How can anyone drive a 460 with open headers...no exhaust? I just finished doing a build on my 75 f250 and...oh...my...god!!! Currently I have no exhaust connected to the full length headers, just 3" collectors and loud does not even begin to describe it.

How any one drive their vehicles like this without going totally deaf?? It sounds like an alcohol burning drag car. My friends noisy harley is quiet compared to the way the truck sounds right now.

I will be installing dual exhaust shortly...

 

You said it! During a break in college, I volunteered in my high school's auto shop and set up a few engines on test stands, and most of the engines had open exhaust. Yes, it will wake the dead.

Now I volunteer once a month at an auto shop where we provide free labor for people in need, and last year I went out in the parking lot to bring a car down into the shop to work on. I started it up and just about jumped out of my skin - the shop manager somehow forgot to mention that the catalytic converter had been stolen out of it, and it had open exhaust right under the driver!

 

This is also VERY BAD practice. You run a high risk of warping your heads if you run without an exhaust system of some sort.

If you warp your heads it will require removal and milling the heads to even out the surface. I think the going rate is well past $1,500, maybe even into the 2's

Not a good idea.

Jim Henderson

 

I have heard of burning an exhaust valve but how does head warpage occur?

 

I've run exhaust stacks (open headers) on my 460 ski boat for 20 years and never had a problem with warped heads OR bent valves. All my buddies that have V-drive boats do the same. No problems yet......

 

I ran my 89 grand marq 5.0 with only manifolds and about 3 ft of pipe each side for thousands of rumbly miles without incident. Young and naive at the time but perhaps also lucky.....?

 

In '96 I built the ******* (OK, it was a fairly mild build, but the car ran a 13.75 @ 101) out of a '74 truck 460 and put it in an '78 LTD II I had at the time...I went with cutouts in the exhaust for the dragstrip. I can STILL remember the poo-eating grin on my face the first time I took the caps off the cutouts, and the ONLY thing I heard was the engine running...sounded like a top-fueler to me!

It's 15 years later...would I run cutouts on another 460? Hell, yeah...except now, I'd wear earplugs...

Pat

 

I have heard of people that did not run a header or exhaust manifold that caused a burnt valve from sucking in cold air. Open headers are used all the time in racing. Depending on the header outlet and routing, most times it is louder for people outside of the car, than inside. But what some people will do is run some turn-downs / turn-outs on them to move the noise away from the driver.

 

head warping occurs when ther is NO exhaust system or just the old cast iron "log" style manifolds. The long headers or even a 3 foot pipe seems to slow down the flow of cold air back up into the heads after shut off. The rapid cooling is what warps the heads. It isn't much but it can be enough to cause problems. Rapid cooling causes the heads to contract unevenly as it cools, so it warps.

It also requires the heads to have been heated up to normal operating temperature say a freeway drive several times for adding up to a few hours. Short runs don't really heat up the heads enough to cause a problem with the thermal changes. This is what an ooooold Car and Driver magazine said way back, and it follows my experience.

I had this experience back in the early 70s with my 383 Dodge engine. I thought it was cool to run with the exhaust pipe off and just blasting out of my cast iron manifolds. My boss, an old dry lakes racer in the 40s/50s said that was a bad idea.

I think I drove the car this way for a week , say 30 minutes at a time. After that I had some issues pop up that I forgot what they were(maybe exhaust in the coolant??). The shop I took it to said yup heads are warped, I think they were off something like 10mils, that is about 2 sheets of paper. It could have been worse if I had driven it hard or longer. BTW, this was a shop that I did trust at least with basic engine issues. Cost a$100 to get the job done. That was back when I was making $2/hr so it hurt and lesson learned. This issue started my long journey down the road of hot rodding my car.

So yes warping can occur, but short runs without exhaust probably won't do much damage, it is the hard or hot runs and quick cool down that does it.

Jim Henderson

 

I put headers on a 302 when I was 16. I had to drive it 35 miles to the exhaust shop to get the pipes put on. I thought it was awesome!!!... ... for about 5 minutes. The guy at the exhaust shop could have charged me whatever he wanted to get that thing quieted down.

 

It is pretty obvious none of you have ever driven a race car or especially a drag car. There is reason NASCAR dumps the exhaust out the right side of the car. Mainly so their drivers don't end up deaf, but it makes the crowd happy too.

 

I used to race a 1966 Shelby GT350 with exhaust dumps just ahead of the rear wheels. My friend and I found out that earplugs were good for 2 seconds a lap on our SCCA Solo II course. Loud didn't begin to describe it!

 

I install headers on my 97 F250 with a good ol 460 and I was 30 miles from town after I did my install. Those 30 miles were the most fun/ deffening miles I have ever driven. I drove around town a bit with open headers and I'm pretty sure I got reported because about any person I knew, I had to rev it up for them.