Header wrap question

[Jeff Berk]

I'm having overheating problems if my car sits in a traffic jamb or between heats when I previously did autocross. I've reestablished a fuel return line to replace the deadhead system installed by a PO and did some other minor changes. I don't want to add hood vents. 

I hesitant to wrap the header and exhaust due to possible overheating the exhaust and trapping moisture but I found a product by Termo Tec. It wraps loosely around the header so it likely will not trap moisture and heat as much as a tight wrap tape.

Does anyone have an opinion on this product?

https://www.summitracing.com/parts/the-14004#overview 

[Jeff G 78]

What year is your Z?  Is it a 240?  If so, try what worked for me.  I struggled for years with vapor lock while racing and NOTHING helped until I removed the heat coming through the brackets that support the fuel rail.  In 10 minutes, you can do a trial and it's reversible just as easily.  It costs about $10 in hose, a fitting and clamps.  Replace the supply hose between the fuel rail and the chassis supply tube with a hose long enough to reach the front carb.  Install a T fitting and run one hose off the T to the front carb and another hose to the rear carb.  Finally, clamp a small pair of needle nose Vice Grips to the fuel return hose between the fuel rail and the chassis return pipe.  Now go run the same route/Auto-X or whatever used to cause the issues.  

In my case, it was a 100% cure.  I had previously tried everything including header wrap, extra heat shields on the header, carb bowls, fuel rail, etc, propping the hood open, electric fuel pump, no fuel return, etc, etc.  The dead headed fuel system helped a little as did the electric pump, but overall, they didn't help enough to bother.

Even if you have a FI 280Z, the same thing might be causing the heat issues.  Unbolt the fuel rail from the head and isolate the rail with ceramic or other non-conductive spacers to keep the heat from transferring to the rail from the head.

[Mark Maras]

10 hours ago, Jeff G 78 said:

What year is your Z?  Is it a 240?  If so, try what worked for me.  I struggled for years with vapor lock while racing and NOTHING helped until I removed the heat coming through the brackets that support the fuel rail.  In 10 minutes, you can do a trial and it's reversible just as easily.  It costs about $10 in hose, a fitting and clamps.  Replace the supply hose between the fuel rail and the chassis supply tube with a hose long enough to reach the front carb.  Install a T fitting and run one hose off the T to the front carb and another hose to the rear carb.  Finally, clamp a small pair of needle nose Vice Grips to the fuel return hose between the fuel rail and the chassis return pipe.  Now go run the same route/Auto-X or whatever used to cause the issues.  

In my case, it was a 100% cure.  I had previously tried everything including header wrap, extra heat shields on the header, carb bowls, fuel rail, etc, propping the hood open, electric fuel pump, no fuel return, etc, etc.  The dead headed fuel system helped a little as did the electric pump, but overall, they didn't help enough to bother.

Even if you have a FI 280Z, the same thing might be causing the heat issues.  Unbolt the fuel rail from the head and isolate the rail with ceramic or other non-conductive spacers to keep the heat from transferring to the rail from the head.

@jalexquijano

[Jeff Berk]

Mine's a '74 260z with a modified 280 engine, round tops, MSD ignition. I did have vapor lock problems early on. A PO had removed the fuel rail and ran the fuel to a low-pressure regulator=> fuel log => separate hoses to the SU round tops. No return flow. I changed that to a simple fuel rail made from an extruded off the shelf part and ran hoses to the two SUs and a regulator. The regulator sent excess fuel to the tank so as to keep a steady flow of fresh (cool) fuel to the SUs. I installed cork gaskets to reduce conductive heat transfer to the rail from its attachment points on the engine. 

I am assuming that I solved the vapor lock issue now but I'm concerned that my temperature gage is climbing while stopped in traffic. 

