Poor decisions.

Not bad, almost guaranteed to help, theres almost no way to make these flow worse than factory without doing something really crazy. It’s hard to offer advice on whether to cut more or not, it’s the kind of thing you gotta see in person. Looking forward to seeing it run!

RichieRichOverdrive wrote:

Not bad, almost guaranteed to help, theres almost no way to make these flow worse than factory without doing something really crazy. It’s hard to offer advice on whether to cut more or not, it’s the kind of thing you gotta see in person. Looking forward to seeing it run!

Well, it looks like it may be a while. I spent over 2 hours attempting to lap the intake valve, and it still does not seal perfectly. Apparently all I succeeded in doing is ruining the valve. I ordered new valves, but now my dilemma is the seats. The seats seem unbelievably hard. When I lapped the valves in the oppy, it took literally 30 seconds. These things are insane. As stated, I spent over 2 hours on 1 valve. Seat still looks ok, but I'm worried that it is no longer the correct angle or shape. The seats are not replaceable, and I'm afraid they will have to be cut. I can get a cutter, but don't want to spend $40 on something I will use once. I'm also not confidant that I understand the sizing of the tools anyway. I do know that it needs to be a 45 degree.

Ok, scratch that. I just ordered a NOS block, with valves. It was a brand new motor that was parted out before ever being run. Bore looks absolutely perfect. Valves shouldn't even have to be touched.

This will also solve my bore problem with the current motor. Bore had rust and some pitting, and I honed it best I could, but wasn't happy with it. But, this also means I will have to port another block!

Update: block order was caneled because the usps somehow managed to destroy it. Guess I'll have to try fixing this one.

Wow, we have the same mailman!

Usually our mailman puts the mail in the mailbox real gently and then runs the whole mailbox over

Engine is most of the way back together now, but I have encountered one of the strangest engine problems I've seen. Engine has oil up to the fill line. If I try to turn it over by the flywheel nut, it will not move without a hammer or breaker bar. Once it gets moving, it is perfectly smooth, and easy to turn. If I stop and let it sit for more than a couple of seconds, it does the same thing again. Obviously a rod issue. However, when I got this engine, it turned over perfectly fine, in fact too easily. I will not be happy if I have to tear this thing down again, and waste more gaskets. I can't figure this out to save my life.

> Obviously a rod issue.

Or a piston ring is hanging up? If someone lined up all the gaps together, it tends not to go well.

How much end play is there on the crankshaft? Have you tried pushing up on the pulley from below and then tried turning the engine flywheel by hand?

JB_4x4 wrote:

> Obviously a rod issue.

Or a piston ring is hanging up?  If someone lined up all the gaps together, it tends not to  go well.

How much end play is there on the crankshaft?  Have you tried pushing up on the pulley from below and then tried turning the engine flywheel by hand?

Piston rings are installed correctly. Crank play is noticeable end to end, but none else.

Did you actually check the ring gap in the bore before you installed them with the piston? Did you install the rings and piston with a coating of oil?

RichieRichOverdrive wrote:

Did you actually check the ring gap in the bore before you installed them with the piston? Did you install the rings and piston with a coating of oil?

No and yes. But I know the rings aren't the problem. Before tightening the rods bolts, I could turn it over by hand easily. With the new rings. I used a ton of oil and assembly lube.

> Tecumseh HM100

My area of knowledge is Ford trucks and class 7/8 trucks, I only recently got into chainsaws and then OPE 4 cycle.

So, I do not know what this engine is, BUT, does it have some sort of compression relief where an arm/cam could be swinging free because a retaining spring is broken?  Once you force it and keep moving it goes along, but, once you stop, it slides back down angled against the CW rotation?  

When the engine gets stuck, have you tried turning it CCW?

On a B&S "L head" I pulled because of problems, you can not really see or do much to the valves without taking the engine part. When it is jammed, can you see if a valve is hanging up or crooked?

I know on the older engines with the split valve stem retainers, if you do not install them with the correct tool, they can either pop off or pop up on one side.  I mention this because going by this schematic:

https://www.partstree.com/models/hm100-159493u-tecumseh-engine/engine-parts-list-hm1003-0/

if #151 Valve Spring Keeper fell off, I could see that jamming up, once you stopped and the valve spring fell back down.

Or the valve is being raised by #48 Valve Lifter, with the retainer gone, but, once you stop and take tension off, because one or more of them are domed on the end, they slide pass each other and jam up again.

