Mikuni Carburettor Id Thread - Phh
Posted 16 December 2016 - 12:09 PM
So I figured I'd start a thread with photos of each style so that we can all more easily identify these carbs.
Contributions and corrections are welcome along the way.
- locklock and Des like this
Posted 16 December 2016 - 12:11 PM
As the numbering suggests these are 40mm sidedraft carbs.
These were fitted to the S20 motor found in the KPGC10 GTR
Posted 16 December 2016 - 12:22 PM
These are earlier style 44 MM Solex / Mikuni's. Nicknamed "Mag" Solex carbs.
Mikuni/Solex - NPHH-2 (Type 2)
These look like the 50mm versions, but are in fact only 44mm. Also found on Datsun Roadsters with the U20 motor sold in Australia (Solex/Mikuni N44PHH-A5a is the designation).
Z432-R photo taken from Alan Thomas (Facebook post). These carbs have been fitted later (not factory fitted).
Be careful the screws are different and the throttle shaft is clocked differently. Also be careful with the threads. Zinc is really soft and the thread pitch is totally different.
Posted 16 December 2016 - 12:38 PM
432-specific S20 parts: Unique to the 432 and 432-R. The original triple Mikuni N40PHH-A24 carbs
Posted 16 December 2016 - 12:42 PM
Posted 16 December 2016 - 12:44 PM
Posted 16 December 2016 - 02:08 PM
The 44mm "Type 2" were indeed fitted to U20 engined Roadsters in Australia and Japan. American U20's only got SU's. Because of this, a lot of pics you see of American roadsters which have had Mikunis fitted will show the later (more readily available) carbs.
Out of interest, the upgraded carbs and a "hotter" cam gave a 15hp improvement over SU's, up from 135 to 150hp.
I've got a small collection of 40mm Mikunis of various types, will get some pics tonight.
Roadster carbs :
Edited by 1600dave, 16 December 2016 - 02:14 PM.
- gav240z likes this
Posted 17 December 2016 - 08:55 PM
First up, type "T". To the best of my knowledge, these are OEM Toyota Carbs.
Part numbers 21100-88254 (front) 21100-88255 (rear).
Factory standard on Toyota 18RG Twin Cam Engines
Posted 17 December 2016 - 08:59 PM
Part No's: 21100-88220 and 21100-88221
Often found on Toyota 2TG motors
Posted 17 December 2016 - 09:01 PM
The 44s are usually identified by the number of the screws in the top cover. S4 (early 4 screw carbs) and S5 (later model 5 screw version).
Posted 17 December 2016 - 09:11 PM
Type "S5". At least in the 40mm version, both these and the "S4" use a sleeve to reduce the diameter of the body from the front of the carb back to the main venturi (I've taken them out of the S5 carb pictured) . The "T" type carb does not have this feature, the bore of the carb is pretty much the same size as the bore of the sleeve in the others.
Edited by 1600dave, 17 December 2016 - 09:13 PM.
Posted 17 December 2016 - 09:26 PM
And the rare and elusive "Type S4" in 40/46mm size
This was a broken S4 40mm body that I performed a bit of "exploratory surgery" on to see if it is possible to convert 40's to 44's.
This one is out to 46mm without hitting anything / boring through into any air / fuel passages. Boring the rear of the body in to the main venturi and running without the "sleeve" at the front should get a 40 to approximate a 44.
Doing this to a S5 may not work as well, it has more air / fuel passages that look closer to the bore of the carb. And a type "T" would be very difficult due to needing to bore the front of the carb out as well (and on an angle) du to not being able to simply remove the "sleeve"
Its not that simple though, from what I can work out I will need (at least) custom throttle butterflies and custom venturis. Venturis as its not (easily) practical to bore right through the carb without re-doing how the inner venturi mounts (you will bore the existing mounting bit away). The main benturi will need to be a 40-type, possibly re=profiled to some of the larger sizes. Butterfly needs to be custom as it looks like it will need to be on a different angle to what it is in 44mm carbs to get it sitting right with regard to the progression holes.
Anyway, I haven't gone further with this so don't go whacking your 40mm carbs in the lathe then complaining when you can't convert them to 44's because I've overlooked something. I was just messing around because I had a busted carb body (and because I have a stash of 40's and no 44's....)
Edited by 1600dave, 17 December 2016 - 09:34 PM.
