timing mags/ snapping the impulse coupling

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krazymatt
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timing mags/ snapping the impulse coupling

Postby krazymatt » Thu Nov 01, 2018 10:16 am

can someone explain to me the procedure to "snapping" the impulse couling before setting the mags? i understand the timing procedure with normal str8 couplings. just want to make sure my mags are set correctly. both my mags have impulse couplers and set them both the same way so the buzz box doesnt indicate anything different for me. boat runs real good but gets hot, wondering if maybe it wasnt set right and have more timing than i think in it. i have 0435 bored to 480 with o320 jugs, 9.1:1 pistons and 290 grind cam. justin ficken advised set timing to 25 degree btdc.

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Re: timing mags/ snapping the impulse coupling

Postby John Fenner » Thu Nov 01, 2018 11:25 am

Turn it same as you would a straight drive, the dog will engage the pin and stop the shaft, the coupler will turn till it ramps the dog out of pin and snap through. You can turn it backwards to line up e-gap for the timing mark in the window.
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Re: timing mags/ snapping the impulse coupling

Postby krazymatt » Fri Nov 02, 2018 10:11 am

John Fenner wrote:Turn it same as you would a straight drive, the dog will engage the pin and stop the shaft, the coupler will turn till it ramps the dog out of pin and snap through. You can turn it backwards to line up e-gap for the timing mark in the window.


hmmm, the coupling on mine isnt like a regular one with sthe top pins. it is just round with what im guessing is a large clock spring inside and a direct gear to gear mesh. i looked in the overhaul manual and it doesn't say anything about the impulse coupling... maybe gmac would know? my motor is getting hot and cannot figure out why. trying everything i can!

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Re: timing mags/ snapping the impulse coupling

Postby John Fenner » Sun Nov 04, 2018 8:50 am

Just turn the drive cog in rotation, it should click through, then back up to E-gap.
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Re: timing mags/ snapping the impulse coupling

Postby GMAC 76 » Sun Nov 04, 2018 10:00 am

I have found that when ya start frankeinsting engines with different cyls, cams, compression ratios, carburetors etc that a slight retard in timing helps in several ways...I have my modified 0-360 set at 22 degress btdc and it preforms much better,runs cooler and starts better than at 25 degrees...but all engines are different ...I am familiar with the impulse assembly you have and what John Fenner is telling ya is right on for setting it for timing....with all the modifications you have it is very important you have the right carb on it...I have recently worked on a 435 that was running hot and it had a ma-4-5 carb on it but it was a carb for an 0-360 and not near enough fuel flow for the 435 so it was running lean a simple nozzle change and economizer reset solved the problem and woke up that ol 435

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Re: timing mags/ snapping the impulse coupling

Postby krazymatt » Mon Nov 05, 2018 10:21 am

GMAC 76 wrote:I have found that when ya start frankeinsting engines with different cyls, cams, compression ratios, carburetors etc that a slight retard in timing helps in several ways...I have my modified 0-360 set at 22 degress btdc and it preforms much better,runs cooler and starts better than at 25 degrees...but all engines are different ...I am familiar with the impulse assembly you have and what John Fenner is telling ya is right on for setting it for timing....with all the modifications you have it is very important you have the right carb on it...I have recently worked on a 435 that was running hot and it had a ma-4-5 carb on it but it was a carb for an 0-360 and not near enough fuel flow for the 435 so it was running lean a simple nozzle change and economizer reset solved the problem and woke up that ol 435


greg, im not at my boat now but when i get home ill check the number on my carb and see if you can tell me if its good for my setup. when i had my boat torn apart my buddy was running my carb on his go-480 and it ran fine on his boat and he turns it higher than i turn mine being a direct drive...

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Re: timing mags/ snapping the impulse coupling

Postby GMAC 76 » Mon Nov 05, 2018 11:20 am

if it run a go-480 without heating up then I would bet it is all right for your 435.....I was just thinking that there are several 4-5 carbs that would bolt right up but would not be enough for the 435 but if ya got a number that will tell ya what engine that carb is for and then there will be no question

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Re: timing mags/ snapping the impulse coupling

Postby krazymatt » Mon Nov 05, 2018 11:53 am

GMAC 76 wrote:if it run a go-480 without heating up then I would bet it is all right for your 435.....I was just thinking that there are several 4-5 carbs that would bolt right up but would not be enough for the 435 but if ya got a number that will tell ya what engine that carb is for and then there will be no question


10-4 thats what i was thinking also, thats why im more leaning towards my mag timing... may try resetting them to 22 and see how it runs. they were set at the factory 15 degrees as adviced by you prior to rebuilding and it ran fine like that. will check the carb number and run it by you because i would like to know anyways. always appericate your help. john aswell you guys always have good input.

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Re: timing mags/ snapping the impulse coupling

Postby krazymatt » Mon Nov 05, 2018 4:20 pm

Carb is a 4-5 model number 10-2518. After a search here you posted about this carb in the past. See this post: viewtopic.php?t=69713

Do you think it's possible this carb isn't enough for my setup now.

