351W EFI upgrade

I am a newbie to this forum but I am a long term boater and engine buff.

I recently purchased a 21’ four wins (1991). It came with a blown OMC 302, 2bll and a cobra drive. I immediately proceeded to replace the motor with a 351W.
Fortunately the original motor had new manifolds and risers so I decided go the length and fresh water cool the system. This turned out to be a bit tricky but in the end it worked well and allowed me to use a street motor.

Anyway last summer I managed to put about 60 hours on the boat and it treated me well with only a few after the fact tweaks. My only issue was WOT. Running the 19 inch prop that came with the boat (2 passengers, ½ fuel) I was only able to bring it up to 33-3400. Considering this was the prop from the 302 I was expecting more. I concluded that the 500cfm carburetor from the 302 was just too small. This being the only issue I ran it for the summer and saved that as a winter project.

Well winter is here and the 500cfm carb has been replaced with EFI, another tricky upgrade but it works. At least it starts and runs. Having looked through the threads I noted a few things I need to look out for i.e. fuel bubbles, ventilation ect. I was hoping that some others have attempted this upgrade and would be willing to share there experience particularly what may have stung you.

Thanks in advance

Nixes mate

You mean tbi ?

Its not a TBI (throttle body injection) its EFI (electronic fuel injection). the book interchanges the term EFI and multiport.

Here's what some rough math shows if you consider the lower RPM that a Marine engine operates at.

2 crankshaft revolutions (4 complete cycles) brings in 351 cu in of air under perfect and ideal conditions.
At 4,000 rpm it will bring in 702,000 cu in of air (4,000 divided by 2 X's 351 cu in)
702,000 cu in divided by 1,728 (cu in per cu ft) = 406.25 CFM.

The numbers that this calculator will show are a bit more conservative.
http://www.carburetion.com/calc.asp

4k rpm (near the higher rpm side) shows 345 CFM
5k rpm (which is too high for Marine use) shows 431 CFM

Unless you will be running at a higher RPM, I'd think that 500 CFM should be adequate.

This is what i thought you installed.

Good luck with it.

Thanks Rick

I did see your reply in another thread and it made me realize I needed to consider increasing the air flow to the engine box. Part of this project was to better sound proof and in so doing I blocked air flow. So I will be increasing the vent openings. This is only a 21 footer so the 351 maxes out the engine box. I also noted in another thread options on how to utilize the fresh water cooling. At the moment I am cooling the lower manifolds with engine coolant (antifreeze). The lower manifold gets the coolant from the motor just before returning to the exchanger. Basically they get hotter than I would like (200f). So I am going to convert to a partial system this will bring manifold temp way down. And still allow for a 180/90 thermostat.

Master mech

I considered that and several other package systems but there was just one common draw back $$$$. Fortunately window shopping is free. There tempting and if my budget allowed it would be a bit more strait forward to go that route. Even so I am close to 1K using parts (harness, fuel rail) from a 302 and aftermarket intake.

The first ride with this beast should be interesting.

Thanks for the reply.

Nixes mate

Yes... air flow, and the cooler the better. More air.... the cooler it will be..., usually.
I run twin engines, and I also use twin continuous duty squirrel cage blower motors that each have their own independent exhaust scuppers.
All four vent louvers are now dedicated to incoming air.
When my engines are operating, so are my blower motors.

OK, on your 5.8L Ford CCS (closed cooling system), the T stat housing should have a by-pass port in it.
This may be up to 1/4".... and some have gone even larger.
Start small.... increase ONLY if need be, or the balance can become disrupted.
This allows some engine coolant to circumvent the T stat and continue the flow into/out of the exhaust mans.
If this is not functioning correctly, your mans may run hotter than need be.
Your risers should be cool enough to touch.

The H/E capacity and the sea water pump volume must be sufficient for a "Full System".
If not, this may be an indication that the sea water volume to/from the H/E is not sufficient to remove enough heat from the E/G (ethylene glycol) side of the system.
If this is the case....., you may continue fighting this issue.

Good for you re; the CCS ........... I don't leave home without one!

