HELP! 60's/70's Montgomery Ward/Briggs issue

[ZeroPoint]

I've been having a sorta gremlin issue with my snowblower because everywhere I turn the problem isn't apparent and then the second I try to start it again it comes back.

Backstory:
The snowblower was used in a residential driveway from the 60's when it was purchased up to around 2003. It ran for the final time in 2006 and then sat, I got it running again and everything seemed fine. Last winter came and I tried to fire it up and it kicked at me one time but I managed to hang onto the cord since the engine was cold and barely fired. The pull start stopped retracting and due to lack of parts that's the last time it ran for the season. This year I was on the internet as one is and I found a guy selling a recoil starter in it's original box from the 70's and decided to try it again.

I figured it would be fine I got the starter and it decided to kick back at me every time I would pull the cord. This is the work I've done so far:

-Replaced the head gasket(blown)
-Pulled the flywheel off and inspected the key found it to be okay but replaced it anyway.
-Checked the points they were perfectly in spec at 0.019".
-Checked the valves as per manual, they were perfectly in spec as well.
-I checked the air gap coil to flywheel and found one side at 0.009" and the other side at 0.011" when spec is around 0.020" which I adjusted and set to that spec and verified.

Put it all back together tried to fire it up last Friday and it kicked back so hard it ripped the cord out of my hand and slammed the cord all the way back into the housing. This resembles a timing issue since it's preignition. I've worked with small engine shops they're confused. Anyone with any insight into these motors, anything you have to say is appreciated even if it doesn't bring me closer to solving the problem, I want to hear from you.

Briggs Model: 190402-0653-01

 

[jacob j.]

@WillG

 

[Nutball]

Check the spark plug gap. I had a wood splitter that liked to kick when starting. It may have been the plug since it got to the point where it just wouldnt start or something. I know it used to flood each time I tried starting it unless I slowed it to a low idle before shutting off, and didn't use full choke when starting. Could have been a weak spark from the worn plug. I don't know how a bigger gap would seem to advance the timing, but I vaguely remember it kicking often.

 

[Stump Shot]

I have an old Brigg's and Stratton off an old snowblower from 1975 that acts just in that manor at the beginning of the season. I finally put springs under the handle to help alleviate this.
I don't believe that anything wrong perse is going on it is just one of those things that happen once in a great while. If happening all the time, then maybe a tune up is in order.
When mine was first acquired I went through the carburetor, installed a new electronic ignition coil as well as new filtration, spark plug etc., and it would fire on the first pull and run.
One thing that may help is a good vigorous pull on the starter, so it has a better chance to fire when it still has some momentum left to it and keep rolling forward to start and run.

 

[Nutball]

I wonder if just a little starting fluid would richen it enough to slow the burn rate so it doesn't kick.

 

[ZeroPoint]

Check the spark plug gap. I had a wood splitter that liked to kick when starting. It may have been the plug since it got to the point where it just wouldnt start or something. I know it used to flood each time I tried starting it unless I slowed it to a low idle before shutting off, and didn't use full choke when starting. Could have been a weak spark from the worn plug. I don't know how a bigger gap would seem to advance the timing, but I vaguely remember it kicking often.

I actually have replaced the spark plug to ensure that wasn't the problem. It's still doing it, it kicks every single time.

I have an old Brigg's and Stratton off an old snowblower from 1975 that acts just in that manor at the beginning of the season. I finally put springs under the handle to help alleviate this.
I don't believe that anything wrong perse is going on it is just one of those things that happen once in a great while. If happening all the time, then maybe a tune up is in order.
When mine was first acquired I went through the carburetor, installed a new electronic ignition coil as well as new filtration, spark plug etc., and it would fire on the first pull and run.
One thing that may help is a good vigorous pull on the starter, so it has a better chance to fire when it still has some momentum left to it and keep rolling forward to start and run.

