GURU HELP PLEASE, VAC45

[tom galdys]

Hey Guys, I have a 45VAC CMB in my sport40, it has been a real screamer until the last race. I changed nothing to it and now it falls off the pipe after about 4-5 laps. Pipe length is 10 1/2",running both a 450X3 and 452/3 Sholund prop. and the boat using either prop does the same thing. It is faster with the 452/3 but it still falls off using the 450/3. So I don't think it's the prop. I have one race to go for NYS high points and could use your help. It's a PT sport40,I run 55% nitro. Earlier this year I had a different VAC in it and blew out the piston bosses and that motor is now toast. Head clearance is factory set. Ideas please on what I should do. Bearings are smooth. Thanks Tom Galdys

 

[FloridaScaleBoater]

Could be you have a partially plugged water line, engine getting too hot after a while of running.

Could be a water leak into the boat, filling the hull up with water till it's to heavy to pull the weight.

or you have a cracked fuel line inside the tank, running the fuel down to the crack and creating your problem??

 

[tom galdys]

I will check the water lines for leaks,there is no blockage, I'm running a hopper tank and that is full when I bring it in but will check it out. Thanks Tom Any other ideas would be appreciated.

 

[moparbarn]

any signs of detonation or leaning out, tom? might be bearings. even though they feel fine, they could be starting to fail. they can lose their "seal" as they get hot, causing issues after a few laps.

 

[SayMikey]

Ditto on the bearings

 

[tom galdys]

Ok, you guys are dam good. 1st,my strut broke 2 races ago and I put another one in(under the hull) and forgot to silicone the different strut hole.So,it WAS taking on water. It definitely is not lean as it would never die. I have a message out to Stu for bearings that I needed yesterday if bearings are the problem. Am going to change them ASAP. Need them for Friday. I just PM'd Stu for the bearings and hope he gets it in time. Thanks Tom

 

[Samuel Hagan JR]

Send Stu a email. It may be quicker. He's quick at shipping stuff to you.

 

[Tim Kish]

Sounds like bearings , has it been taking out plugs?

Tim

 

[tom galdys]

It has been eating plugs from the beginning. I added .004 head shim and tried lengthening the pipe to no avail. I think I need to email Stu.Thanks Tom

 

[Terry Keeley]

Cut down the water and richen the needle...

 

[tom galdys]

Thanks Terry, I need Stu's email, can someone pm me it please? Thanks Tom

 

[MattMurany]

[email protected]

 

[SayMikey]

[email protected]

 

[Tom Foley]

It has been eating plugs from the beginning. I added .004 head shim and tried lengthening the pipe to no avail. I think I need to email Stu.Thanks Tom

What plugs ? Mine runs like a watch on 60 % , OD 99 , or KB HP , head clearance @.009 - .010" pipe @ 9-1/4 " 1655 prop

 

[Tim Kish]

It has been eating plugs from the beginning. I added .004 head shim and tried lengthening the pipe to no avail. I think I need to email Stu.Thanks Tom

Something's not right Tom , shouldn't be killin plugs at all.

I think Terry is dead on running to cold to burn the fuel.

I would change the bearings for piece of mind then fatten the needle and restrict the water.

 

[Duck899]

If you did not change anything and the engine starts running odd, ie; taking out plugs, not getting on the pipe, ITS BEARINGS!

Do you notice any dark black oil around the flywheel?

What oil content with that 55%

I run 65% with 20% total oil content (castor as well) and I can typically go 6-8 races (4 heats each) on an engine and its bearings. 21 size go longer, especially outboards.

YMMV

 

[Stuart Barr]

Tom,

I'll call you today (Sunday)

Stu

 

[tnrcboatracer]

I also have the bearings in stock, and can ship in the morning. PM if Stu isn't able to provide in time.

Jon

 

[ALLAN YUEN]

Maybe Look between Crankshaft and Con Rod burn from friction needle bearing did you check inside ?

 

[tom galdys]

Thanks everyone, I think I have it straightened out. I talked with Stu at great length and is getting me what I need. Tom