I have reversion but I shouldn't
 

Trying to figure out why I am getting reversion when based on everything I know I shouldn't be. Most likely something I have done wrong, but I cannot figure out what.

Here are the engine specs

SBC
9.4:1 compression
Davis Unified Ignition (base timing set at 10 degrees)
Edelbrock e-tec 170 heads with 1.52 roller rockers
Comp Cams xms270hr cam
specs in attached picture
Brand New custom, very long risers from Stainless Marine (picture attached)

I am new to assembling engines. I purchased this short block directly from GM. I installed the cam and the heads etc etc. The cam was installed 'dot to dot'. I went through the steps to degree the cam. I was fuzzy on the process but had all the tools and got some numbers that told me I was good and left the cam straight up.

I went through the process to make sure that rocker arm geometry was right and got proper length pushrods.

The boat starts and runs with ease. I have not had it in the water yet.

Is there something I could have done wrong during cam installation that would cause this?

Any ideas on where to go from here would be greatly appreciated. I was thinking the boat was going to be in the water next weekend, now I am wondering if I am going to have to pull the engine again.

Here is a picture of my risers:


https://cimg8.ibsrv.net/gimg/www.off...7a9bae1e46.jpg


Here is my cam card:


https://cimg2.ibsrv.net/gimg/www.off...bd95be3185.jpg

Here is pictures of how much water is in my manifolds:


https://cimg6.ibsrv.net/gimg/www.off...65b135994f.jpg


Thanks,
Russ

Where does the riser dump the water ?

Right at the bellow hose connection to the tailpipe all the way down at the transom.

Are both sides wet?

yes, both sides the same amount of water.

Here is a picture from the other manifold


https://cimg4.ibsrv.net/gimg/www.off...1b4b08eb03.jpg

I think you have way more rise then needed for reversion to be an issue (emptying out at the ends), so I'm wondering if there is something wrong with the new pipes

I was wondering about that as well even though Stainless Marine has a great record of quality.

I am not sure how to properly test a pipe, but what I did was hook a hose up to the water inlet and turned the hose on all the way with very good water pressure and no water came out at what is supposed to be the dry end (where it connects to the manifold).

If that is an adequate test, then I think the pipes are fine.

I really appreciate the help! On my own, I am at a loss at this point.
Russ

Do we know it’s not leaking head gaskets blowing water out of chambers??

PS, good for you thinking to ck this before lighting it up and eating a motor.

I'll go do a compression check and also check to see if there is water in the oil right now.

Thanks again

compression numbers. Engine has maybe 25 minutes run time all out of the water with no drive installed.

1 = 170
3 = 165
5 = 168
7 = 168
2 = 172
4 = 170
6 = 170
8 = 172

The oil in the pan is slightly milky. I can tell from just looking at the dip stick.

I ran the engine for about 15 minutes this AM and it would not heat up. Hottest it would get is about 100 degrees. I have a 140 degree thermostat. I am running a crank mounted water pump and I have a water pressure gauge. At 650 RPM the water pressure gauge read less than 10 psi. When revving to a max of 2500-2750 the water pressure gauge would come up to maybe 12 psi.

An exhaust leak can cause this. It did on mine on brand new exhaust. In my case I had to resurface the risers mounting flange. It could also be at the head to exhaust manifold surface.

If you have any plugs that are wet, then maybe intake

Fella on another forum with fresh rebuild stock motor and stock exhaust had water showing up. Then timing was set correctly and this went away. Strange even for a stock motor even if its out of time a bit, but I'm just spit balling

I can’t see this being a cam issue unless it is installed wrong. You .006 overlap is only 48.5 and .050 is -3. Try advancing the idle timing some. That may help

Is there a way to determine if the cam was installed correctly without removing the engine and going back through the degree'ing procedure?

650 rpm is pretty low. Turn it up a little bit at see what happens.

On a hose your not going to get much pressure, the hose is unable to supply enough water at anything other then about idle

I think you have something else going on with water or air leaks or maybe even some bad condensation.

Your cam installation should be fine the way you described everything. You did the math and found that dot-to-dot was good... I wouldn’t be worried there.

I’ve run small blocks with a heck of a lot more cam and less riser and never ran into reversion.

Make sure your risers are sealed up tight. I’ve used high-heat RTV and gaskets to seal up SM risers (the surfaces can become pitted and cause air leaks that in turn create a vacuum). As mentioned earlier, make sure the head to manifold surfaces are sealed well too.

Aside from the exhaust, look for a leaking intake or head gaskets (as mentioned). It doesn’t take much to make a mess of things.

Couldn’t hurt to pop off a valve cover to see how much water is in the oil.

What are the air temperatures like where you’re working?

Bump the idle to 750.

I would bump it even further. If too low of idle is in fact causing an issue it will continue to be an issue when you put it in gear and the idle drops 150-200rpm. I run Small block LS engines in my Daytona. My idle is set at 950 in neutral, drops to 650 in gear, and recovers to 800. Granted I was running a much larger can which hurts my idle more (237/252 113+3). I was also running 22 degrees ignition advance at 1k and below via an msd box to stabilize idle. My point is bumping the idle will help a lot with reversion if that is the case. Just keep it below 1000 to not injure the outdrive. Also, double check your cam timing and validate your ignition advance is correct as well as the balancer marks are correct.

As others have stated, bump your idle 750-800rpms. Running cold water on the hose and your engine not getting hot will cause crazy condensation. Cold or near freezing ambient temps make it worse.

