My #3 and #5 primary, start to redden when I rev the 305 up. Just started this engine a few days ago after slight rebuild...When they cool off my coating is powdery..Got to get this taken care of right now.. I set the timing at 6* advance with the dist unplugged. Revs and idles good. Wondering if I got burnt valves or something. Going to pull those plugs tomorrow. Anyone ever experience a one- two tube glow? It's a comp 268 HE installed straight up . Adjusted all the valves the same too. ...Damn

 

Carburated ...cc-Q-jet if that helps

 

Being that it's 3 and 5, and assuming no mechanical issues, I'd verify that you don't have the plug wires swapped on those two cylinders.

 

Look closely for vacuum leaks. Glowing tubes can be caused by a lean mixture, creating very hot chamber temperatures.

Since #2 and #8 aren't glowing as well, a mixture problem in that carb bore can probably be ruled out - probably. Since it is apparently isolated to one side of the engine, and any dual plane intake feeds cylinders on opposite sides alternately, a lean condition from the carb itself is not as likely.

Are your headers equipped with A.I.R. fittings and do you have a working air injection system connected? If so, you may also have a rich mixture and excess (unbalanced) air delivery to the center left-side supply tubes.

Just guesses.

 

Also make sure your valve adjustement on the exhaust valves on those cylinders is correct. Hanging open and exhaust valve slightly can cause the tube to get hot and glow.

I know you did it already but check those 2 cylinders again.

 

Rich i have had the same problem for a while. my #5 glows more than the rest but both sides of mine glow. I have had the following checked by mech.
1 timing
2 cam timing and position of balancer
3 valves checked for seating
4 replaced tpi w carb in case of tuning issue

I have not ran a compression check on my engine but im about too. I have an older set of headers on my car that i had jet hot coated. but i can feel the exh temp it is very high.

 

Thanks everyone.. To answer some replies... I checked my plug wire routing and thats o.k. Looked for vacuum leaks and could find none. Vader, I don't have the air tubes or smog pump, but am still running my O2 sensor and everything else expcept EGR. Though I did plug the EGR connector back into the unmounted assembly to clear a check engine light. Decided to pull the sparkplugs and check them over . What I found was that every plug I pulled was mostly white with fine specks, but was blacked on the ceramic near the electrode. So now I'm thinking I'm too lean . Why?..Because upon further engine running in darker light they will all slightly glow, but 3 and 5 seem to lead the way. So what is the next step in getting a richer mixture? Is my O2 working the mixture control solenoid to the max or should I test the solenoid? Is my flow beyond what my cc Q-jet can handle? If so, what mods need to be done to the q-jet? Answers appreciated, thanks

 

The ECM will try to correct the mixture as much as it can within the limits of the rich and lean stop settings. It will modulate the solenoid as much as possible to satisfy the oxygen sensor. If the MC solenoid setting procedure is followed, the mixture should be right. If you perform the procedure and can't get the solenoid to duty cycle at the proper rate, you may need to open the idle mixture screws.

 

Thanks , will do a search to get info on the adjustment. Was searching earlier and found where the "IAB" has something to do with mixture...Is that right?

 

So first I got to do the dwell meter thing, right? If the duty cycles are right, then I need to adjust my rich stop to a greater range? Is the hayne's manual the route to go only to a degree because it is considering stock specs....Geez, I don't know what the !#$% to think..

 

Get a propane torch. Shoot the propane down the carb while running. Make sure your feeding the right side of the carb for the Cylinder in question. If the mixture is lean the extra propane (fuel will richen it up. The glowing will go away.
If it is infact an ignition or valve problem the propane will not help.