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Hunter

RB Motor with Triple carbs, Can it be done? Z432 Z432-R

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I know there is alot of electronics etc on the RB motor, but is their anyway that you could hook up triple carbs to an RB motor?

 

It would be basically removing the injectors and replacing with carbs,

 

vacuum signal would have to be taken somewhere. maybe a airbox over the carbs could give a balanced vacuum signal.

 

Could the engine run without the computer controlling injectors? It would be very complex if it could be done. Anyone with RB experience chime in with your thoughts.

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Of course, an ICE only needs fuel and air to run. It's been done before in Japan there were a few S30's and even some Skyline C10's with RB25 engines that were converted to Carburetors.

 

The big question is why though? EFI has so many advantages and I imagine the EPA would not like it either. I'm fairly certain the rule books say that an engine swap must conform to the emission standards of the year the engine was produced.

 

It may be different with a 240z shell since they were pre-emission but anything after 75 I think you have a problem.

 

I have no experience myself with RB motors so I'm not the best to advise on the topic.

 

 

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Sounds like we are lucky here in NZ no emission for post 75 not until 89 ;)

 

Back to the question at hand - yes can and has been done. You would need a custom intake manifold or modify a RB26 intake manifold to fit on the RB25/20 head (whatever you are going to use). If using the RB26 intake manifold you will need to make some adaptors to go from the RB26 TB pattern to DCOE/PHH/DHLA pattern. Re EFI vs Carb - well if the carbs are setup to for the engine correctly they will perform very well and be right up there with EFI so no lose.

 

I have considered this myself - safe me a lot of wiring on the car :( never know might do it yet ;) just need a plan for a dizzy and keep it very old school.

 

Not much electronics on a NA RB, Knock Sensors, CAS, Water Temp for ECU, Coil ignitor, coils and injectors rest is standard engine electronics/electrical stuff, alternator, temp and oil gauges that is about it really.

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I was almost there with the setup I had; I made my own triple manifold for the RB25 head (approx $300) and then all you need is a system from MSD that can take the signal pulses from the CAS, and run a coil pack. I think they have a system but it costs around $500. You may not be able to fit a distributor as the sensor bolts to the front and may poke into the radiator. Plus running a coil pack, you will have a bullet proof ignition system good enough for 10,000 rpm. Look at the MSD website and have a dig around..

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The reason I ask, is I want to make a Z432-R or Z432 Replica.

 

Basically a RB20 to match the 2.0L donk in a 432. possibly a RB25

Triple Dual throat carbs.

A custom made airbox made to look similar to 432 air box.

Extrators 6 into 2 with twin exhaust.

Doubt I will find 432 mags, so Black Rota Grids would do.

Custom plug cover to match the 432 motor.

Paint the plug cover and cam covers to match the 432 motor.

Possibly 432 rear spoiler.

Possibly source all the extra little things that makes a 432 a 432.

clock, tacho, rear bumber rubber, etc etc.

 

Car body colour would be Orange with black bonnet. or 432 Gold with black bonnet.

 

Does anyone know the paint code or equivilent for the 432 Gold?

 

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Ive seen 280ZX wheels painted black to resemble the 432 / Safari Rally 240's pattern. Only downside is they are 14". Cheap and plentiful! 432 badges pop up on eBay now and then but the rocker cover will be the biggest challenge I think.

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Dimitri, I was thinking I could make a cover to go over the top of the motor whole motor, weld tabs onto the cam covers and screw it on that way.

 

Do you still have the RB Triple carb manifold? That I could either copy or buy? I would like to plan the project first though to make sure it will work, and I will also need another shell.

 

The 280ZX wheels would be a good option as 432 I am guessing come with 14" wheels. but from reading the 432-R was released with steel wheels and was mainly sold to race teams, who put their own wheels on the car, Watanbe's or similar.

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432 images

post-930-144023568151_thumb.jpg

post-930-144023568158_thumb.jpg

post-930-144023568169_thumb.jpg

post-930-144023568174_thumb.jpg

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Best of luck in your quest, I'll be watching and drooling.

Will triple carbs physically fit on an RB twin can head? Strut tower wise I mean.

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Found my older build thread when I started my RB25DE conversion:

http://www.viczcar.com/forum/index.php/topic,2377.30.html

 

Read through and see how  the manifold was done.. triples should fit without any issues as my throttle bodies which are almost the same dimensions to a Weber carb fit easily. The only clearance issue I had was a fuel return line from the fuel rail came very close to the clutch master; carbs sitting on the opposite side means more things in the way! One other detail you will have to do is the throttle linkage. Rather than trying to get the mechanical one mated, I got a cable from a TE Magna. Worked like a charm!