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Re: timing mags/ snapping the impulse coupling

Postby GMAC 76 » Mon Nov 05, 2018 8:24 pm

that is possible but the carb itself should be ok cause it is a 4-5 with the #187 throttle bore but the jet/nozzle may need to be bigger and the economizer tweeked...im thinking an 0-470 jet and richen the economizer just a little but damn if it run a g0-480 it should run yours...if it was me I would back off the timing first and then if need be look at the carb...just my opinion now...if the factory stock timing was 15 and you are now at 25 even with all the modifications 10 degrees advance is a lot..ya might even try setting it at 20 that is right in between the numbers your dealing with and see how she acts.....when ya do all these things to an engine ya just have to play with it to get it right...that's why they call it tnt......lol

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Re: timing mags/ snapping the impulse coupling

Postby Slidin Gator » Mon Nov 05, 2018 9:07 pm

GMAC 76 wrote:if it was me I would back off the timing first and then if need be look at the carb...just my opinion now...if the factory stock timing was 15 and you are now at 25 even with all the modifications 10 degrees advance is a lot..


This is a great point. I keep forgetting about the O-435 timing spec at 15 BTDC. I have no idea why it is different from the rest of the fleet unless it has something to do with providing throttle response vs. top end in Heli or gear nosed applications?? But, if that was the leading cause of the oil over heating problems here, I would expect some noticeable detonation from those hot cylinder heads!

If chasing suspected combustion chamber related overheating, Spark plug CHT's are around $25 each and a 2 cylinder gauge can be found for $80 new. This will tell you if cylinder temps are the key issue, as well as help tune the timing to your needs.
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

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Re: timing mags/ snapping the impulse coupling

Postby GMAC 76 » Mon Nov 05, 2018 9:42 pm

I think some of the 0-435 engines were actually used in tanks which would be a whole different ballgame I would think....this is a military numbered carb so I wonder if it was on a tank engine instead of an airplane engine....maybe someone else has that info cause it is certainly an oddball number that does not show up on any aircraft lists that I can find and maybe those engines had a different timing spec...lots of questions pretty interesting though...just keep tuning krazymatt youll get her right....bottom line is still if it worked well on a go-480 it should be all right on your engine

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Re: timing mags/ snapping the impulse coupling

Postby Slidin Gator » Tue Nov 06, 2018 7:40 pm

GMAC 76 wrote:I think some of the 0-435 engines were actually used in tanks which would be a whole different ballgame I would think...

Yes, that would be a good reason for a low timing spec. First you want low, low, low end grunt with a tank, so retarded timing for sure there. Add in a hot a$$ tank that still needs to run decent under enemy fire with the engine cooling fans down and a low timing spec makes a lot of sense! You don't want the crew getting too used to running them things in hot rod mode. :violent1:

I am not getting the feel that ignition, carburetor or generally overheating cylinders is the issue here. Matt ain't Krazy, he has a problem and he is looking into all the potential issues that may be causing it. The primary complaint is high oil temps after 15 hours of break in on new set up. I think the following thread is directly relevant.

https://southernairboat.com/phpBB3/viewtopic.php?f=47&t=71784

Matt summarized the primary issue with the first post in that thread.

krazymatt wrote:Can someone explain to me how the oil relief valve cooler bypass operates on o435. I'm wondering about the main relief valve that is also the oil cooler bypass located on the sump. My boat gets hot after about 30 minutes of riding (2100 rpm) temperature rises to around 220 so I pull over and drink a beer or 2 n let it cool down. Once I restart the motor temperature is around 180-190 and I can ride for another 15-20 minutes then it climbs up again. Oil pressure is good (50) psi when hot. After talking with justin Ficken we both decided maybe my oil cooler was too small so I purchased a Haden 1260 which is about 2x the size of the cooler I was running. This hasn't made a difference. I'm not sure if oil is circuitlatong through the cooler or not I forgot my temp gun last time I went out to check. I'm wondering if the valve isn't operating correctly. It almost looked like there was small amount of pitting on the plunger last time I had it removed. If I remove the plunger and spring will that allow it to flow to the cooler or block it? Motor has all been bored to take larger jugs, using o320 cylinders making it a straight valve 480 now. All new bearings, crank and rods overhauled by d&s Camshafts, 9:1 pistons, new rings, h290 grind cam and fresh ground lifters from justin Ficken. timing was set to 25degree btdc Per justin. All 6 cylinders were overhauled by mark @ don george aircraft. Have about 10-15 hours on tach since Motor overhaul. Boat runs excellent other than the temperature problem. Doesn't appear to be consuming much oil if any maybe half quart on last 30 gallons I burned. Could it be the rings arnt seated and having some blow by? Is timing too much? It was originally set at 15 degree btdc with 7.5:1 pistons before I bored the case. Motor turns 2800ontrailer and cruises around 21-2200 rpms. Has fresh Phillips 66 Victory 100 AW oil n only run avgas 100LL.


