I have several revos, a 2.5, 2.5r and a 3.3. I just put a header on the 3.3 that has a spring instead of the screws since it is such a pain to remove with the screws. I left the little orange rubber washer on the motor and added the black washer that came with the header. Seems like I have an air leak now with the set up. When I am on the throttle and let off the motor revs up then goes to idle. I know this is an indication of slight lean and think it may be from the header. Has any one else added this style header with the same issues?

I put a small hose on the stinger of the exhaust and blew in. There is a TON of air coming out where the header meets the head. I am do something wrong with the install of the header/spring mount??

How loose or tight does the header fit on the exhaust port of the motor? I ask because most spring headers I've seen are kind of universal fit and use a double seal exhaust gasket and would fit very loosely on a Traxxas engine that was only using an o-ring. Traxxas O-ring forms a seal on the inside of the header, while typical exhaust gaskets also seal the face of the header, two sealing surfaces.

The link shows a typical exhaust gasket with double sealing surface.
http://www.amainhobbies.com/product_...e-Seal-Round-2

It seems fairly loose.....not sure how the setup is able to seal.. Those in the link however seem like they would be MUCH better. I wonder if I could get those to work on the revo.

I know there is an issue as I destroyed my 3.3 engine last week with this header. The connecting rod SPLIT right down the middle. I had to get another engine for it.

The rod splitting down the middle is typical traxxsucks. It's main reason for doing such is too high % nitro or running the wrong head shim. Pre-det is typically the cause but can happen if there was not enough back pressure from a leak or the wrong plug heat.

What happens is the pistons wrist pin is slapping down on the rod from pre-det before the crank pushes the rod to TDC. Lots of stress for a traxxsucks engine!

That and the rod's in those engines are recycled cheap aluminum that are used in the traxxsucks 2.5 engines as well, doesn't help any.

Not sure about other failures but this one was my fault. It was after the new header and the truck seemed so much faster. I was chasing the lean condition knowing it was not right. No matter how much fuel I gave it, it just seemed to get leaner...... Once it shut off I hit it with the temp gun and it was 298*.

Running 20% fuel with the right plug. 99% sure it was the exhaust header that led to my problem