MAC Troubleshooting

[Terry Keeley]

I was surprised to find I had to open my needle quite a bit when running 18% oil vs. my normal 12%. If you think about it there's 6% less "burnables" in the 18% mix so you would think you would need to lean down but just the opposite is true. Wonder if that has anything to do with all of this...

 

[Charles Perdue]

I was surprised to find I had to open my needle quite a bit when running 18% oil vs. my normal 12%. If you think about it there's 6% less "burnables" in the 18% mix so you would think you would need to lean down but just the opposite is true. Wonder if that has anything to do with all of this...

Yep. The higher oil percentage, the higher the viscosity ( Its thickerarur), the more friction/drag, the richer the needle setting needs to be. Maybe? :blink:

 

[AndyBrown]

I was surprised to find I had to open my needle quite a bit when running 18% oil vs. my normal 12%. If you think about it there's 6% less "burnables" in the 18% mix so you would think you would need to lean down but just the opposite is true. Wonder if that has anything to do with all of this...

Yep. The higher oil percentage, the higher the viscosity ( Its thickerarur), the more friction/drag, the richer the needle setting needs to be. Maybe? :blink:

Yep I agree with Charles and if you use much castor, there will be a big change with temp too.

Cold castor is really THICKERARUR. :lol:

 

[carlnoki]

Andy;

one more thing to add to the equation so to speak,,,,,,,,,,,,,,,

i am sure you have seen what THIN wall fuel tubing can cause compared to running THICK wall fuel tubing.

Found that out years ago flying C/L D-Speed

carl

 

[Scott Norris]

Andy;

one more thing to add to the equation so to speak,,,,,,,,,,,,,,,

i am sure you have seen what THIN wall fuel tubing can cause compared to running THICK wall fuel tubing.

Found that out years ago flying C/L D-Speed

carl

I was thinking along those lines last night Carl. With tubing between the needle valve and the venturi being on the small side or with a wall thickness too thin, could the venturi develop enough suction to suck the fuel tubing down to a restricted or closed situation?

 

[Terry Keeley]

Think about how much fuel passes through that line and you can get an idea of what's going on. A .67 or bigger motor can drink maybe 16oz of fuel in a heat, if it's a good one those 6 laps will take about a minute. That's roughly 1oz every 3 seconds, a lot of fuel to pass through 3/32" I/D tubing... :blink:

I've always used 5/32" tubing for feed in my tanks and large tubing, I also try to keep the lines as short as possible.

 

[Brian Schymik]

Terry, That is a brilliant observation

Brian

 

[Wesleys Custom RC]

Something don't sound right here! How can a line, a sergical line colapse due to suction? Don't you use a electric fuel pump to "suck " the fuel out. With out colapsing the line?? Surely that little carb is not going to pull harder than the pump.

 

[RaceCraftBearings]

Something don't sound right here! How can a line, a sergical line colapse due to suction? Don't you use a electric fuel pump to "suck " the fuel out. With out colapsing the line?? Surely that little carb is not going to pull harder than the pump.

I agree Wes, while I dont doubt that there is a wealth of knowledge with many of the posters here I sometimes think that they go into Rocket Scientist mode spending way to much time digging deeper than they must go.

Here is why I say this: I have an electric fuel pump that will fill or empty my 22 oz main and hopper tank in 22 seconds that is 1 oz per second. I have not had any problems with line colapse. Although I really dont know and have not checked to see if I have heavy wall or thin wall tubing. I use Bruline tubing so what ever is in that bag is what I have.

Ron

 

[Wasted wages]

Something don't sound right here! How can a line, a sergical line colapse due to suction? Don't you use a electric fuel pump to "suck " the fuel out. With out colapsing the line?? Surely that little carb is not going to pull harder than the pump.

I agree Wes, while I dont doubt that there is a wealth of knowledge with many of the posters here I sometimes think that they go into Rocket Scientist mode spending way to much time digging deeper than they must go.

Here is why I say this: I have an electric fuel pump that will fill or empty my 22 oz main and hopper tank in 22 seconds that is 1 oz per second. I have not had any problems with line colapse. Although I really dont know and have not checked to see if I have heavy wall or thin wall tubing. I use Bruline tubing so what ever is in that bag is what I have.

Ron

I have an electric fuel pump that will fill or empty my 22 oz main and hopper tank in 22 seconds that is 1 oz per second. I have not had any problems with line colapse.

