homemade rat racer

That's a very interesting build! What is that lever? What engine is that, Looks like Briggs shroud, but I never saw a Briggs with the carb opposite of the exhaust like that.

More pix!

Can't a mower engine on its side run into trouble as the internal oil distribution stuff eventually cause some seals to fail and what not? Again I might be wrong, but it is something I remember seeing some where once.

Lookin good! There's a very old thread here in DIY I think, where a vert. shaft was converted very similar to that. I think he used a piston rod with a dipper, like the horiz. engines use.

Not too sure what kind of dipper the vert engines use, if any.

In the first pic, I not too clearly saw the red filter on the black hose and thought that was a lever LOL

That things gonna run great with a torque converter. I like that old style vert. pull starter. Saves a couple inches on engine width too.

Keep up the good work!

You might need to change to a cast iron flywheel.

I built a vert shaft fricton drive once, and it would kick back and yank the rope outta my hand when I tried to start it.

The mower engine relies on the blade for flywheel effect. The alumunium wheel is there for magneto and cooling and starter mount. It's built light on purpose, to help reduce chance of damage when the blade strikes something solid.

When I put a cast iron flywheel from an edger on mine, it started easily and ran smooth.

Check to see if the flywheel or pulley is loose.

You could also use a brake lever and cable to control your idler like I did here.
the belt squeals some when first engaging, but it works great.
you can see better pix in this forum under the "In frame Predator fricton drive" thread

Very impressive, Harly. How did you learn so much in so few years? As I recall you said you were 16 years old? What, was your first toy a crescent wrench? Is your dad a mechanic? Just curious where this wonderful aptitude you have came from.
SB

Could be the timing of the points and the cams should be left where they are marked. Also aside from the points having to do with the timing, the flywheel and the keyway part of it should not be damaged. I really didn’t think the magnet on the flywheel and the magneto had such tight tolerance to cause a problem, but I’ve heard that a engine may not start due to a shearing and trying to still use the same keyway if really mashed.

The reason for the valves the way they are has something I heard the name called porting is what is happening.

It allows better flow. Gets better horsepower.

They way I first became aware of this I was pulling the starter cord after having the valves and seats cut for better seal. I felt the exhaust suck for a short bit and visa versa. When engine is running this is not causing a problem, but helping.

Maybe someone out there can explain better or know of a good web site explanation. Maybe try howsuffworks.com or another site specific to engines.

I just read again and you said half way down (on power stroke) this happens before the piston is going up for the exhaust stroke. I didn't think porting would happen that early.

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Anyway As I remember it is a way to clear out the burned gases quicker to allow more new fuel air mixture with less of any left over burned gasses mixed in with it.

The last point above is wrong, but nearly right.... the exhaust gas mass moving out pulls fuel in on last bit of exhaust stroke even though the piston is not going down causing suction. The momentum of the exhaust open at thhe same time the intake is open before intake stroke help get more fuel in better flow. Careful I suppose to not get too much or the exhaust pipe gets unburned fuel and there I suspect is a back fire.

Did anyone mess with the cams maybe to try something and you don't know if this is a stock briggs.

here is the site where I read and also on howstuff work is I not yet read but it is there and lots of places to read more

http://www.btc-bci.com/~billben/camlore.htm

"c) Valve Overlap: This is the number of degrees where the exhaust valve is still open - on it's closing ramp . . . and the intake valve is starting to open on it's opening ramp. In early gasoline combustion engines, no overlap was used . . . therefore they had really short valve durations. At some point in the 20's or 30's (I believe), somebody figured out that increasing the duration and overlap really helped performance. Having the exhaust valve still open when the intake starts to open uses the exhaust "pull" out the exhaust port to help start the intake charge entering the chamber -- before the piston has started down and has generated it's own vacuum. Also, leaving the valves open longer (duration) increased the density of the intake charge and allowed the headers to better scavenge the exhaust gasses out. Overlap/duration amounts steadily increased from the 30's where little/none was used all the way to today, where the guys running flatheads at Bonneville are using lots of it. (Just look at a cam timing tag -- see the degrees the intake starts to open BTDC and the exhaust is still open ATDC).

"

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Some other part of this I think has to do with carb having a mass of fuel moving through it and it has already momentum to get in the air fuel mixture in the cylinder even if the piston is not on it's way down yet. Then when the piston is going down it gets drawn in as we all know as well.

Hope someone else can help. Something about size of some measurement of the flywheel?

Measure Twice

Post #4 on the 1st page I see the last picture and notice how the crank for the pedals hole goinh through the frame is now used for the jackshaft.

That is using the old noodle! Neat

Hopefully the flywheel on two different size engine hp will work if you are trying to use what is accessable or free left over. Sometimes this can be the case, but I don't know about this situation.

The way I know some of these strange things, like how the same displacement engine on a Honda Outboard can be an 8 or a 9.9 is the lobe is bigger on the 9.9's intake cam to get more time to load up on fuel air mixture. So I've heard where hp is limited at places to 8, the change is made but no change of label on the engine cover, sneaky. Unless the engine is being totally overhauled, making this change would be sort of more work than the relative gain you would get for the time involved break down and reassembling.

MEASURE TWICE

I know what you mean about not being able to use and allen wrench and just change the gap with all the work of taking the flywheel cover, flywheel, point cover....

Using feeler gauge getting it to slip through the gap at the open time and try it, then again with just slightly larger or smaller and keeping a record of what happens, over an over till it runs right sounds like nuts!

For a lot of the Briggs I have had it was supposed to be pretty much all 0.020"

You can also clean with emory cloth with the points in closed position, slide the sand paper cloth inbetween the points expanding the spring out and getting the surfaces flat. Any pitting can make the setting hard to get right. At some time the waring should be such that you just replace the points. Ones like these old engines with out magnetic pickups and done electronicly, wear the points at some rate, new ones don't even have points, nothing to wear. Magnet not touching the pickup, just passes near by.

Measure Twice

Would like to know what the engine model and other info is so I can look to see what this different than I have seen before is like from some documents possible available online some how.

I was thinking it is a two stroke, but if there are valves and not reed valves and ports, then I guess the thing is four stroke. If cover is stating 3 or so hp, the size makes sense, two stroke would have about twice hp for the same displacement.

How then cams have the intake and exhaust valves, would hope you have pics to post of the crankcase to see. There would seem to have to have two cams or it is traversing across all the way from one side of the cylinder to the other for the fact that the intake and exhaust are on opposite sides. I am I wrong here, am I missing something?

Measure Twice