Carb/timing help . . . I am really stumped

[Dive 30]

OK, I have a complete Edelbrock setup, 1405 carb, performer intake, cam, MSD distributor, 6A, Blaster 2, Headers,etc.

Gwen was running OK (not great, but smooth). I had this problem with this loud clacking sound, turned out to be an exhaust leak. No problem, replaced the header gasket, noise reduced (but not eliminated, I think I burnt a valve :( )

Now she idles better than ever, but she shudders like crazy off-idle and has lost all power! She literally is shaking like crazy! Also, now when she idles in gear, she loads up and dies or backfires.

The timing was set by a local shop by a guy that I trust, but check this out. I checked the timing (which is steady on, now that I fixed my exhaust leak, which is a first), she is at 20 deg BTDC, and won't run any lower, which is way wierd. With the vacuum advance hooked up, she is at 35 deg. BTDC!!!

What did I do? How do I fix it? Heeelllpp!

Thanks in advance,

Phil

[RichCal]

Did this just start after replacing the cam? Sounds like your timing chain may be off a tooth.

[Dive 30]

I put the cam and stuff in in august, I have been chasing down leaks since then. I used the Edlebrock double roller timing set, and I know I double checked it. I just finally eliminated the exhaust leaks (for now) and started having this problem. so I don't think it's off. She was running so much better than this with the exhaust leak!

Phil

[Michael]

Sounds like you have a vaccum problem....the vaccum advance should not increase your timing at idle. Only if you rev it up..... I would question the integrity of the way you vaccum lines are hooked up. Sounds to me you have the wrong one going to the dizzy for sure. If that is good....you may have a cto problem......one ore the other I think.

[Dive 30]

I don't have any CTOs anymore, I didn't think my vacuum should have advanced at idle either, but I swapped vacuum sides and it ran worse. Maybe I need to swap sides and up the vacuum springs?

Thanks for all the help guys

Phil

[coolram]

Do you have the vac advance hooked to a ported source and not a manifold source?

[Agent Orange]

<blockquote>quote:</font><hr>Originally posted by Michael:
Sounds like you have a vaccum problem....the vaccum advance should not increase your timing at idle.<hr></blockquote>

Not quite sure I understand this comment. If you pull off the vaccuum line on the dizzy the timing changes right? Even at idle. :confused:

[Dive 30]

My vacuum is hooked to the passenger side of the 1405, per Edelbrock's instructions (I don't know if that is manifold or port 'cause I don't have a vacuum gauge), but I didn't think it was supposed to change the advance at idle, only at speed. Is my MSD distributor different from a stock dizzy? My destructions don't say anything different . . . hmmmmm.


Phil

[Dive 30]

Update . . .

OK, went out to read and look at things. On my carb, the port vacuum is the passenger side, manifold is the driver's side. I had left the advance hooked to the manifold side on accident which is why my timing was off at idle. Swapped that around, timing is steady at idle now, but still shaking like crazy and no juice. Set timing to 15 Deg, made things way worse. Reset timing to 20 Deg. Checked all vacuum connections and PCV valve, all good. Read through Edlebrock book to make sure I had my connections in the right spot . . . everything checks out. So I'm figuring if she's backfiring (in the tailpipe) my spark isn't burning fuel somewhere. So, I went back to basics. All plug connections are good, didn't pull the plugs, but they are only two months old, so they couldn't be that bad. Checked plug wires and firing sequence . . . (music comes up) Ta Daaa!!! The #4 and #6 plug wires were reversed. It seems my buddy over at the shop and myself missed that when we were checking things over (back in August/September mind you). Swapped plug wires, re-timed, re-adjusted carb . . . Gwen has never run smoother. Not smooth as glass, but still way smooth. Plus, I have better throttle response! Now, if I can just get that air/fuel monitor in . . .

Anyways . . . thanks for all the help guys, I am so relieved to be back on the road.

Phil

[Jeepzilla]

Exhaust backfire can also be a leak in the exhaust connections, especially near the manifold. If you get some popping on deceleration, check all your connections. An engine that shakes (or has shaken hard) can loosen bolts.

[Dive 30]

Jeepzilla,

You are dead on there, I had to retighten everything on my headers, they had shaken so bad. Gwen still isn't running perfect, but I have an intake manifold oil leak, so when I pull it to fix that, I will go over everything again, to eliminate any smaller vacuum/exhaust leaks and hopefully get her in tip top shape.

Phil