YS950S vs. YS637S

JAM · Post by **JAM** » Sat Mar 05, 2011 9:11 pm

wesk wrote:They are different. M38 uses the YS637S which has the mounting bolts on 2 3/8" centers and a throttle body throat diameter of 1 1/4". The M38A1 uses the YS950S which has the mounting bolts on 2 11/16" centers and a throttle body throat diameter of 1 1/2". Hope this helps.

I have a YS950S (new, unused) and I want to install the 134L, and these differences and I checked.
Also fabricated an adapter plate to the intake manifold so that the curve is toward the air filter and accept the distance between bolts.

I still have to solve the connection to the throttle pedal, but that does not bother me too much for now, I have the idea.

I wonder if there is any inconsistency for the proper functioning of 134L engine, installing YS950S carburetor, throttle body by the throat diameter of 1 1 / 2 "instead of 1 1 / 4" or other consideration that I do not know.

José Angel

Post by **wesk** » Sat Mar 05, 2011 9:56 pm

The YS950S larger bore carb was set up for the air flow thru the much larger intake valves of the F134. It is a bit overcarb for your L134. You may want to consider down jetting it. Like using the M38's YS637S carb metering rod and jet.

JAM · Post by **JAM** » Sun Apr 17, 2011 8:36 am

Well, I made the adapter to guide YS950s carb inlet manifold on my 134L.

Missing only develop the idea of the change in the throttle linkage, as in this case should be cross, unlike the YS637s.

This is what I did

You can see that the weld is not one of my skills

I have not even started the engine, and mechanically I do not think this is no problem ...., is just to test the performance of the carburetor itself, and this will take a while longer.

José Angel

Post by **wesk** » Sun Apr 17, 2011 9:22 am

Very nicely done. Have you worked out the routing of the choke cable yet? Looks like it may rub the throttle to bracket link? Have you worked out the hand throttle installation?

As you should be aware the L134 using a flow divider that is part of the thick base heat insulating gasket. Have you made provision for a larger bore version of that special M38 gasket?

This thick gasket is a necessity with the L134 intake manifold which transmits too much heat from the attached exhaust manifold to the carb. The metal "V" helps to better diffuse the fuel / air mixture to improve the atomization of the gas a low engine RPM's.

JAM · Post by **JAM** » Sun Apr 17, 2011 10:48 am

I need constructive criticism, and is the reason for posting the photos, with his experience will avoid making mistakes.

I always wondered why the thickness of the gasket, now I understand.
I put two, one below and one on the adapter between it and the carburetor, I guess I can get an asbestos-based material that resists heat, and let me make it thinner.
The metal "V" Yes I have seen, and I still have the old broken for new plant. Try to keep the same angle of inclination of the "V" and fins, changing the distance between holes.

The diameter is seen in the first picture is the same as the carburetor YS950S
As for the cables you mention, did not I think I'll have to check that.

Wes, thanks for the comments and advice.

José Angel

Post by **wesk** » Sun Apr 17, 2011 1:03 pm

Jose,

You can install a new stock "V" gasket between your adapter and the original manifold base then use a thin YS950S gasket between your new adapter and the YS950S.

JAM · Post by **JAM** » Sun Apr 17, 2011 5:08 pm

I thought that at first, but I got the question whether increasing the vertical separation of the carburetor to the inlet manifold, there could be some characteristics in the supply of fuel to produce than the normal behavior of the engine.
I checked that doubt with some mechanic friend, and confirmed my assumption.
I remember I said that it was carbs that work for greater response at low RPM, but lost at high RPM.
I'm not sure if it was true or otherwise.

Or is it a myth?

Obviously would not work as a separate carburetor 1 / 4 "or 1 " inlet manifold.
With this conservative assumption, I made the adapter as thin as I could, so try to place the gasket also thin.

Wes, you have a technical opinion based on reasoning about the thickness between the carburetor and the manifold?
Sincerely in that area I have no great knowledge.

Post by **wesk** » Sun Apr 17, 2011 10:02 pm

Using Bernoullie's principles the larger diameter venturi of the 950S being suddenly reduced at the adapter will result in increased velocity of the fuel air charge below the adapter. The "V" gasket will most likely help reduce this velocity closer to the original air flow numbers.

The thick gasket is needed on the L134's because the exhaust manifold transmit so much heat to the carb base. This heat translate into warmer air in the venturi which had adequate ratio of fuel to air until the air was suddenly heated which has the effect of enriching the ratio. You will not want this since the 950S will already be supplying a richer mixture at idle and low RPM's then the L134 needs.

JAM · Post by **JAM** » Tue Apr 19, 2011 4:37 pm

In this case does not apply Bernoulli's principle, the diameter of the adapter is the same as YS950S carburetor and inlet manifold itself.

But I will take into account the thickness of the gasket by heating the mixture of fuel and the metal "V" as I carefully watching the effect produced cyclonic help direct the mixture to the sides of the intake valves.
Inform you when to start the engine order.

RICKG · Post by **RICKG** » Wed Apr 20, 2011 7:41 am

May i say, Jose, that you possess exceptional engineering
and fabrication skills. GOOD LUCK and keep us posted..

Claudio · Post by **Claudio** » Wed Dec 04, 2013 9:35 pm

Jose - hey can you tell us about result of your experiment? how did the Carter YS950s worked out on a CJ3a engine?
Claudio
Florianopolis, Brazil

Bretto · Post by **Bretto** » Thu Dec 05, 2013 7:05 am

I agree with Rick, very nice work. I need to get myself a nice CAD program and learn how to use it, along with the proper fabrication tools. What program are you using?

Brett

JAM · Post by **JAM** » Sun Jan 19, 2014 11:09 am

Hi Brett, thanks for your opinion, I was using autoCAD 2002 when I developed my idea.
Drawing programs eventually will facilitate capture on paper the pieces you have in mind, but more important is knowing without drawing programs. this is essential to undertake any project.

In my case, I work drawing 42 years ago, long before the era of CAD, which forced to handle much geometrical calculation, and this learning is what prevails. The only CAD facilitates and provides remarkable speed and accuracy when working.

JAM · Post by **JAM** » Sun Jan 19, 2014 2:00 pm

Claudio , in tests on the engine once I had to correct two things .
I developed this adaptation with a removed body , so I did not connect the accelerator pedal , it did not. Then I estimated its length.
Now I have to slightly reduce the turning radius of the first arm to fully open the throttle .

Another detail is that the excessive fuel pressure reaches the carburetor choke .
Now I think I solved it .
In the absence of a pressure regulator , made a referral to a " T " between the fuel pump and carburetor with return hose to the fuel tank . This hose I have placed a ring with a screw to tighten down the section of hose getting less pressure to the carburetor fuel inlet .
So far, I have managed to avoid choking .

Just need to observe the behavior with the car running . But I still end up missing mechanical parts to make the car run .

When I finish I will discuss the results

Claudio · Post by **Claudio** » Mon Jan 20, 2014 12:23 pm

Well, still awaiting for a successful result Jose.
I am very pleased to see your creative ideas.
Que venga el toro!

Claudio
Florianopolis, Brazil.