Engine Cylinder #8 header glowing red after rebuild?

BigPapiVin · Sep 17, 2021

Hey all!

I'm new here, and I'm sure its been spoke about but I have a 84 fox with a carbureted 87 5.0. I'm a little new to cars and just rebuilt the engine. Stock bottom end with TFS2 cam and gt40p heads. Upon the first start up, we let it run for a minute or so and noticed that the cylinder number 8 header started to glow red and burnt up my spark plug. I'm assuming the timings off as my step father told me the balancer line wasn't matching the TDC which was odd. Is this a problem with the head exhaust valve being stuck open? Or most likely a timing issue?

Thanks in advance!

manicmechanic007 · Sep 18, 2021

Find TDC
You can use a long bolt with spark plug thread 14mm- 1.25
Screw the bolt in about 20 threads
Use the damper bolt to turn the engine over slowly until it stops
Make a mark
Reverse direction and turn the engine over backwards (ccw) until it stops
Make another mark
Divide the distance and that is your TDC
If you do that using #1 plug you will be looking at the actual timing marks and can easily see if the dampner has slipped

manicmechanic007 · Sep 18, 2021

Cherry red is okay
Want to see them all cherry red
Possible intake leak near cyl 8
Fix the plug wire check the timing
Sounds like you have a bit of a hotrod
They run plenty hot
Not real concerned about a header that gets cherry red
When you out and around your first camaro
They will all be cherry red

manicmechanic007 · Sep 18, 2021

The carbureted ones flow more air with a 600 holley than the fuelie motors
I would be more worried about lean
The outside 4 cylinders are leaner than the inside 4 with a carb setup
That is okay and normal
Also is normal for one cylinder to lean misfire first
That cylinder is usually 4 or 8 on a sbf
imho the 84 was the fastest one until well into the 2000's because of the carbureted 5.0 HO
I used to align cop car mustangs at the dealer the 84's would do 85mph in second gear. The fuelie 1985 models would only do 72mph in second gear
When you hit the rev limit the factory processor has in mind... All bets are off...
The Holley however keeps revving higher and higher until the ignition cant keep up

Noobz347 · Sep 18, 2021

manicmechanic007 said:
The carbureted ones flow more air with a 600 holley than the fuelie motors
I would be more worried about lean
The outside 4 cylinders are leaner than the inside 4 with a carb setup
That is okay and normal
Also is normal for one cylinder to lean misfire first
That cylinder is usually 4 or 8 on a sbf
imho the 84 was the fastest one until well into the 2000's because of the carbureted 5.0 HO
I used to align cop car mustangs at the dealer the 84's would do 85mph in second gear. The fuelie 1985 models would only do 72mph in second gear
When you hit the rev limit the factory processor has in mind... All bets are off...
The Holley however keeps revving higher and higher until the ignition cant keep up

This is good conversation but I don't know that it makes perfect sense...

84 Mustangs while being carbed, have a different set of heads, a different cam, intake, pistons, and so on. About the only thing they had in common was the block and crank.

"fuelie" or fuel-injected models didn't start until 1986 and top speed in second gear is a product of gearing and not induction. A fuel-injected Mustang cutout doesn't come around until 6250 rpm. It stopped making power before that.

General karthief · Sep 18, 2021

BigPapiVin said:
Hey all!

I'm new here, and I'm sure its been spoke about but I have a 84 fox with a carbureted 87 5.0. I'm a little new to cars and just rebuilt the engine. Stock bottom end with TFS2 cam and gt40p heads. Upon the first start up, we let it run for a minute or so and noticed that the cylinder number 8 header started to glow red and burnt up my spark plug. I'm assuming the timings off as my step father told me the balancer line wasn't matching the TDC which was odd. Is this a problem with the head exhaust valve being stuck open? Or most likely a timing issue?

Thanks in advance!

Ok, this reads sooooo familiar. Let me look around and find it

manicmechanic007 · Sep 18, 2021

Noobz347 said:
This is good conversation but I don't know that it makes perfect sense...

84 Mustangs while being carbed, have a different set of heads, a different cam, intake, pistons, and so on. About the only thing they had in common was the block and crank.

"fuelie" or fuel-injected models didn't start until 1986 and top speed in second gear is a product of gearing and not induction. A fuel-injected Mustang cutout doesn't come around until 6250 rpm. It stopped making power before that.

The ssp cop cars all had the same gears 3.08 X code and 5 speeds I think the fuelies were out in mid year 85 but no matter

General karthief · Sep 18, 2021

Glowing headers at idle after 5 minutes?

Okay, this kinda scared me. I finished swapping in the Mach 1 springs last night, and wanted to take the car around the block and check it out. (they're f'n awesome btw) and the car has been sitting for about 3 weeks since I haven't had a chance to get this swap done. So I had to jump it cause...

www.stangnet.com

Here's one, there are others.
Now let me get you pointed in a direction.
Since it is a new rebuild, I would check compression, pull all the plugs, squirt a little clean oil into the cylinders, guard against cylinder wash.
Note the compression on each one pay'n attention to #8, there should be very little difference.
A glowing red header tube is not good.

General karthief · Sep 18, 2021

manicmechanic007 said:
The ssp cop cars all had the same gears 3.08 X code and 5 speeds I think the fuelies were out in mid year 85 but no matter

SFI started in 86, there were CFI (central ?? Fuel injection) which kinda looks like a carb and was only marginally better but I'm not sure cfi came on HO engines.

Noobz347 · Sep 18, 2021

manicmechanic007 said:
The ssp cop cars all had the same gears 3.08 X code and 5 speeds I think the fuelies were out in mid year 85 but no matter

The first of the 86 model year cars would have been released in the spring of 1985. I have an 86 GT. It came with 2:73s and has very long legs.

manicmechanic007 · Sep 18, 2021

The fuelie is what I would want
The carb'd ones were hell to start hot
The under carb heat plate made it almost impossible to adjust the fuel mixture
Cool cars though and I have a 750 vacuum secondary on mine
Steel alky needles in the holley That helps keep the holley blues away

Engine Cylinder #8 header glowing red after rebuild?

BigPapiVin

New Member

manicmechanic007

manicmechanic007

manicmechanic007

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

General karthief

wonder how much it would cost to ship you a pair

manicmechanic007

General karthief

wonder how much it would cost to ship you a pair

Glowing headers at idle after 5 minutes?

General karthief

wonder how much it would cost to ship you a pair

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

manicmechanic007

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Engine Cylinder #8 header glowing red after rebuild?

New Member

Stangnet Facilities Maint Tech... Er... Janitor

wonder how much it would cost to ship you a pair

wonder how much it would cost to ship you a pair

wonder how much it would cost to ship you a pair

Stangnet Facilities Maint Tech... Er... Janitor

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