Hi Altitude AQ125a settings?

Any idea on setting advance or carb for 7000 feet?

Cannot find hi altitude jets for my Solex 44pai. Should I advance or retard timing? Noticed it does run better with more advance.... but also have heating issues and wonder if it is related to my advance.

Any info on hi altitude adjustments would be appreciated.

Thanks
John

Re: Hi Altitude AQ125a settings?

Set everything to spec for the engine, 7000 feet is'nt high enough to warrant anything special. I regularly drive my car at higher altitudes without any modifications and with no problems or loss of power at all.

Re: Hi Altitude AQ125a settings?

If your car is one that has a carburetor and point ignition and no ECU then you will feel 7000 feet.

Timing advance but not too much or you can have pre ignition /heating problems. Also get a prop that is one size lower in pitch.

Re: Hi Altitude AQ125a settings?

^^^ yup, with a carbed engine you will notice a power loss at 7000' elevation, somewhere around 20%

Leaning down the carb is 1# smaller for every 2000' elevation, #55 jets would lean down to #52 jets at 6000', same for 7000'. Just remember, once you make the change you will have to put the stock jets back in when you drop back to a lower elevation or risk engine damage from running lean.

Re: Hi Altitude AQ125a settings?

Cant find jets for the Solex pai. Any ideas???

7000 feet is VERY significant. My snowmobiles are set for 10000 and run like crap at 7000 where my house is. My Johnson was set for 6000 and would not even run at 10000... so, not sure what kind of car you have, but I have not had the same experience. Even with EFI, my Isuzu did not have enough power to back up in a level parking lot at 14K on Pikes Peak. Altitude has a huge effect on carbs (and ballistics for that matter.)

Still have major overheating problem. Not sure why. Popping my 13# radiator cap after running WOT for 30 min. Shouldnt. will be at a steady 180 for a long time, then temp suddenly spikes and I have a steambath on my hands. I am two prop sizes down and only holding 4500 rpms at 10 deg BTDC... a good 700 less than when I was running at 20deg BTDC and still overheating just the same. Any ideas??? Never did check my advance... hmmmmm. You know, I am wondering if I am boiling at a lower temp due to altitude as well.

After doing some reading... my 13 psi cap tells me the previous owner had the same problem and tried putting a heavier cap on it. I have gone beyond that and rtv'ed the damn thing down in case it was just blow by venting. Clearly it is not. My next plan, unless you have a better idea is to yank the thermostat and let her run wide open. It is a new thermostat, so that is not the problem either. May lose a little efficiency, but so what... better than burning it up.

Any better ideas? Planning on pulling thermostat, checking advance, and setting dist to at least 15 deg BTDC. Better ideas welcomed. You out there Don?

thanks
John

Re: Hi Altitude AQ125a settings?

have no idea what a aq-125 is
would be checking for cracked head or block or blown head gasket
will pass this on; as we travel from1000 ft to 8000 ft with boats all the time.
mecruiser dosnt recommend changing jets or timing on there motors for elevation changes. (the ib-ob i am familiar with anyway)
they recommend propping for recommend rpm and lower gear ratio for drive.

you have a lake full of cold water to cool your motor so cooling shouldn't really matter at higher altitude.
i suspect you have other problems.

i to used to sled a lot before a injury sidelined me a few years ago. tuning 4 stroke boats and 2 stroke sleds dont have much in common. IMHO

Re: Hi Altitude AQ125a settings?

lutherfetch said:

Cant find jets for the Solex pai. Any ideas???

7000 feet is VERY significant. My snowmobiles are set for 10000 and run like crap at 7000 where my house is. My Johnson was set for 6000 and would not even run at 10000... so, not sure what kind of car you have, but I have not had the same experience. Even with EFI, my Isuzu did not have enough power to back up in a level parking lot at 14K on Pikes Peak. Altitude has a huge effect on carbs (and ballistics for that matter.)