Actually I am having a problem getting the motor up to temp. The lower manifolds get a bit hot because there last in the flow but my 180 thermostat is never opening. Basically the bypass is allowing too much water to get by. If I close up the bypass to bring the motor temp up then the manifolds will get even hotter. None of this was an issue last year because I was using a carburetor but with the fuel injection I need to get the temp up to satisfy the Engine controller. I could trick the controller by altering the temp sensor resistance but then I loose efficiency.

Anyway I think the compromise is to raw water cool the lower manifold. Its only Jan I have time to tinker.

Thanks again

Nixes mate

Post an image of your system in schematic form. We can take a look at it.


Perhaps something like this, but showing your exact layout.



.

.

This is exactly the system I now have. My exchanger is mounted at the rear of the motor but as to flow it is the same.

Well, that image that I show is for the GM engine.
Your Ford T stat housing will be different, but the flow path should be very similar.

When we include the manifolds in the system, the balance becomes delicate.

Here's what I believe is happening:

The circ pump charges the block with coolant.
The T stat and housing is the means of allowing the coolant escape and return to the H/E.
I call this the "As Required" or "On-Demand" basis.

As the coolant is allowed to leave the block (via by-pass AND T-stat opening), it makes it's way to the exhaust mans.
From the exhaust it makes it's way back to the H/E.

Meanwhile, the by-pass is NOT allowing the thermostat to hold back enough coolant to maintain your 180* temp.

If you further restrict the by-pass, it cures the engine temp issue, but now further increases the manifold temperatire.

Catch 22!

Juat how hot are the manifolds when up and running?

Believe it or not I am using a GM T-stat housing. Seems they don't make a Ford one. When I went to add the cooling system to my motor the parts guy told me that Ford motors as a rule are all raw water cooled. What he set me up with is a goose neck that goes to the ford intake that both turns it up and acepts the GM T-housing. Even the original raw water goose neck converted to GM.

Anyway,, you are right on it is a catch 22. Using an IR thermo prob it reads around 110 coming out of the T-housing the lower manifolds are 190 ish and the return at the H/E is 200. All over the motor heads, manifold ect is 110 to 130. This is all at idle feeding the exchanger directly with a garden hose. I didn't check but I guess the tap water at around 50.

If I raw water cool the manifolds and flush the sytem at the dock it should work.

Nixes mate

........... I am using a GM T-stat housing. Seems they don't make a Ford one. When I went to add the cooling system to my motor the parts guy told me that Ford motors as a rule are all raw water cooled.

Click to expand...

Not necessarily so on either account!

I've installed these over the years... some aluminum..... the good ones are bronze.
Here is a dual outlet style.... the single outlet is also available.
This one was sold to a man who basically did the same as you.
Note that it is not yet bored for the by-pass. This allows it to be used with dual coolant return necks on the H/E where a Half System is used.

Rick

The housing I have the tubes are angled forward and yes it has the bypass cut out. I can see the advantage to the one your showing but what I have will work. I intend to put a weld on the bypass. I just made the list of fittings to redo the hoses and it actualy will be simpler with less hoses to deal with.

I exspect to have all the changes and a few other loose end cleaned up over the next few days. Once I restart it I will give an update.


Thanks for your input.


Nixes mate

If you were to remove the exhaust manifolds from the E/G side, you can now use a single outlet T-stat housing, and convert your H/E inlets to a single return inlet.
The shell is copper and can easily be silver soldered.

Rick

I did consider that or at least pluging one of the returnes but for the moment it is just a mater of few feet of heater hose. Once I get it running and enshure it all balances out as planed then I may do a clean up.

I had to stop and think for a moment E/G (engine glycol) you must come from the high tech world.

Thanks again

Nixes mate

nixes mate said:

Rick I had to stop and think for a moment E/G (engine glycol) you must come from the high tech world.

Click to expand...

Yep, me been a work'n on dem dar "motors" fur a long time now. Can't wait til eyes start a work'n on sum a dem dar transmisytions 'n such.

Nah, not really. I'm just a stickler on using decent terminology when we can. E/G, H/E, SBC, CCS, TAT etc, are all just abreviations and short cuts.

OK I bit

Rebember me the newbe ?