Something is definitely wrong with it, it's been family owned since it was purchased new and it has never kicked in the time my parents had it. Can't speak for when my grandfather had it because my parents got it when he passed. It never kicked when I first got it running and it never kicked when my mother used it before it sat either.. Also it does seem to kick every time I pulled that thing must've been 6-8 times and it kicked every single time. Every time it has kicked I've pulled it pretty hard. It definitely has something going on I just can't seem to figure it out.

I wonder if just a little starting fluid would richen it enough to slow the burn rate so it doesn't kick.

I actually did try this and it didn't seem to have an impact. It hit's almost to the top of compression stroke and rolls backward.

 

[ZeroPoint]

I just pulled it over with the spark plug on top of the cylinder head and put it in slow motion. The spark plug fires when the piston visibly is not at TDC. It's hard to say how far in a measurement it is, but I have 2 photos showing what I'm talking about. The weak spark is on the camera's end it doesn't have weak spark in person.

 

[Stump Shot]

I just pulled it over with the spark plug on top of the cylinder head and put it in slow motion. The spark plug fires when the piston visibly is not at TDC. It's hard to say how far in a measurement it is, but I have 2 photos showing what I'm talking about. The weak spark is on the camera's end it doesn't have weak spark in person.

All engines fire btdc
Sounds like it needs a tune up of sorts. I'd want to check the carburetor out for a possible rebuild and that the spark is hot enough to jump a 5mm air gap as a test of the coil output.

 

[ZeroPoint]

All engines fire btdc
Sounds like it needs a tune up of sorts. I'd want to check the carburetor out for a possible rebuild and that the spark is hot enough to jump a 5mm air gap as a test of the coil output.

I can try rebuilding it, I had put fuel stabilizer in the fuel and then completely drained it in hopes to prevent as much as I could. I may also replace the coil to completely rule that out if I can find the correct one for my model.

 

[Stump Shot]

I can try rebuilding it, I had put fuel stabilizer in the fuel and then completely drained it in hopes to prevent as much as I could. I may also replace the coil to completely rule that out if I can find the correct one for my model.

If I can recall correctly, the coil will supersede to an electronic unit. Just install as normal and remove the wire to, or along with the points and condenser. Carburetor is fairly simple inside as straightforward. Check and make sure the fuel tank is clean.
Should fire right up first or second pull and run like a Swiss made watch when you have it all dialed in. I have much nicer splitters with modern engines on them, but I like listening to the old Brigg's and Stratton chug along best.

 

[blades]

for the life of me i can't think of the proper part name, it controls advance and retard based on the airflow from the fly wheel. critters like to build nests in there which blocks its action ( anything, spiders , wasps, mice ect) . sometimes the linkage just gets crudded up doesn't take much. ah governer is the part name. Seen mice chew off the the plastic vane.

 

[Nutball]

I used to attribute kick back to the perfect mixture almost detonating. I wonder if old gas looses octane and burns faster?

 

[ZeroPoint]

If I can recall correctly, the coil will supersede to an electronic unit. Just install as normal and remove the wire to, or along with the points and condenser. Carburetor is fairly simple inside as straightforward. Check and make sure the fuel tank is clean.
Should fire right up first or second pull and run like a Swiss made watch when you have it all dialed in. I have much nicer splitters with modern engines on them, but I like listening to the old Brigg's and Stratton chug along best.

It's crazy because I have a fairly modern Honda motor that would fit on this snowblower but part of me just loves this old Briggs. It's loud and not necessarily efficient, but it definitely is my favorite motor. Currently rebuilding the original carburetor, I had a replacement carb on it and I'm almost wondering if this isn't a great quality carb. It ran fine on it last year but not sure I'll try to get the original back on it.

for the life of me i can't think of the proper part name, it controls advance and retard based on the airflow from the fly wheel. critters like to build nests in there which blocks its action ( anything, spiders , wasps, mice ect) . sometimes the linkage just gets crudded up doesn't take much. ah governer is the part name. Seen mice chew off the the plastic vane.

