Underhood Temperature

[comet_666]

I am trying to do something about under hood temperatures. I was thinking about header wrap but I really don't want to remove the headers. Has anyone used one of those brush on or wipe on coatings for your stainless headers? If so did it reduce the temps under the hood?

https://www.summitracing.com/parts/zyc-11016?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-zycoat-llc&gclid=EAIaIQobChMI-5X-m5ir2wIVQmSGCh0qLAzMEAYYASABEgI8FfD_BwE

[RECHRGD]

I have no knowledge of the product, but at that price, it better work.  No reviews though.  I would think that to do a decent job you should still take the headers off.  I would go ahead and get them professionally ceramic coated......

[HPP]

I've never had a big block mopar that didn't have scorching hot underhood temps; car,truck, wagon, they all have been hot. Coolant temp has always been manageable, but the underhood air is stinking hot, headers or manifolds both.

I have tried a couple different do it yourself treatments. None wiped on, all needed sprayed and headers had to be off and sand or bead blasted, then wiped with acetone. Both did better than paint, but didn't last as long as professional thermal coatings and eventually failed.

[Kern Dog]

I would bet that a car with manifolds would radiate more heat than one with headers. Headers don't store/retain the heat as long.

[comet_666]

The car runs rock solid at 180, but after it sits off for about 10-20 min or so it's hard to start. By hard to start I mean I have to hold gas pedal down and try to keep it running for around a min or so then I can go. I figure if I can lower under hood temps it will help?

[justcruisin]

Best thing is to vent out the heat, pretty hard to do though on a stock hood. Ceramic coating is well worth the effort with headers, as is a phenolic carb spacer to insulate heat from the carb. Lower engine coolant temps help but sounds like you got that sorted. Fuel return line can keep fuel temps down. Sorry don't have any experience with your question.

[comet_666]

I have a fiberglass hood on it now, I may cut the turn signal spots out, see if that helps and I totally forgot about installing my 1 inch spacer...wonder if hood will clear it though..

[cdr]

Thats why I have a fuel return system & a 1970 Road Runner type hood

[c00nhunterjoe]

You have described vapor lock. The air temperature under the hood has nothing to do with it. The hot intake manifold boiling the fuel in the carb does.

[comet_666]

Ok, I am going to order a spacer then for sure before it gets even hotter outside lol
Any other suggestions?

[69wannabe]

Is it a big block? If so do you have the heat cross over in the intake blocked off. Blocking off the heat crossover will help this alot then ordering the cool carb technology spacer kit for which ever carb you are running will also help alot and even wrapping your metal fuel lines with cool it thermo wrap will help too. It's all about keeping the fuel cool these days and it will still heat soak a little bit but it won't be doing what it is doing now. I had the same problem with my 493 RB engine and after doing all of the above it is down to a minimum and so much easier to work with now in the summer months.

[HPP]

I installed a home made cool can between the mechanical pump and carb. A one pound coffee can size painted black, bolted in the corner of the engine bay with a coil of copper line in it. Looked unobtrusive and kept fuel temps down a bit.  Added a thin composite spacer for good measure. Never had hard start issues and could ice the can down when at the track.

[Dino]

Do you have the crossovers blocked? That's step one of getting rid of that heat issue. You can't do much about underhood temps except ceramic coat the headers, but I doubt it's worth it.

[comet_666]

I have Edelbrock RPM heads and an Edelbrock RPM intake, I think there is no crossover in that application ?

[68CoronetRT]

No, the aftermarket heads do not use the cross over.

I too am battling under hood temps right now since I can see whats going into the motor and I know is causing my pinging. I'm thinking about going with some kind of hood scoop to help vent the heat and also add a "cold air intake" to draw ambient air in from the front bumper somewhere.

When I was running a carb, the carb spacer did help with hard starts and dieseling on shut down.

[Dino]

A phenolic body carb would help, if you were in the market for one. For sure I'd get a return line in place.

[flyinlow]

A Buddy has a 55 Nomad . Chevys get hot too. He had four rows of lovers cut into the hood. Works great. looks good on his car.

[c00nhunterjoe]

A cowl hood or cold air intake wont do anything for a car that is not in motion and engine off. Heat soak comes through the engine out. The fuel starts boiling the instant it stops flowing. You can run with no hood at all, and it will still cook off. The coolcarb spacer is your best bet. Followed by making sure none of your fuel lines are in contact with the engine and are routed away from the exhaust. Wrap if neccesary.

[comet_666]

I just bought the cool carb spacer last night... Here is how I have my fuel lines. (might be hard to tell from this older pic)

[c00nhunterjoe]

Fuel line appears to be laying on the block/head and then behind the distributor? I would reroute it. You will be pleased with the cool carb. He is a good guy. Lives near me.

