500 stroker

[Flyte risk]

So I’m new, looking for a little guidance. I have a freshly built 500 stroker motor in a 1990 Commander Jet Boat.
I recently noticed my oil pressure slipping and I originally thought it was because it was 110° out on the water. I took the boat out last weekend and it was only 85° and still having low pressure. The guy who built my boat explain to me the pressure should stay at approximately 70.It’s now dropped to about 50 varies quite a bit between idyll and WOT.I checked dipstick last week and I’m smelling fuel in the oil. I have 100% faith in the guy who built the motor for me but he’s too busy to help me now. Can anybody give me an idea of how this might happen and how I can remedy it?

 

[azsunfun]

depends on pump, at idle my pressure will drop to around 35 psi, hit the throttle and up to 55 psi

 

[Flyte risk]

depends on pump, at idle my pressure will drop to around 35 psi, hit the throttle and up to 55 psi

So when I fire it it sits at about 50 then when it warms up it drops to between 35 and 40.Ive seen it drop as low as 20 at idle.
I’m assuming this is because the oil has been thinned out by the fuel.
Still wondering how the fuel gets in oil.
I’m going to change the oil and see if the pressure goes up. But I want to solve the real problem. It being a new motor concerns me. I don’t wanna do any permanent damage.. Any help is much appreciated thank you guys.

 

[mash on it]

What oil pan and how many quarts in the pan?

Dan'l

 

[azsunfun]

So when I fire it it sits at about 50 then when it warms up it drops to between 35 and 40.Ive seen it drop as low as 20 at idle.
I’m assuming this is because the oil has been thinned out by the fuel.
Still wondering how the fuel gets in oil.
I’m going to change the oil and see if the pressure goes up. But I want to solve the real problem. It being a new motor concerns me. I don’t wanna do any permanent damage.. Any help is much appreciated thank you guys.

new motor, try the filter first

 

[Flyte risk]

I’m going to talk to the builder today and find out what Oil and how many quarts he suggests. Not sure of oil pan manufacture. That being said the oil pan is new. The original oil pan on the new build had crack in the weld and was replaced. This is around the same time that I started having issues with the oil pressure. That may be a contributing factor. I’m going to pull the filter and all the oil today to see if I can’t get the oil pressure to go back.I love this forum. Everybody responds so fast. Really is great. Thank you guys

 

[azsunfun]

penngrade oil for wherever you live, not cheap, good stuff.

 

[Flyte risk]

Got it I’ll keep everyone posted.Thanks

 

[DRYHEAT]

Does this engine have a mechanical fuel pump or electric? May be leaking on the backside of a mechanical pump

 

[rivermobster]

Does this engine have a mechanical fuel pump or electric? May be leaking on the backside of a mechanical pump

1990 Commander has to be a carb motor right? Could easily be a fuel pump issue...

Jets dont use a sea pump, right?

 

[Flyte risk]

It’s an electric fuel pump that sits outside of the motor. This is why it is so curious to me.
And yes it is a carb motor. 1100 dominator carb on it.

 

[JUSTWANNARACE]

1990 Commander has to be a carb motor right? Could easily be a fuel pump issue...

Jets dont use a sea pump, right?

No they do not. The water is supplied from the jet! The biggest thing with a jet is trying to build heat in the motor because the water moves so fast from the pump pressure. So most jets run on the cold side. There are ways to slow it to build proper heat in the motor.


If he set the motor up loose to compensate for heat(most normal builders set up for 180⁰-200⁰, a jet is lucky to build 120⁰ without flow restriction) then you might be getting fuel past the rings from lack of heat expansion.

 

[Flyte risk]

That makes a lot of sense. Especially since it has aluminum heads and seems to maintain about 120°.Appreciate the good information.
This forum is awesome and all you guys are really great.Appreciate all your input.

 

[rivermobster]

No they do not. The water is supplied from the jet! The biggest thing with a jet is trying to build heat in the motor because the water moves so fast from the pump pressure. So most jets run on the cold side. There are ways to slow it to build proper heat in the motor.


