My Solution - Mikuni Carbs on an R16 / 1600

[dridge11]

Cannot thank Will enough for all his help. I borrowed him for a good 12 hours yesterday.

I'm hoping to venture out on Wednesday and limp to the muffler shop to get the exhaust done. Most of last night, we had the header connected to the flex pipe with one bolt (and it wasn't lined up) and then the flex pipe just slipped over the old exhaust. Sounded loud. While I added transmission fluid, Will got 2 more bolts in it and it sounded quite a bit better...like it just has the bad exhaust leak and not like it had a side pipe. And I was thrilled to see the gauge indicate the alternator charging.

Here are the pics, all put together, hood on. After I get through the exhaust install and wideband tuning and we get the throttle arms sorted out, I'll be sure to document our learnings from this whole experience.

[jamesw]

I drove my car to the exhaust shop after putting on a new header. There was about a 2 inch overall mis-alignment...

I just drove at idle and did it mid-morning on Saturday - it was fine. It was actually a lot of fun - especially that off-throttle "crackle (read backfire)" you get w/ the Mikunis

Cheers
James

[dridge11]

Yeah, probably going to take it for a brief drive up and down the road today just to make sure it's happy moving since it hasn't actually left the garage. The muffler shop is about 25 miles away.

[spl310]

Carbs look good! That alternator is hanging way out front though...

[dridge11]

That's just where it ended up to line up with the pulley on the fan.

[roadstermike]

Wow, great work on the roadster! I am almost at the same spot with my rebuild as well. Can you share some more detailed photos of your linkage setup? I am runnig 40 mikunis on my car too and am trying to figure out how to set it up as well.

I wish I had someone to help me wrench on my car too, it really makes a big difference.

[notoptoy]

Roaadstermike, where are you located? You might have some help nearby - you need to update your profile with your location!

[dridge11]

roadstermike - some close ups of the linkage on page 4. Not entirely sure it's the best setup and might get adjusted a bit, but that's how it looks now. If you want some other angles of specifics, let me know and I'm happy to help.

[SLOroadster]

We made some big steps in the right direction this evening, however we more or less ran out of fuel so testing came to a stop prematurely. The current setting is WAY fatter than I thought would be correct (and way different from where Wolf Creek set the carbs up with to start.) The car is running much better than it was, however its still on the lean side. I figured it was going to want 140 ish fuels with 175-180 airs with 57.5 pilots, however that setup was really lean. Currently we are running 165 fuels, 190 airs and 62.5 pilots. Its still got a hole at about 1500 rpm, but it pulls well from 2K on. I think another half turn on the pilots will solve that.

No its not a fast process, and the fact that the exhaust is pretty close to an open header (Huge leak after the flex pipe soon to be fixed after the carbs are dialed enough to get the car to the exhaust shop.) isn't helping anything.

Will

[shifty]

I thought I'd add a few pix of the progress on my set of 40's for an H20.

I'm using a 1" thick spacer to move the carbs out enough to use modified throttle arms on the carbs.

The kit-supplied rose joints have been replaced to allow the use of a 10mm rod for the linkage (roadster and z-car use a 10mm rod). The arms are from a 280z as are the stops holding the rod. The throttle arm, bell crank and service-screw tab are from the stock R16 SU set up.

I had a heck of a time figuring out how to mount the throttle arm, and keeping the service screw was one of my goals. I'm using a 7/8" joiner nut attached to the carb mount studs to mount an aluminum plate for the the throttle arm. I hope there won't be too much flex! I can always make a thicker mounting plate.

IMG_6388.jpg

IMG_6389.jpg

IMG_6380.jpg

I plan on doing a more detailed write-up once the whole project is finished. I hope to have it finished and sorted by Blue Lake!

[jamesw]

Leigh: That is some great Aggie engineering - I like it!

Did you have the spacers custom made out of delrin? Did you make them yourself?

Cheers
James

[dridge11]

Looks great! I do have a question...when your throttle cable pulls with that setup, it's going to pull the arms attached to the carbs UP. At least on my carbs, to open then, it would need to push those arms DOWN.

Do your carbs open by pulling upward?

Also, as an update on mine, I have a truck and trailer set to tow the Roadster to the muffler shop first thing tomorrow, get the exhaust done, get the o2 bung welded on, then it's time to get this thing tuned, slap the new wheels on, and back on the road!

[shifty]

Yes the arms on the carbs are modified U20 pieces - they operate by pulling up.

carb-linkage.jpg

[dridge11]

Pull up from the back rather than push down from the front. NICE!

[SLOroadster]

Pull up from the back rather than push down from the front. NICE!

You know, I think I might be able to make that work. I have the parts I think. It still doesn't allow them to be easily balanced, but it might work better.

Will