rust spots in exhaust ports of head
 

Took my exhaust manifolds off today to replace my port engine starter and noticed some rust spots in the exhaust ports of the head. I pulled all the plugs and they are dark tan with no signs of rust. Twin 509 500 HP
Boat ran great last year. Could it be condensation on cool down or slight reversion? EMI exhaust with short ss risers and silent choice. My cam is a crane 551/534 lift 226/234 duration and a 112 LSA. I know the 112 LSA is borderline with short ss risers but that's how it was built years ago.

Thanks

its Okay, Id say condensation from sitting over the winter

...Boat is garage kept but does get down to 30 degrees at times. Thanks for your reply

How bad? This is what reversion looks like

http://33outlaw.zenfolio.com/img/s5/...73381563-3.jpg

Thats the top of the port

I would say 75% less than that...rust spots not together and no errosion

rust spots in the exhaust port almost always a result of reversion.try turning your idle speed up a little if you can.also don,t idle in gear long if you can help it.

sometimes a small amount of reversion won,t make rust,just white spots in the port.

Doubtful with the exhaust your using but I'd ck for cracks in them also as long as you have off. They all seem to be that way on that bank or just one. Also you ck other side?

I'll post some pics tomorrow..Last summer I turned down the idle to help save the cone clutch (Bravo1). I was getting a loud clunk while shifting into gear. After lowering the idle clunk sound reduced..
Fix one problem Gain another...As I said previously the plugs are perfect. 3 years ago I had a head rust out on several ports. The plugs all had rust on them sitting over night. This time no rust

An option you might consider is to the leave your idle low for shifting only and then move the RPM up when in gear.

just hard to keep these things from doing that no matter what it seems...

These are photos of both sets of heads from both engines. They all seem to be pretty much the same



http://i1071.photobucket.com/albums/...psiymy9dgy.jpg

http://i1071.photobucket.com/albums/...psblmrltoo.jpg

http://i1071.photobucket.com/albums/...psgfqm2hox.jpg

http://i1071.photobucket.com/albums/...pscsiqp8z5.jpg

http://i1071.photobucket.com/albums/...psprnykxjr.jpg

that is reversion,i am 100% sure.

How bad of reversion is this ? What can happen from this? I know the remedy (extend the pipes longer so the water comes out father away) but I like the silent choice. Its been this way since I got the boat back in 2008. The exhaust manifolds were pretty clean by the ports. Dark exhaust stains only except one port looked like # 7 cylinder had some white residue. If it was reversion wouldn't there be some kind of water stain inside the SS elbow and the aluminum manifold.
Any other solutions?

smaller cam.

The face or gasket surface looks pretty rusty on some of the ports .could have been a minor exhaust leak leading to this as you have been running the same setup for this long. Definitely test for any leaks and downstream flappers as well.

I don't think you will ever stop this, looked a many and all have it to some degree, when you shut engine down, water drips into exhaust, as pressure bleeds off sits there, the heat from the engine seems to draw that moisture back to it....seen stock low H/P cam motors show same signs to some degree...

Thats not ideal . And everyone ,myself included loves the sound of a lopey cam at 800 rpm idling through the no wake zone and idling up to the cove . A radiator pressure tester with cone adapter and a tub of water will get you a quick test of manifolds and risers and make sure you have a thermostat in there it can help roll back dump water flow at idle and keep moisture damage in check. This would be a great time for a leakdown test too .if manis are still off

The manifolds and risers are only 4 years old. EMI's. There is no sign of water leakage inside the manifolds or risers. No stains.. After each use i run my engines on a garden hose to flush out any salt water from the block and manifolds. I remember years ago I had a Gil exhaust setup on another boat and between the riser and the manifold was a piece of metal called a terbulator. This was supposed to catch and burn off any condensation from the pipes on cool down without letting the water down to the motor. Gil is the only exhaust setup i've seen this on. My EMI's don't have this. SO on cool down the condensation in dripping down into my manifolds

Possibly??

Could be but you've got me planning on pulling my sm and having a close look!

When I was removing the manifold bolts some weren't tight. I never heard any leak noises though. Why would a leaky gasket cause this?

My thought would be if you have less exhaust pressure due to a leak water has a better chance to revert, just a thought, definitely not an expert on this.

Looking at these photos I would think if it was reversion the rust would be a lot worse than the pictures show. The rust would be more concentrated .I would thinks its condensation on cool down or running it on a garden hose. Last November 2014 It was cool outside 50's and I ran it on a hose to fog it. After fogging the engines I put the boat away for the winter inside my garage. The engines were close to operating temps of 150-160. Cold water in the manifolds and risers and heat from the cylinders during cool down has to condensate IMO. I'm not going to worry about it..Back together it goes today... Its been this way for years and runs great

Thanks for everyone's input

Have you looked at your bores with a borescope. If not try an borrow one or purchase or pull a head on the worst side. Something just seems strange. I just can't imagine your cams causing any issues but then again....

