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Old 07-09-2010, 01:35 AM
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350 power problem....

I have a 71 chevy PU, '86 model 350, bone stock except for the new Edelbrock carb (1405 performer series). Here's the problem: Great idle. Rev the engine... get lots of pops and backfires (no need for eyebrow waxing after today...but thats another story ) In forward or reverse, almost NO power. The truck can hardly pull its own weight, and that's IF it doesn't die die as soon as you put it in gear (which is usually the case). Vac lines are where they should be. Fuel filter and pump are new (and working). Any useful ideas? I suggested my 9MM pistol, but hubby said I wasn't helping matters, so now I'm trying to get some ideas.....?

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Old 07-09-2010, 02:41 AM
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Quote:
Originally Posted by Roxanne
I have a 71 chevy PU, '86 model 350, bone stock except for the new Edelbrock carb (1405 performer series). Here's the problem: Great idle. Rev the engine... get lots of pops and backfires (no need for eyebrow waxing after today...but thats another story ) In forward or reverse, almost NO power. The truck can hardly pull its own weight, and that's IF it doesn't die die as soon as you put it in gear (which is usually the case). Vac lines are where they should be. Fuel filter and pump are new (and working). Any useful ideas? I suggested my 9MM pistol, but hubby said I wasn't helping matters, so now I'm trying to get some ideas.....?
Double check the plug wires:

CW on the distributor cap, the firing order is 1-8-4-3-6-5-7-2.

The engine is driver side front #1, then #3, #5 , #7. Passenger side front #2, then #4, #6, #8.

If the distributor was disturbed it could be wrong, so check the timing to be sure it is set right. Be sure the timing wasn't set w/the vacuum advance connected- it needs to be disconnected and plugged when the timing is set!

Be real sure the vacuum lines are good.
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Old 07-09-2010, 09:18 AM
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Vac lines are new and on good. Reset timing yesterday too. Tried 4, 8, and 10 deg... no improvement. Will check plugs and wires, maybe its a bad plug or 4, the Qjet that was replaced was set very rich... we'll see. Thanks!
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Old 07-09-2010, 09:29 AM
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My truck did the same thing right after my rebuild (79 350). Initial timing was set at 4 BTDC to get the truck runing and acted just like you described. Advancing the timing made a big difference, but I also had a HEI module trying to crap out on me.

Setting the timing to 16-18 BTDC (Note: Performer Plus Cam) and replacing the module made it run very well.
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Old 07-09-2010, 11:40 AM
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We didn't try to advance it quite that much, think it is set on 8 now. Above 10 it sounded all kinds of crazy, but we can try going further. The idle is great, nice and smooth, so I don't think its bad plugs or wires but worth a check anyway. At this point, I'll check the tire pressure if it helps!
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Old 07-09-2010, 11:57 AM
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If it makes "noises" when you advance the timing further than it is, I wouldn't advance it further until you've verified other possible causes.
I believe the cam has a bit to do with where timing is happy, and I'm not stock, so what works for me may not work for you. I'm sure somebody much more experienced than I will chime in.

However, checking the components of the distributor/ignition isn't a bad idea.
Mine idled and reved great with no load, even though I had a weak spark. However, when under load it missed, popped, and wouldn't hardly pull itself out of the garage.
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Old 07-09-2010, 12:39 PM
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I had the same issue, It came down to my Vac lines to the distributor being split twice, I ran a single line from the distributor to the carb and the issue was solved.
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Old 07-09-2010, 02:55 PM
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Will check ignition components.
The engine starts easily and idles good, but when you rev it, it pops and backfires through the carb. Then under load, she just quits.
Truck was running fine before replacing the Qjet. Carb malfunction maybe? Not enough air? Fuel mix off? But the idle is good where its set now. I did use a 5/16 fuel line instead of a 3/8 (bought wrong size, used it anyway for time being). Didn't think it would have too much of an effect only being a tiny bit smaller.
I already have a single line from distributor.
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Old 07-09-2010, 08:38 PM
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Anyone else want to give an opinion?
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Old 07-09-2010, 10:02 PM
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Quote:
Originally Posted by Roxanne
Anyone else want to give an opinion?
My personal opinion is replacing a working Q-jet for an Edelbrock is a step in the wrong direction. If it needed tuning, I'd have done that instead of replacing it.

That said, there are thousands of Eddy carbs out in the field running fine. If the carb is the ONLY thing that was changed, then it would certainly appear the carb could be at fault. What is the Eddy carb's history? Did it work in your presence before this? If it's brand new, no telling- it SHOULD work, but in shipping they can be damaged, float level changed, assembled wrong, etc. Has it been apart to check anything?

But the description of the way it runs makes me thing that the timing is incorrectly adjusted (like set w/the vacuum advance hooked up instead of disconnected and plugged.

What is the vacuum at idle?

What is the initial timing (w/o vac. adv.)?

What is the total timing (w/o vac. adv.)?

What type vacuum is being used for the vac. adv.- ported or manifold?

Double check wires to #5 and #7 at the plugs- they're often reversed.

Double check the wires on the cap at the cap- also often reversed or mixed up.

Be sure the cap is clean inside, no cracks or carbon tracking. Be sure the carbon center electrode is in good condition.

Be sure the HEI is getting a full battery voltage- not voltage from a resistor wire.
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Old 07-10-2010, 12:21 AM
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Thanks so much for the answer, that's the kind of answer I was looking for!!!!
Carb history: Was running before on my hubby's '85 f150, but has been sitting for a while. Was out of the box NEW when installed and was run occasionally for about +/-2 months with no probs. Truck was parked. Carb removed, torn down and deep cleaned with all gaskets replaced. Did not replace anything else, as movement was free, needles, seats, etc all in excellent shape... still was "shiny" with no wear or carbon etc.
Reason for swap? The 71 chevy is HIS project with me assisting... MY project is a 63 AMC Rambler (with him assisting...hehehe) that I just bought a 327 (chevy engine, not AMC) to drop in, and to make a long explanation short, I want the Qjet. It fits MY goals for the Rambler better than the Eddy. That's the only reason for the swap. I don't disagree with your opinion on the carb swap, but, you see, I do have a reason for doing it this way!
Now you see why I want it to work?!?!?!
Thanks again... I'll check those tomorrow.
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Old 07-10-2010, 03:57 AM
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Quote:
Originally Posted by Roxanne
I don't disagree with your opinion on the carb swap, but, you see, I do have a reason for doing it this way!
Now you see why I want it to work?!?!?!
Aah, very devious... I like!

It would seem a reasonable certainty that the regasket job on the Edelbrock was *ahem* unsuccessful. I would suspect the float level be rechecked and adjusted if necessary and the jets and air bleeds be checked for blockages from old gasket material, etc. Obviously something was forgotten or not adjusted right, so I would strongly suggest you go back through the Eddy taking care that all the orifices and jets be thoroughly cleaned and blown out before reassembly.

Dollar to a donut it runs fine afterwards.

Detailed Rebuild Instructions

Owners Manual

Installation Instructions
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Old 07-12-2010, 04:29 PM
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UPDATE:
After (careful ) observation, it appears the secondaries were not receiving fuel. Appears a bit of trash was still in there. Yea for me! I guess I get the qjet after all!
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