Hello everyone, I am just finishing up a 305 to 355 swap and i am nearly ready to fire it for the first time. My stock ex. manifolds wont bolt on to the stock exhaust y pipe now for whatever reason, maybe the 355 sits a little higher anyway, will breaking in my engine without the exhaust pipes connected damage it? My old man seems to think it will but i dont see how.

 

I know that without manifolds you will burn your exhaust valves... it probably won't be a problem if your manifolds are properly attached to the heads, but it will be hellaciously loud.

 

Do you have a Hydr. roller cam in there?
if so there is really no break in period so to speak. As far as the lack of exhaust you can possibly burn a valve with the ex. manifolds being short and open especially in cold weather.....I normally fire a new engine long enough to check for leaks and get to operating temp 170-190 degrees.

 

not a hyd. roller cam

 

I broke mine in with just shorty headers on it and with a flat tappet cam. It was pretty loud but I didn't mind. Some of my neighbors and some kids from about a mile down the road came up to see it. The said they could hear it at their house and knew who's car it was.....lol. Then I had to drive it about 30 miles to have the exhaust hooked up. I had to make a turn at a intersection and setting there was a state trooper. I didn't rev it up or give it very much gas, but he smiled and gave me a thumbs up

 

only in Kentucky, lol just kidding, i am from ohio, 10 minutes across the river. Wisconsin cops would call for backup if they heard it

I just ordered some heddmans shorties and they should be her friday so i am gonna wait till then. I am gonna cut my y pipe and put a little patch in there to hold me over for now (with some clamps) but i am gonna wait till i get the headers. I have heard bad things about the heddmans but i also here better low rpm torque with smaller pipes and this is just gonna be a street cruiser so it should work fine.

 

i broke in my old supra open all the way to the turbo, so when it spools its sending the exhaust straight out to the atmosphere. the open turbo sounded sick when it spooled but I had 2 problems while breaking it in open like that. 1. the exessive noise was driving me crazy and 2. the exhaust coming into the cabin and poisening me and making my eyes watery

 

As long as you have a set of headers/manifolds on, you will be just fine. I have heard that running an engine without anything can cause the valves to warp after the engine is shut off because they cool off too fast. But never heard any problems with break in using just headers.

 

How many people fire there cars up with no exhaust manifolds or headers at all? I mean really.

 

i had my 72 olds rocket running with only one exhaust manifold, thats because i broke it in the accident and couldnt get it to shut off, it sounded horrible and no back pressure what so ever, id atleast put a set of long tubes on it and leave it at that

 

Like others have said. If you have the manifolds on it will be fine, just damn loud. Also make sure to remove anything flammable from under the car and keep a fire extinguisher handy.

Ear plugs would be a good thing to purchase as well.

 

The headers wouldnt fit so I just cut my Y-pipe and put a piece of that flexible pipe in there and clamped it down. The car sounds like crap now but it runs!!!

Gotta find new headers now. Are there any headers with y pipe that will bolt onto the factory cat? I cant find anything in the search.

 

i've heard that several header manufacturers say not to use their headers for break in as it could cause problems. something about warping or something

 

from what i've heard you shouldn't use headers for break in if they have any sort of coating like ceramic. the extreme heat of a new engine ruins the coating

 

This^

 

I have run open headers to the exhaust shop before and yes its very loud but usually the cops know whats going on when you are on the street with open headers and will not stop you. if they do if you explain you are on the way to get exhaust hooked up they will usually just let you go, at least around here they will. California may be allot different than NC since thye have so strict rules about everything but I don't understand how they expect you to get the exhaust hooked up short of having the car towed to the station but that may be what they require. here we have allot of cruisins at the 50's restaurant and some of those guys just have pipes sticking out of their hood for exhaust and never have seen them ever pulled over

 

I have broken in several engines with only manifolds/headers attached. I usually go to my exhaust shop and have a pair of short tubes attached to the collector adapters to point the exhaust away in a general "in the dirt" direction and use these for the first break in 20 minutes. Then they will get me to the shop without the flow burning any wires.
Craig

 

I build my own racing engines and no way shape or from would i fire one up with no headers or some type of exhaust manifold and a pipe of at least 18 inches connected to it... i can hear the machine shop screaming at the thought of it lol!!!

 

I wouldnt do that. I want to hear anything and everything with the engine durring breakin. If it is to loud you cant hear a valve or a rod none of that. Even comp,crane and the like say hook up exhaust so you can hear when and if something goes wrong.