[comet_666]

Fuel line appears to be laying on the block/head and then behind the distributor? I would reroute it. You will be pleased with the cool carb. He is a good guy. Lives near me.

Ohh..I will have to check tonight, I may have secured it to the alternator bracket to get it off the head but I don't remember off hand.  Thanks for the tip!

[firefighter3931]

Ceramic coated headers make a big difference. I checked mine with the infrared heat gun and the surface temps with ceramic coating was 250* less vs. an uncoated (painted) header !!  

Use a phenolic spacer or at least a base insulating gasket. Those fuel lines are too close. Get some insulating conduit and relocate those fuel lines.  


Ron

[flyinlow]

 

Temps idling after a several mile road trip as soon as I could get out and get the hood open.  Black painted headers on the first bend  650*F  Ceramic coated headers on the first bend  375*F

650* will ignite most of the fluids in my car unfortunately.

[Just 6T9 CHGR]

I have my stock HP manifolds Jet-Hot coated inside & out.....going on over 15 years and they still look good....cool under the hood as well

[Back N Black]

I have my stock HP manifolds Jet-Hot coated inside & out.....going on over 15 years and they still look good....cool under the hood as well

Nice engine bay, how do you keep it that clean after 15 years driving?

[c00nhunterjoe]

I have my stock HP manifolds Jet-Hot coated inside & out.....going on over 15 years and they still look good....cool under the hood as well

Nice engine bay, how do you keep it that clean after 15 years driving?

Just a simple wipe down with a rag sprayed with lucas spraywax is all i use. Paint on the 63 is almost 40 years old now and shines better then new cars.

[JR]

 I chased lower underhood temps for over two years before i got them to a manageable amount. Before I started, ambient temps by the air cleaner would climb up to 160-170 at 70-80mph interstate cruising, and climb to 180 plus in 10 min of city driving, which would cause the car to vapor lock and die for 20 min. (Back when I had a carb.)

Before I started working on them, I found underhood temps to be the highest during substained 70 mph+ cruising, slow city traffic, and immediately after shutdown. (If i drove it downtown, stopped for 15 min and went to restart, air temps at the carb would be 190 or more during the summer. The engine didnt want to run with air that hot, and it would cause vapor lock.) Not to mention, the heat made the cabin extremely uncomfortable.

It would run the coolest at a 35-55 mph cruise.

About 3 years ago, i set out to fix it. I bought a lab thermometer with a remote probe, and monitored air temps by the carb.

In order of effectiveness, here's what I did:

Blocked heat crossover in intake manifold.

Replaced original HP manifolds for ceramic coated shorty Hedman headers. (This caused a HUGE reduction in underhood temps, around 20plus degrees cooler at the air cleaner or so.)

Replaced original cast iron intake for aluminum performer. Cast iron retains/radiates heat MUCH longer than aluminum. I want to replace the water pump housing and cast iron cylinder heads next.

Replaced flex fan for original clutch fan.

Moved battery to trunk, which increased air circulation underhood. Also removed all service plates in the inner fenders. And removed every single unnecessary component underhood. (Relocating the battery showed a measurable drop in ambient temperature on the gauge. It was around a 2-4 degree drop or so, I'm not sure if it's attributed to air circulation, or the battery being a heat soak itself, but it made a definate drop in temp on the thermometer when I moved it.)

Installed an aluminum/poly carb insulator. Part no.h1155.  Like this: http://www.coolcarb.com/order-products.html

Routed fuel lines to rear corner of engine bay to get them away from exhaust heat.

170 degree thermostat.

And I'm sure there's more im forgetting. I live in the southeast, and have got the underhood temps at the carb down to 115-120 degrees on an 80 degree day. (I measured a handful of temps from late model vehicles with the same probe, and found most of them stayed just around 120 degrees, so I thought this was an acceptable figure.)

I want a fiberglass six pack hood next, with an insulated base around the scoop. And water meth injection is on the list, too. The car runs MUCH better breathing 80 degree air rather than 120 degree air.

For the guys still running carbs who use their cars in traffic, under hood Temps are a bigger deal now than they were 20 years ago, as modern gasoline boils off and causes vapor lock at a much lower temp than older blends.

I spent a ton of time working on this to make a reliable car, and these are the main things I picked up from it.

[Just 6T9 CHGR]

I have my stock HP manifolds Jet-Hot coated inside & out.....going on over 15 years and they still look good....cool under the hood as well

Nice engine bay, how do you keep it that clean after 15 years driving?

Just a simple wipe down with a rag sprayed with lucas spraywax is all i use. Paint on the 63 is almost 40 years old now and shines better then new cars.

See above....wipe it down every now and then.   Pics hide a lot.....see it in person and its dirty!!  LOL