Need Help getting my engine to run right.
Thread Starter
TheCorvetteBen
Joined: Feb 2007
Posts: 4,987
Likes: 144
From: Van Alstyne, TX
Need Help getting my engine to run right.
I have a Chevy 350 in my vette (from what who knows but its anything but fast 
)
Anyways, It was leaking out of the front of the intake manifold, so i decided to stop the leak with new gaskets etc.
It ran great before, and after I got done installing the new gaskets, it now does not want to idle when cold. (But no leaks... one step forward one step back...)
When I first start the car, it takes waaay to much gas to get the darn thing to idle. Once I get it to idle, if I put it into gear, it will die unless I give it a large amount of pedal.
Once I get the car moving, it likes to bog down, almost back firing out of the carb. I have to drive it at least a half mile babying the throttle for it to stop this behavior. It dosnt matter if its warn or cold outside, it will still do all of this.
The wierd part is once I get the engine about 150 degrees, it runs fine, just like it used to.
We have already set the timing etc. What do you guys think that it could be? Vacuum leak somewhere? Idle not set correctly?
)Anyways, It was leaking out of the front of the intake manifold, so i decided to stop the leak with new gaskets etc.
It ran great before, and after I got done installing the new gaskets, it now does not want to idle when cold. (But no leaks... one step forward one step back...)
When I first start the car, it takes waaay to much gas to get the darn thing to idle. Once I get it to idle, if I put it into gear, it will die unless I give it a large amount of pedal.
Once I get the car moving, it likes to bog down, almost back firing out of the carb. I have to drive it at least a half mile babying the throttle for it to stop this behavior. It dosnt matter if its warn or cold outside, it will still do all of this.
The wierd part is once I get the engine about 150 degrees, it runs fine, just like it used to.
We have already set the timing etc. What do you guys think that it could be? Vacuum leak somewhere? Idle not set correctly?
Instructor
Joined: Sep 2007
Posts: 198
Likes: 0
From: Colorado Springs Colorado
Here is a good site to help you with diagnosing what could be wrong with your car. A vacuum gauge isn't very expensive, but it can tell you alot about the condition of your engine. Good luck, and let us know what you find.
http://www.secondchancegarage.com/public/186.cfm
http://www.secondchancegarage.com/public/186.cfm
Advanced
Joined: Nov 2010
Posts: 76
Likes: 0
From: Arlington MA
2 things to check for:
1. Massive vacuum leak
while it is running spray carb cleaner around the manifold edges and any sealing points (carb base ect). That stuff is flamable so be careful. If you find the problem the idle will jump up.
2. Distributor off a few teeth or 180 degrees off.
good luck!
1. Massive vacuum leak
while it is running spray carb cleaner around the manifold edges and any sealing points (carb base ect). That stuff is flamable so be careful. If you find the problem the idle will jump up.
2. Distributor off a few teeth or 180 degrees off.
good luck!
Le Mans Master
Joined: Aug 2001
Posts: 7,804
Likes: 4
From: Standing still with all my might Texas
Cruise-In X Veteran
St. Jude Donor '09-'11
Sounds like an improperly adjusted choke, or a vacuum leak, or both.
I have a vacuum gauge, a timing light, and a rudimentary knowledge of carburetors. I will probably be home doing some work on my vette tomorrow, if you want to bring some beer over I would be glad to take a look at it with you.
PM me for address.
Last edited by Kevin_73; Mar 18, 2011 at 11:11 AM.
Instructor
Joined: Oct 2001
Posts: 106
Likes: 1
From: Erlanger Kentucky
Sounds like you have the vacuum advance hooked to ported vacuum insted of manifold vacuum or a vacuum leak when cold but once everything heats up and expands it seals up. Try the carb cleaner as mentioned above and a vacuum gauige when cold a see if it smooths out as the motor warms up.
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Drifting
Joined: Jul 2009
Posts: 1,534
Likes: 14
From: Dallas-Fort Worth TX
Ben, I am also having some issues, with my carb and idleing. I think I might possibly have a vacuum leak. I did try the carb cleaner spray test, but realized that the over spray or any miniscule amount that finds its way to the carb will surge the idle. Especially on a windy day. I found it to be a difficult method.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Make a foot-high cardboard tube to duct tape to the top of the carb. The overspray won't reach up there!
P.S. I normally use just little, tiny puffs of that stuff pointed right at the area I want to check.
P.S. I normally use just little, tiny puffs of that stuff pointed right at the area I want to check.
Thread Starter
TheCorvetteBen
Joined: Feb 2007
Posts: 4,987
Likes: 144
From: Van Alstyne, TX
Ben, I am also having some issues, with my carb and idleing. I think I might possibly have a vacuum leak. I did try the carb cleaner spray test, but realized that the over spray or any miniscule amount that finds its way to the carb will surge the idle. Especially on a windy day. I found it to be a difficult method.
Im hoping soon ill be able to talk to Mike (mds3013) and we can all have it figured out.
Sounds like an improperly adjusted choke, or a vacuum leak, or both.
I have a vacuum gauge, a timing light, and a rudimentary knowledge of carburetors. I will probably be home doing some work on my vette tomorrow, if you want to bring some beer over I would be glad to take a look at it with you.
PM me for address.
gotta love the forum
Melting Slicks
Joined: Mar 2009
Posts: 3,126
Likes: 15
Looked at Bens car yesterday. I adjusted the choke as described in Lars papers. The car started well but it was around 70 degrees out. Idles well at 1050 rpm cold and 750 rpm warm. I do not think there is a vac. leak. Adjusted idle mixture screws to obtain max. vac. Vac. gauge read 18in. Hg.. Initial timing is set to 12degrees with vac. adv. disconnected. Vac adj. is hooked to manifold vac. port on carb. and increases timing adv. to 26 degrees at idle. When revving engine we noticed that there was no mechanical adv.. Took off dist. cap and the mech. adv. is stuck at the center shaft. Weights move freely but they will not return with the springs due to stuck shaft. I could not move it with small needle nose pliers and did not try too hard as I did not want to damage it. Mechanical adv. is stuck partially advanced at this time. What is the best way to free this up. We did not pull the dist. yet. He plans to chg. the diff. this week. Also the engine shakes at idle but smoothes out with any opening of the throttle. He stated that the engine did this before the intake gasket change. Thanks guys. mike...
Thread Starter
TheCorvetteBen
Joined: Feb 2007
Posts: 4,987
Likes: 144
From: Van Alstyne, TX
So after letting the car sit all day sunday and then starting it up Monday morning, I had no problems with the choke, with it bogging down or anything. It feels 100% different. Thanks again Mike for helping me out and tuning the motor a little bit. No we have to figure out what is to be done with the distributor