85rotarypower

I bought what is supposed to be a Mikuni 44phh from a fellow forum member. I've got a few questions about it. I'm pretty sure it is the 44phh, but I'm not sure if its actually a RB prepped carb or not. Its got a RB air cleaner assembly on it with an old K&N filter. The air cleaner top says Racing Beat and Mada 6 port rotary. Its got the upper manifold to mate to a 2nd gen 6 port lower manifold. Was this carb originally tuned by RB to work with a stockport 13B 6 port? Here are a few pictures.

KansasCityREPU

iTrader: (9)

That looks different then my Mikuni 44

'84-12A-GSL

That's a Solex carb. Mikuni had the rights to make Solex carbs thou.

So I don't think you bought a Mikuni, you bought a Solex made by Mikuni. I don't know what the differences are thou, they're probably similar in design.

DwArF

I hope you didn't get bamboozled. Was it running on a rotary car before? I'm sure someone must have had it running with all of those manifolds connected to it?

85rotarypower

It came out of a 79 with what seemed to be an S4 13B 6 port in it, same as the engine its going on. It says solex on it, but in fine print below that it says Mikuni. AFAIK, all mikuni automotive carbs have the name Solex on them.

According to the Wolf Creek Racing website Carb ID page, going by the carb top, I've got an early Type Q carb. KansasCityREPU, yours is a type S5 version. Anyway, according to the website, the type Q was available in 36, 40, 44, and 50mm styles. I guess I'll have to take the manifold off and measure up the barrels to see what I've got. I sure hope to god I don't have the 36 or 40. Forgot to mention that these are considered PHH2.

85rotarypower

Ok, Where the carb meets the manifold, the barrels measure approx. 1 15/16" across, which translates to about 49.2mm. I'm not entirely sure where the actual size is supposed to be measured from.

Midwest 7's

iTrader: (4)

racing beat preped dellortos some other company did the mikunis.

85rotarypower

Ok, I found out for sure what carb I have. Turns out the 180 marked on the butterflies makes the carb a 50mm!! So, I've kinda hit gold here, its actually a very rare carb originally for race prepped datsun's I think. But I can't mount it up right now, apparently the upper manifold I got with the carb mates to a 1st gen 13B lower manifold, not my nicely modded S4 lower manifold.

Quick question, will a 1st gen 13B lower manifold mate to a S4 6 port engine? I should know this but I'm not entirely sure.

broke7

iTrader: (1)

you just use your stock lower intake

85rotarypower

Thats what I did. I have a S4 13B in my rx-7. The S4 lower doesn't bolt up to this upper that I have. I think its actually made for a 1st gen 13B lower manifold which is different.

Siraniko

iTrader: (13)

slot the holes on the upper intake to match the S4 LIM

85rotarypower

The upper intake I have is not even close to even bolting up. Its far too narrow, almost makes me think its a 12A upper, but RB only made 2 different uppers for sidedrafts and thats for the S3 13B lower or their own lower, or the 2nd gen lower manifold. Seems I got the 1st gen upper of a sort.

So, my choices are to either buy an upper to mate to my current modded S4 lower, or buy a S3 13B lower, which may or may not bolt up to my S4 engine properly. I'm not sure on port positions and sizes between the S3 lower and S4 lower. I've heard they are interchangable, but need a definate answer before I go searching for one.

Siraniko

iTrader: (13)

there is a no difference between a 12-A and 1st gen 13-B upper intake. let me back off for a second. which S4 intake do you have? turbo or non-turbo. Im just too lazy to search

85rotarypower

Its a S4 NA LIM. 6 port engine. The upper I got is much closer to fitting the S4 TII lower I have here, could probably make it work but the ports are nowhere near close enough on the engine side to fit. I'm stuck having to buy something. I may just go for a new upper made to fit the S4 lower.

I'll go out and get a pic of how much its off, just so all can see.

85rotarypower

djessence

That is definetly a different size.

just thoughd id throw that out there

broke7

iTrader: (1)

I think you may have a s5 intake. If I remember right the ports are oval not round. I may be wrong and if I am someone will let me know also check the 2nd gen section

dean7

Yes, I did it on my current build... The primary ports on the s4 are about 1/5" taller than the s3 lower intake... so when you put the s3 intake on the s4 1/5" of the s4 ports is below the s3 intake.. The bolts holes match up perfectly to the engine.

85rotarypower

So basically your saying I would just have to port out the S3 manifold to the S4 port spec. Not too bad really.

Also, I've never seen fractional inch measurments put into 5ths before. 1/5 is .200, if I am reading right. So a little over 3/16 of an inch.

nick812

I dont think racing beat ever modded the mikuni Rotaryengineering did. That an really early version.

85rotarypower

This carb might not have ever been tuned for a rotary by a shop, I don't know for sure. I just know its an early carb. The one all others are based on if you think about it. This one version of the Mikuni has all the sizes Mikuni's were available in. From what I've read, the 50phh2's were used mostly for racing in the old datsuns and some others. This particular carb might go back as far as the mid 60's as Mikuni doesn't even make a rebuild kit for it anymore, yet all others they do. Wolf Creek Racing has a rebuild kit for it, but thats just one they put together, not original Mikuni rebuild kit. All the jets are the same as other mikuni's. Chances are, this carb would perform very nicely on a streetported or even bridgeported 13B.

dean7

LOL I think I was a little faded... Its less than 1/8" bigger than the s3. Sad thing is I use measurements EVERY workday alot... You could port it, very easily, or leave it alone, as long as your intake is on securly, the other ports seemed to match up perfectly.

85rotarypower

Alright, thanks dean7. I'd probably port the primaries out to help match the intake to the engine for better airflow. I got this real nice carb, so I want to make the most of it. It will probably make at least the same power as a Weber 48IDA.

680RWHP12A

definatly not


it is a nice carb however and should run well.. as far as i know the 50 mm phh goes it was a full race carb built my mikuni under liscense for solex..they didnt come with a choke ..

the smaller solex production carbs came on toyota 18 RG and 2TG motors and also on the nissan S20 motors


what size are your venturies? they are very unusual looking

85rotarypower

I'll have to bring home a micrometer from my toolbox at work and get a measurment on the venturies.

As far as I can tell, this carb has a working choke. But it is confirmed that its a 50mm. I'm not up on Mikuni's though. I just know its a 50mm cause the butterflies are marked with 180 and according to Todd at Wolf Creek Racing, thats a 50mm carb.