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All,
I have a ‘78 base model with 383 stroker, long tube headers, TH-350 and aluminum radiator with electric fan. Engine runs around 200 regardless of the outside temperature or how I drive it. The problem is the under hood heat. Engine compartment gets so hot you can’t lay your hand on the hood or fenders. I wrapped the headers which helped some but it is still too hot. Considering hood or fender vents to let some of the heat out. What say you guys?
Many views or opinions on this topic may come in. Some may suggest removing items off of the engine so you get a better air flow. Because with you having an electric fan...it is not blowing air when sitting still while it is off. So the heat from your engine can just linger there and build up.
I know you wrote you wrapped the headers...but how far did you wrap them. All the way to the collector and then even past it???
My thoughts on this are to try to stop the heat at the source and that is the headers. You can not do much about the heat coming off of the radiator.
As for cutting into the hood and adding vents of some type. I would suggest that you find a used hood and cut into it and make sure that it will do what you want so when you go and cut into your hood and find out it is not helping. You just did not get into a bunch of time and money for nothing.. So the used hood you find would not even need to be a nice hood. Just one that can bolt up..and it would not even need to latch either.
You can put small fans by the fender side vents to push air out, it helps in stop and go traffic.
I was typing when this was posted and this is a good idea.
I would wire it so when I was off idle...the fans would not run due to I would be moving down the road and see how that would work. That way they are not on all the time.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
PC POLICE ANNOUNCEMENT>>>>> I'm sorry to but in, but the Lefties prefer the term, " Timing of insufficient advancement" to be inserted over "retarded" as it gives the engine a complex that may result in a self esteem issue further down the road as the miles rack up. Thanks for you time
Please continue with your regularly scheduled advice
Radiator fan runs with engine off if temperature is above 190. Headers and exhaust are wrapped to where they go through the rear transmission cross member. As for timing, running 12 degrees initial with 36 degrees all in at 3000 rpm. I like the idea of small fans in the fender vents. Will try that.
Radiator fan runs with engine off if temperature is above 190. Headers and exhaust are wrapped to where they go through the rear transmission cross member. As for timing, running 12 degrees initial with 36 degrees all in at 3000 rpm. I like the idea of small fans in the fender vents. Will try that.
depending on the cam I would expect your initial to be in the teens, high teens if you got some decent overlap on that cam. Combined with vacuum advance you should be in the 30’s at idle. Use manifold vacuum for advance if your not currently doing so. See what that does for you.
If you do install these fans ...come back and let us know who well it did for you.
And I guess the engine that I am working and all those 'Lefties' will just have to get over me using the word 'retarded'. I guess the engine will also need a trophy for just being an engine and it can crank up and run.
Good way to monitor your engine bay temp.
I bought a rear view mirror with temp gauge off Ebay and put its sensor under hood against back firewall.
Now I can check engine bay temp at a glance.
Do you have a port for an O2 sensor on those headers? If you are running lean, or retarded, you may be able to detect that and make adjustments to your carb and/or timing. Both conditions will make your exhaust hot.
All,
I have a ‘78 base model with 383 stroker, long tube headers, TH-350 and aluminum radiator with electric fan. Engine runs around 200 regardless of the outside temperature or how I drive it. The problem is the under hood heat. Engine compartment gets so hot you can’t lay your hand on the hood or fenders. I wrapped the headers which helped some but it is still too hot. Considering hood or fender vents to let some of the heat out. What say you guys?
Is your lower front spoiler still mounted on the car ?
Thanks to all for the help.
No O2 sensor on headers - All old school GEN I SBC.
Cam is a mild Lunati Bootlegger with decent overlap but nothing radical.
Original front spoiler has been replaced with a pace car spoiler and a 1 1/2" splitter.
Plenty of air gets to the radiator/engine it just can't get out.
Now that the weekend is upon us I am going to:
Add a little initial timing (from 12 degrees up to about 14 or 15 degrees)
Move distributor vacuum to manifold side
Fatten up the carb
I had a '75 years ago that had the same type of heat issue under the hood.... I would pop the hood (if driving around town at slower speeds) as well as open the head light doors. Alot of hot air would either flow out of the engine bay from the opening in back of the hood or it may have allowed cooler ait to flow in (who knows). The open headlight doors allowed some extra outside air (although not alot) to flow in. I'm not sure how much it helped but it did somewhat....., and at no cost. Good Luck.
I know when I mention this to many of my customers with some serious engines in and they do their own tuning and have problems I often times suggest that they spend some time on a chassis dyno and get the bugs worked out.
Some have take my advice and bring me the sheets back in and show where the changes made increased power and also stopped there other issues due to knowing air/fuel ratios and the other stuff.
This way they can have a 'tune-up' card that they can refer to...and in the winter when it is obviously colder...they go back in and check it again and do any tweaks to the previous tune-up and get a set-up for the colder months that they drive in.
My 73 BB really has engine compartment heat issues as there is no air flow through the engine compartment.
I'm removing the front license plate and bracket and installing a center grille and a better air dam to lift more air.
I'm also looking at making an air dam of some type that will force air up into the engine compartment behind the radiator.
I'm planning to remove as much engine compartment clutter as possible like the smog equipment, going to a smaller a/c compressor and vapor canister. Basically I need to force more air in and give it someplace to escape like the side vents.
Im also looking to raise the center portion of my 73 hood by a couple inches for air filter clearance, remove the cowl ventillation and allow the airflow to escape through the rear hood grille and opening at the rear of the hood where it will be modified.
When I researched headers for my 73 I found a couple articles where they tested heat from headers that were ceramic coated inside and out and the results showed there was a huge heat reduction in the heat emitted from coated headers inside and out over no coating or just coated on the outside.
I also found that short tube headers have less obstruction area on the sides of the motor and amongst other advantages would possibly allow more air flow to the side vents.
I was also looking into small fans mounted inside the side vents.
I found several fans used for electronics bay cabinets that are a good size and can be set up with sensors to activate them at certain temps.
Figuring how to mount them will be something to look at when the body comes off.
06-20-2018, 02:41 PM
Excessive under hood heat
