1994 omc 5.0 ho 2 to 4 bbl swap

[jj50cal]

hi, looking for info on what i did wrong. apparently boats are not cars. i have a 1994 four winns horizon 190. paper work says i have a 5.0 ho ford engine. i was only getting up to 4500 rpms from the engine with a 14.8 x 17, three blade prop. and a 2 bbl holly carb. two different marine engine mechanics suggested to change out the carb. they both said the 5.0 ho should have a 4bbl holly. when i purchased the boat in 2011 it had a 21 inch pitch prop which was fine for up to 3 passengers, and a tube. but for knee boarding or skiing, i had to bump up to the 17 pitch. but could never get above the 4500 rpm. Now i have installed an edelbrock performer aluminum intake, a holley 600 4 bbl. (did not move the distributor so timing should still be exactly the same as before), new triple platinum plugs set at .055, i know the old plugs were no. 24 autolite set at .045, but plug chart said to set new ones at .055, (who am i to argue), where did i go wrong? or have i just not done enuff, i can only get up to 3500 rpms now, and the boat will only plane off if only 2 people are in it. it sounds great in nuetral, revs up great, idles great, acts as if it wants to jump clean out of water at launch, (as long as its in nuetral), put it in gear and it's bog city, PLEASE HELP......

 

[Bondo]

(did not move the distributor so timing should still be exactly the same as before),

Ayuh,... Welcome Aboard,.... Who's to say the timin' was right before,..??

Ya shoulda been runnin' well over 4500 rpms when ya switched to the 17" pitch prop, from a 21",......

Have ya done a compression test,.... Maybe she's just tired, 'n worn out,.....

 

[Scott Danforth]

You had to have pulled the dizzy to swap manifolds. If you didn't put a timing light on it, shame on you.
Also, check your rpm with a service tach. The dash gauge may be wrong.

 

[Bondo]

Ayuh,.... It's a Ford Scott, I think the distributor mounts in the timin' chain housin',....

Not that I've looked very close at one in the last 20 years,.....

 

[jj50cal]

sorry guys, i was busy still looking for answers.... anywho, yes did compression test, 145 pounds plus, all cylinders. next the distributor on a ford is located on the timing cover, not the manifold, so no need to disturb it, and yes it was correct before, i don't have my cheat sheet with me at this time it is with my son about an hour away..

 

[jj50cal]

p.s. also the fuel tank was removed, cleaned, dried, and reinstalled just because i fugured it was time after all these years, it really wasnt bad enuff to clean, but any trash is bad trash, also replaced the water separator, and added an additional fuel filter, and replaced the fuel pump with a holley high volume 120 gph pump just because of age also.

 

[jj50cal]

p.s.s. if i have to put the 2 bbl carb back on, can i keep the aluminum 4bbl intake just use the 4bbl to 2bbl conversion adaptor by edelbrock, or holley?

 

[Bondo]

if i have to put the 2 bbl carb back on

Ayuh,..... No reason in the world to do that,.....

Ya just gotta sorta out the tunin',....

Checkin' the timin' is a step I wouldn't skip,....
Set the plugs to .045 if that's what's called for, ya didn't change the ignition, why change the plug settin's,....??...
Get a shop tach to verify the dash tach, as I said, it don't sound right,....
What rpms were ya gettin' with the 21" prop,..??

Doin' spark plug color test runs might tell ya where the carb needs tunin',.....
Run a time at low speeds, shut the motor off, 'n check the plug color,....
Ditto mid-range,....
Ditto hi-speed runs,....

 

[jj50cal]

ok, got the timing light out, timing was a bit off, about 4 degrees, put it back to where the factory mark was, sounds a little better, but no lake test yet. also pulled dip stick to check oil again, i'm a fanatic about clean oil, i don't go by hours run, or mileage, if it aint see thru it's outta there. anyway, it had bubbles, not sure what the bubbles are yet, but i drained it. and put a quart sample in a jar to look at tomorrow. (should separate by then), i will regap plugs tomorrow also, and like you said, i will check low speed and mid range then top speed colorations.... the answer to your Q about the 21in prop, it was about 2800 but not more than 3000. it just simply would not get off plane with passengers aboard.

 

[Scott Danforth]

Ayuh,.... It's a Ford Scott, I think the distributor mounts in the timin' chain housin',....

Not that I've looked very close at one in the last 20 years,.....

Forgive me, was after 10 pm here and I've been running on no sleep for a week. I thought the dizzy shrouds the front corner of the manifold requiring the dizzy to be removed for ease of access. Still, after swapping the induction system, the timing still needs to be looked at.

Regarding the Holley carb, which carb is it? 4150? 4160? CFM?What are the jet sizes? What is the vacuum spring color, and which power valve? The carb needs to be tuned to the motor.

Should be a 600 vac secondary with #25 or #35 power valve, aprox #64 primary jets, approx #80 secondary jets, and the lightest (yellow short or white) spring.

What color are the plugs?

Another issue it could be, if this is an older holley carb( pre blow out check ball ), if there was a backfire, it could have blown the power valve. The blow out check came out in 1992.

