I recently bought a new set of older style CMI Sport Tube headers for an engine build I am doing but now I am a little worried about reversion with the new cam. The CMI's are pictured below. These ones do not use a tail pipe, just 4" exhaust hose to the transom. The cam I am using has a 236/246 duration on a 114 degree cam timing with .610 lift. Any ideas on issues with reversion with that set up? I'd hate to not be able to not be able to use this exhaust but would rather try to sell now before they have been installed if I need to.

It sounds like you have basically a 525EFI cam, so I think you should be ok with those CMI's, but make sure to check for reversion after its in the boat.

I had issues this spring. The cam is .610/.632 236/244 with a 112 LSA and with exhaust with risers that extended to the transom it would consistently pull water back at idle and start running horrible.

A few revs to blow it out and it was fine and with some rpm OK but then as soon as you returned to idle it started pulling water again.

I don't know how much difference there is between 112 and 114 LSA but the rest of the specs are pretty close.

That's interesting you had issues even with a long riser? What exhaust were you running if you don't mind me asking? That is really not that aggressive of a cam.

Not sure about the reversion but I'll bet the top tubes crack from lack of water.

Why would there be a lack of water?

Thinking most of the water would go out the lower pipes

I see what you mean but I would hope that CMI would have had that issue figured out. These are top quality pieces and I have not heard of that being an issue before with CMI's, hopefully I won't have any issues like that.

Is there any difference between old style and new style in regards to the water.

I actually tried 3. CMI E-tops, EMI thunder, Stainless marine. Could not get it to stop pulling water back until I tried my friend's stainless marine that is dry thru transom. I spoke with a local performance shop and they told me that they have had the cam I used work with long risers but to be safe go dry.

I am by far not an expert. Just telling you what I was dealing with..