newly rebuilt engine is stalling
Thread Starter
Pro
Joined: Sep 2002
Posts: 541
Likes: 5
From: Epping NH
newly rebuilt engine is stalling
The other day, we fired up my newly rebuilt 350 and we are having stalling problems.
When on the road, it has excellent power, but, when stopped it is stalls. The idle is now set around 1,000 rpm. Any lower and stalling is worse.
The engine specs are as follows:
355 (.030 over)
stock 69 SB quadrajet, recently rebuilt by Lars
stock 69 intake
stock 69 "186" heads with 2.02 / 1.60 ss valves
Rebuilt distributer (Lars)
Comp Cams XE 268 H cam
Speed Pro domed pistons - estimated 10.5:1 compression
Scat cast crank and Eagle rods.
Newly rebuilt Muncie M-21
Anyway, we have fired up the car, and have about 15 miles on the new engine. Realizing that things are going to be a little tight until the rings set, etc, I'm prepared to do some playing with timing.
As this is a stock 69 setup, we have disconnected and plugged the vac advance at both the distributer and the carb. Initial thoughts are possible vac problem, but the lights and wiper door seem to work fine. No power brakes or other draws on vacuum.
We are wondering about the springs in the distributer being to light and will try replacing them. Other than running the engine a bit, I am looking for suggestions. Anyone???
Thanks
When on the road, it has excellent power, but, when stopped it is stalls. The idle is now set around 1,000 rpm. Any lower and stalling is worse.
The engine specs are as follows:
355 (.030 over)
stock 69 SB quadrajet, recently rebuilt by Lars
stock 69 intake
stock 69 "186" heads with 2.02 / 1.60 ss valves
Rebuilt distributer (Lars)
Comp Cams XE 268 H cam
Speed Pro domed pistons - estimated 10.5:1 compression
Scat cast crank and Eagle rods.
Newly rebuilt Muncie M-21
Anyway, we have fired up the car, and have about 15 miles on the new engine. Realizing that things are going to be a little tight until the rings set, etc, I'm prepared to do some playing with timing.
As this is a stock 69 setup, we have disconnected and plugged the vac advance at both the distributer and the carb. Initial thoughts are possible vac problem, but the lights and wiper door seem to work fine. No power brakes or other draws on vacuum.
We are wondering about the springs in the distributer being to light and will try replacing them. Other than running the engine a bit, I am looking for suggestions. Anyone???
Thanks
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
sounds like an ignition problem, not sure why the Vac is diconnected, I would have thought it should be connected. Look at run voltage at the coil, if your resistor is flaking out it won't idle.
Thread Starter
Pro
Joined: Sep 2002
Posts: 541
Likes: 5
From: Epping NH
Originally Posted by SIXFOOTER
sounds like an ignition problem, not sure why the Vac is diconnected, I would have thought it should be connected. Look at run voltage at the coil, if your resistor is flaking out it won't idle.
Actually, Lars disconnected the vac last year at a Tunning for beer stop. The coil is a brand new MSD blaster 2, no external resistor.
Race Director
Joined: Sep 2002
Posts: 10,362
Likes: 5
From: San Diego - Deep Within The State of CONFUSION!
"When stopped it stalls?" Can you be a bit more descriptive of the problem?
All the goodies in the engine are great to read about but have nothing to do with this post ...
Not trying to be cruel but we'd like to help!
Your carb was rebuilt by Lars so GREAT!
Have you set it up for the new motor? Did you make any adjustments?
Ignition isn't causing your stalling it's carburetion and/or vacuum leak. VErify that you have no vac leaks FIRST. Then raise the idle speed on the Qjet until it stops stalling. Finally, adjust your idle mixture and recheck timing.
All the goodies in the engine are great to read about but have nothing to do with this post ...
Not trying to be cruel but we'd like to help!Your carb was rebuilt by Lars so GREAT!
Have you set it up for the new motor? Did you make any adjustments? Ignition isn't causing your stalling it's carburetion and/or vacuum leak. VErify that you have no vac leaks FIRST. Then raise the idle speed on the Qjet until it stops stalling. Finally, adjust your idle mixture and recheck timing.
Drifting
Joined: Oct 2004
Posts: 1,496
Likes: 1
From: Lafayette Louisiana
I agree with SanDiegoPaul, you have to adjust the carb and get the timing right. Get a timing light and vacuum gauge. That cam is gonna want 14 to 16 degrees initial. Mine is at 17, but I have 1.6 rockers with the same cam. Hook up the vacuum gauge and adjust idle mixture for max vacuum. Mine idles at about 900 in park and 600 in gear.
