Datsun Roadster Forum-311s.org

redroadster68 wrote: ↑Sun Oct 23, 2022 9:40 am D08E8F03-1233-4275-9670-69E00A1C61C4.jpeg

Installed ITG air filter. Tight fit .

I had to angle the clutch master to get mine to fit.

Since my stroker continues to go flat in the 3-4000 rpm range no matter what we have tried going to try a set of 2L SU. Three distributors, two sets of 1600 carbs including a fresh Z Therapy set, and richening the carbs has not worked. Richening helps some and the pulling the choke does too.

I'm learning all about 2L carbs which you wouldn't think are that much different but just enough to confuse me here and there. Like where is the vacuum port I don't see it on the bottom? Oh, look at that it's on the top.

Thanks to Steve's linkage write up and that I already have a hogged out 1600 manifold it should go smoothly.

My 1800 block has come back from the machine shop and has been painted and new brass freeze plugs installed and painted. Next up assembly after I clean out all the passages and also take the head in for porting.

Spyder, Do you have enough room for stacks within? Looks pretty shallow

Yup, I run short stacks . Seams to fit ok
Just fits under clutch master.

Curtis wrote: ↑Sun Oct 23, 2022 10:49 am Since my stroker continues to go flat in the 3-4000 rpm range no matter what we have tried going to try a set of 2L SU. Three distributors, two sets of 1600 carbs including a fresh Z Therapy set, and richening the carbs has not worked. Richening helps some and the pulling the choke does too.

Hopefully the switch will cure this. However, improvement from richening the mix suggests that's it's not starving for airflow but more about fuel ratio, so it may be a combo... who knows, all you can do is try. Needle choice may make a difference. I've learned that there are a number of things going on inside the intake tract, including "reversion" that can be due to any number of factors. On my car, the recent cam switch has produced a loss of power at that rpm. I know it's the cam as I can control and adjust fuel ratio and timing considerably and doing so has made no difference. If after your efforts the problem continues, then it might be worth running it on a dyno so you can see exactly what the ratio is, where power drops off, play with timing a little, etc. Are you using a filtration system that has velocity stacks? They do make an airflow difference and influence torque bands some. Longer stacks will improve low end torque but they are harder to fit. It may be worth the time, at least temporarily, to fit a wideband sensor so you can see ratio in real time. They have become a lot less expensive, and I'm sure you could create (with your wiring expertise) a system that could easily be "plugged" into a typical Roadster for tuning and then be available for others who are curious but don't want a permanent install. The only other thing you would need is an exhaust bung welded in for the O2 sensor. Just another project eh?

This is my redneck temporary SU air cleaner setup. I cut out the cover for both carbs and since my stacks are longer than width of aircleaner profile I fabbed a framework from rain gutter mesh then slid wife’s old pantyhose over the entire frame. Yeah crude and not the most effective way to keep crud out but they breathe nicely especially with thinned throttle shafts and profiled damper pistons.

Love the creativity! Can you elaborate more on "profiled damper pistons"? Thinned throttle shafts gonna help much? Interesting!

Perused SU performance mods and one way to increase airflow is to cut half the diameter off throttle shaft. The other mod is smoothing the 90 degree damper bottom edge a bit. This combo has wakened the response some. Also running RC needles since increasing the engine bores. Butt Dyno says it’s happy !

Got it! thanks for the tip!

nismou20 wrote: ↑Sun Oct 23, 2022 11:00 am Spyder, Do you have enough room for stacks within? Looks pretty shallow

Space is not a problem because they are about an inch tall.

Curtis wrote: ↑Sun Oct 23, 2022 10:49 am Since my stroker continues to go flat in the 3-4000 rpm range no matter what we have tried going to try a set of 2L SU. Three distributors, two sets of 1600 carbs including a fresh Z Therapy set, and richening the carbs has not worked. Richening helps some and the pulling the choke does too.

I'm learning all about 2L carbs which you wouldn't think are that much different but just enough to confuse me here and there. Like where is the vacuum port I don't see it on the bottom? Oh, look at that it's on the top.

Thanks to Steve's linkage write up and that I already have a hogged out 1600 manifold it should go smoothly.

My 1800 block has come back from the machine shop and has been painted and new brass freeze plugs installed and painted. Next up assembly after I clean out all the passages and also take the head in for porting.


IMG_3292.JPG

I never tried SU carbs with my current config but I'll share a story about my solex mid range problem I ran into. When I put together this setup and was testing and tweaking with the butt dyno, I got to a point where I was happy with the performance and decided to button it up and start driving it again. This involved putting in the after market air filter, Drilled two holes in the filter backplate which I plumed the air vents for the fuel bowls. Went out for a drive and the mid range had a shudder and loss of power. Long / short, the air pulses in the filter impacted the air going into the fuel bowls. Removed the rubber hoses into the filter and vented the bowls outside of the filter, . Have you tried it without a filter?

spyder wrote: ↑Mon Oct 24, 2022 9:43 am I never tried SU carbs with my current config but I'll share a story about my solex mid range problem I ran into. When I put together this setup and was testing and tweaking with the butt dyno, I got to a point where I was happy with the performance and decided to button it up and start driving it again. This involved putting in the after market air filter, Drilled two holes in the filter backplate which I plumed the air vents for the fuel bowls. Went out for a drive and the mid range had a shudder and loss of power. Long / short, the air pulses in the filter impacted the air going into the fuel bowls. Removed the rubber hoses into the filter and vented the bowls outside of the filter, . Have you tried it without a filter?

Filter? What's a filter? Haven't put it on since we're still trying to get rid of the problem. Tried two sets of richer needles from Keith and it made some difference. Did some clean up yesterday on the 2L carbs I'm going to have Keith rebuild.

Bought a trunk lid for my car at the body shop that hasn't been violated by damage and bondo. The other two I have would require too much work to make them look decent.

Last weekend it was a shock upgrade. The stock ones were spent and the KYB gas adjust were just the remedy. Oddly, the fronts were easier than the rears. Then came today and let me just say, I think that the placement of the starter is quite possibly a human rights violation. The job is done but I'm pretty sure my neighbors suspect that I have Tourettes Syndrome.

Many of us can relate on the starter issue if the triangle "plate" from the body is not cut out. However, I do remember a guy (a now since passed owner... Bob?) who had only one hand assist another owner at the Shasta meet to remove his starter. The car's owner and several others had been trying for a bit until Bob (?) lay down, stuck his hand in there and magically pulled the starter out in like 15 seconds. I think we all clapped, but of course he couldn't but he just smiled... he was that kind of guy! Buy that man a beer!

Gregs672000 wrote: ↑Thu Nov 24, 2022 2:33 pm Many of us can relate on the starter issue if the triangle "plate" from the body is not cut out. However, I do remember a guy (a now since passed owner... Bob?) who had only one hand assist another owner at the Shasta meet to remove his starter. The car's owner and several others had been trying for a bit until Bob (?) lay down, stuck his hand in there and magically pulled the starter out in like 15 seconds. I think we all clapped, but of course he couldn't but he just smiled... he was that kind of guy! Buy that man a beer!

Now that’s cool!