Now that your aware of it you'll more than likely isolate the problem.

Or you'll put it back together and try and forget you ever pulled exhaust,

Or put dry pipes and and once again solve one problem and create another.

Good luck and keep us posted on any new findings. Call emi or Hardin marine tomorrow and see what they say.

Could very well be reversion issue but my gosh I would have to go back and look however if I recall they looked similar to 454/420 hp cams.

Condensation.

Next time you winterize or run on the hose maybe cut off water supply just for a second or two and crack the throttles before storage.

I plan on calling Eddie Marine tomorrow and forward some pictures to them. If you look back at the begining of these posts there are 2 photos that someone posted of reversion. The rust in those pics are concentrated in one area of the port. Mine are a bit spread out like it was a mist of water not water itself.

This is the first time I ever heard of silent choice setup ever causing a reversion problem. ;)

Its not the silent choice, its the cam i;m using with the silent choice

Are you sure those are the correct cam specs???? Don't know of a Crane with those specs. Flat tappet or roller????



Bumping up the idle about 100 rpms will help some.

Thanks I'll try that. Here are my cam specs.a few numbers off from my original post



Crane Cams 134241 - Crane Cams Hydraulic Flat Tappet Camshafts Details

Big Block Chevy 396-454ci 1967-95

Notes:
1980 and later engines should use 271-96801 springs and 271-99957 retainers at an assembly height of 1.800".
Good mid range torque & HP, fair idle, moderate performance usage, mild bracket racing, auto trans w/2500+ converter, good w/plate or manifold nitrous system, marine applications; primarily used in 350+ HP mildly modified engines with free- flowing above water exhaust systems for performance applications, responds well to improved cylinder heads. 3200-3600 cruise RPM, 9.5 to 11.5 compression ratio advised. Good w/centrifugal or Roots supercharger, 10 lbs. max. boost w/8.5 max. compression ratio advised.

Grind Number H-286-2 (Replaces CCH-286-2)
Operating Range 2400-6200 RPM
Duration Advertised .286°/.296°
Duration @ .050" Lift 226° Intake/236° Exhaust
Valve Lift with 1.7 Rockers .534" Intake/.553" Exhaust
Lobe Separation Angle 112°
Max Lift Angle Intake: 107° ATDC
Exhaust: 117° BTDC
Open/Close @ .050" Cam Lift Intake: 6° BTDC (opens)
40° ABDC (closes)
Exhaust: 55° BBDC (opens)
1° ATDC (closes)

How much room do you have from the end of your riserto your silent choice I would weld stainless extensions onto the inner exhaust portion of your risers. Sometimes a few inches can go a long way.

fountain35,silent choice and eddie marine manifolds are the worst for reversion.i know you don,t want to hear that but it is what it is.silent choice and your cam will revert at low rpm,s.believe me,it is not condensation,sorry,

I ran that cam in a hopped up 454 mag with Imco exhaust and never had an issue.
I've even recommended it to a lot of people for an upgrade over stock. Its close to the 420/525SC cam specs.
I did have the longer risers and no silent choice.
I had the idle set around 900rpms if memory serves me. It was long time ago.

I would do a leakdown seeing as how the exhaust is off . If the valve seats pass now your on the road to buttening it up and not worrying about it -truely not worrying about it .especially with what looks like a street car cam grind .

Doesn't reversion cause some kind of idling issue. I had a problem and few years back with idling in loud mode. It would seem to load up quickly, start missing idling out of the no wake zone and I would have to rev it up to clear it out BUT.....if i turned on the silent choice (quiet mode) the missing, loading up would stop and she would idle normally. I then spoke to Drew marine and they told me to add water dumps to my exhaust just before it gets to the short riser. I made up custom tee fittings for this and ran 1/2" lines from each exhaust out the side of the boat. There was plenty of water still coming out of the risers. Drew marine said (quote) I don't care what cam you have and what pipes you have, If you do not want reversion dump the water. I also purchase 2 sets of shotgun silencers, not for noise reduction but for adding some back pressure. That was it !!!!. Problem solved!! I can idle in loud mode all day with no problem. No load up, no missing, etc. So maybe, after doing the above what Drew marine suggested my problem went away 75%. So those rust spots are only about 25% of reversion for about 3 years now. Maybe i'm still getting a slight mist of moisture not causing any idling issues with this new setup. My heads have been on the boat only 3 years. Does this make sense to anyone??


http://i1071.photobucket.com/albums/...psmcrifgwz.jpg

it does.a lot of boats have minor reversion and never know it.

I guess i'm going to have to bite the bullet and get rid of the silent choice. I just bought one set of EMI 111 long risers .I don't want to ruin another set of heads...I need another set of EMI 111.

Thanks for the input

My rear spark plugs would be wet, even a day later. Thats one way to see how bad it is.

appreciated...silent choice is coming off and i'm having the emi pipes extended

good move.