Still have major overheating problem. Not sure why. Popping my 13# radiator cap after running WOT for 30 min. Shouldnt. will be at a steady 180 for a long time, then temp suddenly spikes and I have a steambath on my hands. I am two prop sizes down and only holding 4500 rpms at 10 deg BTDC... a good 700 less than when I was running at 20deg BTDC and still overheating just the same. Any ideas??? Never did check my advance... hmmmmm. You know, I am wondering if I am boiling at a lower temp due to altitude as well.

After doing some reading... my 13 psi cap tells me the previous owner had the same problem and tried putting a heavier cap on it. I have gone beyond that and rtv'ed the damn thing down in case it was just blow by venting. Clearly it is not. My next plan, unless you have a better idea is to yank the thermostat and let her run wide open. It is a new thermostat, so that is not the problem either. May lose a little efficiency, but so what... better than burning it up.

Any better ideas? Planning on pulling thermostat, checking advance, and setting dist to at least 15 deg BTDC. Better ideas welcomed. You out there Don?

thanks
John

Click to expand...

I'll try this again, 7000ft is not high enough to start messing with the ignition or the jets. The difference between 7K and 10K is significant, and 14K even more so. Comparing 7K to 14K is not really helpfull.
People drive over the Sierra mountains and the alps everyday without issue. Actually thousands of people do this every single day, and where I live, in Norway, almost all roads go from sea level to similar altitudes, and noone here adjusts their timing or changes carb jets. There is a loss of power, as mentioned earlier around 20%, or 3% for each 1000ft, but no amount of fiddling with the engine will correct that, at best it will run a little smoother, at worst it will just cause problems. You can never correct for the loss of oxygen and get more power, all you can do is decrease the amount of fuel to make it run a little smoother.

Once again, at 7000ft I believe the right thing is not to fiddle with the engine adjustments, but only run a smaller prop. Besides a loss in power, wich is unavoidable, 7000ft is usually not high enough to cause any other problems, as long as air temperature and humidity is not in the extremes.

Your overheating has nothing to do with the altitude, and removing the thermostat does not fix the problem, it wil only help you destroy your engine sooner. However as this seems to be your goal, go ahead, adjust the timing to whatever you think is right, start messing with all the screws on your carb to see what they do, and by all means run your engine without the thermostat .

Re: Hi Altitude AQ125a settings?

To the mechanics who have responded, thank you. I have dropped 2 pitch sizes and am still only pulling 4500 rpms. 5deg more gets me another 3-400 rpms.. right at the max I want to run and the spec on this engine. I still suspect the advance may be the culprit and I have made up for it by advancing timing manually. I also suspect the possibility of the head... but I am trying to NOT pull apart another engine this summer. Dont want to magnaflux this thing if I dont have too. Was hoping to have fun with it instead of working on it. There is no evidence of a blown head gasket. Checked that too. Changed impeller, boiled out heat exhanger, changed thermostat, water pump has pressure.

OK Adnoid, thanks for your theory on life. I will try this again too (big sigh). I actually live here and make my living working on engines. I have built a custom rock crawler out of a 73 Steyr Puch Haflinger set to the altitudes. I even tuned my lawnmower and weedwhacker for our altitude. Altitude and jetting is critical to optimize performance whether people want to mess with it or not. I get this is not a high performance engine... but it is the same concept... a big pump that sucks in air on one side, blows it out the other. Get the fuel and fire right for your altitude, you get more power. Crossing the Alps riding your mothers goat probably will not require much thought from you or knowledge on carbs and advance. That engine and Solex carb has major issues. Now I am adding another variable called altitude. Get it? The real mechanics who have responded to this post do.

If you had more than 2 minutes experience with this particular engine, you would know the exact same issues I am dealing with plague this motor. It is infamous for overheating. The thermostat only begins to open at 180 and fully opens at 195. Mine boils over at... drumroll please... 195. Hmmmm. Pulling a thermostat will run it at 165 deg according to another user who owns this engine. On what planet does that blow up an engine? May not be ideal... but pretty sure in the real world 165 is preferable to the bomb I have. Will gladly trade 15 degrees for something that doesnt end with a loud boom at the end of the day.