If he set the motor up loose to compensate for heat(most normal builders set up for 180⁰-200⁰, a jet is lucky to build 120⁰ without flow restriction) then you might be getting fuel past the rings from lack of heat expansion.

Possible, but the fuel pump theory needs to be investigated for sure. We all know that's a very comon thing!

With new rings on a properly built fresh engine? Unlikely.

 

[JUSTWANNARACE]

That makes a lot of sense. Especially since it has aluminum heads and seems to maintain about 120°.Appreciate the good information.
This forum is awesome and all you guys are really great.Appreciate all your input.

I have an inline ball valve on mine back at the pump to regulate the water flow. Just takes some time getting it adjusted to where you want it with my cheap fix and will still fluctuate about 40⁰ from idle to wide open. There is some fancy shit(pressure valves) you can buy to do that will keep a more constant temp. But the ball valve seems to work fine for me and you can get one at any hardware store. My buddy plumbed his ball valve right next to his seat so he can control flow which is what I will eventually do. I was going to do the fancy pressure valve but I have heard some stories of the getting shit in them and get stuck open or closed, closed would be very bad. So that's why I just went with the ball valve.

 

[Flyte risk]

All of these ideas make total sense.
So after looking I was unable to find a regulator on fuel pump. Could this be part of the problem and contributing to excess fuel.

 

[Hydroman55]

I have an inline ball valve on mine back at the pump to regulate the water flow. Just takes some time getting it adjusted to where you want it with my cheap fix and will still fluctuate about 40⁰ from idle to wide open. There is some fancy shit(pressure valves) you can buy to do that will keep a more constant temp. But the ball valve seems to work fine for me and you can get one at any hardware store. My buddy plumbed his ball valve right next to his seat so he can control flow which is what I will eventually do. I was going to do the fancy pressure valve but I have heard some stories of the getting shit in them and get stuck open or closed, closed would be very bad. So that's why I just went with the ball valve.

This

 

[rivermobster]

All of these ideas make total sense.
So after looking I was unable to find a regulator on fuel pump. Could this be part of the problem and contributing to excess fuel.

No. You do have a carb, right?

Post up a few pics of your engine...

 

[Flyte risk]

No. You do have a carb, right?

Post up a few pics of your engine...

 

[Flyte risk]

Let me know what your thoughts are.Thank you

 

[azsunfun]

All of these ideas make total sense.
So after looking I was unable to find a regulator on fuel pump. Could this be part of the problem and contributing to excess fuel.
[/QUOTE unless the pump is pumping past carb seats fooding when cold passing rings?

 

[rivermobster]

Holy fuck, is that an 1150 Dominator sitting on your engine?

If it is, you might be a tad over carburated I'm thinking!

Was this engine dyno'd before it went in the boat?

 

[Flyte risk]

Learning a lot just from peoples comments.Like I said it only gets to 120° so I don’t know if that is hot enough to prevent you from leaking back down past cylinders.
Just thinking out loud here but my thermostat starts at 120°. Meaning when I first fire the motor up it may not actually be at 120° and I have no way to tell.Meaning the motor could actually be cooler and contributing to what you are describing.

 

[Flyte risk]

Holy fuck, is that an 1150 Dominator sitting on your engine?

If it is, you might be a tad over carburated I'm thinking!

Was this engine dyno'd before it went in the boat?

No, I don’t think it was dyno’d and yes it is an 1150 dominator. The engine builder is well known and a friend of mine. I don’t want to put him on blast. Just trying to come to some conclusions.Like I said I appreciate everybody’s input and all you guys are awesome.

 

[rivermobster]

No, I don’t think it was dyno’d and yes it is an 1150 dominator. The engine builder is well known and a friend of mine. I don’t want to put him on blast. Just trying to come to some conclusions.Like I said I appreciate everybody’s input and all you guys are awesome.

What Size Carb for My Engine?

