Engine swap (repower)

[jimmbo]

Re: Engine swap (repower)

Have you had the heads off? This a long shot but perhaps the engine was assembled with the pistons installed rotated 180 degrees so the deflector is facing the exhaust ports instead of the intake ports. I saw an engine like that several years ago. It ran but not too good.

 

[ddbyrd3]

Re: Engine swap (repower)

OK.. had a chance to verify timing this weekend. It is at 28* at WOT. I cant come close to 5000 RPM though. The most a saw was in the mid to upper 4s.<br /><br />I have the idel set at 850 in the water with prop engaged. at times it will cough and stall. It will refire no problem if I raise the fast idel lever and run great there after. This doesnt happen all the time, but occasionally.

 

[Dhadley]

Re: Engine swap (repower)

Well, we're back to "something is really wrong". That motor should idle at 500 in gear very smooth. I've been trying to avoid just what Jimmbo mentioned but we may have to consider that. <br /><br />Pull a plug out and see if you can tell which way the slope on the dome goes. (Toward exhaust or intake)

 

[Dhadley]

Re: Engine swap (repower)

One other thing, are we sure the firing order is right? Its awfully easy to get 2 of those orange primary coil wires mixed up. Thats kinda where I was going when I asked if any plug(s) looked different from the others.<br /><br />If theyre crossed it should backfire out the exhaust when it tries to start.

 

[ddbyrd3]

Re: Engine swap (repower)

I replaced the coils last season. I was very careful to do one at a time to make sure I didnt cross any wires. If one of the orange primary wires were crossed, how would I be able to tell.. <br /><br />Also the motor starts fine when I lift the fast idel lever, it doesnt pop, spit or anything.

 

[ddbyrd3]

Re: Engine swap (repower)

I will verify the piston slope tonight. I ordered the "std" head gaskets from iboats, and should get them this week. I measured mine and they appear to be .055 or so using a digital calpier. <br /><br />Just to eliminate them, I am going to replace them.

 

[ddbyrd3]

Re: Engine swap (repower)

DHadley, IF a piston or pistons are in wrong, what is the possibility of additional damage to the motor if this is the case??<br /><br />I know that is more than likely an unknown, but I am just curious.

 

[Dhadley]

Re: Engine swap (repower)

Different motors do different things but none will achieve full power and will act a lot like this one. Luckly with most piston/head configurations in a crossflow the pistons hit the head so the mistake is found before the rebuild is ever completed. <br /><br />The biggest "additional damage" scenario is that the ring end gaps end up in a port and get broken off. I'd have to look at a crossflow piston to see the locating pin positioning but I dont think thats an issue on them. Besides, if it were going to happen, it would have already.

 

[ddbyrd3]

Re: Engine swap (repower)

Thanks for the responce, I will post the results of my findings tomorrow.<br /><br />How can I check the Orange primary coil wires inorder to eliminate them as a potiential problem??

 

[Dhadley]

Re: Engine swap (repower)

They have a "tracer" color stripe on them. Your service manual will tell which is correct. I'd have to look it up but its usually Orange w/blue stripe is up and Orange w/green stripe is down. Or solid Orange is up and the Orange/xxxx is down.<br /><br />Does it ever backfire thru the exhaust? (Exhaust -- not thru the carbs. Even if it does sneeze thru the carbs were only looking at exhaust now)

 

[ddbyrd3]

Re: Engine swap (repower)

No never... But I will look in order to eliminate another possibility..

 

[Dhadley]

Re: Engine swap (repower)

Well -- dadgum. The firing order is probably OK. I was kinda hoping it wasnt -- thats pretty easy to fix. Although if the pistons are indeed in backwards the rebuilder should gladly correct his mistake. Especially since he knows youve been having issues since the rebuild.

 

[ddbyrd3]

Re: Engine swap (repower)

I can only hope.. If in fact they are backwards, it has been this way since "2002" I probably have 100 hours on it since it was rebuilt.<br /><br />Personally, I do hope this is it.. I have been chasing the power loss problem for nearly 3 years now and it is nice to keep narrowing it down... I just hope, as you said, he will be willing to fix his error.

 

[ddbyrd3]

Re: Engine swap (repower)

 

[ddbyrd3]

Re: Engine swap (repower)

OK, agiain forgive the ignorance.. After looking and making sure what I am looking at..<br /><br />The big smooth slope is towards the inside of the motor ( I believe this is the Exhaust port) <br /><br />The LARGE 1/2 moon top of the piston is outward..<br /><br />One other thing I did notice.. the top of #2, #3, & #4 pistons were black & wet looking. Number 1 cylinder was very dry and black, or even dark grey compared to the other 3. It also appeared to have detonation looking white type spots. (If that makes any sence at all)<br /><br />Is it possible that I may have a plugged venturi, jet, whatever on the top carb feeding that cylinder??

 

[ddbyrd3]

Re: Engine swap (repower)

What do ya think DHadley??

 

[Dhadley]

Re: Engine swap (repower)

Sounds like they are in correctly. The long gentle slope should be from about the center of the piston and going down towards the center of the motor. The sharp rise "pop up" side should be toward the outside (intake) of the block.<br /><br />Now, the condition of the #1 plug concerns me. If its dry and sooty, the ignition could be double firing. Or you could have an air leak.<br /><br />We might try looking at each of the 4 cylinders with a timing light. Heres how we do that. We mark TDC on the flywheel for each cylinder. (We're not really concerned about total timing although you can check that at the same time.)<br /><br />As you mark TDC for 2, 3 and 4 (1 should already be there) we mark the cylinder number by each mark -- very important. I like to use White Out. It shows up good and is readily available. <br /><br />OK, now as we run the motor we watch each individual cylinder thru the rpm range. Lets say youre looking at #1. If at any time we start to see another number, we have an ignition problem. This is why its important to number each cylinder. Just looking at a line we may never "see" that its actually firing that cylinder twice per revolution.<br /><br />Now, if you really want to check it close, on the #1 timing grid count the number of flywheel teeth from TDC to 28*. It'll be the same on every other cylinder.

 

[ddbyrd3]

Re: Engine swap (repower)

Am I checking this under load, or can I do it on the trailer running a hush muffler????<br /><br />Worse case ignition, are we looking at the power pack possibly being bad on that side..<br /><br />Should I still consider re-building the carbs???

 

[Dhadley]

Re: Engine swap (repower)

Under a load. And it might not hurt to go thru the carbs just to be sure. Soak them in something good like Engine Tuner.

 

[ddbyrd3]

Re: Engine swap (repower)

Prior to reading your last post, I disconnected the throttle cable, connected the timing light to each plug wire and ran the motor up to 3500 RPM (after marking TDC for each cylinder) and I only saw each cylinders number. I didnt see any jumping around under NO LOAD conditions.<br /><br />Static time is at 24* and at idel it shows 4*. Not that that means anything, just thought I would post it.<br /><br />I will order my carb rebuild kits from iboats tommorrow..<br /><br />Is it imperative that I perform the timing test under load?