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Loss of power, need help...


Rareform92

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I know "loss of power" has been answered before, (and believe my I've searched) but I feel my situation is unique. As soon as my 302 swapped Ranger was driveable, it ran great. The slightest tap of the gas pedal would roast the tires (or tire, with the stock 93 open differential haha). About a week into driving it though, the electronic choke on my Edelbrock 1406 shit the bed, as well as the Echlin coil overheating. Unsurprisingly the truck stalled out because of virtually no spark power from the coil and my choke didn't work it all. So I bought a brand new Pertronix Ignitor coil which fixed all the spark problems WITHOUT a load on the motor, and the carb was replaced with an EXACT same 1406 from my dads 68 Mustang with a 289, and that carb was tuned and ran great on his motor (which is basically the same thing as a 302 with some minor diffs). After I changed the coil and carb, the motor runs great and revs without hesitation in park, but when I mash the pedal going down the road, it feels incredibly sluggish and occasionally backfires.

I honestly don't think it is a fuel delivery or carb tuning issue, the carb was tuned and running great already on a virtually identical motor. Could it be a bad plug wire? The spark plug boot on my #3 cylinder got slightly melted, but I have checked all the wires and plugs and they all seem fine. Could it be something like clogged catalytic converters since I've been using the truck for a few months?

Sorry for the long post. :icon_confused:
 


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dangerranger83

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289 may be close to a 302, but they have their differences. It needs to be tuned to your engine. Does your 302 have the same heads, cam, intake, etc... as the 289, probably not.

As for the backfiring, the plug wire could be the problem. I have a wire that has melted through and mine backfires at a certain RPM, I still need to replace that. Another thing that can cause backfiring is a vacuum leak around the base of the carb where it bolts to the intake.

Edelbrocks are good for getting you up and running out of the box, but if you want more, you will need to tune it. If you remember your jet size, metering rod size, hg spring size, etc...that you did have, that's a good starting point for you. A vacuum gauge will help you out too.

I'm running an edelbrock 1403 500cfm. I love it but when I get on it, sometimes I get hesitation and serging. I just need to recheck what edelbrock suggests and order the parts.

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dangerranger83

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Another thing, you could be getting use to the power. I remember when I first started driving mine after my 302 swap and felt like I was going fast doing 30mph.

You could take a look at your CATS and see if they are getting clogged

Do you have emissions where you are at? If not then you need to get some "high flow" CATS.

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sparky2eh

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My guess..... accelerator pump seal is worn out or the linkage is on the wrong hole for the engine and it isn't getting enough of a fuel shot when you jab the go pedal.
 

RonD

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Get a vacuum gauge, they are very handy for tuning and other things as well, and not that expensive.

One of the other things is a clogged/restricted exhaust.
With vacuum gauge hooked up to the intake manifold, not carb. vacuum.
Run the engine at approx. 2,000rpm, for 15 seconds or so.
Let off the gas, vacuum should jump up when throttle plate closes, that means a clear exhaust, air is still being pushed out the unrestricted exhaust valves, so intake pressure drops rapidly until RPM drops.
If gauge doesn't jump up when throttle plate closes then exhaust is restricted, pressure in the exhaust system holds pressure against intake air coming in so no rapid drop in pressure in the intake.

Backfiring is a symptom of high exhaust pressure.

Lazy accelerator pump would produce what I would call a hesitation, not so much a sluggishness, but that's the problem with "descriptions", lol, is it a "tap" or a "knock" :)

Put your foot down on the gas and engine would hesitate until airflow past throttle plate(jets) pulled in the required fuel then it would accelerate as normal, accelerator pump gives it that instant reaction squirt of fuel, but it doesn't keep adding fuel, just one squirt until it's primed again.

What are you using to advance the timing?
If timing is not changing correctly then sluggishness would be the symptom.
Timing light will tell you if its reacting with RPM.
Another backfire causing issue.
 
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Rareform92

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All great suggestions. The cats I installed were pretty well cleaned out before I put them in, but it is possible that the heat could have melted or burnt up some material in the cats, which would make sense because I've been putting the truck through its paces. I put about 200 highway miles on it this weekend, and a LOUD exhaust leaked developed again, even after I had snugged up both manifolds and collectors. The sluggish-ness is REALLY felt going up hills, it's almost embarrassing. A loud bang happened a few times when I really got on it to get up the hills. I will try the vacuum gage test and inspect the carb and get back to you all. Thanks again.
 


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