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Heavy Isolated Misfire Under Load

Drunkie said:
Everything mechanical seems fine then. Going back to what bill said earlier...You have a huge vacuum leak somewhere...or something electrical.
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I'm feeling like its the cam even though the lifter came up to the same height as the others.
When I had it apart, I could see the can lobe through the bottom of the lifter valley. So I ran my finger nail across it horizontally. I felt small ridges towards the edge of the cam lobe. So I did the same on the opposite side of the lifter valley and it kinda felt the same.
 




I didnt put a borescope in there if that's what your asking. I could see the cam through the lifter bores and it looked alright.
 
HighOctaneRacing said:
what the hell? you can't just check the cam through the bores man. Pulling out the cam and inspecting it is the correct way to go. Trust me.
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Never used a camera? you can do the same through the plug holes to check piston tops....... settle guy it would be a hell of a lot easier and faster than pulling the cam!
 
I could see the lobe clearly from the hole in the left middle part of the lifter valley. I don't think the camera would help any.
 


I'd be putting the bigger pulley back on seeing you said you saw no misfires with it and see how it runs again with it.
Theres something going on there if you see misfire with the small pulley and not the bigger one.
If it was the cam you would see missfire on either pulley I would think.
 


Jomamma said:
Put a new lifter in today. Took it for a quick ride. Went wot a few times. And it felt good.

Came back home put the new pulley on and the second time I went wot with the new pulley it started to misfire again.

I wanna say its the cam but I checked the height the lifters were rising as I turned over the motor and everything checked out. I marked the highest point on the lifter on a different cylinder then swapped the lifter over to the suspected bad lifter. When I turned it over it came up to the same spot.

8oaK9BO.jpg


Damn this car man.
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Well in this post you said it "felt good" then you said "Came back home put the new pulley on and the second time I went wot with the new pulley it started to misfire again."
 
HighOctaneRacing said:
**** I just remembered some cams cause misfire codes lol. If this is the issue, tune is needed
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I didn't put an aftermarket cam in.
231FUN said:
Well in this post you said it "felt good" then you said "Came back home put the new pulley on and the second time I went wot with the new pulley it started to misfire again."
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I think I was just a fluke. I took it for 5 minute drive after letting idle. I did like 2 wot bursts. I probably just didn't drive it enough to notice it after I put it back together.
 
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