Intermediate
Joined: May 2006
Posts: 49
Likes: 0
I have said this a million times, If you rebuild an engine at home then it will be junk. I have worked at an engine rebuild shop and you will not believe all of the parts matching and testing we did as we assembled the block. you can't do the same at home. I would say pull the engine and take it to an engine shop or buy a new crate engine.
Le Mans Master
Joined: May 2006
Posts: 9,993
Likes: 1,136
From: League City Tx
Originally Posted by Vette-73
I have said this a million times, If you rebuild an engine at home then it will be junk. I have worked at an engine rebuild shop and you will not believe all of the parts matching and testing we did as we assembled the block. you can't do the same at home. I would say pull the engine and take it to an engine shop or buy a new crate engine.
You are an idiot.
Burgandy 69, check for vacuum leaks.. That is what causes idle fluctuations and stalling. The vacuum leak may not be at the carb or manifold, it can be anywhere in the car. Just because the wiper door and lights work doesn't mean something else is not disconnected. My guess is its leaking under the carb insulator. Vacuum leaks are a biotch to find in vettes. Set the timing, then set the idle air bleeds although lars probably set them pretty close to start, definetly not lean enough to kill it. Is the car an auto? Make sure its not leaking at the modulator
Racer
Joined: Mar 2006
Posts: 309
Likes: 0
From: Ocean City MD
I am with you ajrothm, vette -73 you are a moron. I remember building my first motor by-myself at the age of 16 and it is still running today almost 20 years later.
Burgundy 69 what are you running for base timing? It sounds like a vacuum leak.
Burgundy 69 what are you running for base timing? It sounds like a vacuum leak.
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Drifting
Joined: Mar 2006
Posts: 1,526
Likes: 2
From: Oak Ridge NC
Originally Posted by Burgundy 69
Actually, Lars disconnected the vac last year at a Tunning for beer stop. The coil is a brand new MSD blaster 2, no external resistor.
OK. Did he disconnect it while tuning? I have not heard of running with the vacuum permanantly disconnected on a street machine...I believe you will have other issues if running it disconnected. You might want to check with Lars why he did not reconnect. Perhaps someone more knowledgable than I will chime in....
My BB has a solenoid which cuts vacuum in 1st and 2nd gear....but allows vacuum advance in 3rd and 4th.
Also, as others have said, check for vacuum leaks around carb base and intake manifold.
Last edited by SmokinBBC; Jun 9, 2006 at 11:15 PM.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
I agree with BBC, I understand why Lars disconnected the vac for tuning, but would have thought he would hook it back up. Check with him
I wasn't gonna call 73 an Idiot, Misinformed, overeager, Drunk, FOS, maybe...
He is a newbie too
73, would you yank your engine ans swap it for a crate because it stalls?
I wasn't gonna call 73 an Idiot, Misinformed, overeager, Drunk, FOS, maybe...
He is a newbie too
73, would you yank your engine ans swap it for a crate because it stalls?
Drifting
Joined: Sep 2004
Posts: 1,307
Likes: 1
From: Milford Haven Pembrokeshire
Well, I have rebuilt many an engine at home - and plan to do my own 383.
Fair enough, the average home mechanic may not have some of the fancy balancing machinery - but there again , is probably dealing with a road engine - not formula 1.
If a pro builder does his own engine at home it must be crap then ???
Fair enough, the average home mechanic may not have some of the fancy balancing machinery - but there again , is probably dealing with a road engine - not formula 1.
If a pro builder does his own engine at home it must be crap then ???
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Me thinks it needs vac can to be connected & working ... it will pull in a little advance at idle ... advance you may need.
Build a motor wherever you wish ... what matter most is capability of mechanic. Mech can have a spit-shined floor & a PC-based inventory & billing ... but if the mech don't know or don't care ... the job will still be crap.
Build a motor wherever you wish ... what matter most is capability of mechanic. Mech can have a spit-shined floor & a PC-based inventory & billing ... but if the mech don't know or don't care ... the job will still be crap.
Last edited by jackson; Jun 10, 2006 at 12:35 PM.
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
A simple test I use when a Vette comes in and stalls alot. Take the air cleaner off, and with the engine idling, cover the carb. with your hand. If the idle picks up, you either have a vacuum leak or the idle mixture is set too lean.