Every engine is different and has its own personality. Some engines are affected more than others by altitude and temperature. Domestics (that means American) do great. Older Nissans barely run. Every engine and every carb is different. The Solex 44pai is a can of crap on top of the engine. Unfortunately, that is what I am stuck with. You are clearly way out of your league. The problem is an engine that runs notoriously hot, has an undersized heat exchanger, and possible complications with altitude. I am holding out hope I am not going to have to build another engine this summer.

I remember dealing with an internet moron who said something similar about my custom mitsubishi engine that developed a wicked tick immediately after having the heads redone and a timing belt change. Marks all lined up. By the racket, I figured I bent a valve somehow. Anyway, (and this this is the part that pertains to you) the internet moron was telling me how stupid I was. He was even condecending like you too. The real Mits mechanic said it was completely normal for that particular motor to start like this. Go figure. The racket was caused by just needing to wait a minute for lifters to get oil pressure the first time after reassembly. No other way to do it like you can with a drill on a proper God fearing Chevy 350. It was the most excruciating minute of my life. Then, the sound magically went away and it was gone for good. What is the point??? I needed very specific information for a high performance engine most mortals would not know anything about, let alone attempt to work on. The internet moron was guessing at it... badly. And, like you, he was unfamilar with that particular engine and a pompous self agrandizing sphincter to boot (sigh). Get the picture?

Thanks for your post Adnoid... have clearly given it all the attention it deserves. So here is my humble suggestion for you as well... perhaps try knitting. No risk for you, it does not require thought or knowledge on how things actually work, certainly no "tinkering" with those decorative but pesky dials they put on there just to annoy the stupid people, and the altitude really should not effect your yarn. Just follow all the factory directions and keep them tucked in your skirt for quick reference to yodel at those who might have an original idea of their own. I know its hard to believe, but some folks do things differently. For example, we ride our horses here. Have no idea or desire to know what Trigger tastes like. Still wanna "try again" with me?

God that was fun! i could go on forever, but its getting late here.

Real mechanics, thanks for the responses. Will let you know what I come up with. May end up having to tear that head off before this is over, but before I get there, I want to try and do all the problem solving I can in between fishing and cruising trips with the family. If that means running it at 165 and pulling the head after the lake freezes, thats the way I will go with it. Fisherdan, you have a line on those jets???

Thanks again,
-j

Re: Hi Altitude AQ125a settings?

Here's an interesting "Mercruiser" bulletin I found, look at the bottom of page 5.

http://www.boatfix.com/merc/Bullet/97/97_08.pdf

They say prop, timing and jet changes can be made. Though they do say that boats going to high altitude for short periods of time should only have prop changes made,,, because every change made needs to be reversed before operating at sealevel again..

Next time I go up to 9000' I'm doing everything, prop, jets and timing. The hour it takes to make those changes (and hour changing it back again) will be a small price to pay for a good running boat.

Re: Hi Altitude AQ125a settings?

Fisherdan, thanks for the post.

Well lookey there! Advance and carb jet changes. I can see why the Vikings stuck to rowing their boats. See that Adnoid? BTW, could use a new pair of knit socks. Anyone else reading... this is why you need to be very careful about whom you listen to. People who give you attitude with their "suggestions" generally dont have a clue what they are talking about.

Anyway, wanted to wait to post my findings after running my changes. I am convinced I am fighting 2 seperate issues. I have figured out one of them. Both are BAD design flaws of the Volvo AQ125a. First, the heat exchanger in this unit is woefully undersized. pulling the thermostat made only little improvement. I put it back in. what did fix the problem was pulling the heat exchanger all together.