I'll have a look at it!

I used to attribute kick back to the perfect mixture almost detonating. I wonder if old gas looses octane and burns faster?

It's got fresh gas in it though.. I dumped it and refilled with new.

 

[wizard346]

The condenser is nothing more than a capacitor, and when those fail, they can open or short which would affect your timing.
Opening the gap would retard the spark ever so slightly since the coil has to build to a higher voltage to jump the opening.
Have the could tested properly, at the proper settings. Some shops leave the machine on 1.21 gigawatts and that will mask any problem inside.

 

[ZeroPoint]

The condenser is nothing more than a capacitor, and when those fail, they can open or short which would affect your timing.
Opening the gap would retard the spark ever so slightly since the coil has to build to a higher voltage to jump the opening.
Have the could tested properly, at the proper settings. Some shops leave the machine on 1.21 gigawatts and that will mask any problem inside.

How would one go about testing it? There aren't really any shops for that around here, just dealers that won't do any more than change your spark plug.

for the life of me i can't think of the proper part name, it controls advance and retard based on the airflow from the fly wheel. critters like to build nests in there which blocks its action ( anything, spiders , wasps, mice ect) . sometimes the linkage just gets crudded up doesn't take much. ah governer is the part name. Seen mice chew off the the plastic vane.

Found a dumb problem although I think it's A problem not THE problem. When I removed the head I removed the carb to get access to the valve cover/breather. I never connected the throttle linkage back to the carb when reassembled. That would explain the massive kickback I'm getting now compared to the less strong kick I was getting before. I'm going to give it a shot tomorrow since I just figured it out and it is now almost midnight here. I'm sure my neighbors would appreciate a briggs with a blown out muffler roaring in the middle of the night.

 

[ZeroPoint]

Still working with this, I managed to get it to run for a little bit the other day. Since the carb was rebuilt I had cleaned the mixture adjustments, engine ran VERY rich but did start first pull with no kickback. I didn't have time right then to mess with it since it was getting dark and was hard for me to even see the screws. Can rich mixture make an engine backfire like this? What is a safe initial setting for the mixture screws that's something close to the mixture it should run at?

 

[legdelimber]

I'll throw in few things that I can still recall.

Most of that era of Briggs in that size (19cu in and down), you could start at 1.5 turns out on both screws and should be crankable if no other issues.

I'm guessing that you've already noticed the main jet and its related brass tube bits, have to out in order to remove the carburetor bowel.

Weak ignition might like a hair richer setting.
Will the spark jump a .200" gap at normal pulling/cranking speed?not jumping a gap of that size? then somethings not up to snuff and we'll have problems.
That era of Briggs (with points ignition), you should be able to hand spin the flywheel and get a decent blue spark if all is good.
I used to hand spin the fan on a yard fan, to start a 1975~ish briggs 5hp that drove it.
The electronic version that followed, has a lowspeed cut out (about 200 rpm) and takes a sorta stiff pull to make sparks.

check for oil coming around the plunger that pushes the points open.
We used to roll the plungers for worn ones (worn block hole) in a puddle of crazy glue and let them dry. Wear a disposable glove of course!!
Then when the glue is absolutely dry, you check it for fit in the hole.
Yep Oily points can cause issues too.

A failing condenser/capacitor will cause erratic spark. look for crusty or arc burnt points
That is a sign of failing condensor and/or oil vapor getting on them.
Rust is a trouble maker too.

Check for loose wires chafing or age cracked that can cause an intermittent spark.
Any cuts in the coil wire where it passes around any sheet metal? air shroud etc.
Same questions for all other wire conditions.

Check the grounding clip that should be somewhere in the throttle control. Cracked or loose or oily may give issues.
Internal governor on those engines. But your linkage being loose could be a problem.
The loose throttle linkage could be bumping the wiring and causing intermittent spark issues and the backfire.