E/G = engine glycol

H/E = heat exchanger

SBC = sume bad crap

CCS = could come soon

TAT = (don't want to go there)

Rick I am kidding but truthful.

The 351 will be back up tomorrow or sat will update then.

Thanks again.

Nixes mate

There are so many abriviations that we could dedicate an entire thread on the subject.... and no two guys are going to see it the same way.

E/G = engine glycol ........... Close, buy no prize. Ethylene Glycol.

H/E = heat exchanger .... Yes.....

SBC = sume bad crap ..... Well, that works also, but it actually means Small Block Chevy. (you were pulling my leg on that one)

The Ford guys don't care for SBF or BBF, since the Fords are series grouped.
I think that the Cleveland and the M block are a 335 sereis, the BB is a 385 series.
Not sure if the Windsor has a series class or not.

CCS = could come soon ... good one, but actually means Closed Cooling System.

Many use the term FWC (fresh water cooled), of which in my book is a misnomer.
In my mind, there is nothing fresh about Ethylene Glycol and h20 mixture.
Then there is confusion between Lake/River water being "Fresh" .... so you'll see some using the term incorrectly.
You may hear: "it's a fresh water cooled engine", when what they actually mean is that they run in River/Lake water only.
The opposite may be "OCS" (Open Cooling System) or aka RWC (raw water cooled)
If we call it CCS, there's little room for confusion.


TAT = (don't want to go there) Hah...... TAT = total advance timing... or TA (total advance)

Well, at least that's my version.

Rick

Thanks for understanding I was making more fun of me than you.

Looks like I should have the 351 back together today with the "CCS" changes.

Nixes mate

OK its up and running.

As best I can tell running the motor as it sits on a roll around cart all looks good. The conversion to a partial E/G solved the high temp problem with the lower manifold
(100 ish) and closing of the bypass took care of the low engine temp. For the first time the engine temp reached 170/180 allowing the system to enter closed loop. After adjusting the timing and playing around with the base idle settings its like fuel injection, starts right up with no throttle and settles down to a to a nice steady 700 RPM.

If this were and inboard it would have been a bit easier but with the IO it gets crowded. Even though the partial system reduced the amount of hoses I hade to get creative as to how to run them. There are some things you just can’t move like the exhaust bellows.

I am not completely out of the woods yet there will be a few more challenges once I get the motor back in the boat. One is what to do about a flash arrester. There no longer available new. All looks good on the shop floor but the only true test is a good run in the water, considering it is only 8 degrees outside my shop today I can wait.

I do have one sort of related question. OMC IO systems run power steering with oil cooler. Has anyone eliminated the cooler and if so what issues did you have? I myself think it is overkill and it reduces the raw water intake from 1’ to ¾’ I realize autos have a lot of ventilation under the hood but I have never owed a vehicle that used one.

Thanks again!

Nixes mate

Run it without the power steering. I don't have it and most of my friends don't ether.

Master Mech

That is basicly my take on power steering. I have had IO's in the past without P/S and never found it an issue. My only reason for keeping it is I also have auto pilot and it makes it easyer on the drive that is actualy turning the wheel. My only concern would be the fluid getting to hot. I am going to run without the cooler and just keep a eye on the the pump temp, like I said I think the cooler is overkill.

I know auto pilot in a 21 footer, trust me I would not be without it wish I had it on my earlyer boats.

Nixes mate

Being the Ignition Timing ZAZI that I am, are you certain that you are using the absolute correct Ignition Advance and Curve/Limit?
You DO NOT want to Detonate this new engine due to excessive advance per RPM.

Yes.... you need to have the PS oil cooler in the loop if you are going to keep the power assist steering.
If you are concerned about flow restriction, replace the cooler with a larger less restrictive one.
NOTE: the OEM designed the system to work with that oil cooler.
Minus an amount of efficiency differential (whether an "open" system, or a "closed" system), BTU's are BTU's, and the sea water's job is to dump these!
I doubt that you'll have a problem.