Choosing the right size carburetor for your engine can be tricky unless you know some basic math. We’re here to help!

www.hotrod.com

 

[DRYHEAT]

Holy fuck, is that an 1150 Dominator sitting on your engine?

If it is, you might be a tad over carburated I'm thinking!

Was this engine dyno'd before it went in the boat?

I kind of glossed over that the first time but yeah he said it was, does seem a bit over carbureted. I’m curious what the tail pipes look like

 

[DRYHEAT]

No, I don’t think it was dyno’d and yes it is an 1150 dominator. The engine builder is well known and a friend of mine. I don’t want to put him on blast. Just trying to come to some conclusions.Like I said I appreciate everybody’s input and all you guys are awesome.

Not trying to put you or your guy on blast but it does seem a little extreme for what you have. But I know a lot of guys run giant carburetors.

 

[rivermobster]

I kind of glossed over that the first time but yeah he said it was, does seem a bit over carbureted. I’m curious what the tail pipes look like

You know exactly what they look like. At least now we know why his fuel smells like gas!

It should probably have a 800 double pumper Max. Unless he's running alcohol or something, but that wouldn't make the fuel smell like gas?

 

[Flyte risk]

Sorry, am I missing something? (Fuel smell like gas) i’m sure that’s a typo. I looked on the Holly website and according to what I found yes maybe it should be closer to an 800. Max., Would it be better to go with EFI?I know it’s expensive but would this solve my problems.This is why I had somebody build the boat in the first place. I prefer to enjoy my time on the water rather than diagnosing issues offshore or when I’m trying to relax at home.It is greatly appreciated you guys are the best.

 

[rivermobster]

I kind of glossed over that the first time but yeah he said it was, does seem a bit over carbureted. I’m curious what the tail pipes look like

I just read this thread again. I see I missed it the first time as well.

OP...

Change the oil and filter...

Run both a compression and leak down test...

The rings may be washed out at this point.

When you get to good compression and leak down numbers, ditch that carb before you start that engine up again.

The article I posted should help you out. And don't forget to get a marine carburetor while you're at it.

I prefer Quick Fuel over Holly myself...

Quick Fuel M-800 M-Series 800CFM Marine Carburetor

QFT brings its engineering expertise to the marine market. The M-Series feature billet-style metering blocks and throttle bodies for more precise performance and exceptional strength. •Exclusive Black Diamond coating for enhanced corrosion protection and appearance, coating provides a 6%...

www.holley.com

And yes I know, Holly bought QTF.

 

[rivermobster]

Anyone can build an engine.

Tuning is a whole different world, and there is no way an 1150 is going to run right on a 500ic engine.

Stay away from EFI. Good luck!

 

[Flyte risk]

Motor always been great at least for first 60 hours., Never backfired, never sluggish, always performed well. Always maintained 70 on the oil pressure and and always maintained 120 on temperature. Biggest concern is that rings are washed out.. so sad.Taking motor back to builder on Tuesday. Will keep you guys.

 

[rivermobster]

Motor always been great at least for first 60 hours., Never backfired, never sluggish, always performed well. Always maintained 70 on the oil pressure and and always maintained 120 on temperature. Biggest concern is that rings are washed out.. so sad.Taking motor back to you builder on Tuesday. Will keep you guys.

I wouldn't trust this guy on the diagnosis. Have another shop do the compression and leak down test, or do it yourself to be sure.

If your boy put that carb on that engine, he's not going to be your best option on tuning...

If you get good test numbers, buy a new carb and install it yourself.

If you get bad test numbers, then take it back to the builder with the numbers in hand.

He will have some splaining to do at that point...