Oh and pull the recoil flyball clutch and clean inside the center hole where the crankshaft stub fits inside of it.
Crankshaft stub needs cleaning too.
Don't put any grease or lube in with balls though.
Makes them tend to stick in outer area of that grooved cup and then The recoil cant engage (and it gets worse in the cold weather)
put a few drops of oil on the crank stub before screwing the ratchet back on.
Check for that felt puck up inside of that ratchet center, it needs to be there to hold a bit of oil for things to stay happy..
When the ratchet center gets dry, they grab and spin with the crankshaft. this usually ends with the recoil being being spun backwards and tearing it apart, harshly!
Busted rope pulley and the spring rolled backwards into a mess.
IF it's squawking or squealing any at all, you're getting pretty close to it grenadeing!
Keep them cleaned & lightly lubed (every year) and these starters are pretty danged good for many years.

Blown out muffler? Check your exhaust valve for leakage. check both valves while you're at it. leaking exhaust will burn off mufflers. does it look like it's had a torch in it?
Or muffler gets orange when running?
Check clearances of both valves. too tight promotes leakage and erosion/burning.

I would want to see and hear a nice blue spark at an easy cranking speed, that jumps that .200 inch test plug gap.

Forgive me being a bit rambly, but trying peck what comes back to me.

 

[legdelimber]

A bit more about the coil.
Does it have any signs of damage?
Flaking insulation or varnish or burn marks.
Are the lamainations (iron) in pretty clean shape, no swelling from rust?
How about where it bolts to the block, any corrosion or other nastiness?

Any signs of rubbing fly wheel or belts or any controls or cables, linkages touching wires and causing leakage to frame.

 

[ZeroPoint]

A bit more about the coil.
Does it have any signs of damage?
Flaking insulation or varnish or burn marks.
Are the lamainations (iron) in pretty clean shape, no swelling from rust?
How about where it bolts to the block, any corrosion or other nastiness?

Any signs of rubbing fly wheel or belts or any controls or cables, linkages touching wires and causing leakage to frame.

Just got back to this, I haven't really been able to get around to starting it I've been pretty busy as of late. I don't recall seeing anything abnormal with the points or coil. Are these motors known to kick with lean mixture alone? It had a pretty cheap chinese carb on it before and ran first start up although very rich with the original carb. Not sure really what to make of it but if it works it works. Main jet was about 3 and a half out and idle jet was about a turn and a half. You can imagine how rough it ran on that.

 

[legdelimber]

Been a while since I've had hands on the older Briggs stuff, so my recall is going a bit dim.

Typically a lean mixture tends to not fire.
A weak ignition will tend to want a slightly richer adjustment but not too much (maybe extra 1/4 turn out) The kick back makes me think of an issue with ignition timing or worse, a camshaft that's out of time.
Have you checked the spark for jumping that .200" gap and being healthy blue?
If it's not, then we need to check everything that could be touching any wires and causing an intermittent grounding or disconnection (loose wires). Either one can cause an out of time spark.
A weak spark needs to found out why so and then fixed.
Weak spark can be from a failing coil or other issues.
Again track every thing from end to end and look for anything rubbing or oil covered that could cause an errant path for electricity.

Of course we need to look under the recoil clutch and washer to see if the flywheel key is dead straight.
Even a small bit of twist or shearing of the key can give trouble.

Sometimes the internal governor gear breaks and throws a weight off.
Did the valves open and close with the piston passing top dead center?
Tecumsehs were bad to do this and the loose weight would often find it's way into the camshaft gear and knock off teeth.
Briggs tended to have much less of the governor gear breaking, but it does sometims happen and we've got a pretty old engine here.
When that happened you got an engine that would kick and no adjusting of the carb will solve it of course.

But I'd focus on making certain that the ignition is making that strong spark over the big gap before chasing anything else.

Forgive me if I'm in and out of here. I'm doing a bit of battle with this laptop and software, so sometimes I'm offline for a couple of days messing with it.