Stay positive. I applaud your feed back on suggestions all have made. Often without this feedback we as fellow members never learn anything either. In the end a synopsis will help us all. Good Luck.

I know it will work out because I'll be hunched over it with tools until it is. :)

I have it mostly back together, just need to get my gaskets from Stainless Marine. Should have it running again sometime next week and will report back.

Russ

I had a wet exhaust problem with my 10:1 383 SBC and that cam.
It finally went away when I moved my adjustable roller chain cam gear from 4 degrees retarded to straight up. I also did a Davis Ignition, more timing, surfaced my heads and did head gaskets at that time. I was able to put in a lot more base timing since my 22 degree DUI ignition needed 13 degrees base to get 35 all in. My prior Mercruiser ignition had 8 degrees base.
This was my first engine from scratch though, so I could easily have caused the leaks from the heads. The first gaskets were .015" shims that I put on dry with new heads and never retorqued. When they failed I did Cometic MLS gaskets which also did not seal. I bet the heads were already imperfect from the first fail. I was too stupid to show my heads to my machinist.
By the time I went to do the 3rd set of HG's I pulled the engine to do some plumbing for my remote oil filter, and while it was out I checked and found that I had mis-set the cam gear because I hadn't understood the symbols that indicate position.
So to recap. Cam went to straight up. New steel shim gaskets with copper spray coat on resurfaced heads. Retorqued them after a minor heat cycle. New ignition, More timing.
It ran fine after that, but 3 season of issues had me questioning myself a lot.

I assume you used the RTV that Stainless Marine provides on BOTH sides of the riser gaskets?

Just given the OP's throughal work and build/pics I would have to say neither RTV nor instructions came with. I could very well wrong though. If new into offshore mods etc the importance of might not have come to mind during install. Regardless rather inexpensive experience and piece of mind to catch before potentially what could have been catastrophic.

I have the roller version of that cam in a 9.5 to 1 385" SBC. It idles at 650-700 with no reversion. When I purchased and installed the Stainless Marine exhaust the instructions were emphatic about using the RTV at the riser gaskets to stop reversion.

Stainless marine exhaust has a gap/space where the riser meets the manifold, between inner and outer jackets???

I did not use the RTV on the exhaust gaskets. Either there were no instructions that came with it or they got thrown away while I was cleaning up.

A number of people have mentioned this and I since I didn't find anything else wrong, I bet this was the problem.

I'll know tomorrow.

Thanks again for the all the responses.

Russ

Directions.... Who reads those??? A yellow important warning sticker on top of manifold that says please read instructions might get ones attention. I tend to over use rtv even on machined surfaces. Just an old habit.

Regardless no harm done and no down time.

Got it back together and ran it today. I used permatex ultra copper gasket maker on both sides of the riser gaskets and tightened the snot out the band clamp.

Only ran it for 5 minutes and still have some water in my manifolds. Pictures attached. Still seemed to run quite well.

I put new plugs in before running this time and after running for about 5 minutes, they are all still damn near new looking. Shouldn't they get dark pretty quick? There is one plug in the picture that is dark and that is because that is an old one. Somehow when I got home from the auto parts store I only had 7 new ones.

After the last time I ran this engine and had a lot of water, I pulled the plugs and they each had a small area of dark and the rest appeared clean. I assumed that this was because of the water coming in from the manifolds.


https://cimg3.ibsrv.net/gimg/www.off...3c410d7439.jpg
https://cimg7.ibsrv.net/gimg/www.off...df9ecbdc0c.jpg
https://cimg8.ibsrv.net/gimg/www.off...a91e00307e.jpg

As a recap, since the last time I ran this engine and had a lot of water in the manifolds including a milkshake in my oil pan, I removed the heads and replaced the head gaskets, replaced the intake manifold gasket and also double checked the cam timing (it was right on). I also used silicone sealant on the riser gaskets this time which I had not done last time. I also set the idle to 750 this time around.


I need a beer.

quick update

I went back through the suggestions on here and saw that one member had suggested to run the engine without the risers on there and just extend the water from the manifolds over the side of the boat.

I did that and can see the water forming in the manifolds. It looks as if it is coming out of the exhaust valves. Or at least I can say, the water is forming from way down in the manifold towards the exhaust valves.

