Dto13

Background on car: bought a 72 cutlass supreme convertible 2 weeks ago. Restored both mechanically and cosmetically 8 years ago. 107k miles since 1972. Under 20k since rebuild. Original 350 block #395558 2. 1972 Heads 7A (A much smaller than 7). Engine vin plate shows same last 6 digits of cars vin (can't see the first 3 numbers/letter). The guy added the w29 442 appearance package when he restored it - 442 hood, grill, badges, front and rear sway bars, but put the paint scheme on only the hood ( no side stripes or trunk stripes). Has MSD 6AL ignition and MSD distributor. Has 4 barrel Holley carb which I believe to be a 650cfm (what he told me). Not sure what intake manifold.

Problems:
1. When driving car runs at good temperature around 180. When parked or in traffic it overheats up to 200. Once went to 230 when parked for 30 minutes and idling ( first day I got the car) . The guy installed a second fan operated by a switch which does help. Soon as you start driving again the temp goes back to normal. This May or may not be related to the second and more serious problem.

2. I always drive with the windows and roof down, but I was just driving with them up and noticed a hissing noise coming through the air vents from the engine bay. I located it coming from the carburetor. This maybe have been happening the whole time and I just noticed it or it may of just started not sure.

I attached pics of engine bay, carburetor, and videos of the exhaust (which seems fine to me) and video of the engine idling with no hissing noise. Then a video of me moving the throttle and the hissing. With heavy throttle you can't hear it only easy throttle. The iPad camera makes it sound wierd but it is a hiss and the noise is from the gas being sprayed against the metal (see in video). I'm new to working on cars and I just want to make sure this isn't bad. The gas is spraying out in the front 2 carb barrels but not the back 2. Is it designed like this and the back two aren't spraying because it's not at full throttle? Or do I have some type of leak? Also is that metal flap supposed to be stuck like that or is it supposed to pivot? Thanks in advance.

Pic 1

Pic 2

videos - sorry couldnt do it on the ipad. had to email to self, access on computer, and convert

MDchanic

Carb sounds normal to me.

You have a problem with inadequate or improper fan, fan clutch, and/or fan shroud.

More pictures would help.

- Eric

rjohnson442

Carb sounds good to me. The amount of air the carb sucks in makes a pretty good hiss sound when running perfect to begin with. As to the back two barrels you will never see those open with you looking under the hood in your driveway. A load needs to be put on the motor in order two open the secondaries,not just revving it.
if your really worried it could be the base plate or base plate to manifold. test with starting fluid while running, spray around the outside of the carb and if the rpm change you found a leak. another hiss noise may be a vac hose thats loose under the dash. see if all the vents function properly and check hoses for cracks.

oldcutlass

With an open element air cleaner, your going to hear air getting sucked into the carb. Check all you vacuum lines and fittings on the manifold and carb for leaks or missing hoses and plugs.

Dto13

MDchanic. appears to be the original fan (not talking about the one he added). i seen some posts on here and did what they said which was: try to move the fan while the car is not running - it did not move at all. And also slowly inserted a roll of newspaper into the fan while it was spinning. it did not slow the fan, just chopped the paper up. what other pictures would you want?


rjohnson442. i did try spraying carb with starter fluid, showed no change in rpms. i also tried the unlit propane torch method, and im pretty sure the torch caught fire and then went right out, but i tried it again and it wouldnt catch. all vents work - its only the 2 floor vents and left and right dashboard, the center dash vents (above ashtray) were blocked for some reason? how can i access the hoses behind the dash?


oldcutlass. i see a couple spots on the carb were maybe something like a plug could be. is there any particular process to determine if im missing a plug etc?

oldcutlass

Yes, there will be a port with nothing connected to it and it will be sucking air until you put a finger over it. Look around the manifold and the front and back of the carb. They should have a hose or a plug over them.

Fun71

Someone correct me if I'm wrong, but I think only the Hurst Olds had trunk stripes. Chevelles had trunk stripes, not 442s.

Dto13

rjohnson442 - tried again with the starting fluid with no change in rpms except when i spray it directly into the top of the air filter the rpms dropped. also retried the propane torch with no affect


oldcutlass - looked around carb at the couple holes on left and right front sides. no sucking. seem to be places for things to screw in (they are threaded inside) although i dont know what would screw in there.


fun71 - i think your correct, just looked at alot of pictures with no trunk stripes. but still missing the side stripes, although im not a big fan of them in the first place so i dont mind

rjohnson442

If you can't find a unconnected or cracked hose then I'd say you're good to go then. Maybe find someone around you with a carburated motor and give that a listen.