Possible Engine for Repower - Snowblower Forum : Snow Blower Forums
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post #1 of 19 Old 01-13-2016, 03:32 PM Thread Starter
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Possible Engine for Repower

So about 2 months ago I brought back to life a 30 year old single stage Bolens 320 with a lot of help from guys on this forum. I really enjoyed the work, and I want to do something much more ambitious.

Not so long story short, I just unexpectedly got a brand new engine. I would love for it to be attached to a snowblower that I could turn around and sell on CL for a small profit. That's if it CAN be attached to a snowblower.

Here is the engine. Model No.: AP170F,A-iPower

The problem is I really don't know anything about repowering anything, but I'm fairly well mechanically inclined and definitely willing to put the time in to learn. I know I need to look at the shaft, however, what are the specific measurements I need to look for in a snowblower to make sure that this engine is compatible?

Last edited by Smolenski7; 01-13-2016 at 03:41 PM.
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post #2 of 19 Old 01-13-2016, 03:50 PM
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Looks like a standard clone engine. Would be the same steps as the Predator engine a lot of people are using now.

Please direct all snow blower questions to the forums and not to me with PMs.
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post #3 of 19 Old 01-13-2016, 05:56 PM
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basically you will want to rejet the carb to make it richer and stronger for cold temps. Might be easier to repower with a predator since there is so much info for using that particular engine. Stock jet is .028 I think, and preferred jet is .030. But I haven't found an aftermarket .030 jet. They sell all the other sizes for only like $2 but people are hand drilling out the stock jet with a mini drill bit (you must find the exact size bit to use because slightest variations will make it too rich), or they are opening up the jet hoel with something called superfloss or something like that. Some have used the .032 aftermarket jet and said it runs superbly with the air filter off.


Then you want to build a heater box/shroud over almost the whole engine and also possibly containing some of the muffler heat (but not the exhaust) to be drawn over to the air filter if you plan on keeping the air filter in because the reason most SBers don't have air filters is because it will ice up and seize the engine if not caught early. Also no air filter is common because usually no dust while snowblowing but that's only like when it first snows, you go out the next day or when the snow is dirty and black and there is dust, and there is dust in summer when you work on the machine and when stored without an air filter you might even find spiders in there. I would at least tape over the intake when storing. I would try and make it work WITH the filter but most modders I think are not using an air filter. The heaterbox/shroud is basically sheetmetal you bend and cut and bolt on (but easily removable) so that you cover the governor and carb linkage springs etc so they don't get iced up. On all my machines, I grease the shjt outa those mini springs, they are so thin and easy to rust out. I grease over all small metal parts like this that won't be compromised from the lubrication (like the metal drive disk wheel that goes by friction of the other rubber wheel if yours has that, you don't want to grease that of course.



first thing you want to do is make sure the engine will actually fit the frame without getting in the way of things. The crank handle to move the chute, sometimes people furr that out a bit with metal clip so it's not in the way, that can get complicated with the ball joint or whatever it's called near the worm gear if you have to fur it out a couple inches might need to search out new parts. since you machine is older like that, you might have a separate shaft coming from the engine for the drive and auger instead of one shaft for two pulleys. That can get a bit tricky also.
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post #4 of 19 Old 01-13-2016, 07:47 PM Thread Starter
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Snow2345......Thanks.

I noticed immediately that this engine has an air filter. That's why in my initial post I wrote "if it CAN" be used for a repower. I was hoping that it could fairly easily, however, from your post it sounds like this engine is not "the right tool for the job."
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post #5 of 19 Old 01-13-2016, 11:39 PM
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Quote:
Originally Posted by Smolenski7 View Post
Snow2345......Thanks.

I noticed immediately that this engine has an air filter. That's why in my initial post I wrote "if it CAN" be used for a repower. I was hoping that it could fairly easily, however, from your post it sounds like this engine is not "the right tool for the job."
You *DO* realize you probably have what is known as a "Honda Clone" ....right? (albeit 208cc not 212cc)
EDIT: Compare Predator 212 and Powerhorse 208
If you look at my avatar you'll see yet-another-Chonda-clone....it's my fictitious "Power Tiger" brand that resulted from too much caffeine one day.

I wouldn't say "it's not the right tool for the job".... many people have re-powered their snowblowers with cheap Honda clone engines and they seem to be happy. (like Shryp already mentioned).
I have a couple of these engines myself... one is already on a snowblower and the other will be once I get my act together.

Just search through the re-powering thread for any posting that mentions any of these words...

