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Does not accellerate well??

Does not accellerate well??
Trigger said:
Torxhead - I checked the timing advance spring, and it seems real tight. I'm not sure what elese do do to check it. I have a question about your suggeston to diagnose a slipped chain. The harmonic balancer is directly attached to the crankshaft with a key way. Won't it always show TDC when the #1 piston is at TDC?
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Not necessarily. Finding your TRUE TDC does not involve using the "0" mark on your balancer at all. Most times, this may not even be in the right spot.

You are correct though -- yes, your balancer is located on the crankshaft via a keyway, but the outer ring of the balancer is only bonded on with rubber between the inner and outer pieces of the balancer. Over time, especially if it is an old balancer, this outer ring can slip on the inner, making the timing marks on them essentially useless.

You can find your exact TDC by buying or making a piston stop -- you can make one with an old spark plug, a bolt and a nut, or you can purchase one from somewhere like Jegs or Summit Racing.

To find your TDC with a piston stop, remove all your spark plugs (just so it's easier to spin the engine over) and install your piston stop in the #1 cylinder. Spin the engine over slowly by hand via your balancer bolt. When the piston comes into contact with the piston stop, take note of the location of your timing marks, for example, if it reads 10 degrees BTDC. Now, rotate the engine counter-clockwise, again, slowly and gently until the piston once again contacts the piston stop. This time, you'll come up with an ATDC reading, for example 8 degrees ATDC. Your exact piston TDC will be the halfway point in between them. For instance, if you had these two readings I gave here, your exact TDC would be 1 degree BTDC. You would find this by taking these two readings, averaging them, and subtracting the mean from your BTDC reading (i.e. average of 10 BTDC and 8 ATDC = 9, 10 degrees BTDC - 9 = 1 degree BTDC).

Sorry if I broke that down a little too much, I just wanted to explain it clearly. Let me know if that helps.

Good luck! :chug:
 
Thanks. I am pretty confident I have TDC correctly located, and it matches very closely with the mark on balancer/housing (maybe 1 degree off). I had the oil pan off, so I was able to watch the piston movement carefully before I set the timing.

One thing to point out is the engine starts up quickly and easily (literally on the first crank), and the timing light suggests the timing is right on. Could the timing chain have slipped only affecting the cam-shaft? Maybe just barely where it is not noticed until I try to accellerate?
 
How about doing a vacumn gauge check? Hoping for a steady reading of about 18-20 inches at idle.
 
Torxhead said:
How about doing a vacumn gauge check? Hoping for a steady reading of about 18-20 inches at idle.
Click to expand...

Good idea......I went and bought a vacuum gauge. Was able to hook it up directly to the intake manifold...I even used a clamp to make sure it wasn't leaking through that hook-up. I don't get 18-20 inches, but I get a steady 14, and I mean a steady 14. I used the chart on the following web-page to help troubleshoot, and I get a worn-ring conclusion. What do you think? Do I have worn rings, and my acceleration issue is possibly a carburetor problem? I ran it out of fuel a few 100 miles ago? Did I suck some trash into the carburetor?:confused:

Here is the vacuum reading chart I used:

Technical Articles: Engine testing with a Vacuum Gauge - at Greg's Engine & Machine
 
Did you try playing with the timing when you had it hooked up? I ask because you can get more vac buy messing with the timing.
 
If you look at that chart you were using at the bottem part in the middle it says 8-14 and 14-16 is incorrect ignition timing.
 
When I did the open/close throttle quickly, it went all the way to zero versus 2, which would confirm worn rings...I bet I end up having to take this darn timing cover off. It wasn't hard but sure did take a while. Now that all of the bolts are replaced, it should be easier. I sure wish it was a fuel issue :-)
 
I also played with the timing...went 5 degrees either way, and it didn't affect the vacuum reading at all
 
Its just strange that all you did was pull the cover and now you have this problem I would pull it back off and take a good look at the chain.
 
I can't disagree with you. I am just hanging on to hope! lol. I did run the jeep out of gas not long before I took after this project, and something got hung up in the carb jets, but I was able to clear it out w/some cleaner and fuel additive. I can't help but wonder if something else is restricting fuel flow, but that chain did seem to have a great deal of slack. Is there any amount of slack that is normal?
 
I finished the timing chain job..took a while b/c of Christmas Holidays, etc. There was definitely too much slack in the chain. I had no idea how snug a new chain w/new sprockets will be. Once I finished, and set the timing, the vacuum gauge is now reading 20 inches vs the steady 14, so it definitely needed it. This even fixed the knock sound I couldn't find (the chain was slapping the cover b/c it was so loose. Now I have to say, it runs much better now, but I still feel like something is holding it back. When I am in third gear with the gas pedal completly down, it bogs down and struggles to accelerate. If I let off of the gas in the last little bit, it runs much better. Is something not adjusted correctly in the carb??
 
Glad to see that you straightened out your timing issues and that it's running much better now. Your current problem does seem to be a fueling issue. It's been a while since I've read the whole thread, but what carb are you running? And what fuel pump? I assume that you've got a stock fuel pump. If the fuel pump is old, this could be part of your WOT issue. I'm not trying to tell you to go ahead and change anything, just trying to narrow down the problem.

:EDIT: Another one to try and find out would be your vacuum advance on your distributor. That one is much harder to track down, but also a potential issue. I'd start with the fuel pump, though.
 
There usually aren't any internal carb adjustments with the exception of the float level, and I don't see how that would have changed. What type carb are you running? Also, in an earlier post, when the engine backfired, tho often caused by timing, or incorrect routing of the plug wires, it does not always mean its a timing issue. It can also mean you have a "lean" fuel issue. Just to be clear, when you are accelerating, there are no hesitations, popping, and so on, just a lack of power, right? Is the choke plate completely opening when engine is fully warmed up?
 
The carburetor is a 2 bbl. I will look for some identification on it tonight? Any suggestions on where to find the info on the carb? It is a stock fuel pump and I replaced it when I did this job. It was too easy to replace. It seems to have a good flow. I pulled the return fuel line off of the filter (new filter too) while it was idling and it kept running and sprayed me with gas (I know I know...dumb move).

How do I check the timing advance? The spring seems to have tension on it and the timing does seem to appropriately advance on acceleration (checked a/basic timing light).

When I accelerate there is no popping, just a clear loss of power. From the exhaust (dual w/headers and glasspacks) I can hear a pop pop but not a backfire issue....sounds like it is bogged down to me. I'm open for any troubleshooting suggestions....
 
Here is a picture of the carburetor. Motorcraft is stamped on top....there is a sticker that isn't very legible on the side where I can make out 'remanufactured by Holley'. It doesn't look exactly like the ones in my technical service manual, but it is close. I can't seem to find the tag the manual says should be on the carb, but the manual doesn't tell me where to look for it. While I was up there taking this pic, I manually opened the choke, and depressed the throttle. I only saw one stream of gas squirt into one of the barrels. Shouldn't both squirt with a fully depressed throttle, or does it have something t do with low fuel pressure since the engine wasn't running? Just a thought...:confused:

_662962.jpg
 
Yes you should see both sguirt, I think you need to do a rebuild. Those are pretty easy to rebuild and the kits are cheap, just get it from someone like NAPA not Autozone or one of the other cheap places that sell China :dung:.
 
It looks like a Motorcraft 2100, just get one for the year Jeep and engine you have and you should be fine. They sell a 5gal bucket of carb cleaner where you can take it apart and soak it over night that is the best way to get it good and clean and then blow it out real good with air.
 
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