Can a bad intake manifold gasket make my exhaust really loud?

There it is! Time to call - Tom- do you have these?

 

Who is Tom?

 

What specifically is wrong with it? I already wasted $300 on an exhaust manifold that I didn't need so I would prefer to keep this one unless you can give me a good reason why I shouldn't....

 

The intake doesn't look too bad, but yes, it'll be useable with a good cleaning, but judging from the burnt paint and rust showing I'd say that was your noise issue. It's old, what do you expect? Talk nice to one of the guys who has an early Nailhead, they might have a spare under-plate gasket. CARS has the manifold gaskets if your local NAPA can't get them anymore. Or yes, Tom (telriv) more than likely has all of them. Proper engine paint is also available on line, and yes, if you're not a stickler for detail, it is something that with a little careful masking can be done once the car is all back together.

If you want to go a few steps further; - take the 4 bolts that hold the carb on and carefully peel it off. When you do, you'll lose the gasket between the carb and the manifold. Carefully scrape the residual gasket material off with a razor blade. Remove the residual hoses and then take the manifold to your local machine shop/engine builder and get them to "hot-tank" it. That will clean up a lot of the mess. Scrape off any rust and try as much as possible to sand the gasket face on the under-plate as flat as humanly possible. Do not, repeat do not scrape or sand the gasket face between the manifold and the block; - unless there's some dried goop or silicone there, just clean it up as best as you can with a solvent. Make sure that nothing like nuts, gasket chunks or any foreign debris gets into the open ports; - if anything metal gets in there it'll hammer your pistons to death. If anything you know of has fallen in there, you're going to be taking the heads off. If anything, while the manifold is off, loosely stuff some clean rags in the holes to prevent crap from falling in there. But insure that these rags can still be pulled out. But, on any engine, cleanliness is next to Godliness, so try and keep things as clean as you can.

Above all, take your time; - you're doing great! :TU:

 

The engine has 7,000 miles on a complete rebuild so I thought it would look better than that. As far as cleaning, do you mean just around the square hole on the bottom so there will be a tight seal when I put that plate back on? Also, can I make a gasket out of cork or will cork deteriorate because it gets so hot down there? I was hoping to get the car back on the road tomorrow....

 

Interesting to note that the plate already looks like a replacement one, it's of a different metal and looks home-made, and unless I'm missing something, the carb doesn't have the starter switch on it. I'd say the carb is definitely a post-1961 issue or one from a different model. Were there any wires going to the carb? And that choke set up; hmmm...a manual cable choke, definitely not stock, I hate those things because they usually screw up.

The plot thickens...somebody has done some "fixin" to this thing...at this point I would seriously think of taking that carb off just to see if the tin spacer plate is there or what if anything was done to the heat riser. Maybe the holes are already plugged off in it, which might account for the burn-though on the gasket.

I'd try and locate some carb to manifold gaskets first though, the best ones are usually available in rebuild kits. That triangular tab on the top of the car bolted to the air-horn will have a number on it. Use this to get a carb kit, and then have it on standby. If that car is running regular gas, you might need it soon anyway.

 

NAPA has the carb and intake gasket; they used to have exhaust gasket material (that perforated silvery stuff)...just cut a square and some bolt holes. The plate over the hole is not original, but should work if flat. The surface around the square hole needs to be flat and free of pits...use a coarse file; you can build up small irregularities with JBWeld and/or use high temp RTV.
If not salvageable, use a manifold from an earlier nailhead and you won't have to mess with the hole.

 

NAPA had the exhaust gasket material and hi temp sealer. I had to buy a big piece of the gasket material ($21) and used only a 4" square piece so if anyone needs some (for the cost of postage) let me know. They didn't have the intake manifold gaskets so I just reused the old ones. I called my 71 year old neighbor next door and he came over and helped me set the manifold back on the engine and hook everything up. When I started it it was just as loud as it was before. That's when I decided to check the driver's side connection between the exhaust manifold pipe and the exhaust pipe. (I replaced the passenger side exhaust manifold last November.) When I pushed on the exhaust pipe I could see the flange move some so I tightened up the nuts and that was the cause of the loud exhaust. WHAT AN IDIOT!!! I obviously should have done that first and I wouldn't have had to replace the other manifold or mess with the intake. Now it's a lot quieter and all you can hear is the glass packs, which I'm going to remove and replace with mufflers. Thanks again to all those who offered advice and encouragement....

 

Congrats on a job well done. By the looks of the manifold, that plate may have been part of the problem as well and it is fixed now. I've overlooked the obvious myself from time to time, so no need to beat yourself up over it. Just be glad it is quiet and drive it with pride cause you fixed it!

 

Why would they have a hole that big on the underside of a manifold? I don't get it. Can someone enlighten me?

 

Probably part of the process of fabricating the exhaust track under the carb.

 

We all learn from these exchanges...

 

Hooray !!:TU:
Nice Work

 

The only problem is now the manual choke doesn't work. The choke flap thing always stays open even if I push on it hard and try to close it. Any suggestions?

 

Crack the throttle a little and try it again...

 

What does that mean?