3.5 mac and hawk

[tmunn]

I tried most of the day saturday to get the engine dialed in and was only able to get a few good runs after a couple hours teeeking and then batteries died and it was too windy.It did seem to work o-k and was swinging the stock 1445 and a cut down and modified 1450 but i went back out today and it would not work well at all.

It still will not turn the modified H4 no matter what I do.

I was all over the board with the needle...too lean too rich etc.

The only prop it would turn was a small abc prop 1514 which is only 39 mm dia. even with that i would only get a couple good laps and the engine would quit and the whole element would be gone.

The couple times i was able to get the 1445 or the modified1450 up on plane or pipe the engine would only do a couple laps and then quit sometime the plug element was there sometimes mangled sometimes fine.

I gave up for the day and ran my other boat a bit.

I just took the engine apart and everything looks and feels fine.I was running the supertiger carb yesterday and it seemed fine but did not get a lot of test time on it.

Today at one point the screw that the carb barrel rotates on was loose.Perhaps this was my problem and it was sucking air.

I ran it up on the beach one time and mangled the prop blades on mt 1445 pretty good but i have straightened it out as well about 1mm from each side in past the damage and am going to sharpen and balance it and try it what the heck..

If it was not the screw being loose does anyone have any engine tuning advise.I may have to go back to the mac carb and give it a try...

Terry

 

[Tim_Duggan]

Are the bearings in the motor very old?

Is there much wear on the drum rotor / rotor housing? P&L fit still good?

 

[tmunn]

I bought the engine used and i do not know the age of the bearings.They feel fine.I will check the drum rotor and housing .The pl has a good fit but still kinda new at this stuff so not quite sure...... and the liner was stuck in the case so the piston could definately not have moved it up like i have read they should do when thre is still a good amout of squeeze left ...

i will check it over some more and compare it to the other 3 macs i have.

 

[Richard Dahlheimer]

I bought the engine used and i do not know the age of the bearings.They feel fine.I will check the drum rotor and housing .The pl has a good fit but still kinda new at this stuff so not quite sure...... and the liner was stuck in the case so the piston could definately not have moved it up like i have read they should do when thre is still a good amout of squeeze left ...
i will check it over some more and compare it to the other 3 macs i have.

If you know for sure one of your other Mac motors is in good running condition, maybe it would be a good idea to try it in the Hawk. Richard D

 

[Blaise Recca]

I had the same type of problem until I shortened my pipe....a lot! How long is your pipe from plug center to fat section of pipe? I'm running about 7 1/4" with a CMB 21 LS turning a stock 1450 on my Firefighter.

 

[carlnoki]

Terry;

you got mail.

carl

 

[tmunn]

I would have tried another engine in the hawk but the mount has very narrow mouning holes and i would have to redrill one of the other engines to make it fit.I have been thinking about it and i could just try the mac in my sport 20 which currently has the valvola, same hole pattern.

I tried the pipe at 8 and it was no good and would not run so i am currently at 8.5" we also trued different fuel and different plugs still nothing.

I think carl is correct in his PM and it's bearings.I knotices the metal seal on the front /outer bearing is ment ?

I will try and find some bearings.

Anyone know the sizes of them or better yet have a new set for sale.

Terry

 

[Terry Keeley]

Sounds to me like you have some sort of fuel delivery problem, I find when I have motor issues about 90% of the time it's fuel delivery.

If you think for a minute what these little motors consume (a pint per minute per ci ?), for they're size they're on par with a fuel dragster, any "hickup" in the flow will cause a lean condition and blown plug.

I'd go through everything to do with the fuel system very carefully and I'm sure you'll find it. Here's some starters:

Did you pressure test the tank for leaks (under water)? Did you fill the tank then pump it dry looking for bubbles in the line? Before and after the needle?

Is your pressure fitting clear? Does the cowl pinch any of the lines? Do any lines look like they could kink when it's running?

When you get your flowmeter, connect it to the system and wiggle the needle, if the ball jumps around much it's not good. Did you back flow the needle (into a paper towel) to see if any crud came out?

