Running Rough?
Thread Starter
Advanced
Joined: Jul 2013
Posts: 62
Likes: 0
From: Phoenix AZ
Running Rough?
I have a GM Mr. Goodwrench crate motor. It was in the car when I bought it. I put new plugs, wires, dis. cap and rotor…but it still seems to run rough at idle. I turned the distributer and seemed to make it a little better (I can't afford a timing gun right now)
So I filmed it, maybe you guys can hear something? Or is it just my imagination?
So I filmed it, maybe you guys can hear something? Or is it just my imagination?
Race Director
Joined: Mar 2003
Posts: 11,608
Likes: 780
From: Eustis ( Area 51 Bat Cave ) Fl
I hear you on budget 
but borrow or some way get a vacuum gauge and a timing light, running to too far advanced might help the rough but you could get the engine running hotter and pinging, timed right it will run better, 
Does that engine have a mild cam?
Put a vacuum gauge on it to be sure it has no leaks, vettes love to have vacuum leaks,
Also could be a little trash in the idle jet.
but borrow or some way get a vacuum gauge and a timing light, running to too far advanced might help the rough but you could get the engine running hotter and pinging, timed right it will run better, Does that engine have a mild cam?
Put a vacuum gauge on it to be sure it has no leaks, vettes love to have vacuum leaks,
Also could be a little trash in the idle jet.
Pro
Joined: Apr 2012
Posts: 517
Likes: 2
From: Orlando FL
Re-Check your plug wires making sure you got the correct firing order, The PO may have had a wrong plug wire on the wrong plug or cap, Pull all of plug wires off, and do one wire at a time. You can use a sharpie to lable the wires.
Do you have a CF member that lives near you, maybe you could stop over after work and they could set the timing for you. Hope this helps.
Do you have a CF member that lives near you, maybe you could stop over after work and they could set the timing for you. Hope this helps.
Thread Starter
Advanced
Joined: Jul 2013
Posts: 62
Likes: 0
From: Phoenix AZ
Re-Check your plug wires making sure you got the correct firing order, The PO may have had a wrong plug wire on the wrong plug or cap, Pull all of plug wires off, and do one wire at a time. You can use a sharpie to lable the wires.
Do you have a CF member that lives near you, maybe you could stop over after work and they could set the timing for you. Hope this helps.
Do you have a CF member that lives near you, maybe you could stop over after work and they could set the timing for you. Hope this helps.
Pro
Joined: Jul 2010
Posts: 545
Likes: 0
From: Jacksonville Fl
I replace my intake, and carb at the cost of $435 to fix my rough idle. But my problem was a leak in my carb. Yours maybe a vacuum leak. And with all those so wonderful vac lines it will be fun.
First thing first, get a timing light, and vac guage.
Get the timing right and block off all vac lines. If your idle improves it one of the lines. Just find which and replace. If it stay the same the look on youtube with this search "how to find a vac leak" theres hundreds of these videos. Pick the one you feel safe with.
First thing first, get a timing light, and vac guage.
Get the timing right and block off all vac lines. If your idle improves it one of the lines. Just find which and replace. If it stay the same the look on youtube with this search "how to find a vac leak" theres hundreds of these videos. Pick the one you feel safe with.
Thread Starter
Advanced
Joined: Jul 2013
Posts: 62
Likes: 0
From: Phoenix AZ
I hear you on budget but borrow or some way get a vacuum gauge and a timing light, running to too far advanced might help the rough but you could get the engine running hotter and pinging, timed right it will run better,
Does that engine have a mild cam?
Put a vacuum gauge on it to be sure it has no leaks, vettes love to have vacuum leaks,
Also could be a little trash in the idle jet.
but borrow or some way get a vacuum gauge and a timing light, running to too far advanced might help the rough but you could get the engine running hotter and pinging, timed right it will run better, Does that engine have a mild cam?
Put a vacuum gauge on it to be sure it has no leaks, vettes love to have vacuum leaks,
Also could be a little trash in the idle jet.
Thread Starter
Advanced
Joined: Jul 2013
Posts: 62
Likes: 0
From: Phoenix AZ
I replace my intake, and carb at the cost of $435 to fix my rough idle. But my problem was a leak in my carb. Yours maybe a vacuum leak. And with all those so wonderful vac lines it will be fun.
