[lfnel]

This post is the same as an e-mail I sent to Roger, but I got to thinking that if I posted it, maybe others would have helpful ideas to suggest too.

Roger, Before I get to the topic at hand, nice job putting that Briggs in a 70!

So, surprisingly I got all the needed parts for my 70 project from Jacks Small Engines. Just a couple of parts I deem to be non-critical are on back order. I have it all back together but can't get it to run. It will pop a time or two until the starter kicks out, then quits! I can't even nurse it along keeping it running with a spray can of ether. I have the throttle plate above the carb positioned correctly according to the three alignment holes. The choke and throttle lever seem to function as they should. I put on new carb-to-governor linkages, including spring. The carb seemed to be OK but I went through it anyway. I soaked it out, run a tag wire through all accessible passages without taking the plugs out, blew out everything with carb cleaner and compressed air, then gave it a new needle valve and seat before setting float lever to spec. As I put the engine back together after rebuilding the governor with all new parts, I was careful to see that the camshaft is timed correctly. I didn't mess with the compression release which is on the exhaust valve. It has a good hot spark. I changed the plug. I didn't accidentally interchange the cam followers. I had the head off and the the valves look good - cylinder wall too. With no manifold nor air cleaner ahead of the carburetor, it spits back out through the carburetor some as it tries to start, but it did that before I started working on it. Except for over-speeding and the resulting governor problem it started and run pretty good before I tore in to it.

I'm pretty befuddled. Could it somehow be an ignition timing problem? Of course I had the engine upside down, but didn't take the flywheel off. That's about the only gremlin I haven't chased. Any ideas or thoughts from your experience would be appreciated.

Thanks, Leon

 

[woodpecker41]

This is my response via e-mail to Leon. Roger

Sounds exactly like my VH70 engine. I have have replaced everything you have and a few more. I can get it to start and run on my engine stand from time to time but not always. The only thing I haven't replaced is the rings and I have them here but it will probably be a Winter project. When you say you cleaned the carburetor was it by soaking in carburetor cleaner over night or with spray. Those carburetors have a small check ball in them internally that if you shake the carburetor with the float off you should hear rattle. If you can't hear the rattle you throw them away and replace with a new or different carburetor. The check ball is something that can't be taken apart to fix. The new ultra sonic cleaners may work or letting it soak longer. NEVER USE EITHER to run a small engine. If you had bad rings that will make them worse in a hurry. I don't have any answers and feel your frustrations. Roger

On Aug 28, 2014, at 7:45 PM, Leon Nelson wrote:

Roger,

Before I get to the topic at hand, nice job putting that Briggs in a 70!

So, surprisingly I got all the needed parts for my 70 project from Jacks Small Engines. Just a couple of parts I deem to be non-critical are on back order. I have it all back together but can't get it to run. It will pop a time or two until the starter kicks out, then quits! I can't even nurse it along keeping it running with a spray can of ether. I have the throttle plate above the carb positioned correctly according to the three alignment holes. The choke and throttle lever seem to function as they should. I put on new carb-to-governor linkages, including spring. The carb seemed to be OK but I went through it anyway. I soaked it out, run a tag wire through all accessible passages without taking the plugs out, blew out everything with carb cleaner and compressed air, then gave it a new needle valve and seat before setting float lever to spec. As I put the engine back together after rebuilding the governor with all new parts, I was careful to see that the camshaft is timed correctly. I didn't mess with the compression release which is on the exhaust valve. It has a good hot spark. I changed the plug. I didn't interchange the cam followers. I had the head off and the the valves look good - cylinder walls too. With no manifold nor air cleaner ahead of the carburetor, it spits back out through the carburetor some as it tries to start, but it did that before I started working on it. Except for the governor problem caused by over-speeding it started and run pretty good before I tore in to it.

I'm pretty befuddled. Could it somehow be an ignition timing problem? Of course I had the engine upside down, but didn't take the flywheel off. That's about the only gremlin I haven't chased. Any ideas or thoughts from your experience would be appreciated.

Thanks, Leon

 

[lfnel]

Well, I bit the bullet and went after the ignition system. I found several things not copacetic. First I found the starter ring gear loose on the flywheel. One of the clamping screws had been twisted off, is way too hard to drill out, and the two other positioning washers were mostly sheared. I'm thinking JB Weld will be the best fix, using just two bolts and washers. I'll probably JB Weld in the third washer and screw head to maintain balance. Then I found the points in good shape though maybe a bit wide. I freshened them up with a point file and re-gapped them to the specified 0.20". Then I found one of two the clamping screws pretty loose, the other finger loose - those that hold the points/condenser/etc. assembly in place to maintain ignition timing. I re-timed the ignition to spec, at least as close as I could, then tightened the clamping screws up good. So now I have yet to JB Weld the ring-gear and round up a new head gasket before I can hit the starter key. Oh, Roger, I soaked the carb out twice in carb cleaning solution, once for the specified 20 minutes, the second time for twice that. I don't recall ever hearing the "ball rattle" you mentioned but I'll have the carb off anyway for a new throttle shaft, so I'll give it a much longer soak, but it did run and start quite well before I went after the governor. I'll post back when I have it buttoned up and have tried to get it running again.

 

[lfnel]

So I went back together, everything "fixed", all be it with the old head gasket while waiting on the new one, even gave her a new spark plug. Still all I get is a pop or two, then nothing. I'm thinking the crank-to-cam timing marks may have been miss-marked at the factory, but the engine initially assembled correctly anyway. Now when I went back together with the timing marks lined up, the valve timing is off. Far fetched - but just maybe. I'll check the timing of the valves relative to the piston when I take the head off to put in the new head gasket. That will sure be easier than taking the engine out of the tractor, turning it upside down and taking the bottom cover off. I took the tappet cover off, watched the valves and confirmed that there's no valve sticking. I've not had the welch plugs out of the carburetor, but as I said, I run a tag wire through all passages, soaked the carb again in cleaner, then blew it out. I heard the ball check valve in the carb rattle even before this third soaking. Can the main-jet stem that contains the seat for the high idle needle be removed from the carburetor body?

 

[lfnel]

OK, new head gasket is in hand so I pulled the head and there checked actual valve timing. If I call compression TDC 0 degrees, exhaust TDC 360 degrees and the next compression TDC 720 degrees, or 0 degrees again, I find exhaust valve opening at 60 degrees, both exhaust closing and intake opening at 273 degrees and intake closing at 510 degrees. It seems to me that all valve event are maybe in the range of 60 degrees too soon. Seems to me that I must have miss-interpreted the camshaft-to-crankshaft timing marks. Your comments - PLEASE!

 

[woodpecker41]

Valve timing is wrong. The exhaust valve should be in the process of closing at the time the intake is opening with the piston at top dead center. They can over lap slightly but the piston must be at the top of the cylinder. Time to take the cam out again. Roger

 

[lfnel]

Sure 'nuf - found the valve timing off at the crank-cam shaft gear set by 7 teeth. I have no idea as to how I came to do that! Going to be a while before I button it up and hit the starter. Got some traveling to do.

 

[lfnel]

Back together. Started right up. Still a little problem with slow idle but not bad.

 

[woodpecker41]

It isn't supposed to idle below 1500 to 1800 RPM which isn't very slow. Roger

 

[lfnel]

Well, since it idles quite nicely down to about 1400 RPM, I guess it's not so bad.