Question maybe timing?

Hi everyone,

Well here we go again I think? I've been playing around with the bobcat and been reading up on the proper way to "break-in" the newly rebuilt engine and stuff like that, in doing that I have noticed at idle the engine sounds really good, but when I give her gas it spits a lot? In fact I can't even get the RPM's up hardly at all, I did adjust the carb as much as I could and the spitting is not as bad but it's still there. Hate to bring this up but could my timing be set enough to start it and now just needs some tweaking? What would be the easiest way start from scratch , find TDC and so forth and if that's the case and something off should I back the timing off of 12 to 9 or go from 12 to 3 I guess what I'm asking is back the timing up or advance the timing and then just line up the X on the mag thru the site window and I should be good right? Nothing like old memories huh guys? LOL Scott
 
Scott,do you know that the timing marks on the flywheel are right with the instructions I sent you? The mark on the mag gear has TO BE in the lower part of the hole in the timing cover when you time it to the flywheel marks!!!If you are off one tooth, timing is like you said.Your main jet could be to big ,a no.23 or 25 fixed jet is the correct size for a nonadjustable main jet.Have you tried running without the air cleaner and is your choke openning all the way?There are other things that could cause problems like exhaust restriction.You could moving mag timing one tooth from tdc one way or other.
 
I'm sure the flywheel is set to the instructions however, the X on the mag is dead center of the little plug hole you look thru. Maybe I should try just fooling around with everything again? No air cleaner is on it yet, exhaust seems unrestricted also. Something is most likely just a hair off, but now that it's running I don't want to screw the pooch. In order to get the buckets moving with a load in them I have to crank up the RPM's and like I said with the spitting coming from the carb that's not going to happen, so I'm going to carefully record where everything is now and just try a few things. Scott
 
The timing is not complete until.........it's tweaked.
To tweak the timing you need to use a NEON timing light as per instructions pg. 12 in the VH4D manual. Their should be enough play in the slotted mounting ears of the mag to do so. The gear could be off by a tooth in one direction or the other to reach the appropriate spark advance, but you won't be able to tell till you follow the proper procedure.
 
Nope not sure about valves, was going to do the timing light thing and see where exactly I am.. No doubt I"m off, I am only timed in enough to get her started. Once it is timed perfectly if it still spits I will post about it.
 
Have you tried using your choke to see if the engine will accelerate? Your engine may be running lean. Hal
 
Yes, I installed a new choke assembly so I can operate it from the drivers seat and when I pull the choke out it starts like its suppose to but when I leave it out it smokes and starts to flutter and choke out too much so when I push it in it seems to run a lot better, so the choke seems to be working as it should. Now when it's warmed up I have not tried opening the choke but I will.
 
Just choke it lightly to see if the engine will smooth out when accelerating. We had a 1972 Ford
with the 429 engine. We were coming back from the York Fair and the engine started losing power and running rough. I nursed it home and found the problem was the new points I had installed. They were the Standard Blue Streak. I bought another set of points and it fixed the problem. Hal
 
Scott,There is no way of moving the mag timing except repositioning the gear .The top bolt does not have a slotted hole it goes into like the bottom does.The valves maybe part of the problem.Did you set them or someone else?
 
David
I have to agree with you. It has been my experience that being out of time will cause one of two problems.
Timed too early can cause pre-ignition or ping, most noticable when acelerating under load, also can make it kick against the starter, either electric or armstrong.
Timed too late will cause it to be sluggish, but not cause missing or spitting.
Spitting back through the carb is most likely lean mixture, either plugged tank vent, carb problem or vacuum leak.
Valves too loose will make it click or rattle.
Valves too tight, if not letting them seat will cause uneven idle, but seem to smooth out at higher speeds. If cold compression test is normal, too tight settings won't cause missing until heat expansion of parts takes over. If tight enough to cause spitt-back, it will show up with a hot compression test.
That's my opinion. I have been wrong before & will probably be wrong again sometime.
Willie
 
The valves were set by the machine shop who rebuilt the engine, when at idle it sounds strong, smooth, PERFECT. When I give her gas she spits, I need to look into the carb adjustment it was rebuilt thru the project. I poked around yesterday and removed a spark plug and found it to be black and dirty kinda wet? Picking up new plugs and looking into the carb sometime in the next couple days.
 
You sure the points are gapped right? This will definitely cause a miss and backfires at higher RPM.
 
Scott,
One other thing if you keep running this new motor too rich on fuel,the rings will be ruined very quickly!A weak condenser can cause problems like this,it will probably be something simple when you found it.
 
If it's too rich how can I correct that? I only have one adjusting screw that I see on the carb , the spitting does almost stop completely when the screw is all the way in?
 
Turning that screw in makes it richer. Spitting is from a lean mixture. You may have to get that carb off & soak it & clean it good.
 
I've read thru the posts below, and have to disagree with some of them. Especially the late timing. Late timing will cause the problems you are mentioning. If the timing is too late you'll have fuel burning yet when your intake valve opens which will back fire into the intake manifold and burn all the fuel in the intake manifold. Late timing will also cause sluggish response. Combustion does not take place when the crank or piston is in the correct position to get the maximum torque.

Gasoline only burns so fast no matter what engine RPM's are. Engine RPM's vary so this is why we have to advance the timing so the fuel is burning at it's peak when the piston and crankshaft are in the correct position to deliver the maximum torque.
 

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