Vintage Mustang Forums banner
  • Hey everyone! Enter your ride HERE to be a part MAY's Ride of the Month Challenge!

1 - 15 of 15 Posts
G

·
Discussion Starter · #1 ·
I am finished with the engine rebuild and ready to hear and see it run but I haven't got the money for the exhaust system just yet. Is it alright on the engine to operated with only headers or for that fact, no exhaust manifold at all??....and they said there weren't any stupid questions!!
 
G

·
Discussion Starter · #2 ·
As far as I know it is ok to run it WITH headers or manifolds. I would not run it for 1 second without headers or manifolds.
 

·
Registered
Joined
·
5,205 Posts
You're right cradskatr, you WOULDN'T run it for 1 second without headers or manifolds - the valves would collapse or burn.. Really putting a stranglehold on your project!

You CAN run the engine without pipes with HEADERS but I would NOT advise doing so with exhaust manifolds. This is because the flame might cause a dangerous condition unless it exits past at least the starter, which most headers do!

Save yourself a LOT of headaches and do not run the engine without an exhaust system. And remember, Flowmaster mufflers aren't the only ones that sound good on these motors. /forums/images/icons/smile.gif
 

·
Registered
Joined
·
916 Posts
Definitely do not run it without some sort of exhaust. Doing so will destroy your valves.
 

·
Registered
Joined
·
391 Posts
Well, This raises a dumb question from me.... Why does running a car without a manifold or headers destroy the valves?
 
G

·
Discussion Starter · #7 ·
With the engine in the car it would not be a good idea to start it without manifolds, cast manifolds would be alright if as another post said if they do not put exaust on things that shouldnt get hot. Open headers are fine you can run them as long as you and your neighbors can stand it.
The problem with the valves is that when they are hot and they get cold air on them they can warp and not set on the seat correctly. This has the most chance of hapening with no manifolds but unless its cold it proably wont cause any problems. We run a diesel shop and we have started tractors without manifolds for a short period of tim with no problem but the exaust was not blowing on any thing and we were inside where no extreme tempture change could cause valve problems.
So put your headers on an make some noise!!!!!!
 

·
Registered
Joined
·
313 Posts
I was told that the short path for air to reach the exhaust valves with no headers or manifolds would cause the valves to distort or warp from cooling too fast when the engine was shut down.

I've never tried to see if it was true, though /forums/images/icons/wink.gif
 

·
Registered
Joined
·
391 Posts
Thanks. I was just curious. I don't think I care to try it to find out either.
 
G

·
Discussion Starter · #10 ·
It can happen but if the engine is only run for a short time and it is not where cold air can get to the ports it won't cause any problems.
We live in western Kansas we have a lot of wind and where I have heard of this hapening was my father and his buddies put straight pipes on their flatheads and in the winter if you parked the rear to the wind after running it hard then they sometimes had a valve warp.
Remember most Harley's run straight pipes and they are very short and you don't hear of them haveing many problems.
The concern here may be more the fact that if this engine hasn't been run of backfires or other problems that hapen on the first start up.
I don't think that if it's inside that starting it with no manifolds would hurt it I would't do it in the car and if I did it on an engine stand I would't do mor than hear it run and shut it off.
 

·
Registered
Joined
·
795 Posts
The valves are heated by the engine's combustion. Without a manifold or Headers, cool air may be pulled back into the heads and make cool spots on the valves, which could cause the valve to burn or worse, break.
 

·
Banned
Joined
·
925 Posts
We used to run a Hemi on a stand with just open exhaust ports. Later put the same engine in a 55 Chevy and drove it from Houston, TX to California and also drag raced it alot - no problem. It was real cool to run it at night with those blue flames popping out of both banks!
Ever notice how short the exhaust stacks are on a P-51, P-40, etc? Maybe we were just lucky.
 

·
Registered
Joined
·
1,767 Posts
Those P-51, P-40's were designed with short life spans due to war. Normal protocall would be to "stage cool" the engines. sudden descents could shock cool the engines but water cooling and cowl flaps reduced the problem. Once the planes landed they were generally already cooled from reduced power descents. Tolerences are much looser to account for different themal cylcles of the different metals in the engines. They burned a lot of oil.

Burnt exhaust valves are common on Air cooled VW's with exhaust leaks especially when cheap mexican muffllers were used instead of german.
 

·
Registered
Joined
·
10,588 Posts
no exhaust manifold at all??

I remember, as a kid, building a B/S engine and running is on alcohol with no muffler...lotsa fun...*G*

Just be sure to use high heat paint on the inner fenderwells and keep wiring and plumbing clear...hehehe

Seriously, feel free to run open headers as long as the local cops and your neighbors don't mind. I prefer to fire new racing engines with mufflers mainly so I can more easily hear any funny noises they might be making.

Good luck on the startup!
 

·
Just some guy
67 coupe, 69 Sportsroof, 86 hatchback
Joined
·
21,485 Posts
I always use manifolds at the very least. Be careful, I once set fire to my front yard starting a new engine with just headers alone .
I agree with Camachinist, it's a heck of a lot easier to troubleshoot a new motor without a lot of loud exhaust.
 
1 - 15 of 15 Posts
Top