I bought a Klein bore scope, that works with "smart" phones, and it has a few software problems. The worse being it only works with one of my "rugged" phones. But, it has been handy for looking into engines to find problems without taking an engine or sewer system apart to find the problem.

If you drained the oil, you might be able to see if anything is sitting at the bottom of the engine.

JB_4x4 wrote:

> Tecumseh HM100

My area of knowledge is Ford trucks and class 7/8 trucks, I only recently got into chainsaws and then OPE 4 cycle.

So, I do not know what this engine is, BUT, does it have some sort of compression relief where an arm/cam could be swinging free because a retaining spring is broken?  Once you force it and keep moving it goes along, but, once you stop, it slides back down angled against the CW rotation?  

When the engine gets stuck, have you tried turning it CCW?

On a B&S "L head" I pulled because of problems, you can not really see or do much to the valves without taking the engine part. When it is jammed, can you see if a valve is hanging up or crooked?

I know on the older engines with the split valve stem retainers, if you do not install them with the correct tool, they can either pop off or pop up on one side.  I mention this because going by this schematic:

https://www.partstree.com/models/hm100-159493u-tecumseh-engine/engine-parts-list-hm1003-0/

if #151 Valve Spring Keeper fell off, I could see that jamming up, once you stopped and the valve spring fell back down.

Or the valve is being raised by #48 Valve Lifter, with the retainer gone, but, once you stop and take tension off, because one or more of them are domed on the end, they slide pass each other and jam up again.

I bought a Klein bore scope, that works with "smart" phones, and it has a few software problems. The worse being it only works with one of my "rugged" phones. But, it has been handy for looking into engines to find problems without taking an engine or sewer system apart to find the problem.

If you drained the oil, you might be able to see if anything is sitting at the bottom of the engine.

I have had the engine completely apart. The valves are fine. The compression release idea is interesting, but I had it out today, and it seemed to be working fine. I will try turning it backwards. Still pretty much stumped on this one. Valve clearance is set within spec also. Piston moves freely in cylinder. I am wondering if it could possibly be the crankshaft journals. I put fresh oil in it today, and tried tipping it on each side, to get oil to the journals. Made no effect.

Did you install the rod the correct way? Did you check it on the crank before putting it in the engine? Just spitballing at this point lol

RichieRichOverdrive wrote:

Did you install the rod the correct way? Did you check it on the crank before putting it in the engine? Just spitballing at this point lol

It is on correctly. Bolts facing toward cam side. I did not check it on the crank outside the engine, however. I really don't want to have to take this thing apart again.

Mystery solved fellas. Rod cap was on backards.

Glad you caught that early so no damage could be done.

Welp, that’ll do it so when’s the test run?

Thank you for the update, I was curious of what it could be, where a part had not fallen off.

RichieRichOverdrive wrote:

Welp, that’ll do it so when’s the test run?

About 15 minutes ago. Fires right up but backfires quite a bit. Will need some tinkering. But, I'm just glad to have it off the bench. Will get pics later. Also, is there any way to directly upload a video, without it being from youtube?

MightyRaze wrote:

Glad you caught that early so no damage could be done.

No chance of that. It was so tight I couldn't have started it.

Ifitaintbroke wrote:

Will get pics later. Also, is there any way to directly upload a video, without it being from youtube?

I think you’re stuck with YouTube. You can always upload it as an unlisted video so we can only see it where you link it. The forum is like half the reason I have a YouTube channel lol, those suckers host my videos for free

Looks like I'm going to need this thing sooner than I thought. It runs, but not great and backfires horribly. I think it's running too rich, as it's popping out the exhaust. I have an adjustable, and a non-adjustable carb, both are brand new. Was running it with the non-adjustable when it was backfiring. Can't get it to even try to start with the adjustable carb, but I don't really know how to work it. I'm going to try looking at the original Tecumseh service literature tomorrow, to see if it will give me any pointers. If anyone here knows how to set on of these things up, any advice you have would be appreciated. I don't know what kind it is, but it has 2 screws. One on the fuel bowl, and one on the side of the carb. I'll get some pics tomorrow.

Typical starting adjustment on most carbs is 1.25 - 1.5 turns out from all the way in. (don't force it tight)

MightyRaze wrote:

Typical starting adjustment on most carbs is 1.25 - 1.5 turns out from all the way in. (don't force it tight)

That's what I thought, but it wouldn't even attempt to start with that.