Honda Clone Chonda ...and especially..... Predator or Powerhorse

Re-Powering - Snowblower Forum : Snow Blower Forums

snow2345ffs gave a good summary of the popular modifications and issues that people address.... but don't let that dissuade you..... these are (arguably) optional cold-weather enhancements for people going the extra mile.

The only real gotcha that I know of is the one that affects my Craftsman TRAC snowblower.... (again hinted at by snow2345ffs)... it originally had an engine with 2 shafts. When it was repowered with a single shaft engine the gears ended up working backwards (forwards is reverse and reverse is forwards).... but that's not a fault of the Honda clone per se... that's just caused by switching from a double-shaft to single-shaft engine. Not sure if this is a showstopper or an embarrassment.

EDIT: Then there are the "inconveniences" that spring to mind.... not show stoppers...
1) converting shaft diameter if necessary 3/4" to 1" (or switching out pulleys)
2) getting the chute crank to miss the engine (again mentioned by snow2345ffs)
3) Re-drilling mounting location (if necessary)

There is information on all the above tucked away on the re-power thread.

Maybe there needs to be a once-and-for-all well-written sticky that brings all this information together into a single posting for clones.
It's the kind of thing I'd like to contribute if I had a little more hands-on experience. Maybe one day.

BTW - This thread probably needs to be moved to "re-powering" and I'm guessing one of the moderators will do that.

Last edited by unknown1; 01-14-2016 at 12:43 AM.
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post #6 of 19 Old 01-14-2016, 12:40 AM
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Quote:
Originally Posted by stuart80112 View Post
I wouldn't say "it's not the right tool for the job".... many people have re-powered their snowblowers with cheap Honda clone engines and they seem to be happy.

They seems to be more than happy. All types of go kart and mini bike etc small engine aficionados rave about the predator, and for $99, if you live near a harbor freight, you can't go wrong.
Edit: they are also new on ebay for like $125 shipped.

snow2345ffs gave a good summary of the popular modifications and issues that people address.... but don't let that dissuade you..... these are optional enhancements for people going the extra mile.


EDIT: Then there are the "inconveniences" that spring to mind.... not show stoppers...
1) converting shaft diameter if necessary 3/4" to 1"
...

Very easy to do and only like $10, and a lot of ebay sellers etc have titled them with 'predator' so they're easier to find, but links can be found in threads too.
Edit: might not be very easy. The cover over the pulleys might be too small if you want to extend a single shaft motor to use two pulleys on it. Also, you'll likely have to buy at least one new belt if converting to a single shaft engine, and you might not know which exact size to get, might have to trial and error a few until you find a snug fitting belt.

Maybe there needs to be a once-and-for-all well-written sticky that brings all this information together into a single posting for clones.
I was going to make a thread asking for others to make something like 'simplified predator repower guide' to basically point out the heat box mod, and the rejetting etc and all the steps with minimal discussion (extra pages) to the thread.
As you mentioned, they supposedly do function all right when just thrown on without any modification but won't be optimal but the modding is pretty easy. Like you said, the only time it might be a big PITA is if you have an older machine made for an engine with dedicated pulleys (more than one crankshaft).

Strangely the .030 jet is hard to come by. I didn't search too long but I don't know if it exists sold alone. I think I saw it as part of a kit with other jets but it was like $75 and you only need the one jet anyway. Someone should manufacture a .030 jet or just buy a bunch of .028s for $2 and drill them out correctly to .030 to avoid the sort of gamble of hand drilling them out with a mini bit that most people don't have.

Last edited by snow2345ffs; 01-16-2016 at 09:19 AM.
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post #7 of 19 Old 01-14-2016, 01:00 AM
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Quote:
Originally Posted by snow2345ffs View Post
..lots of good stuff.. read it...
One thing that seems pretty much undocumented is the longevity of these clone engines. We often hear of 20 or 30 year old Tecumseh engines chugging along (somewhat) nicely.
I wonder who has the oldest Predator re-power and just how old that is?
At $99 a pop, maybe people aren't too worried about longevity.. but I would be interested to know.
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post #8 of 19 Old 01-14-2016, 01:24 AM
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[QUOTE=snow2345ffs;860457]
Strangely the .030 jet is hard to come by. I didn't search too long but I don't know if it exists sold alone.[
/QUOTE]

I mentioned on my $50 Predator posting that there are two high-altitude kits discussed in some Predator manuals (but not others)
They are for altitude ranges above 3000 feet and again above 6000.
I haven't nailed down what those jet sizes are yet.