Is the motor sealing properly? Gaskets good? Head torqued evenly? Seal behind front bearing in good shape and not galled? Carb fittings locktited in? O-ring sealing properly?

Anybody add anything else?

 

[Grimracer]

As much as I hate to say it, it could very likey be the hull.. Its very easy to build rocker into the sponsons and when this done you can not make the boat happy regardless of what prop, motor or pipe you are using.

Grim

 

[tmunn]

Grim i have heard that said before and know what you mean but i cannot see that as being the issue .I checked it and steve walked me through it and told me what to look for.

Sometimes it will take off and run like a scared rabbit then the engine acts like it got lean and pulls all the plug element.

I will be busy checking everthing I can and i have bearings and a replacement 1440 and a stock h4 on the way.

The boat is setup like steve ball has told me and everyone knows he knows the hawk..

It put a smile on my face a couple times saturday but then on sunday it would not turn the prop under load.

I will digest this info and give her another try on the weekend.

Terry

 

[dannyual767]

Sounds to me like you have some sort of fuel delivery problem, I find when I have motor issues about 90% of the time it's fuel delivery.
If you think for a minute what these little motors consume (a pint per minute per ci ?), for they're size they're on par with a fuel dragster, any "hickup" in the flow will cause a lean condition and blown plug.........

16 ounces per minute for a 1.0 cubic inch engine ? Terry, was this a typo?

 

[Wesleys Custom Graphics]

Sounds to me like you have some sort of fuel delivery problem, I find when I have motor issues about 90% of the time it's fuel delivery.
If you think for a minute what these little motors consume (a pint per minute per ci ?), for they're size they're on par with a fuel dragster, any "hickup" in the flow will cause a lean condition and blown plug.

I'd go through everything to do with the fuel system very carefully and I'm sure you'll find it. Here's some starters:

Did you pressure test the tank for leaks (under water)? Did you fill the tank then pump it dry looking for bubbles in the line? Before and after the needle?

Is your pressure fitting clear? Does the cowl pinch any of the lines? Do any lines look like they could kink when it's running?

When you get your flowmeter, connect it to the system and wiggle the needle, if the ball jumps around much it's not good. Did you back flow the needle (into a paper towel) to see if any crud came out?

Is the motor sealing properly? Gaskets good? Head torqued evenly? Seal behind front bearing in good shape and not galled? Carb fittings locktited in? O-ring sealing properly?

Anybody add anything else?

That is ALL good advise!! I think every one of those things has happened to me at one time or the other. Also , any of those conditions can cause a lean motor and then bearing problems that will allow a motor to start and run but once you get it up to speed it dies....ask me how I know. ( I called Stu Barr a liar till I changed a set on a 67 CMB at Indy) Found out he was not as dumb as I looked

 

[Terry Keeley]

Sounds to me like you have some sort of fuel delivery problem, I find when I have motor issues about 90% of the time it's fuel delivery.
If you think for a minute what these little motors consume (a pint per minute per ci ?), for they're size they're on par with a fuel dragster, any "hickup" in the flow will cause a lean condition and blown plug.........

16 ounces per minute for a 1.0 cubic inch engine ? Terry, was this a typo?

Well, I don't run a 1.0 but I think they would need at least a 16oz tank, a good hydro will run 10 sec. laps so what's that work out to? Anybody here run a 101?

If 'n I did my math right that would be about 5 1/4 gal. to run 500ci for 5 seconds, and we don't even have a supercharger!

 

[taber]

Grim i have heard that said before and know what you mean but i cannot see that as being the issue .I checked it and steve walked me through it and told me what to look for.
Sometimes it will take off and run like a scared rabbit then the engine acts like it got lean and pulls all the plug element.

I will be busy checking everthing I can and i have bearings and a replacement 1440 and a stock h4 on the way.

The boat is setup like steve ball has told me and everyone knows he knows the hawk..