[Racer X]

1 hour ago, Jeff Berk said:

Mine's a '74 260z with a modified 280 engine, round tops, MSD ignition. I did have vapor lock problems early on. A PO had removed the fuel rail and ran the fuel to a low-pressure regulator=> fuel log => separate hoses to the SU round tops. No return flow. I changed that to a simple fuel rail made from an extruded off the shelf part and ran hoses to the two SUs and a regulator. The regulator sent excess fuel to the tank so as to keep a steady flow of fresh (cool) fuel to the SUs. I installed cork gaskets to reduce conductive heat transfer to the rail from its attachment points on the engine. 

I am assuming that I solved the vapor lock issue now but I'm concerned that my temperature gage is climbing while stopped in traffic. 

It seems you are having two separate, although somewhat related troubles. 

The vapor lock, which you say has been resolved.

The cooling system isn’t performing well. 

So I have to ask, what is the age and condition of the cooling system? How long has it been since it was serviced? I don’t mean how many miles, but how many years? What do you have for a radiator, OEM style brass, or aftermarket aluminum? When was the system fully flushed and the coolant replaced? Is the thermostat performing as it should, and have you tested it to see if it is?

 

 

[Jeff Berk]

Thank you for your help Racer X.

The radiator was replaced with an aftermarket aluminum unit in early 2017 just before I purchased the car. I flushed the cooling system last week after noticing the temperature issue appeared to still be with the car. When I refilled the radiator I noted that the coolant in the radiator would begin to circulate after the engine began to get hot. This suggests that the thermostat is opening when the engine heats up. 

Maybe the car is fine now. I'm thinking I should try an autocross in July and see if I can complete it without having to pull off to the side to cool off so I can limp home. 

[Racer X]

You're welcome.

One thing I didn't mention, the fan. Is it the standard clutch fan, a fan with no clutch, or an electric fan?

Edited June 28, 2023 by Racer X

[Jeff Berk]

Dual electric fans connected to a thermostat, no clutch fan. There is no fan cowling. The fans are attached to an aluminum frame that is mounted to the radiator.

Edited June 28, 2023 by Jeff Berk

[Racer X]

37 minutes ago, Jeff Berk said:

Dual electric fans connected to a thermostat, no clutch fan. There is no fan cowling. The fans are attached to an aluminum frame that is mounted to the radiator.

And you are certain they are coming on when needed?

[cgsheen1]

That's too bad, stock clutch fan and shroud is a better way to go.

That being said - I've had a few radiators now (stock,  stock 280, champion aluminum x 2) and the absolute best is my current Koyo Radiator.  Awesome design, uses two lower radiator hoses (trim one to fit the upper) cools phenomenally.

Mine: Early 260Z (so 240Z style radiator core support), L28ET, intercooler, stock clutch fan, no shroud (should try to make one someday...), Factory A/C converted to 134a, Phoenix Arizona, Phoenix Arizona, Phoenix Arizona, daily driver (I have to take it to the shop...). Doesn't overheat in the 110+ degree temps of rush hour freeway or stop-and-go on surface streets with the A/C screaming (Kia blower, Hayhurst Ultra Heaven center duct).

And, yes I wrapped my header and down pipe back to the CAT. Not so much to lower under hood temp but to help cut cabin temp as well. I don't quite understand the Water and Rust worry as even if it got wet the exhaust temps would melt that away in a heartbeat and how's it gonna get wet again? But then, we don't have that particular problem here...

Edited June 28, 2023 by cgsheen1

[Racer X]

23 hours ago, cgsheen1 said:

That's too bad, stock clutch fan and shroud is a better way to go.

I use an electric fan on a 280Z 4 row brass radiator in my race Z, never had any trouble keeping it cool. I do have to run an oil cooler though, or the oil temp will get way too high, but I needed it even with the stock fan and fan clutch with a shroud.

Edited June 29, 2023 by Racer X

[siteunseen]

280 belly pans are still available and help keep the air flowing through the radiator then over the motor.

I can't afford one for my 240.

My 280 pulls air like crazy with a ZX full shroud and the OE pan on the bottom.