I am done for the weekend but don't give up yet. Take a break and let it sit for a while. You will miss something if you keep at it. Let us mull this over and get back to you.
Pronounced engine miss, suggestions?
- Thread starter KevinGn_WV
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sgtpoliteness
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Sorry, if I missed this. Have you tried spraying brake clean along all the seals that could have vacuum behind them?
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---------- Post added at 05:45 PM ---------- Previous post was at 05:42 PM ----------
And the compression seems pretty low.
Vacuum leaks do some weird stuff. The plastic carb spacer on my Galaxie had a crack internally that caused it to idle like dogs***.
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---------- Post added at 05:45 PM ---------- Previous post was at 05:42 PM ----------
And the compression seems pretty low.
Vacuum leaks do some weird stuff. The plastic carb spacer on my Galaxie had a crack internally that caused it to idle like dogs***.
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KevinGn_WV
TYF Newbie
Ive sprayed an assortment of stuff around the entire manifold, tbi, brake booster etc. Idk that the compression is that low. Its an old engine, no denying that obviously but the numbers are consistent at least. Nothing to point a finger at one particular cylinder. Before I tear the engine apart Id like to try to wash out the sludge real good and get it going with some good fresh oil. Im being told seafoam, kerosene, diesel, among other hillbilly hacks but I dont want to sieze a rebuildable block in doing so.
KevinGn_WV
TYF Newbie
I took a few days off from this, then got poking around a little at something I should have noticed before. Maybe Im grasping at straws here, IDK.
This is on the old cap.
And this I found inside the new cap. The button is riding high enough to gouge the cap but also, check out the wear pattern.
EDIT: Pulled the dizzy. Gear looks ok. No side play on the shaft, but theres about 1.5mm, maybe 2mm of play up and down. Magnetic pick up is rusty inside and out. Who knows. Cap base looks a little off though. Probably causing the off center wear. Not convinced this is my miss but I have no idea how the magnetic pickup works.
Is this a user serviceable part? Can it be cleaned and reinstalled?
This is on the old cap.
And this I found inside the new cap. The button is riding high enough to gouge the cap but also, check out the wear pattern.
EDIT: Pulled the dizzy. Gear looks ok. No side play on the shaft, but theres about 1.5mm, maybe 2mm of play up and down. Magnetic pick up is rusty inside and out. Who knows. Cap base looks a little off though. Probably causing the off center wear. Not convinced this is my miss but I have no idea how the magnetic pickup works.
Is this a user serviceable part? Can it be cleaned and reinstalled?
Last edited:
KevinGn_WV
TYF Newbie
Not sure if anyone is following this still but here is an update.
The distributor base that the cap mounts to was slightly bent. Couldnt really see it by eye alone but meaurements are easy. That and the pickup wires, green and white, both had cracked insulation. Bought a new dizzy. Also took the EGR off, cleaned and inspected, replaced gasket with a new one. Still misses.
So...while setting the timing to 0, the mark was a little....jumpy, for lack of a better word. About 2 degrees I think (moved about 1 cm) at idle.
Now, if I gave it a little throttle, around 1500-2000rpm (guesstimating) the timing mark would advance 10 degrees or more. (about 3-4cm).
Here is what i know for sure. As soon as the timing mark advances itself under throttle, thats about when the heavy miss almost goes away.
So, Im positive I have it set to 0 correctly with the wire disconnected, with the mark flickering to 1-2 degrees I believe, and when i have the wire reconnected the timing mark advances way up at idle and is quite erratic.
I can now rule out worn dizzy gear. How about the timing chain? Im thinking theres enough slack at idle to make it jump a little?
Also, altmeter in dash is still twitchy and multimeter confirms. Engine speed is a factor. Related or just need a new alternator?
I really do appreciate the help and advice so far. If anything Im learning quite a bit about this engine family.
The distributor base that the cap mounts to was slightly bent. Couldnt really see it by eye alone but meaurements are easy. That and the pickup wires, green and white, both had cracked insulation. Bought a new dizzy. Also took the EGR off, cleaned and inspected, replaced gasket with a new one. Still misses.
So...while setting the timing to 0, the mark was a little....jumpy, for lack of a better word. About 2 degrees I think (moved about 1 cm) at idle.
Now, if I gave it a little throttle, around 1500-2000rpm (guesstimating) the timing mark would advance 10 degrees or more. (about 3-4cm).
Here is what i know for sure. As soon as the timing mark advances itself under throttle, thats about when the heavy miss almost goes away.
So, Im positive I have it set to 0 correctly with the wire disconnected, with the mark flickering to 1-2 degrees I believe, and when i have the wire reconnected the timing mark advances way up at idle and is quite erratic.
I can now rule out worn dizzy gear. How about the timing chain? Im thinking theres enough slack at idle to make it jump a little?
Also, altmeter in dash is still twitchy and multimeter confirms. Engine speed is a factor. Related or just need a new alternator?
I really do appreciate the help and advice so far. If anything Im learning quite a bit about this engine family.
sgtpoliteness
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Man, you've got a weird one.
Does the timing jump with the connector hooked up? But, yeah, it sounds like the timing chain is worn. However, I wouldn't think 1-2 degrees would cause a miss.
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Does the timing jump with the connector hooked up? But, yeah, it sounds like the timing chain is worn. However, I wouldn't think 1-2 degrees would cause a miss.
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KevinGn_WV
TYF Newbie
Yes it does. With the connector hooked up, the timing advances like it should, though I dont know if its where its supposed to be, but it does advance and it dances around quite a bit. If I had to guess, ten degrees or more. Im going to try shooting some video as I know just reading text is very hard to diagnose, but i really do appreciate all of the help on this.
sgtpoliteness
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10 degrees advanced sounds about right. But it should bounce around. Unless there's slack in the timing chain or some other influence.
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KevinGn_WV
TYF Newbie
As of 20 minutes ago, I no longer own it. Unlike the person I bought it from I was completely honest about everything I did to it and why. After combining what I gave for it, plus the parts I put in it, I lost about $200. I couldve lied or played dumb and maybe broke even or made a little but it was my fault I jumped on what I thought was a steal and an easy fix and it cost me.
On the bright side, I paid $200 and hours of hands on training for a crash course in OBS Chevys, which will prove to be a great value since my Yukon isnt going anywhere.
Thanks again for all the help, advice and patients.
On the bright side, I paid $200 and hours of hands on training for a crash course in OBS Chevys, which will prove to be a great value since my Yukon isnt going anywhere.
Thanks again for all the help, advice and patients.
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So from now on, basics first. Inspect and address any "obviously" worn parts and do a compression test while plugs are out. All new parts at the top will never fix a mechanically worn engine. Those compression test results seemed a little low, but not drastic, and the spread was a bit much but you never posted wet test results. No biggee now since it is gone.
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