Thread: HELP... red hot exhaust manifold

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I have a mild 350 small block in a dirt track car. When the car gets up to temperature (200deg) and I run a few laps at speed(6000rpm) the exhaust manifolds glow red, any suggestions what might be causing this?

Hot exhaust gasses maybe?The old Hiwinders blown Fiat dragster did this and we never thought it was a problem.

Its just done it the last few races, they were fine up until then and no one else I race with is having this problem. I'm just concerned about it causing damage.

Air/fuel ratio is probably fat. If you've ever seen those dyno photos that have the cast iron glowing red, that's what they've done.

so you think I'm running too rich?

yes

maybe do a compression test on the side with the glowing exhaust manifold, it can be possible that maybe u got a slightly burnt or bent valve, and when the cylinder is firing maybe some of it is seaping through the valve. or i guess ur whole exhaust manifold is getting red hot, not just 1 cylinder... maybe from all the vibrations is loosened the mixture screw??? or something.

This may not help, but I used to have a T-bucket with a 2300cc 4 banger.
Tuned it up by feel one day and the exhaust manifold glowed red hot and it ran like a limp dick.
Took it down to the garage and got the timing set and the problem went away. I have my own timing light now too.

Thanks to both of you,but I have tried both of those fixes. I did a compression test on all 8 and each one had and held at least 170. On the timing I was running 36deg advance and backed it to 30. Still the same thing. I talked with a guy the other day who said the plugs I was running may be too hot. I do not know enough about the difference in a hot and cold plug. Any thoughts on that???

So guys - if you got a 350 and it has been worked on before you become the proud owner, how can you tell where the timing should be set?

Much thanks!

Have you pulled the plugs to do a visual… are you running too rich? Your plugs should be a dark tan color. If you are running too rich, you'll have dark brown or black looking residue. Run your car around the track at the 5,000 to 6,000 rpm range, clutch and kill the motor. Pull a couple of plugs and see what you've got. You can get a pretty good reading on your fuel mixture this way.

Dan J

Thanks for the info. I did find the damper had slipped a few weeks ago, and replaced it w/ a new one. I will try the plug check as soon as i hit the track again.

Do you think there is anything to the hot plug / cold plug theory??????

Hot and cold plugs have NO EFFECT WHAT SO EVER on the temp te engine runs!

Grab 2 plugs of diff heat ranges and look at the sparking end. the tip gets hot when in use (duh) and the heat is transferred to the threads to the head and son on to the rad and air. The DISTANCE from the tip to the threads is what controls the heat range of the plug - the longer the distance, the hotter the plug tip will be when the car is running, less distance menas more heat transfer, so a colder plug tip.

If the tip is too hot: it may glow and ignite the mixture without sparking, or it may melt.

if the tip is too cold: it may accumulate deposits and foul. Hense the idea in oil burning cars to run hotter plugs - to burn off the crud.

chris

My 1978 firebird is having the same problem with part of the driver side exhaust manifold turning cherry red. It has a 350 chevy and I just installed a edelbrock performer intake and 600 cfm carb with electric choke. I know the timing is off because after I got it started up and drove around the block, I couldn't get the car over 20mph and when I opened the hood, I noticed the exhaust manifold was cherry red. Could someone tell me how to set the timing? And also, could the linkage setup cause any problems like the above mentioned? I had to by throttle and kickdown adapters to hook the pontiac linkage to the new carb.

Iwould recomend having your manifolds syramic coated I will help with the heat