I totally agree,,and I'm still waiting for someone to disprove my posts,

Think about that,,22oz in 22 seconds,,,,, can't flow that amount thru a needle at the same rate, so why would the lines matter if they can deliver this amout of flow to the needle,,,OH -I can hear it now,,,,,

"I bet my .67 MAC can drink that amount of fuel"

 

[RaceCraftBearings]

I totally agree,,and I'm still waiting for someone to disprove my posts,

Think about that,,22oz in 22 seconds,,,,, can't flow that amount thru a needle at the same rate, so why would the lines matter if they can deliver this amout of flow to the needle,,,OH -I can hear it now,,,,,

"I bet my .67 MAC can drink that amount of fuel"

Nope a 67 Mac cant drink 22 oz's in 22 seconds because thats what I fueled in 22 seconds and I can run Offshore 2:30 of mill and 6 laps and still come home with fuel. My 67 Mac is fast but it took longer than 22 seconds to do all that as a matter of fact probably it took 22 seconds to get a lap and a half or so done.

 

[Terry Keeley]

Terry, That is a brilliant observation

Brian

Well, I don't know about brilliant, but it's one way of looking at it. Wonder if we're on par per cubic inch with a fuel dragster?

Say a 1 ci motor can burn 20 oz. in a 6 lap heat (about one minute). That's 0.33 oz/sec/ci, so divide that by 128 to get gallons, multiply by 500 ci to compare to a TF motor and finally by 5 sec. for the average run and you come up with about 6.5 gallons.

That's not too far off, ever see the size of the lines in a fuel car, they're huge, 3" or better I'd bet.

 

[RaceCraftBearings]

Terry, That is a brilliant observation

Brian

Well, I don't know about brilliant, but it's one way of looking at it. Wonder if we're on par per cubic inch with a fuel dragster?

Say a 1 ci motor can burn 20 oz. in a 6 lap heat (about one minute). That's 0.33 oz/sec/ci, so divide that by 128 to get gallons, multiply by 500 ci to compare to a TF motor and finally by 5 sec. for the average run and you come up with about 6.5 gallons.

That's not too far off, ever see the size of the lines in a fuel car, they're huge, 3" or better I'd bet.

Hey Terry, er I mean Einstien we can check to see if they have increased the size of those fuel lines in about a month at the Gator Nationals See ya there!

PS If you have ever seen the show Numbers I think they are looking to replace the walking calculator

Later....Ron

 

[Terry Keeley]

Terry, That is a brilliant observation

Brian

Well, I don't know about brilliant, but it's one way of looking at it. Wonder if we're on par per cubic inch with a fuel dragster?

Say a 1 ci motor can burn 20 oz. in a 6 lap heat (about one minute). That's 0.33 oz/sec/ci, so divide that by 128 to get gallons, multiply by 500 ci to compare to a TF motor and finally by 5 sec. for the average run and you come up with about 6.5 gallons.

That's not too far off, ever see the size of the lines in a fuel car, they're huge, 3" or better I'd bet.

Hey Terry, er I mean Einstien we can check to see if they have increased the size of those fuel lines in about a month at the Gator Nationals See ya there!

PS If you have ever seen the show Numbers I think they are looking to replace the walking calculator

Later....Ron

Can't wait to see that great facility and experience "the smell of nitro in the morning" once again. Pomona kicks off the season this weekend, it'll be interesting to see if the Kalitta camp found their late season problems. Also wondering how Scott will do in the F/C... :blink:

Never saw Numbers...

 

[RaceCraftBearings]

Hey Terry, er I mean Einstien we can check to see if they have increased the size of those fuel lines in about a month at the Gator Nationals See ya there!

PS If you have ever seen the show Numbers I think they are looking to replace the walking calculator

Later....Ron

Can't wait to see that great facility and experience "the smell of nitro in the morning" once again. Pomona kicks off the season this weekend, it'll be interesting to see if the Kalitta camp found their late season problems. Also wondering how Scott will do in the F/C... :blink:

Never saw Numbers...

You and Norm will hit it off great he also likes the Kallita Camp alot. I like em but I have other Favs in TF and of course my main man John Force in FC. Scott is a wild child but maybe he can get a handle on it. I wish him luck.

Did you know that Antron has been racing boats (Gas) I have tried to get him into Nitro but he hasnt bit the bullet yet. Angelle said she might give Nitro a try.

 

[Terry Keeley]

Hey Terry, er I mean Einstien we can check to see if they have increased the size of those fuel lines in about a month at the Gator Nationals See ya there!