My thinking here is that there are no complaints about hot cylinder IR gun measurements or detonation/loss of power. The only symptom here is high oil temps.

Just to put it in my perspective, I run a lot of dry, have to when outrunning dogs (by the way, I hope you voted no on 13! Dogs love to run, duhh). 1 Week ago, hog hunting what I think is old orange grove, I gave the motor a serious workout. Whenever oil temps would start pushing towards 215 the motor started detonating. After just 15 seconds of cool down I could get full power again for a few minutes. Oil temps didn't really change, my cooler is working. We had to bail out of that hunt area and move on, too much sitting and cooling, not enough running makes it hard to run the dogs. Motor ran great everywhere else. The problem is obviously hot plugs, they turned into glow plugs and I am sure the cylinder temps are high. The thing is, every time I hit it with the IR I never get a cylinder reading over 400??

My point is that cylinder temps and oil temps are 2 different things. I have run the boat out of dry on 5 cylinders, stopping when oil temp hits 230 to cool with no detonation issues. In that case, the reason for the high oil temp was obvious, a quarter sized hole in cylinder #6 provides plenty of blow by.

KrazyMatt, unless the motor is loosing a lot of power, your primary complaint is high oil temp. The issue is in the oil cooling circuit.
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

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Re: timing mags/ snapping the impulse coupling

Postby Slidin Gator » Tue Nov 06, 2018 8:15 pm

I almost included all of this in the last post, but it was long as He!! already...

I know this is not the original thread, but here is what I am doing regarding cylinder temps. I will make a separate thread once I get some results.

My problem is overheating plugs. My first response in the field was to dial back advance to 23 degrees. That did not work, I thought about going to 20, but we moved on instead, no need to blow up a motor at the start of hunt season.

So I ordered a pack of copper spark plug washers to better move heat out of the plugs. I would like to use lower temp range plugs, but that is problematic, so I am going to start with testing smaller spark plug gap (set at 0.038 with electronic now, going back to 0.025) and less advance.

Next, I know I am pushing the motor, I need to measure cylinder head temps to know what is going on, sort out a solution and know when to give her a break. From Aircraft Spruce I found I can measure 2 cylinders via a single gauge and 2x spark plug sensors for about $160. That is what I would advocate for most at a minimum, but me being me I opted for a full monitoring package with 6x Lycoming bayonet CHT sensors, a gauge and a 6 position switch, look at each cylinder via the switch. I did opt out on the $1,500 engine monitoring package however!

Between the 100 pack of copper washers and the CHT system I came up $2 shy of the $500 minimum for free shipping. So I bought one $3 exhaust gasket and saved $20 in shipping... Waiting for the 6 way switch from California tomorrow.

Image

Time for gauge and sensor install and a baseline WOT test to find where the cylinder temps are actually running.

Next, I assume I need some cooling. I am thinking shroud, but I don't want to give up too much thrust. I am starting with this 8" fan and thinking about a set of 3x puller fans on the outlet of a shroud. They would pull 12 amps total, less than my frogging lights. Besides cooling at low speed-high power, fans will help speed up idle cool down for sure. The goal is a fan system than cools the motor to keep running at high power but does not impede cooling with the fans off when riding, frogging etc.

Image

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Like I said, this is outside the bounds of this thread. I want to hear more about military tank applications for the O-435 and how that applies to Frankenstein :bounce:
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

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Re: timing mags/ snapping the impulse coupling

Postby GMAC 76 » Wed Nov 07, 2018 9:54 am

the 0-435 Lycoming aircraft engine was used in an M22 LOCUST TANK ...developed in 1941.....not real sure when Mr. Frankenstein showed up but he is alive and well in the airboat world as is evident by this entire thread......lol

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Re: timing mags/ snapping the impulse coupling

Postby krazymatt » Thu Nov 08, 2018 1:34 pm

thank you all again for the input. been so busy lately havent had time to get to the river to screw with it! first i will try as it is and take my ir gun and see what the cylinder temps are and also temp in and out of the oil cooler. then possibly try lowering the timing on the mags.

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Re: timing mags/ snapping the impulse coupling

Postby Slidin Gator » Thu Nov 08, 2018 6:40 pm

krazy,

Don't forget this if you have time, heated on the trailer or after it overheats during testing. You should find that output to the cooler is hot and the return is cold, but that is not the whole story. Any oil flowing to the cooler should be hot (like 220+) and the return side should be cool, but that does not tell you how much flow you have. I would time how long it takes to flow 1 quart into a jug when hot. You should have a pretty healthy flow rate, but I don't have a number to quote, just something for further thought.

Slidin Gator wrote:I would heat it up on the trailer and then pull a hose off the cooler and stick it in a bucket. Crank engine with mags off and see if you have much flow. Oil needs to be heated up first, when cold it should have plenty of flow.
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.


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