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Glowing headers, Will not idle

9K views 31 replies 14 participants last post by  455olds 
#1 ·
Several problems with this little edelbrock headed 350. Got it to start up, Doesn't want to idle below about 1800 rpm, Along with both headers glowing red. Tried to get a idea on what the timing is set at, But with it idling so high its not playing nicely. What I'm showing is 15* at idle with no vacuum hooked up. I will have to take another look at it to make sure.


Also the Edelbrock 1406 carb was very nasty before the rebuild, And someone took the choke off the carb before I got my nasty hands on it. Ive tried to turn the idle mixture screws out some, Which seemed to help the idle a bit but didnt fix the problem complely. Any advice on where to go from here? I cant seem to figure out if this is timing related or carb.
 
#2 ·
Glowing headers could be a few things. First make sure you don't have a large vacuum leak somewhere around the carb. Either an unplugged brake booster or some other line.

Next bump up the timing. A glowing exhaust is often a sign of late ignition timing. Depending on the advance springs at 1800 rpms you could have 30 plus degrees of timing. More timing should produce higher vacuum which in turn will richen the idle circuit allowing you to reduce the rpms.

What distributor are you running?
 
#7 ·
Can and lifters are hydro roller from Howard's.

If it is idling at 1800 and the timing only shows 15* that could be your issue. try advancing it and at the same time back the idle down.
Will do this evening and report back.

I noticed that plugging the vacuum back in bumps timing to about 30*, make idle go up to about 2500 and still doesn't want to let me lower the idle. Right now I have the idle screw set to the last 1/4 of adjustment ie almost all the way in. Lowering the idle causes the rom to fall suddly and die. Seems there is no in between.
 
#10 ·
set transfer slot correctly

make it look like a little square.
the more you tighten the idle speed screw the more of the slot you expose. the more exposure the less impact the idle mixture screws have, too much and they will have no effect. use the idle speed screw for fine adjustments, gross idle speed changes should be made with increased timing.

to set this properly you need to remove the carburetor. while you're at it you may want to remove the topp portion of the carb and clean out the fuel bowls and inspect the jets.

also, the gasket has a habit of tearing just around the center where the carb air cleaner stud threads in, i'd replace it or ensure that it is sealed.

check your needles and step up springs. what kind are they? the springs are calibrated to vacuum, the more you have the more spring you can use. if you use a tough spring and you have really low vacuum you may encounter some tuning issues. Edelbrock publishes a chart that covers this info.

ensure tdc between your engine and balancer is accurate.
http://www.crankshaftcoalition.com/wiki/Determining_top_dead_center

sounds like you need more timing to begin with but with your carb outta wack it will be difficult to make timing adjustments. if you're idling fairly high and are using a light distributor advance spring you could be seeing mechanical advance while you thinking that you're checking base timing.
i'd open the distributor to see what springs you're running.

+ $0.02
 
#11 ·
I just rechecked timing. 16* at the closest think to idle I could get 975-1000 rpm. Timing with the vacuum plugged in is at 32*. Again closest thing to idle Tom I could reach was 1250rpm. Trying for a lower rom caused it to die.

I want to mention that the truck wants to diesel out when the key is turned off. It tries to stay running for a second or two. Advice on this matter?

I sprayed a little carb cleaner around the base of the carb and noticed a small vacuum leak. It wanted to rev up some. I rechecked all fittings and carb studs and everything was tight. Might be getting into the carb from the top as air is pulled in. Not sure on this yet. I will recheck this test when the wind dies down a bit.
 
#12 ·
I'd drop it down until it doesn't want to run on when shutting it off. Then put a light on and see where it's at. Also take a look with your timing light, with engine rpm's up around 3000 rpm or more, and see what total timing is when it's all in.
Not questioning your valve lash setting ability, but I'd still double check them after it's run a bit. I thought mine was perfect, but it needed a readjustment to allow it to idle.
 
#22 ·
If you haven't already done so, make sure that the marks on your dampener align correctly with actual TDC.
Glowing headers are usually the result of very lean fuel mixture and/or the timing being way off. Double check your valve adjustment as well.
 
#24 · (Edited)
Ok, Have you adjusted the valves with the engine running since you got it running. If not do so now. It is the best way to adjust the lash. Pull #1 plug and turn engine over until the piston comes up and blows air around your finger. How far is the line on the balancer away from 0 on the scale? Line them up. Do you have a piston stop http://www.summitracing.com/parts/pro-66792/overview/ Remove the distributor. Back the engine up and install piston stop. Rotate engine clockwise until you feel it hit the stop. Mark the balancer at zero, then turn the engine counter clockwise until you feel it hit the stop. Mark the balancer at zero again. Measure the distance between the lines and mark half way. This tells how far your balancer is off. Turn the engine clockwise until the new mark is aligned with zero and drop the distributor in. Install the cap to see where the rotor is pointing. If it is pointing to your #1 spark plug wire fine. If it's not start where the rotor is pointing and wire the cap in the firing order. 1-8-4-3-6-5-7-2. Start the engine and adjust the carb to get it to idle. Set the initial timing at 16 degrees BTDC. Then idle the engine up to 3000-4000 rpms to check the total timing. Start at 3000 rpms and see if it is all in by idling up to 4000 rpms. If you get lucky you will hit 36*. Once you know your total plug the vacuum line to distributor and right side port of the carb. Check the timing at 3000-4000 rpms again and write it down. Here you want to be between 46-48 degrees. Here is a Wiki article to read on HEI distributors. http://www.crankshaftcoalition.com/wiki/Hot_rodding_the_HEI_distributor {Remember after you get it idling spray around the primeter of intake manifold and carb base with carb cleaner to check for leaks.}
 
#25 ·
I haven't recchecked the valve last yet, but will this evening. When I put the motor together I used a piston stop to insure tdc, the kind that bolts to the block deck. I have no doubts that the balancer matches the timing pointer. My main concern right now is how at 1000 to 1200 RPM the passenger side booster or dogleg is dumping a large amount of fuel. I believe I need to go through my carb one more time to ensure that it is clean and in working order. In the process of cleaning the carb again as I type this. Once that is completed I will recheck TDC and go from there along with updates to this post .
 
#28 ·
Ok this evening I checked and reset the floats, Insured that the Valves are correctly adjusted. Still the same problem. The glowing headers have gone away. I just cant get this thing to idle correcly. Its wanting to idle in the 1250-1500 rpm range. I know the weights in the distributor are the lightest set. Base timing with no vacuum is hovering at the 16* mark with 32-34* with the vacuum hooked up.

I ran out of fuel while checking timing so i was unable to check to see what all in was and where it came in at. Any advice on what to check or where to go from here.
 
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