Ron and Robin's new mini

[dak10]

the simi tractor might do u thr job but i have seen mine as high as 1680 degrees i will see if i can find the web page to the airplane junk yard a post it for all but the exhaust aeem to run between 1300 an all most 1700 degrees

[Duane Scarborough]

Buster,

Yeah, same kind of thing. But you may be pegging the needle. Since you've got it, I say try it.

Duane

[buster]

I think I will try it, but which cylinder do I put it on? It seems to me the 300 Mack had it in the header pipe. That is after it came out of the manifold, if I remember right. It was twenty years ago. Two inches from the head seems awful close JMO

Dave

[Duane Scarborough]

Buster,

I've given this some thought , and here's what I've came up with.

2 inches does seem to be very close. But that is what Electronics International says, for thier EGT meter.

What really matters though is that we can judge how the change we've just made affected the EGT.

If we all had identical EGT guages, with the sensors mounted exactly the same way, maybe we could compare numbers. But thats not going to happen.

What's really important (IMHO) is this: Did the change that you just made increase or decrease your EGT compared to what it was before? Forget about other people's numbers. How did it affect YOUR engine?

And since you're not going to be comparing it directly to other people's numbers, I don't think it'd matter which cylinder you choose.

Just my opinion....

Thanks,

Duane

Edit: I've done some more thinking about this. Seems to me that it's better to err on the rich mixture side than on the lean side. On the rich side, you may foul a plug occasionally. On the lean side, you may burn up the engine.

Again, it's just my opinion...

Duane

[gavlanco]

Those guys at Electronic International tech support are very helpful and don't mind answering any type of question. I've had to talk to them plenty over the years. 2 inches below the cylinder is correct. I believe on the E.I. website they have some downloads as far as manuals and installation instructions. If your going to monitor just one cylinder. Be sure to put it on your hottest cylinder, so you won't burn that cylinder up if your mixture is to lean. I'm not sure which is the hottest on the 084 but you can just use yours or borrow someone's laser thermometer and check while running the engine.

[dak10]

so see u people think i was full if it,but i got the info on the egt from the man at the airplane junk yard and i did look in a couple of engines there a they had the prob 2 in from the head i use cyl 1 for egt an cyl 2 for cht and i found by changeing the main jet to a 150 got my head temp down a little more then 100 degrees but i do think i will have to move the timing a bit,so my head temp is running about 350 to 380 at wide open an it was at 470 to 490


have a great day
ron

[airhead]

Ron,

I, for one, never thought you were full of it. And i also agree with finding the hottest cylinder to monitor. But i think ( and may be wrong ) that all engines will have the same ''hottest" cylinder.

Jim


When i say all; i mean all 084's, all 032's etc...

[Duane Scarborough]

Ron,

I hope I didn't ruffle your feathers. I did confirm that what you said matched what Electronics International said.

Thanks,

Duane

[dak10]

ok then i do think i will check for the hottest cyl
i do have a temp gun but it only goes to 999 degree so i will have to do it after i do a short run this way i think i can find the hot cyl , but do think it get better all the time i am not having any trouble with me a robin on the boat we do only weigh about 280 lbs between us so i can get more beer on board {hehehe) i still need to get my tach on and do a timing adjust

[Papee]

Ron if I had to guess on the hot cyl I would say it would be the rear left one viewing by standing at the back of the boat.

[airhead]

Ron,
Never tried it but would think the outside of the exhaust pipe might be below 1000. If not shoot each head near the exhaust this should find the hottest.

Jim

[dak10]

hay to all sorry i havent been on lately i have been do some more work on my 084 i found that 6 gals of fuel was not going to do it for me i was only getting about 4 hrs of run time so i went to a 12 gal. cell about 46 pounds more weight this was a slow down in deep water but in skinny water it do not slow me down from getting on plane that i can deal with start in skinny water then going to deep water was ok the boat stayed on plane ok an was not plowing i am looking for a shop to make me another pully for my crank so i can get the 1.65 i am looking for i need more prop speed i still do not have a tach on board but it is in the works
so small changes make a big differance good day 4 now

[buster]

dak 10,

If you find a place to get that lower pulley made, let me know. I am thinking I should try to get my rpms down to 3600 from over 4000, and I don't want to go to a different prop to do it.

Thanks, Dave

[chuckitt]

I talked to Don at Arrowprop this afternoon about making some crank pulleys 4.25 inch dia.. That would make it a 1.65 to 1 ratio. He said that the cost of the stock 4 inch pulleys was $ 130.00 and if he only built one, it would cost a little more. He said if we order 4 or 5 he might be able to do them for the $ 130.00 ea. We need 2 here plus the one that dak10 needs. If anyone else wants one made, call Don and tell him that you want the 4.25 inch pulley that i talked to him about. Anyone that calls him, post it here so we can see if the quanity is good so i will know when to place my order.
Thanks, Chuck

[Duane Scarborough]

Chuck,

I have NOT called Don yet. But I have just re-read all of the Ron and Robin's thread again. I was trying to get my mind around this whole reduction/ratio, prop diameter/pitch thing again.

It didn't help much. I'm still as confused as I was before. (Big surprise)

I'm planning to measure my pulleys again tomorrow, to determine just what my reduction really is. I thought that I'd determined before that mine was 1.69:1, instead of the 1.89:1 that we talked about months ago. Having CRS does not help.

If that's true, then I can't see going to 1.65:1 to be a big difference.

I'll be back tomorrow.

Thanks,

Duane

[David]

Don has advertised his drives to be a 1.69 but they was 1.89 and then a 1.74 or something like that but I dont think they are a 1.69

[David]

correct me if Im wrong Chuck

[Duane Scarborough]

I told you all that I had CRS.

So I measured my pulleys this morning, and as best I can figure, my reduction turns out to be 1.73:1.

If I figured correctly, at 3600 engine RPM the prop would be spinning at 2083 RPM.

By changing to a 1.65:1, at 3600 engine RPM the prop would be spinning at 2182 RPM.

That's roughly a 5% increase in prop RPM. It still doesn't seem like a big difference to me.

Duane

[buster]

I was wondering that, instead of/or in addition to, installing a larger lower pulley, what is the feasability of turning down the upper pulley?

That way, we should be able to make a bigger difference, while staying within the units adjustment range.

Dave

[dak10]

here is what i think the bottom pully needs to be 4.5 to 5 inches this will put the prop speed where it needs to be but some of us might have to buy a new prop that are runnning wood props that is i did the math and i would like a 5 inch bottom pully but i need to talk to chuck