First thing first, get a timing light, and vac guage.
Get the timing right and block off all vac lines. If your idle improves it one of the lines. Just find which and replace. If it stay the same the look on youtube with this search "how to find a vac leak" theres hundreds of these videos. Pick the one you feel safe with.
First thing first, get a timing light, and vac guage.
Get the timing right and block off all vac lines. If your idle improves it one of the lines. Just find which and replace. If it stay the same the look on youtube with this search "how to find a vac leak" theres hundreds of these videos. Pick the one you feel safe with.
I found these videos, then I realized I had no clue what I was doing. LOL!
http://www.youtube.com/watch?v=UYGU7...ature=youtu.be
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
Pro
Joined: Apr 2012
Posts: 517
Likes: 2
From: Orlando FL
Sgt. Lets work on one problem at a time. Has the engine always ran rough? You can always block off the headlights and get the engine stright first.
Was the crate engine a long block (complete carb, dizzy and oil pan) or short block (no heads, intake and oil pan) used all parts from the engine being removed. How many miles on the engine, was it raced or abused before you got it?
OK, back to the engine, here is the firing order 1-8-4-3-6-5-7-2
Here is how the cyl are numbered
Try this first, if this doesn't work you can check to see if the Dizzy is timed correctly. You can do this by removing the cap off of the Dizzy and bump th engine over untill the rotor is at the #1 firing position on the cap and rotor, if so check and see if it lines up on your timing tab "0" or very close. This is just a rough way. If all of above is correct, you may have a vacuum leak. With engine running you can spray carb cleaner at the base of the carb and if it smooths out, you may have a bad base gasket on the carb, you can also do the intake as well. Or you could put a vacuum gage on the port and see what you have. But I'm guessing you don't have a vacuum gage, I don't have one either. I hope this helps.
Was the crate engine a long block (complete carb, dizzy and oil pan) or short block (no heads, intake and oil pan) used all parts from the engine being removed. How many miles on the engine, was it raced or abused before you got it?
OK, back to the engine, here is the firing order 1-8-4-3-6-5-7-2
Here is how the cyl are numbered
Try this first, if this doesn't work you can check to see if the Dizzy is timed correctly. You can do this by removing the cap off of the Dizzy and bump th engine over untill the rotor is at the #1 firing position on the cap and rotor, if so check and see if it lines up on your timing tab "0" or very close. This is just a rough way. If all of above is correct, you may have a vacuum leak. With engine running you can spray carb cleaner at the base of the carb and if it smooths out, you may have a bad base gasket on the carb, you can also do the intake as well. Or you could put a vacuum gage on the port and see what you have. But I'm guessing you don't have a vacuum gage, I don't have one either. I hope this helps.
Burning Brakes
Joined: Dec 2010
Posts: 945
Likes: 10
From: Winston Salem NC
The position of the vac advance can looks ok for the time being. You could fine tune it later with a timing light.
I agree with those above. Check the plug wires. Another trick I have seen is to run the car at night with no lights. If you have a bad plug wire or boot you will see it arcing.
Good luck.
I agree with those above. Check the plug wires. Another trick I have seen is to run the car at night with no lights. If you have a bad plug wire or boot you will see it arcing.
Good luck.
Race Director
Joined: Mar 2003
Posts: 11,608
Likes: 780
From: Eustis ( Area 51 Bat Cave ) Fl
On my 69 the headlights still are hooked to the mess of vaccum lines, I have a pinch to close off the line so I can do the headlights and not worry about leaks, as much, I will open my lights with electric poppers when I swap the front clip,
I got too attached to correct timing, a acVW engine for example will "sound" okay and be so off it will burn up.
A mismatched plug wire in many cases would pop and act ugly getting on it, but we never know, when I got my trike the dolt had the coil volts coming from a tail light hot lead.....
I got too attached to correct timing, a acVW engine for example will "sound" okay and be so off it will burn up.
A mismatched plug wire in many cases would pop and act ugly getting on it, but we never know, when I got my trike the dolt had the coil volts coming from a tail light hot lead.....