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Discussion Starter · #1 ·
The RR has a 9EFH01-60 and the 600VES has a 9DGN6-57 needle stock

If I read the needle chart correctly the RR is leaner at part throttle and richer at more open throttle.

Would changing to the RR needle help with some of the low end load up that some people have mentioned?
 

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Where did you find this chart? I have to go out to the garage and take a look at my needle numbers (wrote them down last time they were out) but I know they were something FH-60. I have 2 VES engines and I believe they both had the same needles, so I'm guessing they were stock. Also, the parts Fiche on the RR shows the following needle:


3131438 Needle, Jet, J8-9DGN6-57-3
 

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Discussion Starter · #4 ·
Where did you find this chart? I have to go out to the garage and take a look at my needle numbers (wrote them down last time they were out) but I know they were something FH-60. I have 2 VES engines and I believe they both had the same needles, so I'm guessing they were stock. Also, the parts Fiche on the RR shows the following needle:
3131438 Needle, Jet, J8-9DGN6-57-3[/b]
Crap, I reversed them, sorry. The Pro X stock is the 3131207 - 9EFHI-60

If you look at the needle chart the Pro X needle is leaner at the low end and then I don't quite know from there because everything else is a taper relationship. Here is the chart Needle Chart

Have you gotten better than 7700 RPM?
 

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Crap, I reversed them, sorry. The Pro X stock is the 3131207 - 9EFHI-60

If you look at the needle chart the Pro X needle is leaner at the low end and then I don't quite know from there because everything else is a taper relationship. Here is the chart Needle Chart

Have you gotten better than 7700 RPM?[/b]
Not yet... I just put in the 390 mains and it seems to be much better (in the garage anyway). The 600VES maunal says to use 400's for 0-2000ft for 10-30F. So I think my 410's were too rich. I think I was way too lean in the mid range and too rich on top. I need to take it for a ride to find out. I also have 62's and will probably drop to 10-60's. I dont even care about RPM...right now I just want it to pull hard throughout the range without any flat spots... If it doesnt get any better with different main jets, I'm going to start trying different needles. I've done about all of the experimenting that I can with these ones.
 

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so are the rr needles richer or leaner on low end than the 600ho motor needles....
 

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If I read the chart right the RR is richer at the very tip of the needle 2.57mm vs 2.60mm what I don't know is how the taper works, one vs the other.[/b]
I have been using the needle from the 2003 Pro-X 600 with pretty good results. I have a VES engine in a IQ chassis.

As far as the needle designation: The higher the Alpha designator the larger the angle = leaner mixture.

D= the 4th letter in the alphabet; so 15" x 4 = 60" = 1 degree of angle (60" in 1 degree). To find the specific diameter where the transition is between tapers; take the sin of the angle and mulitply that value by the length of the taper. Simply break each taper down into a triangle and use trigonometry to solve for what you are looking for. Length of tapers is the key value.
 

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Discussion Starter · #10 ·
I have been using the needle from the 2003 Pro-X 600 with pretty good results. I have a VES engine in a IQ chassis.

As far as the needle designation: The higher the Alpha designator the larger the angle = leaner mixture.

D= the 4th letter in the alphabet; so 15" x 4 = 60" = 1 degree of angle (60" in 1 degree). To find the specific diameter where the transition is between tapers; take the sin of the angle and mulitply that value by the length of the taper. Simply break each taper down into a triangle and use trigonometry to solve for what you are looking for. Length of tapers is the key value.[/b]
I think it's tan(angle)*length, Tangent is opposite length/adjacent length where adjacent length is the taper length and opposite is the change in length, is that right? Most of the trig I use now is for Phase angle calcs, not geometry.

OK so here goes,

Starting at a diameter of 2.60 the Pro X needle first has an angle of 1 deg 15" then 1 deg 30"
Starting at a diameter of 2.57 the RR needle first has an angle of 1 deg then 1 deg 45"

So the Pro X is leaner at lowest throttle then it gets fatter faster than the RR until first taper is reached then the RR needle has a greater taper than the Pro X. If the two tapers are the same length then each needle should end up the same Dia. If so then maybe this is where the lean spot on the VES is being caused?

I don't have the taper lengths right now. but the First Pro X diameter would be (2.60 - (tan(1.15)*length T1)) then using that same formula (dia - (tan(1.5)*length T2))

That begs the question, since you are at the same altitude and temp as I am. What is your set up? Since I am running an 04 Pro X 600 motor, I am interested in what you are running. Are you pulling better than 7700 RPM? If so what weights/pri spring are you running?
 

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I think it's tan(angle)*length, Tangent is opposite length/adjacent length where adjacent length is the taper length and opposite is the change in length, is that right? Most of the trig I use now is for Phase angle calcs, not geometry.

OK so here goes,

Starting at a diameter of 2.60 the Pro X needle first has an angle of 1 deg 15" then 1 deg 30"
Starting at a diameter of 2.57 the RR needle first has an angle of 1 deg then 1 deg 45"

So the Pro X is leaner at lowest throttle then it gets fatter faster than the RR until first taper is reached then the RR needle has a greater taper than the Pro X. If the two tapers are the same length then each needle should end up the same Dia. If so then maybe this is where the lean spot on the VES is being caused?

I don't have the taper lengths right now. but the First Pro X diameter would be (2.60 - (tan(1.15)*length T1)) then using that same formula (dia - (tan(1.5)*length T2))

That begs the question, since you are at the same altitude and temp as I am. What is your set up? Since I am running an 04 Pro X 600 motor, I am interested in what you are running. Are you pulling better than 7700 RPM? If so what weights/pri spring are you running?[/b]
You are correct; the height of the taper should be mulitplied by the tan of the angle, I was thinking about the length of the taper when multiplying by the sin of the angle. Either way, the angles are so small the values are nearly identical.

I am pulling around 8200.
 

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Discussion Starter · #12 ·
You are correct; the height of the taper should be mulitplied by the tan of the angle, I was thinking about the length of the taper when multiplying by the sin of the angle. Either way, the angles are so small the values are nearly identical.

I am pulling around 8200.[/b]
What's your Primary setup?
 

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Discussion Starter · #13 ·
Ok I am now convinced that some/all of my problem is the needle. I finally got out and realy ran the sled, since I have NO snow to speak of, I had to go north. The top end WOT looks very nice if not a little lean. The sled loads up at idle is lean at 1/4 throttle and as I went from 1/4 to 3/4 throttle the mixture seemed to get richer until the MJ started to play a bigger role.

If the RR needle is indeed fatter on the bottom, would it help this condition.

BTW

1 1/2 turns fuel screw
40 pilot
#2 clip position
420 MJ's (I know "too fat" but the plugs and wash are telling me spot on.)
 

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Ok I am now convinced that some/all of my problem is the needle. I finally got out and realy ran the sled, since I have NO snow to speak of, I had to go north. The top end WOT looks very nice if not a little lean. The sled loads up at idle is lean at 1/4 throttle and as I went from 1/4 to 3/4 throttle the mixture seemed to get richer until the MJ started to play a bigger role.

If the RR needle is indeed fatter on the bottom, would it help this condition.

BTW

1 1/2 turns fuel screw
40 pilot
#2 clip position
420 MJ's (I know "too fat" but the plugs and wash are telling me spot on.)[/b]
It does sound like the needle is part of your problem. Have you tried a 1/2 step shim under the clip yet? If so, them I would say go for the RR needle... Also, if you are loading up at idle, why don't you turn the fuel screws in some or increase the PAJ some?
 
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