 

[azsunfun]

Motor always been great at least for first 60 hours., Never backfired, never sluggish, always performed well. Always maintained 70 on the oil pressure and and always maintained 120 on temperature. Biggest concern is that rings are washed out.. so sad.Taking motor back to builder on Tuesday. Will keep you guys.

as rivermobster said, everybody's a motor builder, you can ease your concerns on ring with $ 20 compression tester will tell a lot right off the bat, if you don't know head flow, and other data, hard to put carb size thats proper, but thats a big 1, bigger not always better. gd luck

 

[Drew]

You really only need 10% of rpm of oil pressure . Sometimes engine builders build a really tight motor on rebuild. Could see some really high oil pressure until broken in. Fuel in oil can be many things. Bad needles and seats in carb is one. But if you have a drastic oil pressure drop just out of the blue again it could be many things. But fuel in the oil will also drop your pressure

 

[Flyte risk]

i think a compression test is in order.
Then like you guys say I’ll have a better idea.

 

[rivermobster]

i think a compression test is in order.
Then like you guys say I’ll have a better idea.

Get that oil replaced ASAP. Fuel and engine seals don't play well together...

 

[Flyte risk]

I’m on it

 

[ibelio]

i think a compression test is in order.
Then like you guys say I’ll have a better idea.

leak down would be better/ you could hear in breather if rings washed out

 

[Flyte risk]

leak down would be better/ you could hear in breather if rings washed out

Got it

 

[Nikwho]

That's not really THAT over carbed. Lots of guys are getting their 454's to run decently with dual 750's! Certainly tons with dual 650's! That's 1,300-1,500 cfm of carb! If you turn up to 6,000 RPM with your 500" engine (500x6000=3,000,000. 3M÷3456=868.05. 868.05×1.15=998.26) So, if his combo will turn 6,000 RPM, a 1,000 CFM carb is warranted. He's not grossly overcarbed. He can be tuned WAY too rich being under carbed OR over carbed!

More than anything, I think that you may need to read your plugs, and start leaning this thing out! Is it running pig rich? Making your eyes water? Wife complaining of smell?

Perhaps try tuning your idle Circuit to max vacuum. Then make a run at 1,800-2,000 RPM, I'd think, to stay out of the secondaries and then read the plugs to see how it's running. Change the primary jets, to lean it out and get good plug color. After you do that, make a high RPM/WOT run to see how it's running on the secondaries. Read the plugs and lean it out as needed.

Download a user manual for your carb and get it tuned. Point being, your carb is not so oversized that you can't get it tuned to run well on your engine! OR, even simpler, buy a Quick Fuel 850 carb and sell your Dominator. But, even that won't get you out of needed to properly tune your setup!

As stated above, after break in, you could see a drop in oil pressure! Additionally, you aren't posting BAD oil pressure numbers. And, if there is fuel in the oil, that thinning of the oil will drop the pressure. Change the oil and filter and get that (or a smaller) carb tuned!

 

[Flyte risk]

That's not really THAT over carbed. Lots of guys are getting their 454's to run decently with dual 750's! Certainly tons with dual 650's! That's 1,300-1,500 cfm of carb! If you turn up to 6,000 RPM with your 500" engine (500x6000=3,000,000. 3M÷3456=868.05. 868.05×1.15=998.26) So, if his combo will turn 6,000 RPM, a 1,000 CFM carb is warranted. He's not grossly overcarbed. He can be tuned WAY too rich being under carbed OR over carbed!

More than anything, I think that you may need to read your plugs, and start leaning this thing out! Is it running pig rich? Making your eyes water? Wife complaining of smell?

Perhaps try tuning your idle Circuit to max vacuum. Then make a run at 1,800-2,000 RPM, I'd think, to stay out of the secondaries and then read the plugs to see how it's running. Change the primary jets, to lean it out and get good plug color. After you do that, make a high RPM/WOT run to see how it's running on the secondaries. Read the plugs and lean it out as needed.

Download a user manual for your carb and get it tuned. Point being, your carb is not so oversized that you can't get it tuned to run well on your engine! OR, even simpler, buy a Quick Fuel 850 carb and sell your Dominator. But, even that won't get you out of needed to properly tune your setup!

As stated above, after break in, you could see a drop in oil pressure! Additionally, you aren't posting BAD oil pressure numbers. And, if there is fuel in the oil, that thinning of the oil will drop the pressure. Change the oil and filter and get that (or a smaller) carb tuned!

