I have received an email from Mimi Myers who has a 454 with headers and she has been having a big problem with engine compartment heat. Starter heat and burned spark plug cables etc. I sent here the GM techsheets on the Hot Starter problems and Vapor Lock.

I have read about wrapping the headers with special tape. The ads say that they reduce compartment heat as well as retaining the heat with in the pipes which reduces the density of the heated gases thereby allowing more airflow out the exhaust and increasing horse power.

What are your opinions on the subject..

Oh, and please comment on starter heat covers.

http://www.autobarn.net/stheshbyth.html

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Header wrap voids header warranties. It's great for race cars. I would use heat shielding for the plug wires, starter cables, & starter. Thermo-Tec and DEI are just a couple of brands of adhesive backed thermal shielding for wires, and spark plug boots. Summit Racing and Jeg's carry a plethora of this kind of stuff.

Wrap-- Don't know

Heat shields--

Our 25 footer with a 454 gets the starter real warm, when the engine is hot the starter motor acts like it is binding. The coach has a metal plate that attaches to the block and provides a barrier between the exhaust manifold and the starter motor. Even with a new starter motor the metal does not appear to help much.

The blanket you have the link to is something I almost added but because the blanket is conductive and it wraps around the solenoid wires I elected not to use it. I was afraid if it shorted the wires to the solenoid it would allow the starter motor to energize at unexpected times.

In an older posting I found from Bill H he said he has ducted air to the starter motor; I plan to copy his design using aluminum 4" duct.

Timothy

One more thought, on our coach the burned spark plug wires were caused by loose exaust manifold bolts. I wonder if the bolts on the headers need to be re-torqued?

Timothy

[This message has been edited by timnlana (edited October 26, 2004).]

[This message has been edited by timnlana (edited October 26, 2004).]

You absolutely positively need heat shields on the plug wires (on 454's)! If you don't believe me ask Bill H. Oh Boy can I tell you stories on this subject.

Feel free to contact me if you want to know what happens without them.

The big block chevy in a motor home has a serious heat soak problem. It is at its worst when the engine is shut down after a long run or climb. At that point, there is neither air nor water circulation to distribute heat.

It is a good idea to let your engine idle for several minutes before shutting down. It is a better idea to have a big electric puller fan controlled by a thermostat. Mine kicks in shortly after shutdown, and runs for 15 minutes or so, preventing any heat buildup under the doghouse. Even with the thermostat controlled fan, I idle for a few minutes before shut down.

The chevy starter solenoid does not like heat. A heat shield of sheet metal is available from Summit, Jeg's or you local speed shop. I add a little fiberglass insulation on the inside. It is probably a good idea to replace you present solenoid with a high performance one. Be sure you have a spring lock washer (belleville is best)under the nut on the small terminal to keep things tight when the stud gets hot and lengthens, loosening the connection. That is why hot chevies need to cool down to start.

Headers, by virtue of their lower mass, are less of a problem regarding heat soak. However, by virtue of their different location of tubes, they can introduce more heat problems. that is because some of the tubes are closer to this and that than before. This can be mitigated by heat shielding. You can use Thermo Tec on the wires and lines, or sheet metal clamped to the header tubing. Thorley includes a few pieces with their headers, and you can copy or modify the design to make more as needed.

Plug wires should be shielded with Thermo Tec or similar sleeves. I have had good luck with several major brands of wire with Spiral core and silicone insulation and boots. I add Thermo Tec sleeves at teh plug boot end. Champion sells a wire set with porcelain boots, as does Jacob$. Taylor sells an Extreme Service wire set with a five year guarantee.
http://www.flatlanderracing.com/wirestaylor_extreme.html

These are their 409 wires with heat shield sleeves added.

Timothy, since I bought a Raytech infra red laser thermometer gun, I have learned that a duct to the starter only cools the starter under way, when ram air is available. The starter gets hottest after shut down, when a duct does no good. I even took a 4 inch in line bilge blower out of my boat to put in the duct to run after shut down. It was an improvement, but the puller fan ran long enough and hard enough to protect the starter adequately.

Anyone considering a new starter should consider a mini starter. These use a small permanent magnet motor and gear reduction to spin the engine. Their smaller diameter spaces the starter (and solenoid) farther away from the heat of the exhaust. There are several brands available, but use the factory Chevy one, as fitted to later models. The main reason is for parts availability in event of a failure. I made my own heat shield, but there may commercial ones available now.

A right side splash shield pn 15983041 improves air flow under way, as does a duct providing ram air to each side to the engine.

There are special "High Heat" RV plug wires available at Pep Boys, and adding some insulation to the wire would be advantagious.

Wrapping the header will cause the header to erode. If the heat can't get out, it will accellerate wear inside. It DOES help horsepower, since the cooling of exhaust flow slows it down. Keeping heat in helps speed exhaust flow, at the expense of hurting the tube steel header.

Selectively shielding the electrical components is the way to go.

The gains in horsepower from lagging headers is at higher RPM, higher than we drive, and higher than the power band of the tri-wye or long tube header design.

Windsor, do you know what brand hi temp ignition wires those are?