Process of elimination from here

Pull your risers, extend your manifold watet outlet hoses over side of your boat, run engine with no risers at idle. Will eliminate your risers, condensation, reversion and narrow your problem down.

I ran the XM276HR in a 355 years back and extended the risers 16" past stock location to prevent water from pooling in manifold center runners.

ok, some good things for me to look into. really appreciate the information. I am going to get started on this stuff today. I'l do the easy, quick stuff first.

The ambient temps here are around 50 degrees and I am pulling water out of a 50 gallon feed tank through my crank mounted water pump. The water is from my well and is pretty cold. No drive currently on the boat.

https://cimg8.ibsrv.net/gimg/www.off...410bf512cd.jpg

Looking good
 

I'd bump the idle and get some kydex (plastic sheathing) and with a heat gun you can make a nice custom cover for you wire connection terminal etc to help prevent any catastrophe plus it will improve the looks on what you've already done a great job on. The filter, fuel line and fuel tank all within less than an arms reach. Just a suggestion but seriously nice work and I think you have more of a condensation/idle issue going on.
https://cimg0.ibsrv.net/gimg/www.off...7079b18477.png

Might be worth checking valve lash.
An exhaust valve that isn’t closing/sealing completely can cause reversion.

compression numbers wouldn’t have been within 4 psi if a valve was hung open

True.......my bad.

Thanks for the idea about the cover for my electrical stuff. I'll definitely put that on my list to do before I finish this project.

Beautiful work.

Im thinking condensation too.

Here is a picture of my oil. Pretty milky. White goopy stuff everywhere.....it's a hot mess. Spend most of last night cleaning it with diesel and fresh oil.


https://cimg6.ibsrv.net/gimg/www.off...6718b008cc.jpg

Could my oil get that milky from condensation after about 15 minutes of run time?

Since it is January, I am going to go back through the things I have done to this motor and just double check everything. Head gaskets and intake gasket looked to be leak free upon dissassembly.


https://cimg5.ibsrv.net/gimg/www.off...0b33f2ebd4.jpg

What a mystery.... That sucks as it certainly appears you did an A1 build and didn't scrimp anywhere. Sealed both sides of intake gaskets around the water ports? Assuming you did and had a good fit. What intake is that. Still nothing would explain the water in your exhaust manifolds. You likely didn't get it hot enough on the hose to burn off any water in the oil. Assuming you used the correct head gaskets for whatever gen block/heads you have. I've had milkshakes years ago at the beginning of my boating days but it was very early on and had 108 lsa crower cam. Wasn't really much talk back then about reversion. Ran the cam last half the season then did a swap. Btw my oil looked way worse until I'd get out the channel. Your deal here is strange all the way around. To bad you couldn't have pressurized your system before tear down. Oh also did you haver water in your ports. Hopefully you get this resolved.

Nows the time to find but woulda been nice to have been able to take a half hour run etc given the weather didn't suck and then see what you had.

I actually just went back and saw the jizz in the oil. Did you scrape that from under valve cover or top of heads. I just looks at oil color earlier but again have seen that also. I know you mentioned upon gasket inspection all appeared fine but double ck both sides of your intake gaskets. Can run a straight edge down both side your intake and heads also. I'm just throwing this out there andcsure you have but just trying to help.

How about the stud's that screw into the block ? Does any of them go into a water jacket and were you required to put parmatex thread sealant on them ? Good luck, Greg

I put thread sealant on all the head studs.

I also sealed both side of the intake gasket at the water ports.

I checked tonight and my timing mark is spot on and cam centerline is 110 degrees which is spot on as well.

Sure would be totally like me to tear down the top of this motor when the real problem was just exhaust wasn't sealed properly. Wouldn't surprise me. Oh well, it's dark early these days and I'd rather be doing this than pacing back in forth in front of the sliding glass door waiting for spring.

Heads go back on tomorrow.

Thanks again for all the advice and suggestions.

Are you running the engines with only 2 bolts holding the manifolds to the heads?

BT

no, that was just a picture I took during assembly.

That is a great post from activator40. I've never used Stainless Marine exhaust and only have heard and read great things about them however wasn't aware of the sealing issue. One thing I might recommend to them if this is such a reoccurring problem they might wanna have a warning label of such issue in with the clamps etc. Regardless it sounds like a relatively easy fix anyway.

Post #6 actually looks like gasket tear but would imagine from riser removal? Did you make any adjustments during install to fit transom outlets that may have fudged up the gasket. I could see where it wouldn't take much with a rather thin gasket. As mentioned sealing both sides of the gaskets is crucial. Not sure if you installed engine with risers or after but they gotta be a bit of a juggling act to mate manifold considering the size/weight. Slightest little screw up could destroy that gasket material rather easily. I wouldn't be afraid go a little on the heavy side with the sealer and once in place clamp and let sit til dry.

You have pictures showing drops of water down the manifold side. Are there signs of water on the upstream side of the elbow/manifold collar area? If not the collar is the suspect. If there is, I bet it's a leak somewhere in the elbow section.

definitely could be the seal at the risers. I did not spend much time there. Just installed the riser and tightened the clamp. I did see the gasket move around some but figured the clamp would pull it all together. Had no idea this was a spot to fuss over. Now I know. more information from the manufacturer would have been great here.

I called stainless marine and ordered a stack of the riser gaskets yesterday. Got the heads back on yesterday and plan on having it all back together this weekend.

Thanks again for all the great information. I'd be a little SOL without a site like this.

Russ