Wow, great info, love your calcs on the carb.As you say I be double pumpers on smaller motors but still like the idea of a smaller carb.Heres a question, has any body used a Holley sniper self tuning carb? A friend suggested to me just don’t know much about.m going to do compression and a leak down test tomorrow just for a better idea where I’m at and then go from there.
Doesn’t seem to run pig rich(not overwhelming fuel smell) and always fires first try.It will flood easy if I pump carb more than twice.Once again all info and am going to cover all base.Tuesday back to builder with my own info in hand to see what he says.Like I said I trust him.
Just want my boat to run right.Revlimiter on it that prevents it from running over him. Maybe I should adjust that to a little higher. I would prefer like that but do not want to wear engine out prematurely.My biggest concern is how the fuel made it to oil tank?
If if it’s truly getting in prior to engine being warm how do you solve that issue?Here’s a question, has anybody ever ran a Holley sniper self tuning carb? Just curious how they perform and if anyone has ran one on their jet boat.All information appreciated. Thanks guys

 

[Nikwho]

I've heard of guys running them on boats, but personally have no experience. The only two issues that I would expect are:

1) you need on O2 sensor bung in the exhaust to take a reading of exhaust gases. That's all fine and good with headers, but a different story (maybe) with jacketed manifolds. Again, I have no idea, just thinking aloud.

2) Ive heard about these (Holley Sniper/FiTech) units having difficulty with self tuning/learning if they don't get up to operating temp (for a car, mind you, so about 180°+). Being that jet boats specifically struggle with getting up above 120° or so, the unit may never actually start tuning itself, even if you do get an O2 sensor in the exhaust. So, you might be stuck with the base mapping forever, unless you are able to change it up with a laptop!

EFI takes the work out, and helps with altitude change, but if you are willing to learn to tune it a bit, you can get a carb super dialed in! I keep running notes in my phone for all of my hot rods. Every single change made gets documented, along with the date, elevation, temperature and any change witnessed! That way, I have a running log of data.

Back when I was a sniper, we called this DOPE, or Data of Previous Engagement! So, once I get any given vehicle running super dialed in, say in the winter, I'll have my base tune to return to in the winter. I live at 6,500' ASL, so I keep notes on when I run my hot rods down in Phoenix, or down at the drag strip in Tucson. Same with my boat at the river! So, once enough data is collected, and I'm headed to the river in the summer, I can look at the best tune that I got in similar conditions, then start there, way ahead of where I did the previous year, then fine tune from there. It's like it's own hobby, within my hobbies. I'm not good at this stuff, but I enjoy trying to figure it out. You would probably (maybe) have more headache trying to get an EFI kit to work, then there's one more thing that can fail. Carbs are simple. Get em tuned a bit, and they work really well!

I'll just wait until we all have to smog our boats, THEN I'll switch to EFI. Good luck! I hope that you get this figured out! That engine should run really hard once you do! Anxious to hear about your cranking pressure and leak down test.

Make sure that you fully understand each test, so that you get good results! For example, you'll want to pull all of your spark plugs and crank engine with all out, while testing each cylinder individually! Make sure to disconnect the power supply from your ignition system prior to cranking, and crank at WOT. Then ask when you get there, and someone can get you all lined out on your leak down test process. That's a little more involved.

 

[obnoxious001]

Heading out for a morning ski ride(yeah it's 5AM), I see some good and some bad information here, I will need to read some of it over again.

#1 if you trust the guy to build the engine, give him a chance to look at it.

More to follow.

 

[Flyte risk]

Heading out for a morning ski ride(yeah it's 5AM), I see some good and some bad information here, I will need to read some of it over again.

#1 if you trust the guy to build the engine, give him a chance to look at it.

More to follow.