As for removing the power assist steering, I agree with MM.
There's a caveate to PS in the first place.
Often the OEM installed PS as to mask prop torque or steer torque (which ever you want to call it), that we typically feel at the helm wheel.
Not necessarily to help with steering while at dock side and/or while at low speeds.
It prevents us from feeling this at the helm wheel while up on plane....... but it's still there, and all of your steering components are subject to it.
When you remove this, you will likely now feel this prop torque/steering torque at the wheel.

This is your oportunity to correct this by properly adjusting the trim fin/torque tab as to counter this torque.

But here's another catch!
Not all steer torque is corrected by one adjustment only for a range of RPM and/or speeds.
Pick the adjustment that works best for your cruising style.
A change in prop will also require a new adjustment.

Like said....., PS masks this from you....., yet all steering components have been undergoing this battle.... sometimes causing premature wear to these components.


Merc did a rather sneaky trick by completely removing the trim fin/torque tab from their PS system A drives.
No wonder their steering components require pre-mature repair and/or replacement.
IMO, we should have the trim fin/torque tab in place and adjusted best we can.

I doubt that we'll see this being discussed in any OEM manual.


.

Rick interesting points

“Being the Ignition Timing ZAZI that I am, are you certain that you are using the absolute correct Ignition Advance and Curve/Limit?
You DO NOT want to Detonate this new engine due to excessive advance per RPM.”

Not certain if you are kidding hear; the timing is set to 10 advanced @ 600 rpm this is the same spec as for the ordinal donor vehicle and the OMC version of this system.
There is also a knock sense in the system so I should be good to go.

“Yes.... you need to have the PS oil cooler in the loop if you are going to keep the power assist steering.
If you are concerned about flow restriction, replace the cooler with a larger less restrictive one.
NOTE: the OEM designed the system to work with that oil cooler.
Minus an amount of efficiency differential (whether an "open" system, or a "closed" system), BTU's are BTU's, and the sea water's job is to dump these!
I doubt that you'll have a problem.”

My real problem here is room. The cooler is bulky and presents problems with routing the raw water and P/S lines along with the reduction to ¾. The cooler is the same one the was on the velvet drive trans of my last boat. Just how hot can the P/S get compared to a velvet drive trans in back of a 350?
Anyway,, I can’t dispute your logic that is why I asked the question in the first place. I guess what it comes down to is just how much heat is generated by the P/S in this application and is the cooler overkill. I think for now I am going to leave it out and see what happens under actual conditions using the laser/IR probe. If I am wrong then its back to the drawing board.

I could always opt to do away with the P/S as Master mech suggested and deal with the torque issues you described.

Thank you guys I much appreciate the sanity check.

By the way how did I get the wrench thingy under my name?

Nixes mate

Oooops, I'm the Ignition Timing NAZI... not the ZAZI... typo!

Not certain if you are kidding hear; the timing is set to 10 advanced @ 600 rpm this is the same spec as for the ordinal donor vehicle and the OMC version of this system.
There is also a knock sense in the system so I should be good to go.

Click to expand...

Nixes mate, I think that I've been misunderstood regarding timing.
BASE advance is BASE advance all day long...... in that we fire up and idle on BASE only.
BASE will have no adverse effects on the higher RPM range.
The more important aspect will be the progressive advance once we leave BASE advance RPM range.... of which is up to 1k rpm.
After approx 1k rpm, we begin to see the progressive advance up to the limit RPM.

Apparently you have an EST (electronic spark timing) system since you mention knock sensor.
You also mention "vehicle" (not vessel) and "OMC version of this system".
OMC (basically no longer after 1994) did not use an EST system to my knowledge.

Is this an automotive ignition system by chance?

The EST and knock sensor is great. However, the module algorithm for the curve and limit must be suitable for Marine use.
If you were to allow an automotive ECU/ECM to control spark lead, you may have problems.
In fact, I'd go so far as to say that you will have problems.

I'd start by looking at an ignition curve that suits your Marine Engine build.
If this was a SBC, Full Dished pistons would predicate a certain curve/limit per RPM (very consersative).
If this was a SBC with a quench built into it, this would predicate a slightly different curve/limit (somewhat less consersative).
Once you find the correct curve/limit, it will be very easy to verify your system by stobing your timing marks progressively.

It's all about PCP @ approx 14* ATDC and Detonation control.