 

[jj50cal]

i understand about the sleep deprivation, i am a retired 25 yr veteran fireman, i understand all too well about sleep, lol. i am not sure at this moment which carb it is, i do know it is a 600cfm electric choke, vaccum secondaries,it is a brand spankin new carb, right off the shelf from O'rielly's, we checked the timing, it was off just a bit, about 4 degrees, got that reset... will be checking coloration of plugs this afternoon when my son gets home, (he is my right hand man these days..) i will check on the exact model asap, and will try to find out about the jets. any idea how to do that without opening up the carb?

 

[jj50cal]

just found out it is the 4160 carb, and a good friend told me ( he is a race car mechanic), that the 4160 comes with the factory 64primary.

 

[Redrig]

right off the shelf from O'rielly's

Is it a marine carb ?

 

[jj50cal]

officially it is (not), we took the spill over tube from the holley 2bbl, and added it to the 600cfm. is there more of a difference than that between the 2? i've been told locally that was it.

 

[Scott Danforth]

If it's not a marine carb, first, it won't be calibrated to run a boat motor (wrong primary jets, secondary jets, power valve and vac spring).

Second, your boat can blow up.

Who ever told you only the j-tubes is uninformed.

The castings are the same...... The final part number for the center section is different, and as I pointed out, all the fuel delivery calibration is different.

With your auto-tuned carb, your actually starving your motor for fuel just off idle. I bet your getting a lean sneeze ( a bit of backfire) at about 1500- 1800 rpm.

Since the vac secondary spring is wrong, I'm willing to bet the secondaries never open up.

This is why you had more performance with your 2-barrel than you have now

 

[jimmbo]

The Holley 500 cfm 2bbl(flows about 379 cfm when rated like a 4bbl) is sized just perfectly for a 5 liter turn 5000 rpm.

Your auto carb, as mentioned, is way off calibration for marine use. Off idle too lean, power valve wrong, main jetting too lean, power circuit calibrated to work with lean street jetting. Accelerator Pump circuit nozzles wrong. Which vacuum secondary spring? Most street carbs will open too soon in a marine app. Secondary jetting. Throttle shaft bores have to have fuel leakage preventers to qualify as a marine carb. You said you used a J vent, there are 2 needed on a 4 bbl holley. What did you do with the choke?Non marine carbs are not Coast Guard approved and therefore not legal to use in a boat.

 

[jj50cal]

ok, thanks, looks like i made a good choice this afternoon in ordering the holley 4160, 0-80492. autozone has it on order for $492.99 and free shipping. i hope this is the only thing i have to do is swap these 2 beasts out. but jimmbo, if i could get 5000 rpms from the holley 500 that was on there i never woulda changed it, the most i ever got from it was 4500, and that was after changing to a 17 in prop. from the 21 that was on it.

 

[jj50cal]

but since my wife wants to use her boat this weekend, i will be putting the old holley 500 2bbl carb back on, but this time it will be on top of the edelbrock performer intake, just gotta get a 4bbl to 2 bbl adapter and all will be well. i hope and pray..... if i am wrong someone please tell me before it happens..

 

[jimmbo]

You sure you have the 500cfm, not a 350? My 5.7 can pull 4800 rpm @ 5 inch pressure drop with the 500cfm with a 20 inch prop and a 1.51:1 gearcase. It is rated 500 cfm @ 3 inch pressure drop. That shows the carb is too small for a 5.7 With a Holley 650 spreadbore It gained another 450 - 500 rpms

302 cubic inches/2 = 151 cubic inches per revolution multiplied by 5000 rpm = 755,000 cubic inches per minute. 1728 cubic inches per cubic foot equals 436.9 cfm. At 80% Volumetric efficiency equal 349 cfm When a 2bbl carb is flow rated like a 4bbl carb, 500cfm becomes 357cfm

 

[jj50cal]

all i can tell you for sure is i have owned the boat for 5 years now, we never got more than 4500 rpms, its is a 1994 four winns 190 horizon, originally purchased from counce marine in memphis tn. the original owner says he forgot to winterize the boat the first year, and had to take the boat back to counce marine for a new engine install. after 4 yrs of running 4500 rpms and the kids growing up wanting to knee board now, the old hot rodder inside me says to give it more gas, the part number on the holley 2bbl that was on top of the 5.0 ho, shows it to be a 500cfm, so there for go to a 600cfm (right)? so now i have ordered a (marine grade) holley 600cfm (4160) (0-8492) autozone, o'rielly's and summit show this to be a new marine carb. the mechanic i hired to install the spark plugs, i chose to go to triple platinum this time because they claim to be better plugs, he gapped them at .055, instead of the books gap of .045. But, so i can put my wife on the water this weekend and help her to destress from her mother passing a couple of weeks ago, i am planning on installing the 2bbl back on top, but continue using the new aluminum intake, instead of putting the 45pound cast iron boat anchor back on. ALL of this was so that i could cheap out by installing a new carb, instead of a bigger motor