I watched this water form then dried it out by jamming a shop rag down there in case it was residual from the previous run with the risers on, but it formed again when I restarted the engine.

I need another beer.

Maybe try disconnecting water from manifolds and run it just long enough to get a peak inside there?
Pressurized leak check of the manifolds been done?
Is it possible these manifolds could have cracked internally due to freezing?
Do you have another set of manifolds to try?

Pressure test the mans, can be done attached

X2

surely rules out cam overlap. pressure test manifolds.

You have a leak.
There is no way that is reversion.
That much water in the oil from 20 minutes on the hose is not reversion. You have a water leak.
Like said pressure test the manifolds.
I personally think you have a leak somewhere inside the engine.
Possible bad block or head. I have seen this before.

yup, plan for today is to pressure test these stainless marine manifolds. I have a hard time thinking that both manifolds are leaking but that would be best case here I guess.

These manifolds have never had the chance to freeze with water in them, so I do not think that is the case.

If the manifolds test water tight, I am seriously thinking about getting a new engine. I missed last boating season working on this boat and boating season is getting ready to start here now and I am not willing to miss another one.

We live on a lake and so boating is our deal. This boat was not supposed to be a long term project. I have a 28 sleek craft enforcer that is going to be a project and is planned to get twin small blocks that I can use this motor in after going through it if I need to. I am not giving up on this motor, I have too much into it, but I really want to be on the water cruising in a few weeks with this boat.

If I end up purchasing a motor, I am thinking about this one:

https://www.michiganmotorz.com/377ci...ent-p-545.html

I am wondering if my exhaust will fit seeing as though the heads will obviously be different. Do all small block heads have the same outside dimensions?

I was thinking about the HT383, but the cam although quite small is 109 lobe separation which from what I know is to tight for water exhausts and this 377 has decent specs for what it is.

Any other suggestions for a nice, ready to go small block with good parts would be welcome. I am not interested in engines from ATK or Blueprint or places like that.

I don't get it. New block, new risers, eliminated risers. Head gasket and intake manifold gaskets basically replaced twice now. What is the history on the exh manifolds? Let us know after you pressure test. I'd pressure test the engine as well.

I have seen head studs that don't seal till a couple hours of at temperature running. I don't know if you are getting seepage there but could be the answer. I had it with one of my motors and my builder suggested running it for a day and it did go away.

Did your oil look like his from seepage? I honestly believe no sealant at all could cause this. Pressure test the whole works. Quick and easy and just need an ear and a beer.

Are you sure heads are not cracked?

Just making sure the heads are compatible with what gen short block OP purchased. Great heads btw. I did catch the NEW short block from GM. Marine or auto? I'll take a guess probably auto. Might be worthy of finding out the rod and main clearances on what you purchased. Just an FYI.

The manifolds pressure checked ok. Just in case, I installed some EMI thunder manifolds I have and ran the engine again without the risers and still have water in the exhaust manifolds.

The heads should be fine with this block as they are vortec style heads and this was a vortec marine long block from GM.

To pressurize the entire system I assume that I can just adapt my garden hose to the inlet on my crossover pipe.....we have a **** ton of pressure.....and let her rip. At that point, what do I watch for. I am guessing that I will or won't see water coming into the manifolds, but not sure what that would tell me. Any advice on what to watch or listen for hear would help.

Here is a picture from my living room window of where I should be today.


https://cimg5.ibsrv.net/gimg/www.off...8d19d6c7e2.jpg


Thanks again.

Need to test with air, not water. Drain the block, plug all ports going to exhaust. Connect air compressor with regulator and gauge to connection coming from sea water pump. Apply 20 psi and listen

Not sure if its the "correct" way but when I pressure tested mine. (I have a crossover no recirc pump) I plugged the 2 houses going from the thermostat cover to the exhaust, then made a schrader valve setup with a pvc fitting and gauge where the water normally goes into the crossover. As far as I know max water pressure should be about 30 psi, so I pressurized the motor to 35 psi with air, let it sit for a while and checked to see if it had lost any pressure.

X2

As far as the milky oil:

What intake gaskets and bolts did you use ? Part#'s please.