Posted 21 December 2016 - 10:03 AM
You're probably unlikely to encounter these in the wild given rarity. But these were fitted to the Toyota 2000GT MF10
Mikuni Solex 2 type N40 PHH
Many 2000GTs have had replacements in the form of Type S and Type 4 carb bodies, so if you find a pair of these they are worth good money now to a 2000GT owner who wants to go original.
These look externally like the other Type 2's (44) and similar to the 50mm version, but obviously smaller.
MF10-10401 and later cars received Mikuni Solex type 3 N40PHH
Posted 21 December 2016 - 07:36 PM
As fitted standard to Datsun 2000 Roadster with upgraded OEM 150 HP U20 motor
These are in GC, stored for some 22 years, off car, and are For Sale
Posted 01 January 2017 - 09:54 AM
Likely to be found fitted to vehicles like Datsun B10, B310, 510 or Toyota TE27, KP61 etc..
Posted 12 January 2017 - 08:48 PM
These tend to be known as Nismo colloquially because they were offered through Nismo catalogs in the late 70s, early 80s in North American markets.
They have the externally adjustable float with the provision for it to be mounted on either side (dual fuel feed lid), unlike regular s5's.
They also came with larger outer venturis too.
Posted 14 January 2017 - 02:33 PM
These are a slightly earlier style, I believe available in the Sports Option Catalog.
The only way I can usually tell the difference is the Wing Nut holding the lid for the jets, and the cover also has Kogyo cast in it.
Can anyone confirm if these are in fact N44PHH-A11 carbs? They have the sticker I believe the A11's are like the ones just below.
Posted 20 January 2017 - 05:54 PM
The 2 photos on the right show the difference in lids between the earlier style (left) and later style (right).
Posted 21 January 2017 - 07:37 PM
Just linking to this article.
I have heard Lou Mondello say this also.
I found out there are actually two types of PHH carbs (homogeneous main system, and Independent main system) the two main systems are very obvious in the jet block area.
I will try and get photos of these differences to add to the thread.
Posted 27 January 2017 - 11:19 AM
RE: homogeneous main system, and Independent main system
The difference appears to be in the Jet Block area. But in order to see it, you need to remove it and look at the under side (the side facing the accelerator pump area).
This is the jet block out of my Mikuni 44 (N44PHH-A11) body.
This is the the jet block out of the Type4 (5 screw lid) set of 44's. (ignore the fact that jets are still installed in this block).
If you look at the pilots, you can see at the bottom of the homogenous type, the holes are blocked off. This is because the pilot and main system is shared.
If you look at the independent system you'll see holes at the bottom - so the pilot and main are separate from each other.
I'm going to quote an email from Lou Mondello taken from here:
Hey Will, I was reading about the Mikuni jet blocks and preferred set ups etc. One basic fundamental thing is being overlooked. There are 2 types of Mikuni S4 and S5 cars. They are homogenous and independent. The homogenous type uses the "8" jet block and bleed pipes.
You cannot put the OA, OB, A or B jet blocks into the homogenous carbs as they simply don't work. The metering of the fuel is wrong. Homogenous carbs are made for a bleed pipe. Same deal if you try and put the 8 jet blocks into the independent type carbs. There are two distinct versions of these carbs and they both have their own assigned jet blocks. One of the mikuni manuals eludes to this in Jinglish. Reading between the lines they specify only the homogenous uses the bleed pipes. Nissan preferred the homogenous on the production cars but independent for racing. I quizzed Todd about the preferred ones for racing but he never answered me.
I suspect he does not know there is a major difference. I suspect many Mikuni experts aren't aware of this either. This has caught so many people out so many times and for so long.
Best was to determine what your are is.... Remove 1 idle jet... use a long stiff bit of wire to see if the drilled passage goes directly to the fuel well. If it does you have the independent type. If the idle passage makes a detour to the jet block passage that holds the jet block then you have homogenous. That simple.... You should try this test on 1 idle jet from each carb. I have seen 1 independent and 1 homogenous used on a U20 with the car being woeful to drive. The homogenous ones as supplied by Nissan on the cars work very well up to 37mm choke. After that say with a 40 mm choke and a big cam, the independent carbs work better.
I have converted a few carbs from homogenous carbs to independent. The alloy jet block holder has to be swapped over, they are not a listed part in the manual. The fuel trend (delivery) is quite different on both types. I can see why there were 2 type made. The homogenous as supplied by Nissan (69 onwards) on the cars with "8" jet block and "M" bleed pipe were almost fuel injection exactness with a 34mm choke. The early 44 type Q carbs and all the 50's were all independent. Every 40mm mikuni I have seen is homogenous. Hope all this makes sense.....
Regards Lou M
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