engine temperature

[Gary Lauer]

Is it possible to run to much water through a cooling system? Could a engine be damaged by running it to cold? I was checking a couple of engines and they don't have any pinch, the compression seems good. these are 21- size.

 

[David Ashcroft]

Yes too much cooling can be of no use and power loss and damage to piston sleeve fit particularly if a knew engine,,,load on the engine is of importance also ,,shim the engine to a desirable setting and run at a richer setting and still make good power and safe on engine , there is too much info in the world about engines to speak of here..You could do a search on here and you will find a lot of good info from experienced old-school boaters.

 

[Gary Lauer]

I have a couple of coyote Daytona riggers with ops 3.5 side port engines with no pinch. I have a water pickup through the rear of the left sponson as Don Pinckert told me to. I have a lot of water going through the engines. any ideas as how to cut down the flow?

 

[David Ashcroft]

Yes sure just pinch the water line to restrict flow..Zip tie at the rudder line etc etc..or block water outlet on jacket and drill a smaller hole in jacket..around .040"-0.60" and run it Rich with a .21 in particular to make power with a .006-.008" head clearance.Be wary though of old ops engines for head clearence .


Edit

 

[Gary Lauer]

how do you check the head clearance?

 

[TomGracey]

Take a piece of .030 soft solder insert thru the glow plug till it touches the side of the cylinder and turn the engine over 1 full revolution remove and mic the flattened solder that will be the squash, add or remove shims as necessary to achieve your wanted squash. Note just make sure the solder did not go thru into a port passage or it will shear the solder and you will have to disassemble the engine to retrieve the cut off piece of solder.

 

[Bill Gibson]

Take a piece of .030 soft solder insert thru the glow plug till it touches the side of the cylinder and turn the engine over 1 full revolution remove and mic the flattened solder that will be the squash, add or remove shims as necessary to achieve your wanted squash. Note just make sure the solder did not go thru into a port passage or it will shear the solder and you will have to disassemble the engine to retrieve the cut off piece of solder.

That is a COOL way to check head clearance!!!!

 

[David Ashcroft]

Although not the best way but yes..

 

[Gary Lauer]

that is he way I thought, but I wasn't sure it was right. Thanks for all the help

 

[Dennis Somers]

Tom's suggested solder test will give you a good "idea" of the clearance. The best way to check is with a dial indicator mounted solidly in the plug hole. That reading over TDC, compared to the reading with the piston out and pushed flush with the button, is the true clearance. But on the smaller engines, that's not always practical. If you use the solder method, I would urge you to put 2 pieces of solder in the hole, 180 degrees opposed, along the wrist pin plane. Don't put the solder in until the piston is above any ports as was mentioned. The reason for 2 pieces is when the piston squashes 1 piece on one side, it forces the piston into an unnatural slight skew. With 2 pieces, the squeezing is more uniform, and being in line with the wrist pin, will minimize piston rock.

 

[Gary Lauer]

what head temp should I look for?

 

[mr_fons]

I've read/heard around 220 - 230 for a .21. I use a airplane wheel lock that fits over the water line to control water flow with the set screw.

 

[GraysonTaylor]

Thanks Fons! I like the collet idea.

 

[Glenn Quarles]

Gary, as stated above, yes over cooling is a very bad thing and yes it will hurt your motor.

The way I recommend to most guys to get the temp about right is by using your fingers. After a full run ( at least 4-5 laps) bring you boat to shore and immediately touch the top of the head with your bare fingers...if you can hold your fingers on the head for 2-3 seconds before it feels too hot then the temp is about perfect. If you can hold your fingers on for longer than that, it is too cool, if it feels like it is burning your fingers as soon as you touch it, then it is too hot.

Hope this helps!
GQ

 

[MarkDanielsSr]

I know this question is now answered, I will add that too much cooling is bad. The early OPS 90 motors were cooled at the center case and head, far too cool. That fact plus the original unbalanced cranks led to an overhaul which included improved timing, finned center section, water cooling only in the head, and the double plugged balanced crank. The motor started lasting and performing, I still run 7 of them. The primary issue was increased running temperature.

 

[Matt Krieger]

I don’t mean to hijack the thread, but I have had trouble with my os air cooled engine not generating enough heat as it barely gets warm after a run.
Anybody have any thoughts on this?

 

[Glenn Quarles]

Matt, all you need to do is machine some of the fins off. I generally machined off all but 3 fins and even turned their diameter down to about what the case is. That always worked on my boats with the amount of airflow I have, yours may differ a little.

GQ

 

[MikeMischnick]

Yes sure just pinch the water line to restrict flow..Zip tie at the rudder line etc etc..or block water outlet on jacket and drill a smaller hole in jacket..around .040"-0.60" and run it Rich with a .21 in particular to make power with a .006-.008" head clearance.Be wary though of old ops engines for head clearence .


Edit

(The information shared here is for inboard motors. I do not race outboards and do not have an opinion one way or the other.) ( Any testing done from information below you do what your own risk) I agree with the 21 Motors (Only) need more heat using the water cooling system. The problem with what is suggested here is there is no way to do it reliably set the water pressure nor can you reproduce what you did on another boat. The amount of water pressure needed also varies with the weather and can change by the hour. Using a tie wrap can take you from too much water not enough water in one click increase problems of overheating which can seriously damage the motor. What I'm going to do is share what some of the big boys have taught me.

The only motors I race are CMB 21 & NOVAROSSI 21. With the Nova Rossi's it all depends upon how cold things really are in air temperature and more importantly water temperature. Novarossi Motors tend not to need the extra water restriction year-round in the south. Here in the North the colder it gets the better idea it is to install the system. I have not done a lot of testing with the Novarossi using system being described below.
CMB 21 motors DO!!!


CMB
You need to install a water metering system as shown in pictures below. You also need a flow meter.
Install the metering system to your waterline. Next hookup your flow meter to the water line coming from the rudder through the metering system. Turn on the flow meter and turn the screw on the metering system slowly in, you will watch meter change when it starts to restrict the flow. You want to start the testing around 70 on the flow meter. You will need to find your own happy place where the motor runs at is Optimum. Each time you test I would move the noodle know more than about 5 Points higher on the flow meter. Once you have a happy setting write that number down someplace where you won't lose it and every time you run the boat flow the waterline to that same setting. The numbers in my boat are not important. The numbers I use greatly very from the people who told me about this system. As I said it's extremely reliable and there's no guesswork involved once the testing is done
I hope this helped.

 

[Matt Krieger]

Matt, all you need to do is machine some of the fins off. I generally machined off all but 3 fins and even turned their diameter down to about what the case is. That always worked on my boats with the amount of airflow I have, yours may differ a little.

GQ

Thanks Glenn,
I will make a fixture for machining the fins down as my lathe is not up and running yet but my mill is.
Do you have a target temperature I should shoot for?
Thanks
Matt

 

[Glenn Quarles]

Matt, the two finger technique will work fine for the air cooled head also, just touch the head up by the glow plug.

GQ