81 305

[Recian]

So I've noticed lately that when I give my truck light throttle it'll actually decelerate and bog. Off idle is good, Idle is smooth and 50%+ throttle is good but 15-50% bogs badly. I've got new AC delco plugs/wires/cap/button etc. This made a great improvement but it's still there. I've heard EGR can cause it but I'm wondering if someone else has input.

[LynnJr]

Is it a carb?

[frog210]

Fuel pump
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[Recian]

Yeah it's got the 2bbl carb mechanical pump. I'm leaning towards finding a quadrajet or 1406 edelbrock soon since I got my hands on a cheap aluminum performer 4bbl intake.

[sl93ex]

I'm only going to suggest this because I spent quite a bit of money and time diagnosing my own 85k 81 305. It had been steadily deteriorating for months, and it started with mid-range bog. I thought it timing, then it was dirty carb, so I changed that and it started back-firing through carb, thought it wasn't getting enough fuel.. the list continues.

Check your rocker arm movement.. make sure each one is moving through the full range. I ended up having a flat exhaust lobe, and a couple others that were getting flat.

Take out all your spark plugs and pop your valve covers and rotate the engine by hand while watching each set of rocker arms.

Our engines fall into the "soft metal" Mexican cam shaft era, so it's probably a matter of when it fails.

The good news is, an inexpensive melling camshaft (MTC-01 cost me $115) will really wake up the ol' 5.0

[Recian]

Actually that makes sense. At times it has a slight rumble at idle, not a miss but like it's got a mild cam. Hell it may even have a bent pushrod, it slightly opens but not enough for full combustion. I've seen old mopar engines run with bent pushrods and not know the difference. I need to pull the covers off and do gaskets anyway. They're oozing everywhere. Been up there about 60k. The engine was rebuilt that long ago and I"m sure they didn't change out the cam. I'll be swapping over an intake soon too. Wouldn't hurt to check that while the covers are off. Is there a way to upgrade say to the 5.3 style roller rockers and maybe some roller lifters since you gota put in new lifters to the cam. It would be nice to get a little less resistance in the engine, if you see what I"m getting at. See just how good of MPG I can get. Our master here at work built a 350 in his 90 pickup with all low resistance internals, roller everything and such and gets well into the 20s hwy. With the 305 I could probably beat that depending on the trans differences.

[beamn7]

EGR valve can cause that as well as a bad accelerator pump in the carb. Both EASY and Cheap fixes....

[Recian]

I've heard both of these. I would think of the 2 that accelerator pump would show its butt more when the a/c is on. I noticed it after I posted and ran to the store. Its much worse with the a/c on
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