It put a smile on my face a couple times saturday but then on sunday it would not turn the prop under load.

I will digest this info and give her another try on the weekend.

Terry

the fello that mentioned the pipe length I think may be on to something.

 

[John Knight]

Sounds to me like you have some sort of fuel delivery problem, I find when I have motor issues about 90% of the time it's fuel delivery.
If you think for a minute what these little motors consume (a pint per minute per ci ?), for they're size they're on par with a fuel dragster, any "hickup" in the flow will cause a lean condition and blown plug.........

16 ounces per minute for a 1.0 cubic inch engine ? Terry, was this a typo?

Well, I don't run a 1.0 but I think they would need at least a 16oz tank, a good hydro will run 10 sec. laps so what's that work out to? Anybody here run a 101?

If 'n I did my math right that would be about 5 1/4 gal. to run 500ci for 5 seconds, and we don't even have a supercharger!

Terry,

I run a CMB 90 in a rigger and normally use 18-20 oz per run in a 22 oz tank. Seriously doubt a 101 can even finish with a 16 oz tank unless it goes into the water at the 45 second mark and run less than WOT for the heat. Fuel consumption is just greater than 16.

 

[Terry Keeley]

Sounds to me like you have some sort of fuel delivery problem, I find when I have motor issues about 90% of the time it's fuel delivery.
If you think for a minute what these little motors consume (a pint per minute per ci ?), for they're size they're on par with a fuel dragster, any "hickup" in the flow will cause a lean condition and blown plug.........

16 ounces per minute for a 1.0 cubic inch engine ? Terry, was this a typo?

Well, I don't run a 1.0 but I think they would need at least a 16oz tank, a good hydro will run 10 sec. laps so what's that work out to? Anybody here run a 101?

If 'n I did my math right that would be about 5 1/4 gal. to run 500ci for 5 seconds, and we don't even have a supercharger!

Terry,

I run a CMB 90 in a rigger and normally use 18-20 oz per run in a 22 oz tank. Seriously doubt a 101 can even finish with a 16 oz tank unless it goes into the water at the 45 second mark and run less than WOT for the heat. Fuel consumption is just greater than 16.

There ya go, I knew there was a reason I don't have a big block, can't afford the gas! :lol:

 

[shoboat]

Terry Munn,

If you replace your bearings,use the Geraghty carb, and try the propellers I sent you,it

should work the way it was designed to run.

Try It That Way,

Mark Sholund

 

[tmunn]

I tried a completly different mac .21, re-installed the geraghty carb and i can only turn small little props arond the 39-40 mm size when testing last then my rudder servo quit, replaced that and then my throttle servo quite.

Won't be buying anymore hi-tec servo's, gonna stick with futaba.

I can run the full tank out witht this mac. it does not quite but not very fast and running wet due to the small prop.

Just about out of good weather for testing this fall we'll see.

I had the engine temp up to as high 212* at one point so i opened my water supply a tad as i did not like it that hot.

I may get one more testing day but i could not turn either of the props you sent mark.Not your fault i must be missing something.

WHere should the strut be in relation to the left or rear sponson.

Terry

 

[carlnoki]

when i was running my hawk i set the strut bottom even with the bottom of the rear sponson tips then kicked about 1.5 degrees negative in the strut.

this helped in the launching and i ran H-5 and abc 1716 props. i was using the CMB green head long stroke motor.

hope this helps.

carl

 

[tmunn]

CARL ,That is pretty much where i am on the strut only a tad bit deeper(the strut bottom is 1/8 lower than the left sponson) not sure how that will affect things but more testing will tell.I hadd no problem getting on plane or pipe once i made it to the first right turn.

I think a lot of my problem initially and steve helped me resolve it was too low nitro and the rear sponsons not deep enough.

The guys in maine wanted me to try higher nitro and i declined.Should have tried i guess.you know what they say about hindsight....

Thanks again everone and it's gonna be a long wait to get testing next summer.

28* here last night and calling for snow flurries tonight.

Terry