.

Rick

I guess I didn’t make that as clear as I might have, I am using the fuel rail, injectors, controller and reworked harness from an automotive system. The intake and throttle body are aftermarket. To facilitate the timing differences from auto to marine I am using an OMC ignition module. The automotive module peaks advance out at 30 deg. The more conservative marine module is 20.5 @ 3000 rpm and only 22 @ 4000 rpm. I agree the automotive advance curve would raise hell with the pistons.

I have to admit this one almost got by me till a friend asked if there were a difference in the advance curve and I didn’t know so I looked into it. Got to love the manuals.

"It's all about PCP @ approx 14* ATDC and Detonation control." (I think I get this but befor I make an A of myself, could you elaberate)

Thanks for the clarification and the heads up.

Nixes mate

Ah.... I'd be glad to share that with you, if you'll tell what an OMC EST Ignition Module is.
Perhaps one exists.... and I'm just not aware.

Like said, OMC was no longer a fully functional company by end of 1993. After 1993, this would be the Volvo Penta designed drive..... although the Cobra name tag was used for a short while.
There is an OMC Ford 5.0L/302CI EFI and 5.8L/351CI EFI listed for the OMC Cobra in 1993.
They do show a Mallory and Prestolite, and an actual Ford Ignition system in 1993, but nothing EST listed for the Ford Engine that I see.
The Delco EST is listed for the GM 4, 6 and 8 cylinder engine.

So if you would, please help me out on what an OMC module would be. I'm just curious.


***************

As for PCP..... this would be Peek Cylinder Pressure, or LPCP = Location of Peek Cylinder Pressure.
This general rule of PCP @ 12-14* ATDC applies to any piston engine... gasoline or diesel, and regardless of cylinder pressure, but more so when "peek" pressure occurs.
Ideally we want all components pulling together (valve operation, fuel/air, valve timing, Ignition timing) so that immediately upon combustion, the peek pressure created by the burn occurs as the piston is on it's way down.... more specifically @ 12*-14* ATDC.
Some suggest as early as 12* ... some suggest as late as 14*.

Now we must factor in the combustion chamber design and piston design.
A poor combination here (SBC + full dished for example), and it may lend itself to Detonation.... of which in addition to damage, will have an adverse affect on PCP if Detonation doesn't kill the pistons first.

There are some great articles on PCP or LPCP on the web.

The automotive module peaks advance out at 30 deg.
The more conservative marine module is 20.5 @ 3000 rpm and only 22 @ 4000 rpm.
I agree the automotive advance curve would raise hell with the pistons.

Click to expand...

I too am glad that you caught this.

An automotive module advance of 30* btdc, + BASE of 10*, would put you way too far advanced, unless this was delayed until 5.5k rpm or so.
The 20.5* module + a BASE of 10* would put you at 30.5* btdc @ 3k rpm, and at 32* btdc @ 4k rpm.
That's more like it!

I believe that more articles on the "squish" or "quench" have been written for the SBC.
However, the 5.8L Ford also incorporates a wedge area off the side of the chamber.
If you brought your quench down to around .038" or so, you'd be better equipped against detonation.

I actually like the Ford 5.8L, but have much more experience with the SBC.

.

I just read back through your thread to see if I missed anything.
General summary beginning at post #1:

1991 OMC 5.8L engine would have the OMC Cobra dog clutch drive..... (not cone clutch Volvo Penta)
This means that you have an ESA (electric shift assist).
Your 500 cfm carburetor was not the issue. (500 should be more than adequate for a 5.8L @ cruise RPM)
The 302 carburetor has now been replaced with EFI.. tricky upgrade, but works.
Knock sensor included in the Ignition system which tells me this is an EST w/ module.
Engine bay airflow will be increased.
Engine coolant sensor not sensing high enough reading... corrected now.
Short class on abbreviations.
Power Steering .... keep it or not keep it, discussed.
Ignition advance discussed and confirmed to be correct.
Short explanation on PCP.

OMC ignition module still has me puzzled! (would this be the Cobra Dog Clutch ESA to Electronic Ignition module?)

Perhaps also explain which Ignition system you are using, and what year it is.

.