What did you use to seal the head studs (btw, why studs ?) to the block and how did you install them ?

Intake gasket part number: Edelbrock 7235. The hardware was pretty basic black oxide bolts from the hardware store that I thought looked cool with the setup. They were torqued in sequence to, as I recall, 12 ft/lbs.

I used the ARP thread sealant on all the studs and installed them as per the manual. Just hand tight with the stud into the block, then apply ARP installation lubricant to the washer and then torque the nuts in sequence in three steps to 80 ft/lbs.

It would be great if I did something stupid here that would be an easy fix. If you see it, let me know.

Thanks

I'd test the engine by making up a gauge and valve for the cooling water inlet, then clamping the cooling hoses that go to the exhaust manifolds. Put about 13 or 15 psi in there. Listen for hissing at the exhaust, valve covers and carburetor. Turn the engine over manually while pressurized. Leaks can come from various places depending on valve positions.

im not saying this is the root cause of your problem but i no longer use arp thread sealer on the head bolts,it just does not seal very good.i use leak lok and no more leaks.you may have two problems,leaking head bolts and leaking exhaust system.

I've always just used Permatex thread sealant. Had an external head bolt or two leak on occasion however they ended up sewing themselves shut by end of dyno session or a little time operating the engine (basically like Tinkerer mentioned). Whether there were any bolts leaking under the valve covers or not I have no clue. In fact years ago I even used just high temp silicone. Just a little messier when removing bolts down the road but very flexible when retorqing. A lot of sealants including permatex thread sealant harden to much and I don't care for that.

What do you use Mike and your thoughts on the hardness of the sealant.

I am an HVAC guy and I HATE LEAK LOC.
It is a great sealant though.
***** to get off your hands and it stinks.

Many years ago I bought some allen head bolts for the intake on my hot rod (sbc). They were abt 1.5 threads longer than original and bottomed out just as the gasket started to compress. Changed the gaskets twice before I figured out what was happening.

Good thinking but I thought all sbc’s were open to the lifter galley and only need about an inch of threads depending on brackets etc.

OP did you pressure test yet?


I just looked this up. Not necessarily water leak related however covers some good intake/gasket info for those who care to read.
https://www.streetmusclemag.com/tech...manifold-seal/

My bad. I think you're right abt the intake/head connection. Now that I think abt it, the bolts I replaced were to attach the runners to manifold (TPI). A couple were a major pain thus the allen heads and ball-end wrenches.

Sorry took me a bit to get back.

I asked about the bolts and gaskets because many people mess this up since there are different style gaskets and thus bolts used for the vortec motors.

Def check the bolt length and don't be afraid to use up to 20ft/lbs torque with a normal composition gasket and non factory vortec intake bolts. The 12ft/lb figure came about from GM because of the OE plastic intake gasket. They'd even crush with the 12ft/lbs.

Also, as with most motors, if using a composition gasket thinly smear rtv around each coolant port of the gasket.

highplainsdrifter,
Old post but FYI.

I've had REVERSION ISSUES on my 502mpi forever. Spent many months trying to solve it. Looked at everything imaginable.
Finally extended the inner tube from the elbow(by welding on an alum extension). I added 6/8 inches at a time and tried it.

Finally, at 20"/25" extensions(slant cut), the reversion completely went away. Has always had condensation in the middle of elbow during winter/fall/spring, but no reversion. At least at the elbow. It does a little at the ends of the exh pipes but never reaches the elbow. Valves last way longer, especially in salt/brackish water.

Mine are stock except filters, exhaust, and bumped up timing. Have Eddie Marine alum log type exhaust. A friend has a little higher HP motor, 550hp, and had to go a couple inches further to stop the reversion. Good luck.

It's too bad that the OP never let us in on the what the resolution to this was. Maybe it was never resolved. I have the feeling this could be another cam or install issue.

Get a oil analysis. Get the oil up to temp not just Idle speed. Like was said raise your idle speed.

What risers are you using, standard or HP500 (hi rise)? Any spacers?
Thanks!

I don’t think it was ever resolved. It looked like had a lot of the parts from that engine for sale in the swap shop a while back - July of 2020.

https://www.offshoreonly.com/forums/...nce-parts.html