SK racing carbs

[grannyknot]

Koalia, just looking at your cold start levers, I think you'll need to reverse those so they open in the other direction,

your technical manual explains how to do that. It's not hard.

From your pics your intake manifold appears to be the standard depth, if the length of the runners from flat to flat are about 13.5 cm. then that is standard not short. No big deal just know that by the time you get air filters on it gets a bit tight for room.

Your last pic shows that you have rod ends already, if you use those rod ends then the rod and levers you buy will have to be the same diameter.

The OER site your buying from doesn't have a lot of description on their linkage parts and they don't seem to sell

the intercouple linkage that is missing from your carbs, see it here, WEBER DCOE INTERCOUPLE LINKAGE<br><font color="red">PM3718

You might want to look at a linkage kit like this, UNIVERSAL LINKAGE KIT<br><font color="red">PM3701-L</font>

I would order one more rod end then they have in the kit but the rest of it seems to be there.

So here are my measurements, main rod, 8mm dia, 50cm. length,

rod levers approx 5.2cm centre to centre,

turnbuckle, 9.5 cm centre to centre, so something like, JPS adjustable rod<br><font color="red">75500.100</font>

intercoupe linkage, 4.1 cm C/C

Are you also going to overhaul the carbs while you have them out on your bench? You won't find a better time than now.

I just installed my SK/OER triples and sofar every thing is running smoothly,

I just previewed this and I don't know where the RED came from, I must have hit some key I shouldn't have.

Chris

[Reverend]

Maybe it was Ted who highlighted it for you? Nice info Granny, i have set of new gaskets directly from OER, only 40 bucks (including shipping!) So far the old gaskets look nice and shiny, so im not gonna change them yet. Atm i have smallest main jets possible(?) (115) but im sure they will be changed to bigger ones. That universal system looks legit, i'll have to compare prices.

I'd love see close up pic how you connected the oem linkage to triple setup

Edited September 5, 2013 by Reverend

[grannyknot]

You can see where I cut and welded the two ends together, This is only temporary until I can get the Lokar cable back on.

[Reverend]

Thats nice, i should do something similar, though i dont have extra rod to destroy/no welding skills. Gotta figure it out.

[grannyknot]

Pick up one on ebay, measure the angle before cutting, cut to fit, find some metal tubing to fit as a sleeve over top of both ends, drill and insert roll pins or even screws. Sand, fill and paint. : )

Here is a bit of inspiration,

[240260280z]

Just got a set of use SK Racing 40's... The PO has broken the inspection bolt off one of the progression holes....I looked at the remnants and it seems like there is some sort of substance between the threads and body? I am wondering if the factory use a sealant or if a wise PO used something like JB weld? Arggggghhh

[grannyknot]

Blue, the only thing the factory would have used is a thin rubber O ring, that might be a hard tap to find.

Congrats on your buy, with all your carb knowledge I'll be interested to hear what you have to say about the rebuild and the performance.

Chris

[240260280z]

Copied from the net:

The following SK Carburetor parts are interchangeable with the Weber DCOE carburetors:

• Main jets
  
• Air correctors
  
• Idle jets
  
• Emulsion tubes
  
• Pump exhaust valves
  
• Pump rod, spring and piston
  
• Auxiliary venturis (45 DCOE only)
  

The following are interchangeable with Mikuni PHH late model carburetors:

• Pump jets (Mikuni calls these pump nozzles)
  
• Floats
  
• Needle Valves
  
• Fuel Union Banjos (I think Mikuni calls these Fuel Pipe Assembly)
  

Another:

I have a set of triple sk carbs on my 3.0 liter stroker motor and I love them.They have the same Idle jets,main,air,jets as the weber dcoe.The pump jet and needle and seat are mikuni parts.You can not get the main chokes and aux venturi in the USA any more.You might be able to find a used set .I had to bore out my main chokes to 34mm at the machine shop ( it was cheap though) I have talked to the people at twm induction (who supplied these carbs in 1992 (they were the biggest suppliers of these sk carbs in the USA they can still get the gaskets for these carbs.I ordered a set of these gaskets back in december and never got the gaskets but I was able to make my own.The guy I talked to told me that the SK carbs were very good carbs and easy to work on and he was right .He also said that these carbs were better than weber and as good as mikuni at top end .I had a set of 72 su carbs on the 3.0 liter stroker before I put the sk carbs on and the power was ok but I thought it needed more so I bought these carbs and now the power in unreal ! The idle sucked on the su carbs I would not idle below 1400 rpm and now it Idle perfect at 900 rpm (I have a huge cam 496 lift and 290 duration) The gas mileage has improved and I am very happy now they are almost tuned correctly .

Another:

Yes, that was the great compromise: the later style SK utilized the superior accel pump design of the Mukini, with the jets/emulsion tubes of the Weber. More like a racing version of the Mikuini (which the Weber was modeled after: the German Solex!) Webers just never worked right with that small pump they had, but the SK had a big shot when you mashed it, unlike the Webers. Just more volume for transition. That's why you can jet down Mikuinis and SK's and get decent gas mileage and still have a car that dosent't buck and pop in transition and light cruise.

And by decent mileage, I mean 28MPG at a steady 65 from LA to Phoenix in a car with 1:1 top gear and a tight rearend! Weber just don't do that...

[grannyknot]

Blue, where do you find this stuff? I've googled these carbs a dozen times and never come across those quotes.

I happened to meet the master mechanic (he's about our age) at Woodbine Nissan a couple of weeks back at a show n shine and what he had to say about Weber, Mikuni and SK was pretty much the same as the 2 quotes you listed.

[240260280z]

I'm just a data geek at heart.

I think it would be good for us to post all data to this thread. if you can scan the sk manual into a pdf that would be a good nugget'o knowledge.

btw the more we enhance this site's content, the more people will come to it and in turn the more revenue for the admin. It is a good thing for all

Edited September 17, 2013 by Blue

[240260280z]

Data

SK40

• inlet dia = 43mm
  
• outet dia = 40mm
  

TWM manifold

• inlet dia = 42mm
  
• outlet dia = 33 to 35mm (variable numbers.....could use a clean up)
  

[240260280z]

Any tips on removing the accelerator pump rod assembly in SK's?

It looks like a weber assembly except for the extra tab on the top that looks like it is pinned down with a peened rod in parallel with the pump rod?

Parts 50 and 51 in the exploded drawing above.

btw these carbs are almost at the point of a tough return... it takes a lot of coaxing to unstick some of the parts due to old gas, glue-like gaskets and corrosion. At least the throttle plates move nicely!

Edited September 17, 2013 by Blue