1974 CJ5 258 with Weber 38 - backfiring issues - Page 2 - JeepForum.com

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post #16 of 60 Old 02-02-2013, 05:44 PM Thread Starter
cj5huntingrig
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If this isn't part of the problem, paint me pink and call me Susan.
Before and after - mocked up.
Now there is no play at all between the crank and the distributor. I'm going to do a RMS tomorrow and oil pan gasket.
I'll let you know how it runs. E

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post #17 of 60 Old 02-02-2013, 05:54 PM
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So can you explain how to test the chain? Do you turn the crank and watch rotor for movement? Thanks
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post #18 of 60 Old 02-02-2013, 05:58 PM Thread Starter
cj5huntingrig
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Yes. Remove the cap on the distributor and turn the crank. If there is more than about 5 degrees of play before the rotor moves, you will have timing issues. When you let off the gas and the chain is slack, the timing will be off by whatever amount of slack you have in your chain thereby causing backfiring/ bad timing. Also, my timing gear had plastic teeth which some say is not a big deal but I think it is just better to get it out and go metal.

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post #19 of 60 Old 02-02-2013, 06:13 PM
Mean Max
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Holy crap! That's a lot of slop!

I hope that gets you going, and it was great seeing your CJ5 in person the other day.

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No one here knows what they are talking about. You should try Pirate 4x4 they will be happy to help you.

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post #20 of 60 Old 02-02-2013, 06:18 PM
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Thank you. I will have to check mine.
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post #21 of 60 Old 02-02-2013, 06:21 PM
Mean Max
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http://static.photobucket.com/player.../VIDEO0008.mp4

http://static.photobucket.com/player.../VIDEO0009.mp4

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No one here knows what they are talking about. You should try Pirate 4x4 they will be happy to help you.

There is no situation that cannot be improved with a small but well-placed explosive.
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post #22 of 60 Old 02-02-2013, 06:38 PM Thread Starter
cj5huntingrig
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Mean Max,
You called it! Crazy slop in the timing chain. I'll tell ya...It can't get any worse after this fix. That's for sure
Thanks Max. You're the man!
E

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post #23 of 60 Old 02-06-2013, 01:04 AM Thread Starter
cj5huntingrig
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Fired it up today with new RMS, new delco 1-wire, and it ran great. No backfiring at all. It's ready for the trail.

1974 CJ5 all stock except for Rocky Road SOA
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post #24 of 60 Old 02-06-2013, 06:21 PM Thread Starter
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Ok spoke too soon. No backfiring but it's hesitating on acceleration from idle. Vinny, I ordered a jet-pack from Weber you'll be pleased to know. I'll let you know how the re-jetting goes.

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post #25 of 60 Old 02-12-2013, 06:54 AM
TOBYWON
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This is an awesome thread, because it (likely) points out issues that many of us have (slack in the timing chain, under-jetted carbs). But, dang, what kind of work/knowledge goes into being able to DIY these two jobs?

I'm experiencing the same symptoms, and was told two years ago, post-rebuild, that I needed to replace the harmonic balancer at some point. Also, and quite timely, I've got a mammoth RMS leak. Could this be a love-story in the making? I mean, can I DIY the chain/balancer myself, whilst swapping in a new RMS and pan gasket?

Also, how would I go about upsizing the jets in my MC2150 carb? I got it from the ebay guy, and she ran fine for a while, but has started bogging down at take-off, and power loss in general. Not sure what size jets it came with (47's?), but I'm pretty sure it's not 50's.

Anyway, any advice you can give, Evan, would be much appreciated - nice job with your rig!

"... God demonstrates his own love for us in this: While we were still sinners, Christ died for us." Rom 5:8 (NIV)

/l , [____],
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()_) ()_)----)_)

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post #26 of 60 Old 02-12-2013, 07:21 AM Thread Starter
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Tobywon, Thanks. These are actually pretty easy repairs if you have a few good tools - namely a harmonic balancer puller and air tools help considerably.
If you are fast, you can probably do it in one day. Most likely though it's a weekend deal. The way I look at repairs and modifications is that you won't be able to discover your limitations until you try first. If you get stuck, there is so much quality (and lousy) information on this forum and on the internet as a whole that really anyone can take on these challenges. Just do your research first, get your parts and come up with a game plan. My three favorite tools are an air ratchet, impact wrench and good quality torque wrench. Just don't use the impact to put anything back on. The rear main seal is a pain but is easy if you approach it following the right steps and don't rush it. Depending on your exhaust setup, you may need to remove your down pipe. You will probably also need to raise the engine prior to removing the oil pan, support it somehow (be creative) and remove the passenger side engine mount to pull the oil pan. It is easier than it sounds but can be frustrating.
I'm happy to answer any specific questions that might arise.
As far as the jets go, I haven't worked on that one specifically. If you can afford the "REDLINE" Weber 38, it's an awesome upgrade (some will argue that the one you have is better). One benefit is that they offer great help over the phone and many jetting options in one kit. Your MC carb may just need a good cleaning, float adjustment, new needle and seat. I know that many of the old carbs are having trouble with the ethanol gas also. Rejetting helps with this.
Best Regards, Evan

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post #27 of 60 Old 02-12-2013, 07:27 AM
TOBYWON
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Hey Evan, thanks! I have a good how-to for the RMS that guys here pointed me to. I know it's time consuming, but I can do it. So, I "can" swap the harmonic balancer and the timing chain when I do the RMS then? And do you have a how-to guide on that? Or can I just trust the service manual? LOL.

"... God demonstrates his own love for us in this: While we were still sinners, Christ died for us." Rom 5:8 (NIV)

/l , [____],
l---L--OlllllllO-
()_) ()_)----)_)

{{{84' CJ7 RENEGADE / 258 I6 / Nuttered, HEI Dizzy, MC2150 (eBay) w/Manual Choke, MSD 6AL Ignition, Engine Totally Rebuilt in 2010}}}
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post #28 of 60 Old 02-12-2013, 08:28 AM
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Evan,

Nice work on the timing chain. I'm glad that fixed the backfiring.

I'm not convinced your hesitation problem is jetting related, however. The 38's factory jets should run just fine for you in Florida, as they are sized for a sea-level application.

Are your plugs showing a lean idle condition?

Matt


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post #29 of 60 Old 02-12-2013, 02:58 PM Thread Starter
cj5huntingrig
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Tobywon, you should be able to just go by the service manual. The only really important thing is t make the dots face each other on the timing gears. You should also verify TDC and make sure it coordinates properly with the distributor. Easy Peasy.
Matt, My jets arrived today. I'll put them in tomorrow and see what happens. My plugs are showing slightly lean. The guy from Weber said they have been having lots of problems because the pump gas is exceeding the 10% ethanol as advertised. We'll see.
Evan

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post #30 of 60 Old 02-14-2013, 02:37 PM Thread Starter
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Hey all. Ok so I changed out my idle jets to 55s. Im at sea level so based on all the info Ive gathered, I went with 55s after upping from 45s to 50s. It idles perfectly and comes of idle without hesitation. My upper accelleration is a little sluggish though so Im going to upsize my air correcters and running jets again to see what happens. Ill update you once it's done. Its raining hard today so no dice. E

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