Everyday drivability of Triple carbs

[jmortensen]

I assume the standard linkages from Wolf Creek are quality. The images Todd sent me look like very good quality actually. I do appreciate all the advice here as well. When little issues work together, you wind up with a big difficult-to-diagnose problem (as I experienced early on with a bum set of SU's). I will definitely also need a solution for the heat either homemade or other.

Thanks Jon, the 44's have actually been what I've been leaning towards. I still have my 4 speed so the gearing doesn't seem too tall to me. Is that me hearing what I want to hear?

Todd has good linkage setups on his Mikunis. IIRC he puts a support rod end in the middle of the chrome linkage bar, from the factory the Mikunis only had rod ends on either end of the chrome linkage bar, and the middle would bend slightly under the weight of the return springs for the throttle plates.

I would suggest with 44's that you get a ZX NA 5 speed and a 3.90 or 4.11 diff. I think the stock 4 speed and rear end would work, but you have such large gaps between the gears that you'll be out of the powerband on shifts. I had a friend with a pretty built 510 and he had the 280Z 5 speed which has similar gaps in the ratios. Our cars turned very similar lap times at autox but when we went to a big track he had to deal with the gap in the 2-3 shift and the one time I was behind him coming onto the front straight, as soon as he made that shift I was in front of him. Now a Z has more torque and a wider power band than a 510 in general, but after that incident he got a closer ratio 5 speed and we were neck and neck again.

[70 Cam Guy]

I didn't realize the wider ratio from the 77-78 would be so pronounced. I was hoping to avoid swapping transmissions because the car is still pretty low mileage but it sounds like another thing to keep an eye out for. The R200 swap was another thing I haven't really tried to wrap my brain around besides needing the matching mustache bar.

If you mean the rotating linkage bar, there looks to be a support rod end at each point on the Cannon manifold where a rod & lever connect to the carb (from the chrome bar). I don't know the proper names for some of these carb linkages. Maybe that is something he added? I haven't actually looked at my Cannon in a while. The pictures he sent look first rate, almost made me throw everything on my card right there.... have to curb my impulsive side for the moment :stupid:

[jmortensen]

The Cannon has 3 "towers" which are rod ends that hold the linkage bar. The Mikuni has 2, and the spring pressure from the carbs acting on the linkage will bend the bar in the middle.

The ratio isn't a make or break deal, but if you're racing and you are next to a car with tighter ratios and a lower rear and all else is equal, you'll lose.

I made a list of the parts you need for the R200 swap here:http://forums.hybridz.org/showthread.php?t=114798

The parts list needed to bolt in a longnose R200 into a 240Z is as follows:

1. mustache bar from 280Z with R200

2. yoke (companion flange) from 280Z with R200

3. rear cover from 280Z or ZX with R200

4. side stub shafts from 280Z or ZX with R200 to bolt up to stock halfshafts

FOR EARLY 70-71 Z's only, you need 5 -7.

5. Longer 72-78 driveshaft

6. Curved transverse link that sits right behind the diff from 72-78 Z

7. Flip front diff mount around on crossmember

5-7 are necessary because the early Z's had the diff mounted forward, and swapping to the R200 moves the diff rearward. Obviously if you buy a diff from a 280Z with an R200, it has everything you need except the mustache bar. If you buy the 300ZX diff, then you need the above pieces.

[70 Cam Guy]

As long as the triple manifolds are forward-to-rear, it doesn't surprise me they flex in the middle without a middle support. I've been excited about my 240Z for a while now and happy with the improvements I've made. I thought that would subside after a little while but it still feels like the honeymoon of a cool new project. I love it

I think the 5-speed and R200 are an "eventual" thing but it hasn't been anything I've thought about real seriously yet. I've always liked the idea of an LSD though. It's great to get some practical advice and opinions on this stuff.

