lowvette

I need to check vacuum readings on my engine under load and plan to route the vacuum hose under the hood while I drive. Since the C3 hood hinges in the front, I'm planning to let it just sit closed without latching it down. My questions are..
1. If you've done this, how fast can you safely drive without the hood rising in the wind?
2. Is there a better way to route the vacuum hose so that the gauge is visible to the driver? I don't want to put any additional holes in the firewall.

:steering:

mrvette

IMO there is less hinge loading with hood open then with it latched.....

but just for hell of it, I"d say 60 is about it....I"v done it....

watch the hinge condition at any rate....that damn thing lofts and it's deep doo doo.....

course with it latched the forces must be greater, I"d imagine...

GENE

gerry72

Slightly below subsonic speed. Air pressure under the hood would have to be higher than air pressure on top of the hood. It just so happens that the base of the windshield is a high-pressure area so you should be just fine at any legal speed.

ettev

Push the vacuum line thru one of the firewall grommets and into the car so you have the guage right there with you.

gliot1

What year? On my hood (78) You could run a hose out throught the back end and still latch the hood.

Garys '68

Probably as fast as you want forward. Had mine towed over 70mph on a flatbed with the hood latched.
Dont try this in reverse though!

turtlevette

i got in the habit of doing that a long time ago because the hood was too hard to pop open. I have driven many highway miles at 80+ with the hood unlatched.

Pauld

I've driven mine at around 70mph with the hood unlatched, did this by accident though, forgot to close it properly :rolleyes:

brooksman9

about 60 mph in a 74 camaro. Ask me how I know! :lolg: :lolg: :lolg: :lolg: :lolg:

norvalwilhelm

I did about 130 mph without any latch on the hood. The problem is the hood can vibrate slight giving the impression that something is wrong. It will not rise due to air pressure but passing over railroad tracks can cause it to jump up a few inches.

joe73vette

It's impossible for the wind to do anything but push the hood down. Even if there was a low pressure area above the hood, when it lifted up it would enter the airstream and get pushed back down. Joe

Jughead

I never added latches to my L-88 hood and haven't seen any bobbing yet.

CrossedFlags77

I gone 80+ on the highway with my hood unlatched. No problems at all. :thumbs:

ZL1powr

You can do at least 130 mph without the hood latched although I wouldn't characterize it as safe. I hit 130 before shut down at the drag strip with my hood accedently left unlatched. There was no lifting of the hood just vibration.

munday

just latch one side.

jeaux

what about those holes on the firewall you can pop the plugs on to open your hood? :chevy

Sharky Guam

If you are really worried about it flying up very high, just put one of those elastic bungy cords on it to keep it from going too high. But I have driven an 81 for over a year with no latch and had no problems. It freaks people out though when it jumps up over the bumps.

70 LS1

Yes and No. I lost a hood because it was latched but not bolted on. When the incoming air hits the radiator, which is slanted back, some of it is directed up at the front of the hood. This air pushes up on the front of the hood and if not hinged will blow it right off around 40mph.

With the hood hinged, but not latched this force would do just as you say and push the back of the hood down.

backtrail69

I have gone about 45 with my hood undone on my bImmer, front hinged.

stingray72

I was driving a 67 L89 convert in Florida last year, and the hood wasn't latched, it was overlooked. At 80 MPH it rose up pretty high; high enough that I couldn't see and had to stop.
This also happened to me with my 69 back in the 80's. I had the L88 style hood and it did the same thing, but at around 60MPH. Again, it was overlooked.
I would not recommend driving around with the hood unlatched, but the bigger question is, WHY would you purposly want to do something like this rather than find another way?

George :shocked:


[Modified by stingray72, 12:39 PM 5/26/2004]