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Unread 03-22-2013, 06:20 AM   #1
neadb22
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1977 CJ7 
 
Join Date: Mar 2013
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Engine bog on 77 cj7 with 304

I recently bought a 77cj7 that has a holley 4412 on it, side pipes, and stock everything else. The problem I am having is that when I try to drive around the block, the engine will bog down and stall out. After a few seconds, the engine will start right up. I have rebuilt the holley to specs, there is a brand new fuel pump and filter on it,added a larger air cleaner i had laying around on a torino with a 351 cleveland. When I rebuilt the carb, I initially used the stock settings with jets and power valve, which are 74, 6.5. Now I've dropped to the 64 with a 10.5 power valve as someone recommended(exhaust will probably light up it smells so rich of gas). I have pulled the distributor to verify no bad gear on it, tested the vacuum advance, found tdc and reinstalled distributor, added new plugs, wires, cap, rotor button. (old plugs were a gray charred color)Then I set timing to 10, based on the nameplate it said 5 at 500rpm, +2 for every 100 rpm and I was pushing right at 800-900rpm. The engine will idle perfectly, and I can rev it up in the yard without bogging except every once in a while. I pulled the egr off and it was definately stuck so I cleaned it up and verified that it was unstuck and working before reinstalling. The only thing I could think of left is checking the timing gears to see if they were installed properly by the PO. I'm grasping at straws here. What happens mostly is I can take the left out of my driveway, drive easy for a mile or so with no issue, but as soon as I press the gas to climb the first hill it bogs down and sounds like it coughs right in front of the transmission. If i'm at cruising speed, and I'm in 3rd(its a 3spd mt) it will start bogging down after about 30 seconds of hitting that gear. 2nd normally has no issues at all until I've had it bog in 3rd and start back up. If I am cruising and slow down to stop, as soon as I let off the gas, the rpms dump down to around 200, back up to 800 then the engine shuts off, unless I pump the gas a little. I had rebuilt the carb to specs, and verified proper float adjustment, now I have it with low jets and a high power valve and proper float level. Still smells horribly of gas, still acts like it is flooding out(it won't start at all for a few seconds and you can smell gas like its flooded. plus if you press the gas at all when you restart it does the same exact thing). I'm half tempted to pull the edelbrock 4bbl off of my torino and see if its just the carb that is causing too much gas or what? i'm at a loss(I know the torino carb is working properly).Any help would be appreciated

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Unread 03-22-2013, 08:07 AM   #2
Herb31
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1977 CJ7 
 
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One simple thing to check/swap out are your rubber fuel lines and fuel filter. I had cracks in my rubber lines just before the carb and would get similar problems as the lines would suck air. Maybe also try removing the gas cap, and then see if the problem mitigates. If the vent is bad, carb can't suck fuel. These may not be the cause, but they are simple checks for common problems.
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Unread 03-22-2013, 08:19 AM   #3
neadb22
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It looked like the rubber lines were decently new when I purchased the jeep, but I will try that and the fuel cap. I did fail to mention the po never washed the vehicle after mudding in it...it lost 50+lbs of mud just on the drive home
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Unread 03-22-2013, 02:05 PM   #4
Herb31
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Mine looked good too...but when I squeezed them, gas would dribble out. They are old rubber that gets heat cycled a lot. So, it is a good thing to check.
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Unread 03-22-2013, 02:15 PM   #5
Trapshooter
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Before you buy another fuel cap, just take a short drive with it loose. If there isn't a difference spend the money on something else.

Have you pulled any spark plugs to check if you have a lean or rich fuel condition? I did not see anything in you initial write up on spark plug condition.

At anytime did the engine ever backfire; either through the exhaust or the carb?
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Unread 03-22-2013, 02:17 PM   #6
neadb22
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I have had a backfire before I set the timing, and it was during initial warm up before I ever drove. It sounds like it coughs at the engine bay area when it stalls, and the spark plugs are a charcoal gray color at the gap when I pulled them yesterday.
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Unread 03-22-2013, 02:26 PM   #7
Trapshooter
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There are only two things that cause an engine to backfire through the carb. Excessively lean air/fuel mixture or timing.
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Unread 03-22-2013, 02:29 PM   #8
Trapshooter
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If I may...how did you determine TDC on the #1 cylinder when you reinstalled the dizzy? I am wondering if the engine could be timed 180 out.
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'45 CJ2A, L134 Go Devil, T-90 Tranny, Warn O/D, T-18 T-Case, Dana 25 Frt, Dana 41 Rear, 531st CJ made

My 401 build: [url]http://www.jeepforum.com/forum/f8/trapshooters-401-build-1338277/[/url]
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Unread 03-22-2013, 02:38 PM   #9
neadb22
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It very well could be 180 out. I pulled the number one plug and put a dowel in there, rotated until it came back up twice. Original time it came up the timing mark was near driver side of engine, second time it was right before the timing plate. When I originally put the timing light to it(before I did this process, the mark was nowhere near the timing plate). I may have done this slightly wrong as I haven't timed an engine for a very long time. I could have it on the exhaust cycle, however it was acting that way before I started running all over the place checking stuff out. It has improved slightly with all the checks and adjustments I've made though.
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Unread 03-22-2013, 02:42 PM   #10
Trapshooter
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The only way I know for sure #1 is on the compression stroke is to place my finger over the hole and feel the compression blow by my finger. Then insert a dowel and find the sweet spot at the very top of the stoke. Check the timing marks to ensure the dampener has not slipped.

I think it would be a good idea to just double check it one more time.

Good Luck.......
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'45 CJ2A, L134 Go Devil, T-90 Tranny, Warn O/D, T-18 T-Case, Dana 25 Frt, Dana 41 Rear, 531st CJ made

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Unread 03-22-2013, 02:54 PM   #11
neadb22
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Thanks I'll check that as soon as I get back to the jeep
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Unread 03-22-2013, 03:11 PM   #12
stamp32
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If your timing is 180 out, I don't think you you would even be able to drive it. It would consistently back fire.

Chris
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Unread 03-22-2013, 03:49 PM   #13
jumbojeepman
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Quote:
Originally Posted by stamp32 View Post
If your timing is 180 out, I don't think you you would even be able to drive it. It would consistently back fire.

Chris
It wouldn't even start if it's 180 out.

Are you using ported or manifold vacuum? Are you setting the timing with the vacuum unplugged from the distributor? Are you sure the harmonic balancer hasn't spun, making all of your timing reading wrong?

On to fuel problems - is the filter in the tank clogged (yeah, there's a screen filter over the intake and if there's a bunch of crap in the tank it gets stuck against the filter in the tank and clogs up. Stop the engine, and it all falls back off so the engine runs fine for a bit.
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Unread 03-22-2013, 04:12 PM   #14
neadb22
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I just re checked my timing, that was set properly on compression, and I don't think its off at the harmonic balancer as it lined up with tdc at top of stroke(though internal hasn't been checked for proper gear setting) I haven't dropped my tank yet to see about any problems there since I've been slowly burning out the gas and I was going to re do the tank. I reset everything at the carb and checked the hoses for leaks and found none. Also popped the gas cap off and took a trip with the same issue still. When I got the jeep it hadn't been run for over a month but in and out of a garage, made it 21 of the 43 miles home before it started to bog like that.
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Unread 03-22-2013, 04:15 PM   #15
neadb22
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I've got the vacuum hooked up to the port on bottom passenger side of the holley(suction only during acceleration) and I've been checking the timing with the distributor capped off on the advance
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