Heres a quick update for everybody,
Ran a compression test on all eight cylinders today with a Bosch compression tester. It’s brand new. Compression readings were between 165 and 175 all the way around. I may have done something wrong because I did not remove all of the plugs I remove them one at a time. Taking to builder tomorrow and hoping for the best.
Hopefully I didn’t blow the compression test. I looked up online and read that I was to pull one plug at a time. Spoke to several different people and got mixed information. I’ll post more tomorrow. Thank you guys and I hope I don’t feelings if I didn’t take their advice.

 

[azsunfun]

Heres a quick update for everybody,
Ran a compression test on all eight cylinders today with a Bosch compression tester. It’s brand new. Compression readings were between 165 and 175 all the way around. I may have done something wrong because I did not remove all of the plugs I remove them one at a time. Taking to builder tomorrow and hoping for the best.
Hopefully I didn’t blow the compression test. I looked up online and read that I was to pull one plug at a time. Spoke to several different people and got mixed information. I’ll post more tomorrow. Thank you guys and I hope I don’t feelings if I didn’t take their advice.

wow, thats tight, easier on starter and cranking with all plugs removed, might want to do it again, double checking, numbers for new motor. ok

 

[obnoxious001]

No they do not. The water is supplied from the jet! The biggest thing with a jet is trying to build heat in the motor because the water moves so fast from the pump pressure. So most jets run on the cold side. There are ways to slow it to build proper heat in the motor.


If he set the motor up loose to compensate for heat(most normal builders set up for 180⁰-200⁰, a jet is lucky to build 120⁰ without flow restriction) then you might be getting fuel past the rings from lack of heat expansion.

The block stays cool, but the pistons and rings run hot due to RPM and constant load, that's why a marine engine gets set up with extra piston to wall clearance.

 

[obnoxious001]

Heading out for a morning ski ride(yeah it's 5AM), I see some good and some bad information here, I will need to read some of it over again.

#1 if you trust the guy to build the engine, give him a chance to look at it.

More to follow.

OK, things I noticed in the thread:

Larger carb does not equate to too much fuel in the engine. What I would be more concerned with is proper float level, along with fuel pressure that others mentioned. A carburetor that is working properly supplies the correct air fuel mixture that the engine "demands".

However, 1150 Dominator is not what I would put on a pump gas, family cruiser "500 inch stroker", perhaps on a high compression race engine. We ran an 1150 on a Comp Jet circle race boat, may have been 499 cu in at the time, been some years ago. 500 cubic inches only requires 850 or less CFM at 6000 RPM. Recently we ran one of my engines on the Westech dyno, 460 cu in (.030" over 454), unported 990 heads, single plane intake, 750 CFM, made 608 HP at 6500 RPM.

Adding fuel to the oil not only would thin the unknown viscosity oil, but raise the oil level in the pan. The increase in oil level alone could be enough to decrease oil pressure at operating speeds, as the oil can be aerated by the crankshaft.

I would ask the engine builder what oil is in it, since he knows what bearing clearances he put in the engine (did he give you a build sheet?). You could also ask him if he calibrated the dipstick, something I always due to know where the oil level is in relation to the windage tray, again to help prevent aeration.

 

[rivermobster]

Heres a quick update for everybody,
Ran a compression test on all eight cylinders today with a Bosch compression tester. It’s brand new. Compression readings were between 165 and 175 all the way around. I may have done something wrong because I did not remove all of the plugs I remove them one at a time. Taking to builder tomorrow and hoping for the best.
Hopefully I didn’t blow the compression test. I looked up online and read that I was to pull one plug at a time. Spoke to several different people and got mixed information. I’ll post more tomorrow. Thank you guys and I hope I don’t feelings if I didn’t take their advice.

What your looking for is consistency...

Normally, you would pull all the plugs, block the throttle wide open, and then check each cylinder one at a time.

The way you did it isn't ideal, but you have each cylinder within 10psi of each other, and that would be a good thing.

 

[Flyte risk]

Here’s a quick update for everybody, still working this out. But oil has been changed and pressure jumped back up to 70.Im happy about that.
Still have a couple things I need to figure out and I will update you as soon as I do. Thanks you guys.