I'll edit this post when (or if) I find out.

Page 7 of this manual:
http://manuals.harborfreight.com/man...9999/69730.pdf

EDIT 1:
Well I haven't found those jet diameters (yet) but I believe they should be smaller than standard.
At higher altitudes, pressure and therefore oxygen is depleted....in carburetors I hear this causes fuel mix to become rich... maybe too rich.
So this seems to suggest that attempts to "tune" the engine by boring larger jet diameters may not actually be the best thing to do.
I haven't researched this sufficiently to get to an exact algorithm for pressure altitude versus bore diameter, but re-boring .028 to .030 might not be the answer at all altitudes.
If anyone has that data I'd love to have it.
That's one reason I have not messed with my jets. I live in Denver (Mile High City). Elevations 5,130 to 5,690 feet.
I'd need the data to convince me what is optimum. It's a pity that things are fixed and nonadjustable. I could trash a lot of jets finding out.

EDIT 2:
I found a rule of thumb that confirms how to reduce bore size with altitude. I hope it applies here.

Main jet metering is of great importance when operating at considerably varying altitudes for which the
following rule-of-thumb may be applied: change main jet calibration by 6% for each 1,000m (3280')
altitude variation. For example,( if ) normal main jet calibration at an altitude of 400m (1312') is 0115;
proper jet size for an altitude of 1400m (4592') is 0110

If I check his arithmetic I get a different number... but that's splitting hairs.

So if I live at 5500 feet (which I do) my stock jet will feel as if it's about 10% wider than if I was at sea level.
Interestingly that means my .028 jet is operating as-if it were 0.0308 at sea-level
So if I'm understanding this, that means that leaving my jets alone is the same as someone at sea-level re-boring theirs to .030
What a coincidence! So simply "throwing on the engine" may actually be quite effective (in Denver).
If you live in the mountains... your stock jets will be even richer than that.
Do the math...for all I know you may actually do better with a California EPA spec engine.
Probably best to check data before drilling based on purely anecdotal evidence.

Reference:
http://www.356carburetorrescue.com/altitude.html
(Sorry if this is hijacking the initial thread... it's turning into a Clone-tuning thread)

Last edited by unknown1; 01-14-2016 at 04:37 AM.
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post #9 of 19 Old 01-14-2016, 12:33 PM
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Originally Posted by stuart80112 View Post
.....two high-altitude kits discussed in some Predator manuals (but not others)
They are for altitude ranges above 3000 feet and again above 6000.
I haven't nailed down what those jet sizes are yet.

I'll edit this post when (or if) I find out.
Ok I called the HF techincal support line minutes ago and here's what I was told.

Standard Jet = 0.75mm (which is 0.295 inches) in both CA and non-CA engines)
Hi Altitude 3000-6000ft Jet = 0.77mm (0.030 inches)
Hi Altitude 6000-8000ft Jet = 0.80mm (0.031 inches)

So now I'm really confused!

The reference I found last night talks about decreasing bore size with altitude. The Predator tech support talks about increasing bore size with altitude.

Does anyone know enough about carburetor theory to straighten this out for me please? Preferably with links to references.

As a side note... this looks like one way of buying your 0.030 jet without drilling!

Also... lot's of posts talk about the "standard" jet being 0.028.... where are people getting THAT number from? At least one tech at Harbor Freight says 0.295

EDIT: I just called a second time to check my facts and got a different support person.
This time he said he did not know what the "standard" jet sizes are but he confirmed the high-altitude sizes 0.77mm and 0.80mm
That's part number 15486 $5 + shipping for both jets in the high-altitude kit. For some reason their website does not seem to have it listed. Phone orders only I suppose.

Last edited by unknown1; 01-14-2016 at 09:24 PM.
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post #10 of 19 Old 01-14-2016, 12:48 PM
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Well I can tell you one thing: on an automotive engine-management-system forum I frequent, there's a lengthy ongoing debate about fueling compensation vs. altitude. Some say you need more, some say less, some say it depends on the engine.

There are a lot of factors at play more complicated than you might think: mass flow vs. volume flow through the carburetor, the fact the venturi suction has to lift the fuel from the float bowl might mean that even though less fuel is needed due to the lower air density, a larger jet is needed to compensate for the air's lesser ability to draw fuel. And just to confuse things further, altitude affects scavenging... there will be less combustion products in the cylinder at the end of the exhaust stroke because the lower ambient pressure draws them out more.

The bottom line is I have no idea, but would go with what the manufacturer recommends since presumably they've done testing...

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