For those of you with an AQ125a... here is how you do it. Your exchanger lives is the small vertical red housing on the left as you look at the front of the engine. pull the filler neck, and then the four bolts that hold it together. pry it apart. That little tiny radiator... that is what Volvo considers adequate cooling. Pull that out. You will want to reuse the white ring on the top of it to place between the top and bottom housing. RTV the crap out of and bolt it back together. Voila! Overheating problems are gone. Boat will run at 178 deg no matter how you run it. I beat it like a rented mule all day. However, this exchanger is what makes this engine ideal for living in saltwater... something there is not much of in WY. If you run in the ocean, you may choose to live with this constant nuisance... and it may not even be much an issue with the exra power you have a sea level.

As for my timing issues, sure enough, I pick up a good 600 rpms by advancing my ign to 20 deg BTDC. THis is a lot more power and way more than the 3 deg the altitude change would suggest according to the Merc standards. However, it will not idle at all. I have read other posts of the exact same issue. I am convinced this is a weight/spring issue within the advance. I will get a Penta dealer on the phone tomorrow and see if there is a remedy. I doubt it. In the mean time, I split the difference and set engine to 15 BTDC.,, only 2 deg more than suggested. It starts fine... and even idles smootiher... and I have picked up about 250 rpms over 10 BTDC. It does have a hesitation in the 3500-4000 rpm range... but I can live with that if this is the best this little engine will do. Thanks again Fisherdan.

Will let you know how it goes,
-john

Re: Hi Altitude AQ125a settings?

Back when carbs were the norm and everyone wanted twin dellorto's on their VW. We would start with some old jets and solder the orifice shut, then would use number drill bits to work up to the correct size. Took lots of test drives to get them right.

Re: Hi Altitude AQ125a settings?

Problem is that I cannot get jets. I did order a spare carb off ebay for it. I have been debating tearing it apart and pulling that jet to do that very thing... hmmmmmm.

Anyway, called a Volvo dealer and, as I suspected, there is no support available for that distributor. Going to live the mods I have made.

Thanks
John

Re: Hi Altitude AQ125a settings?

Search the internet for carb shops. I got several different sizes for my Rochester from a place in So Cal, something like $5/set. Though, it did take some time calling around to find a place that stocked old parts. If a place you call says they don't have them, ask them if they know of any places where you can get them, this has worked great for me in the past for odd-ball parts.

For the distributor, see if you can turn the rotor and have it snap back. If it's not moving or hanging up this will cause you problems, timing not advancing. Have you checked the springs and weights to see if they are working properly? Could be that they are rusted up and sticking, they should move freely under the springs tension. I've never seen a Volvo before, but see if there is a removable plate below the rotor, if there is, it's covering the weights and springs. Clean them up and put a bit of oil on the weight pivot pins. The springs are calibrated for tension, so don't go swapping springs from a different distributor, it will mess up the distributors timing curve.

Re: Hi Altitude AQ125a settings?

Hey Dan,

Yeah, I am with you. Not going to randomly switch parts out. Ordered parts from Volvo to deal with the overheating. I suspect this is a design flaw from what I have read from other posts. I will go ahead and pull it back apart and check. As far as the jets, I have googled it, called Volvo and even VW dealers. That Solex pai is an odd duck... and a real piece of junk. Will post when I know something.

Thanks my friend,
John

Re: Hi Altitude AQ125a settings?

Lutheretch PM me I have some carb stuff lying arround

Re: Hi Altitude AQ125a settings?

I've been reading Volvo posts here for a couple years and haven't heard of anyone pulling the heat exchanger and running the boat that way. I must admit I'm skeptical.

However, if it's working for you...

Re: Hi Altitude AQ125a settings?

not much to it. the sea pump puts cold water into the reservoir and the cirulating pump runs it through the engine. sure, some of the water gets recirculated this way... but it is much colder than the antifreeze where all of it gets recirculated. basically turned it into a system like every other boat. best of all, its reversable in about an hour.

so, you put a 350 in yours? how long did that take?

Re: Hi Altitude AQ125a settings?

lutherfetch said:

so, you put a 350 in yours? how long did that take?

Click to expand...

Mine started out with a 305 so there wasn't much to it.

I can have my engine out in 15 min.