uh oh, stumbling, sounds like a diesel

[flyboy1100]

Adjusted timing today old school way with a vacuum gauge since it looked like the timing marks were missing from near crank pulley (no idea of vacuum advance is working, I doubt it). Anyway it was running better than it has for the last 400 miles that I have owned it but 20 miles into my 40 mike drive home I pretty much lost all power, even at full throttle I dropped from 75 to 50. Pulled over didn't notice Anything obvious and it was idling OK even in gear.

Start driving again and about 3 miles down the road same thing, only this time I noticed it sounded like a diesel. Hard to describe but definitely something sounds loose. Limped it the remaining 20 miles home and without a tach my best guess is it sounds like it might be idling at 400rpm max, maybe even 350. It sounds like we dropped a big lobe cam in, but it is stock from what I can tell.

I should add I had been hearing a miss or something from the passenger side bank , and when we did compression today all cylinders were in the 165-175psi range except #8 it was at 150. The spark plug also had some gray buildup near the electrode. Father in law thought maybe a rocker might be loose, I'm thinking it gave out? Im pretty clueless on small block Chevy's so I have no idea.

Any ideas of what I should be tearing into? Guessing the passenger side valve cover for sure, but no idea where else to look or what it could be.

 

[HotRodPC]

So you've got great compression. Even that 150 on #8 is nothing to worry about. That's good #'s for a low compression motor with a stock cam. With that good of compression, I'd think your vavles should be in good shape too.

So you mentioned you timed it with a vac gauge. Are you sure you tightened down the distributor retainer good? Or did you maybe even miss getting the clamp over the dizzy housing? Sounds like maybe your dizzy turned and retarded the hell out of your timing. Check into that and lets for from there.

 

[Driver4r]

*erased*

 

[flyboy1100]

So you've got great compression. Even that 150 on #8 is nothing to worry about. That's good #'s for a low compression motor with a stock cam. With that good of compression, I'd think your vavles should be in good shape too.

So you mentioned you timed it with a vac gauge. Are you sure you tightened down the distributor retainer good? Or did you maybe even miss getting the clamp over the dizzy housing? Sounds like maybe your dizzy turned and retarded the hell out of your timing. Check into that and lets for from there.

unfortunately the dizzy is still in the same position and very tight. cap and rotor are new (previous owner), we checked them yesterday too, looked great. all plugs and wires still are tight as well.

out of gear it is still idling at about 650-700. we couldn't set the idle any lower than that, i think the linkages are still a bit gummed up, i lubed them. but you drop in in gear and it is just lope lope lope and idles way low. sounds like at least 1 or 2 cylinders are missing. i tried to get video but it over the fan you can't really hear it. the drivers side sounds good, noise/miss i am hearing is coming from the passenger side.

kinda sucks, it was finally starting well without needing to coax it to run, and driving awesome.

 

[Skweegle89]

Mine just started doing almost that same thing this morning. Sounds like an old cummins driving down the road. No power at all and backfires upon acceleration.

 

[rich weyand]

Mine just started doing almost that same thing this morning. Sounds like an old cummins driving down the road. No power at all and backfires upon acceleration.

That definitely sounds like the timing is way retarded. What is your timing set at? On an SBC, should be around 14-18 BTDC at idle with the vacuum advance disconnected.

 

[Skweegle89]

I have no idea yet. I have only had this truck a couple weeks. The motor has had some work done (cam etc.) but I don't know anything about any of it because the PO didn't know. I don't want to hijack this thread so I'm going to sit back and see this one thru and will start a new thread if I need to.

 

[rich weyand]

I advise both of you to get a timing light on your truck and see what you are running.

Not what you think you are running, but what it actually measures at right now.

First thing to check for lack of power. Spark advance is like a horsepower setting, so the more advance the better, up till the point you get knocking under load, then back off 2 degrees.

 

[flyboy1100]

I advise both of you to get a timing light on your truck and see what you are running.

Not what you think you are running, but what it actually measures at right now.

First thing to check for lack of power. Spark advance is like a horsepower setting, so the more advance the better, up till the point you get knocking under load, then back off 2 degrees.

What if I can't find the timing marks? I know what they should look like, but don't seem to be installed

I will look tonight and see if I can find it, it should be there!

 

[HotRodPC]

The balancer will have a mark. Are you saying they didn't bolt on a timing tab to the timing cover? Then find out which one you need and go buy one. Can't imagine they're over about $12 or so. Probably get a cheap China made one in the chrome engine dress up section.

 

[Skweegle89]

Well I found my problem. Part of it anywayThe PO had it wired wrong. Not a single wire was on the right plug.


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[Skweegle89]

Scratch that. 2 were correct.


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[Driver4r]

Well I found my problem. Part of it anywayThe PO had it wired wrong. Not a single wire was on the right plug.


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well that would make a HUGE difference. At minimum they were 45deg off.

 

[flyboy1100]

The balancer will have a mark. Are you saying they didn't bolt on a timing tab to the timing cover? Then find out which one you need and go buy one. Can't imagine they're over about $12 or so. Probably get a cheap China made one in the chrome engine dress up section.

i found it, gotta look straight down from the top between the water pump and the block. that's gonna suck

chiltons is a bit worthless on timing specs too (worthless on everything it seems), so for a 305, most likely stock cam, what would be "normal"?

also going to pick up a new vacuum advance because it is pretty rusty and corroded, no idea if it is working or not

 

[Driver4r]

i found it, gotta look straight down from the top between the water pump and the block. that's gonna suck

chiltons is a bit worthless on timing specs too (worthless on everything it seems), so for a 305, most likely stock cam, what would be "normal"?

also going to pick up a new vacuum advance because it is pretty rusty and corroded, no idea if it is working or not

to tell if its working, lift the cap off. Hook up a run of vacume line, and start sucking on it...... Easiest way.