You know I'd completely forgotten about the FAQ section on Hybrid Z. Before my car was even running properly, I read a large amount of the strut thread and the strut sectioning thread. Also have read the suspension mods faq, and some of the adjustable LCA thread. That was probably about the same I asked you the coilover questions. I've even spent a week of lunches at work reading the Weber jets thread to learn more about the Webers. I started reading the R200 thread months ago but stopped after thinking "I'll never do this swap"... :stupid:

Thanks again everyone for your input on this thread, it's been a great eye opener and hopefully it will help others that are curious about life after SU's.

[george71z]

Here are some pics of the triple linkage I fabricated. Maybe you can use some ideas.

[70 Cam Guy]

Here are some pics of the triple linkage I fabricated. Maybe you can use some ideas.

Nice, did you machine the levers or were those bought? Do they use a set screw? Does it thread into the rod or is there a clamp I didn't notice? I like the heim style rod ends, they are solid and precise.

[redneckz II]

I have 45mm Weber DCOE's on the car now. The car came that way. It started with a L-24 engine and now has a L-28 in it. Both of them had a E-31 head on it, that had been modified a lot. In the L-24 engine we ran with 30mm main venturies tubes and never had any problems on the street. On the L-28 block we were looking for more power in the higher RPM range, so we went with 37mm main venturies tubes in it. With the cam we are now running, we lose a little in the lower RPM range and get a lot more in the higher range. We still get good gas milage out of it, (if we keep my lead foot out of it). What I like with this combination is the sounds it makes. I have a early Z-28 camero hood scope on it and when you put the peddle down, it surprises the people next to you with that sound that it makes. On the street I always got good gas milage with the car (drove it from NC to Colorado, a lot per year). How you peddle it will decide how much you will get. Overall driving wasn't that bad on the street with them on it. Edited October 22, 2009 by redneckz II
edit it again

[70 Cam Guy]

Wow 45's with 37mm chokes, must be a hot motor

I read most run with 32mm chokes on the Weber 40's. IIRC, the Weber book does say 30mm chokes for the triple kit. Do the 30mm chokes compensate since you were running 45s? Throttle response must have been out of sight.

It's interesting everyone seems to be getting good gas mileage with these carbs. I never though I'd see 20 mpg with my car, let alone the 25 I got on a mostly freeway tank of gas. I'll be happy if I can keep it over 20, and will likely be beside myself if I get better than the SU's. It sounds like if you're smart with the skinny peddle you can make them work for you in any situation

I forgot about the rallyX car had the Weber's on it (owned by a friend of the shop owner). It ran like a top, what a fun car!

http://smg.photobucket.com/albums/v283/70CamGuy/?action=view&current=ThunderCross.jpg

Edited October 23, 2009 by 70 Cam Guy
proof reading is good :)

[jmortensen]

I don't think 37's are that huge. That's what I ran on my 44s.

[70 Cam Guy]

I don't think 37's are that huge. That's what I ran on my 44s.

Oh I don't know, I'm still learning these sidedrafts. I figured if the 45s typically come with 34mm chokes, an L28 that needs 37mm chokes has some good mods to it.:tapemouth

I still have a lot to learn

[TexasRider260Z]

Todd is straight shooter and does some really nice work up there. I got my 40's from him and they look excellent. But they are not on the car waiting for some work. He was very helpful and again the quality was tops.

[70 Cam Guy]

Todd is straight shooter and does some really nice work up there. I got my 40's from him and they look excellent. But they are not on the car waiting for some work. He was very helpful and again the quality was tops.

The local guys I spoken to also speak pretty highly of Todd and Wolf Creek. I heard Mikuni guru at the dyno day over the weekend. I didn't run my car but another guy with a '73 with round tops pulled 112.2 at the wheels (exhaust with turbo muffler, stock exhaust manifold). The AFR showed in the 12s so for fun, we pulled off the air cleaner top to see if we could lean it out a hair. It pulled 114.2 but it looked like lost a little on the lower rpm. It did lean it out in the mid-range but it went rich again up top. This was on a Dynapack, sorry I don't have the printouts.

Seeing over 110 at the wheels gave me some hope