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Thanks for the info, I could always get different motor mounts and tilt the engine the opposite way. But looks like it would fit. Would it fit with an airbox though?

 

Also would the throttle linkage out of an American 240Z fit? Seeming they were RHD and the linkages come from that side somewhere. But the cable setup should fix those problems.

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Also check my thread out on my Triple DCOE Throttle Bodied RB25/26DE setup. I am thinking I might hunt down some Mikuni 44 PHH or get some new OER 45 for the carb setup....I am very seriously thinking of doing this and have been for sometime - comes down the $$ I already have tied up in the DCOE throttle bodies and ECU

 

My thread http://www.viczcar.com/forum/index.php/topic,3490.0.html

 

My zed is a Z432 project theme also - but Green with a matt black bonnet, RB engine painted silver like the S20 blocks, twin exhaust setup like the Z432 - it will never be a Z432 just a modern take on the theme. PS30 = 2000cc DOHC Z432. My car RS30 = 260z so factory L26 2600cc (well close enough) now RS30 = 2600cc DOHC Z432 theme 260z. I have 2 sets of 432 badges, 1 set NOS and 1 set close to new with 2 of them missing holding pins.

 

I am going to custom make/modify a rocker cover also but with 2600 on the top not 2000 again for the overall theme of the keeping with in the original car and a modern Z432.

 

Go forth and enjoy ;)

 

EDIT: Re you post on the "yes please" thread on the gold colour = Safari Gold paint code 920. My zed is 907 GP Green/Racing Green which was used on the Z432 as well as other models (both export and domestic) however it was replaced in 71 with metallic greens. That Z432 looks like was known as GP Red/Monte Carlo Red code is 905

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Thanks for the info nzeder and dimitri. and on paint colours.

 

I will check out both posts. I will have to find another car for this project, a 240Z preferably.

 

I will keep my yellow one as a RB25DET.

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it did have solex written in the description, bit hard with google translate.

 

but if you look carefully it looks like the top of carbs on the intake

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If they are carbs on that RB engine above, they look as if they would have to be mounted fairly closely to the head like the picture below of an S20 engine.

 

Also that exhaust manifold looks dangerously close to the battery, but could be the veiwing angle.

post-930-144023568642_thumb.jpg

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I checked my PC but I don't have any pics of when I had the engine in and I was test fitting the intake/exhausts up. But if you check my website there is a pic in the galleries section showing you the length of the RB26 intake manifold with the TB's installed and the trumpets.

 

Now I can tell you that stock clutch MC would not work with these trumpets where my engine sits but I replaced the MC with a Titlon 75 Series unit of the same bore as standard. These 75 series are nice and short in the body and bolts right on to the zed mounts with no mods :) so that has to be good right? But to give you the idea the bell/widest part of the trumpet was close to the clutch MC.

 

Having said that when I did all this test fitting the car was still on the rotisserie (well lowered the body over the engine and then removed and place on axles standard) and I only installed the cross member with the engine/gbox so no suspension and stuff so things might still move a bit more when I install in the hole later.

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how thick are the tops of the rb covers, could you cnc 1-2mm off the top to extrude the same design??

 

Ben

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The two side cam covers are about 4mm thick max. and the center cover is made of plastic. good idea but probably wont work.

If it was to work you would have to make a new center cover and add some meat onto the cam covers, with a piece that comes out over the timing belt cover, and cut the original timing cover top off.

 

I was thinking. Cut the top off the front timing cover, weld some tabs on the side cam covers, take the center cover out, and make a replica cover to bolt over the top.

It would not be perfect but as long as it was a reasonable faxcimilie I would be happy.

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Ok thought I would share an old link I had saved. Not a S30 but a S130 fitted with a RB31D running 50mm Mikuni carbs ;)

1301.jpg

Link to the whole page = http://www.testarossa.jp/library/s130/index.htm

 

Re the cam covers - I think the RB26 centre is not plastic as I have seen polished covers ie alloy.

 

R31 with RB on carbs see http://www.r31house.co.jp/r31/vivi215.htm

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what about welding a aluminium box section over the whole rb cover then get that machined?? it could work with someone who knows there way around cad programming.

 

How good as you bro at it hunter??

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only problem with that benji is that the cam covers either side a seperate units, then the middle section is a plate of plastic that covers the coils/plugs is screwed to the insode of the cam covers.

 

So the inside cam cover bolts would not be accessed without drilling holes into the center of the machined part.

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