Mac 67 or 84 EATS Pluggs

[charles siler]

It was mid 60s at the pond in Alaska today both eagle sgx are mid to low 80s w/55% nitro we went through a 1.5 gallons and a plug every tank we ran . We tried to fatten the needle before docking . Just runnig in and hitting the fail safes all ended with pluggs totally gone . It seems MC-9 work the best the good K&Bs Odonald blue not a chance ! both boats are modded pritty good . Love the boat and preformance not likin the plug situation thanks Charlie

 

[JeremyEdge]

Head clearance to tight, or still way to lean.Also possiable is a bad bearing.

 

[dwilfong]

The eng is running to cold to use cold plugs. Try a OD99 and restrict the water to a .080 or less hole on the output. I bet that the water up there is just above the freezing point. that cold water will take all the heat out of the eng. It will sound rich but it is just not burning the fuel. David

 

[crfabbro1]

Bad bearings

 

[charles siler]

Both motors are brand new . water temp is 45+

 

[Philmunsterman]

Charles, What temp were the motors right when you brought them in ?? Sounds like they are not heating up. Phil

 

[dwilfong]

Both motors are brand new . water temp is 45+

Thats cooooold water! I run in water that is 85+ and still restrict the water on my 1.01 with a special cooling cap that just cools the top of the button.

And run OD99 with 55% nitro.

It is too cold you need heat to burn nitro. the more nitro the more heat you need. with 55% nitro and full water flow you will need to lean the eng to much to get it on song. It will also start to take the bearings out and the P/L fit.

David

 

[charles siler]

Ya Dave we are having to lean them after the first lap to get them to sing . we are at 16% oil mix also. we also played with head shims 84 is .13 with a cmb piston and liner the 67 is all mac it came with .05 I raised it to .08 and it wouldnt come alive .no detination

 

[dwilfong]

Charles choke the water down and it will come alive. fill the out let fitting with solder and dill a hole in it about .060 make sure you use water line not silicon and wire tie it at all the couplings.

then you can start to nail down the clearnce.

 

[ALLAN YUEN]

need add shims .015" better depend on what kind of pipe?

 

[charles siler]

AB parabolic on both

 

[Mike Byer]

Smaller prop, these engines don't like a big load, had the same problem.

 

[Don Ferrette]

Water temp is too cold, no heat in the motor. As others have said restrict most of the water first and try it again.

 

[Rokieboater]

.08 might be a tad tight on the 67

Robert Holland

 

[Tim Kish]

Water temp is too cold, no heat in the motor. As others have said restrict most of the water first and try it again.

45 deg water temp is way to cold for the engine to make the heat it needs , restrict the flow and try again.

Tim

 

[charles siler]

Ok David the OD99s way better going to cut the water down to .60 this weekend . I also used a 16'' cooling line around the pipe to warm the water up . water temp 55 today . out of a gallon and a half we killed three plugs on the riggers and my hydro was perfect and went 64 up from 53 and was singin thanks David

 

[dwilfong]

Ok David the OD99s way better going to cut the water down to .60 this weekend . I also used a 16'' cooling line around the pipe to warm the water up . water temp 55 today . out of a gallon and a half we killed three plugs on the riggers and my hydro was perfect and went 64 up from 53 and was singin thanks David

Those OD99 work real nice with High nitro. hard to blow out the coil. try pulling the coil it will run even better. but be careful it may start on its own when you hook up the igniter. The 89 work in the heat of the summer here in FL 95+ air and 85+ water temps.

.008 on the head clearance will work just don't lean it out to full song keep it just a little on the bubbly side.

 

[John Finch]

I agree with Mike and Allen. Despite everything else, those two things will cure the problem. you will still go fast.

 

[charles siler]

The 67 I've got a H32 and a 1662 on the 84 we have ran the props the Allen supplied with it and also went to a stock H32 . we are at .08 on the shims and im going to go to .015 this weekend sofare every thing is doing better thanks Guys

 

[Roger Hooks Jr.]

Engines are no good. Old technology.... I will be happy to do you this big favor though and take them off of your hands... Hahahaha...