU'S always ran a little rich. I love the sound of the 40's when you put your foot on the gas. I feel the mik's are better suited to my stroked 1600. Very happy with the setup.

Steve

[Gregs672000]

So Steve a few questions
How does the car feel now in the middle of the powerband say 2500-4500 rpm Compared to the big SUs?
And how about on the highway say that your cruising at 55-65mph do you absolutely need to downshift to pass someone or can you just lug it?
obviously she has more power now but do you feel the Miks are better suited to your engine or is it just a different feel?

Thanks in advance
Jack

I'm sure Steve will answer, but some of the performance questions you ask have a lot to do with the cam, compression ratio, ignition timing and venturi sizing in the carbs themselves. Choked with 37mm venturis vs 34mm vs 32mm will make some difference for sure in how responsive the engine is, especially at lower rpms, as will what he is running for a cam. You may already know that and simply want to see how switching to the Mikuni vs SU style carbs changes things, but if you are looking to recreate similar performance the whole thing works as a system...

[S Allen]

Worked on the purple stroker today. I replaced the rocker shaft with a new hardened rocker from Rockers Unlimited out of Redding. Both Stan and Dave Premo carry them. A really nice piece. Got her all buttoned up but now I have a leak at the valve cover. Since the old one is cork I will just get a new one. Got the valves all set and after filling her up with anti-freeze took her for a short spirited drive.

new-rocker-shaft.jpg

The second project was relocating the temp sensor out of the water pump and putting it inline of the top radiator hose. I never liked the stock location as it is too close to the exhaust manifold. The water pump turned out to not be such a good place either as it interfered with the alternator. So I purchased an Autometer stainless steel fitting that has a plug hole for the sensor. I also ordered some 1-1/2" racing radiator hose that were 45 degree L's. I had to custom fit the radiator hose but it turned out pretty nice. That was the reason I had to put anti-freeze back in and burp the system.

water-pump-plug.jpg

sensor-tee1.jpg

sensor-tee2.jpg

She was running around 180-185 during the spirited drive. Happy with both projects.

Steve

[JT68]

So the reason the sender is in the head is to measure cylinder head temp. Having a sensor in the hose tells you coolant temp coming from the radiator. With that configuration you can completely fry the head with little indication from a sensor in the hose. Either very low coolant or a stuck thermostat for example.

The stock location for the sensor really isn't much of a problem (except that it is hard to access on the R16 head), because the sending unit itself is well into the coolant passage, so it tells you pretty accurately what the head temp is. If the head is starving for coolant, the sensor will get hot quickly and report that to the gauge as intended.

There is no harm in a sensor in the hose, but you really do want a sensor on the "hot" side of the thermostat as well.

[S Allen]

I guess my solution will have to be thought out a bit better. Here I thought I was being slick. Thanks for the clarification JT. I will not drive it much until I get this sorted. I still do not care for the stock temp sensor location but I am sure it was put there for good reason.

S

[JT68]

Newer (90's+?) cars use multiple temp sensors and let the ECU figure out what to do with the info (trim the mixture, turn on the fan, turn on CEL, turn on buzzers and sirens or phone home LOL). A T in the hose is a handy spot for a fan switch too.

I like to have the OEM gauge functional and add a Stewart Warner mechanical gauge to rely on. ( Once you have one of those, its hard to ive much serious attention to the Nissan gauge honestly)

The rear of the head is also a very good spot for a temp sender although it will typically read a few degrees hotter than near the cool water inlet. That's OK- with a good gauge it gives you an extremely accurate indication on head temp.

[S Allen]

Think I will have a spacer machined to put the temp sensor probe before the thermostat and then use a an elbow from a 240Z/510 to eliminate the stock tower altogether. Kind of like the U20 setup. Then I will use a U20 radiator so I have the filler in the top of the radiator. So, will have to call it a work in progress.

S

[Daryl Smith]

Often the aftermarket sensors are spec'ced to be away from the exhaust.
I see no problem drilling and tapping a hole anywhere there's room in the front of the head for the water temp sensor. Close to the original location and will provide similar, if not the identical results. Back of the head will likely work as well, hidden, perhaps not as easy to access.
Choose your location so that it's easily serviceable and the wiring is easy to manage.
I have deleted/plugged the stock location, and added 2 temp sensors. One for the aftermarket gauge and one for the EFI ecu.
No problems. Each shows same temp within a couple degrees.
I know many people will not like this solution aesthetically, but, it works!
Picture shows the GM temp sensor on left and drilled/tapped hole for sensor for gauge on right.

[SLOroadster]

Think I will have a spacer machined to put the temp sensor probe before the thermostat and then use a an elbow from a 240Z/510 to eliminate the stock tower altogether. Kind of like the U20 setup. Then I will use a U20 radiator so I have the filler in the top of the radiator. So, will have to call it a work in progress.

S

I was able to install a U20 outlet and spacer in place of the stock tower on the #44 race car. We were having issues with false readings from the stock temp location (the gauge would show 260 degrees within 2 laps of Sears Point) yet nothing was overflowing, and nothing was actually that hot. (Not even close, more like 210, where it should be.) It did require ovalizing the bolt holes slightly, but it works and doesn't leak. I drilled and tapped a bleed port in the outlet to bleed any air out of the system if need be. The U20 radiator is a must have for the setup, but sounds like you already have one. The temp reading went from being insane, to reading where it should.

Will

[JT68]

Think I will have a spacer machined to put the temp sensor probe before the thermostat and then use a an elbow from a 240Z/510 to eliminate the stock tower altogether. Kind of like the U20 setup. Then I will use a U20 radiator so I have the filler in the top of the radiator. So, will have to call it a work in progress.

S

That would work fine Steve. As long as the sender is underneath the thermostat and in the water jacket of the head, that is what you want. The 2L radiator is preferable in every way. so that is certainly an upgrade.

But before everyone gets too moist about the stock sensor location, let's inject some logic back into the discussion:

a. Nissan used the same temp sender location on G,R and H engines from what 1963?, well past 1970 in 10's? 100's? of thousands of vehicles, clearly Nissan didn't have a problem with the stock sender location or they would have moved it. They made COUNTLESS minor design changes over the years. Clearly it was a non-issue for Nissan customer service, service departments, and the Nissan engineers.

b. If the sensor location in the cylinder head was in fact a systemic/design problem, since every 1600 temp sender was in exactly the same location, and used the same type sensor, every single 1600 rolling off the showroom would have had hi-temp readings once they got up to operating temp and on the highway. Obviously they didn't, so it isn't a design issue.

c. what happened on lap2 with a who knows what modified racecar, probably has very little bearing on 99% of the roadster street cars. Besides, if the temp gauge was accurate and trusted, (SW, VDO, etc) then the head probably was really that hot at that location, at that time. Most likely from air trapped in the system. Very common problem, probably resolved when the system was opened again and refilled. Just because someone didn't like what the gauge said, doesn't mean the gauge was wrong. right?