PS If you have ever seen the show Numbers I think they are looking to replace the walking calculator

Later....Ron

Can't wait to see that great facility and experience "the smell of nitro in the morning" once again. Pomona kicks off the season this weekend, it'll be interesting to see if the Kalitta camp found their late season problems. Also wondering how Scott will do in the F/C... :blink:

Never saw Numbers...

You and Norm will hit it off great he also likes the Kallita Camp alot. I like em but I have other Favs in TF and of course my main man John Force in FC. Scott is a wild child but maybe he can get a handle on it. I wish him luck.

Did you know that Antron has been racing boats (Gas) I have tried to get him into Nitro but he hasnt bit the bullet yet. Angelle said she might give Nitro a try.

Awsome, I'll see you guys there. Antron's pretty cool, talked to us quite a bit a few years back, think it might have something to do with the company I was with.

 

[Mike Rappold]

Hey Terry, er I mean Einstien we can check to see if they have increased the size of those fuel lines in about a month at the Gator Nationals See ya there!

PS If you have ever seen the show Numbers I think they are looking to replace the walking calculator

Later....Ron

Can't wait to see that great facility and experience "the smell of nitro in the morning" once again. Pomona kicks off the season this weekend, it'll be interesting to see if the Kalitta camp found their late season problems. Also wondering how Scott will do in the F/C... :blink:

Never saw Numbers...

You and Norm will hit it off great he also likes the Kallita Camp alot. I like em but I have other Favs in TF and of course my main man John Force in FC. Scott is a wild child but maybe he can get a handle on it. I wish him luck.

Did you know that Antron has been racing boats (Gas) I have tried to get him into Nitro but he hasnt bit the bullet yet. Angelle said she might give Nitro a try.

Awsome, I'll see you guys there. Antron's pretty cool, talked to us quite a bit a few years back, think it might have something to do with the company I was with.

I know this is off the orginal topic of MAC troubleshooting but since you were talking about top fuel cars... On our top fuel drag boat, we burn through 8 gallons of fuel on a 1/4mile run. This is for a 484 cubic inch motor using two fuel pumps. Each pump uses a 2" diameter hose. Attached is a photo of the tank/pump arrangement.

Mike

Hey Terry, er I mean Einstien we can check to see if they have increased the size of those fuel lines in about a month at the Gator Nationals See ya there!

PS If you have ever seen the show Numbers I think they are looking to replace the walking calculator

Later....Ron

Can't wait to see that great facility and experience "the smell of nitro in the morning" once again. Pomona kicks off the season this weekend, it'll be interesting to see if the Kalitta camp found their late season problems. Also wondering how Scott will do in the F/C... :blink:

Never saw Numbers...

You and Norm will hit it off great he also likes the Kallita Camp alot. I like em but I have other Favs in TF and of course my main man John Force in FC. Scott is a wild child but maybe he can get a handle on it. I wish him luck.

Did you know that Antron has been racing boats (Gas) I have tried to get him into Nitro but he hasnt bit the bullet yet. Angelle said she might give Nitro a try.

Awsome, I'll see you guys there. Antron's pretty cool, talked to us quite a bit a few years back, think it might have something to do with the company I was with.

I know this is off the orginal topic of MAC troubleshooting but since you were talking about top fuel cars... On our top fuel drag boat, we burn through 8 gallons of fuel on a 1/4mile run. This is for a 484 cubic inch motor using two fuel pumps. Each pump uses a 2" diameter hose. Attached is a photo of the tank/pump arrangement.

Mike

 

[Terry Keeley]

Kewl, so we aren't that far off, the picture didn't come through, can you post it again?

You're not the driver are you?

 

[Ken Retallick]

Ok, but has anyone seen the obvious here??

22oz in a minute verses top fuel cars with 3 inch lines and the amount of fuel used??

Both of these have a PUMP!!

Our nitro engines are relying on a small vacuum at the carb spraybar and a bit of pipe pressure to move the fuel. Small line are going to be much more restrictive with out a posivite displacement pump moving

the fuel <_<

Ken

 

[Charles Perdue]

Ok, but has anyone seen the obvious here??

22oz in a minute verses top fuel cars with 3 inch lines and the amount of fuel used??

Both of these have a PUMP!!

Our nitro engines are relying on a small vacuum at the carb spraybar and a bit of pipe pressure to move the fuel. Small line are going to be much more restrictive with out a posivite displacement pump moving

the fuel <_<

Ken

Yes, but some people are still trying to make an air conditioner out of it. :lol: