Thanks to OMC gurus on the board...

[kimswang]

... I got my engine running nice again. It turned out it was a brand new powerpack that was bad from the getgo. Now however, I can only spool my two outer engines (1987 275HP with 4.0 powerheads) up to 4000 RPM's. The middle engine (1993 300HP) spools easily up to 6000RPM and is ofcourse doing most of the work. I will tear down and check the carbs and adjust the timing on my outers to what the middle has. Is there something else to check for? Am I missing something obvious? The outers cough, spit and runs rough when they are cold while the mid (1993 300HP) runs smooth as silk. The outers got big bore carbs and the baffle in the airbox, would it be a good idea to take the baffle out and rejet?

Again, thanks to ALL input given so far, now I just need another 2000RPM's worth of input and then some prop advice.... (They are all way underpropped right now)

[flabum1017]

That sounds more like propping/setup problem than dirty carbs. What props are you running and how high are the engines?

[Forkin' Crazy]

Before I did anything I would check the linkage and sync adjustments

[kimswang]

That sounds more like propping/setup problem than dirty carbs. What props are you running and how high are the engines?

Props are waaay under what they should be, I was running 20" on the two that would only spool up to 4000, and 22" on the one that will spool to 6000. I have 26" that I think will be the ticket once the engines are all running correctly. The outers are also too deep in the water and I will lift them substancially here in a month or so.


Before I did anything I would check the linkage and sync adjustments

I think (and hope) you are correct, as that will be my first thing to check. Doing so is when I really envy the SOB guys...:D

[Forkin' Crazy]

The outers are also too deep in the water and I will lift them substancially here in a month or so.


You running 2 20"s and one 25" right?

[kimswang]

You running 2 20"s and one 25" right?


No, the outers got 20" and the middle got a 22".

[STV_Keith]

We're talking props AND mids. FC, he's got all 25" motors...running 20" pitch on the outside and 22" in the middle.

With where his outer motors are mounted now, water hits the midsection - they are that low in respect to the bottom due to the deadrise in the hull. He wants to go to 20" mids on the outer two motors, but hasn't been able to locate two 20" mids yet.

[kimswang]

We're talking props AND mids. FC, he's got all 25" motors...running 20" pitch on the outside and 22" in the middle.

With where his outer motors are mounted now, water hits the midsection - they are that low in respect to the bottom due to the deadrise in the hull. He wants to go to 20" mids on the outer two motors, but hasn't been able to locate two 20" mids yet.

Hi Keith,

Thanks for clearing that up with respect to mid / props.. I will keep my 25" mids and raise them up. I have all the pieces cut out and ready to go on the bracket, just need to take the engines off and get the welder here. I know I could weld them myself, but with 1/2" aluplates and the amount of weight / power I rather have a certified welder do the welding. When it is all dialed in I will get the middle engine to 30" and there will only be a slight stagger. First off I have to get my outers to spool up correctly. At least I got my ignition to work now and that was a giant step for me. A little tuning this comming week will hopefully take care of it. I made my own test'n tune prop so I plan to do the adjustments at Calville with the boat on the trailer unless I just make my own test tank here...:D What worries me a bit is the caughing and spitting while the engines (the outer ones) are cold. Could this be an indication that the reeds are need of a replacement?

[Forkin' Crazy]

We're talking props AND mids. FC, he's got all 25" motors...running 20" pitch on the outside and 22" in the middle.

With where his outer motors are mounted now, water hits the midsection - they are that low in respect to the bottom due to the deadrise in the hull. He wants to go to 20" mids on the outer two motors, but hasn't been able to locate two 20" mids yet.

They are around. I saw one in a junk pile last time I was in FL. :eek:

Well that explains a lot!!! :) Mostly I have seen them rigged on Vs is 20-25-20.

[baja200merk]

They are around. I saw one in a junk pile last time I was in FL. :eek:


i know where a few are...

[kimswang]

If you see a 30" mid with the exhaust housing, let me know. I have the parts to extend my 25" to a 30" but a mid without the extension would be preffered.

[STV_Keith]

Kim, I guess they could be spinning up less because the props are so buried. Didn't you run these same props at the same depth before without a problem?

[kimswang]

Kim, I guess they could be spinning up less because the props are so buried. Didn't you run these same props at the same depth before without a problem?


It could be the case. I have always had that problem with my RH engine that I finally solved. I have spun them up to 5500 before, while I had the twin set up. I am checking linkage right now, but sitting reserve so I might have to bail on short notice.... The rough running kindof took me by surprize as they run nice here on the hose..

[kimswang]

Just checked the linkage, it is A OK. Will check timing later, here is some pictures of the carbs / linkage:

http://inlinethumb48.webshots.com/40751/2539817370103325923S600x600Q85.jpg (http://good-times.webshots.com/photo/2539817370103325923QsKkzQ)
http://inlinethumb59.webshots.com/7930/2888827650103325923S600x600Q85.jpg (http://good-times.webshots.com/photo/2888827650103325923diuBQx)http://inlinethumb34.webshots.com/36641/2235614450103325923S600x600Q85.jpg (http://good-times.webshots.com/photo/2235614450103325923iXmlqh)
http://inlinethumb55.webshots.com/40758/2760819260103325923S600x600Q85.jpg (http://good-times.webshots.com/photo/2760819260103325923kmgUAi)

[kimswang]

Is there any chance that being as deep in the water as they are, that could be a reason for them to not spool up? I checked all that I could think of and it all seems fine, problem is they only do 4000 RPM on the water and my mid (an original 300HP from 1993) spools just fine and idles just fine. I am leaning towards my reeds at this time, but hate to replace parts that I don't know for sure is broke. If anyone has an idea, feel free to post a reply - I need all the help I can get and this situation is driving me up the wall....

[markt111]

Hey Kim you would loose a few hundred RPMs with them to deep, they should def spin more than 4000

if they spun 5500 with just two I would think with the third engine you would see a few hundred more

[kimswang]

Hey Kim you would loose a few hundred RPMs with them to deep, they should def spin more than 4000

if they spun 5500 with just two I would think with the third engine you would see a few hundred more


One would think so. This is really frustrating. The outers engines are the problem. When I run them on the hose here at the house, everything is A OK. They start on the first crank and idles smooth as silk. When at the lake, they caugh and spit and is hard to idle before they get warmed up. Once they are warm, the idle somehow smooths out. I have gauges for everything and they are all indicating that the motors got what they want with respect to fuel and cooling. The motors differ from my mid engine in that they have big bore carbs and the old ignition system with dual power packs, otherwise they are identical. This should not cause the motors to top out at 4000RPM's and I am pulling hair at the moment trying to think of what else it could be. I am pretty sure I am overseeing something obvious since the linkage indicates good, compression is good, they all get fuel from the same tank, and nothing has been done to the engines since they once spooled up to 5500RPM's..

[markt111]

timing, all cylinders firing?

do the simple timing light check on each plug wire to make sure all are firing made to to borrow an inductive KV meter and do it at speed

sounds like it is probably a tune or ignition problem, 18* or so total timing, all butterflies opening the same, no vacuum leaks etc...

[kimswang]

timing, all cylinders firing?

do the simple timing light check on each plug wire to make sure all are firing made to to borrow an inductive KV meter and do it at speed

sounds like it is probably a tune or ignition problem, 18* or so total timing, all butterflies opening the same, no vacuum leaks etc...


All sparkplugs are firing and verified with a tester, hence I needed another new powerpack (bought a new one that was toast so it threw me off as there was no change). I just measured the idle timing and it showed 4 degrees. The timing in my 1987 manual is not listed for idle, but it is listed to be 8 degrees +/- 2 degrees ATDC in my 1993 manual. I made a test prop and will head for the lake to do some testing / tuning / timing setting today or tomorrow. All butterflies are wide open and the linkage looks A OK. What throws me off right now is that I have not done anything that would change the timing and I have gotten 5500 out of them before just the way they sit with the exception of new plugs, powerpacks, and wires. I will set the timing to 16 degrees at 4500RPM's if I can get them that high, as that is the number for the 4.0 300HP. Keep them comming though, sooner or later I will say - Aha (and then tell myself I'm an idiot..)! :D

[flabum1017]

let me tell you a little story....

We had a couple guys buy two 300's from us back in the late '80's. Shipped them to Jamaica.

About two weeks later we get a call saying they need a new powerhead and needed a tech down there because the boat would not get on plane. So off I go to Jamaica. I get down there and what do I see? A 40' Aluminum dive boat with these two outboards on it that we sold. It seems they took out the Detroit 8V71's and put these on because they were more horsepower. Long story short, they killed an engine by using it on the wrong application.

How does this apply to you? Simple, with those motors that low, you will never get them to spin up without a 17" or 15" prop; they are simply too deep. You NEED to get those motors to the right height.

[kimswang]

let me tell you a little story....

We had a couple guys buy two 300's from us back in the late '80's. Shipped them to Jamaica.

About two weeks later we get a call saying they need a new powerhead and needed a tech down there because the boat would not get on plane. So off I go to Jamaica. I get down there and what do I see? A 40' Aluminum dive boat with these two outboards on it that we sold. It seems they took out the Detroit 8V71's and put these on because they were more horsepower. Long story short, they killed an engine by using it on the wrong application.

How does this apply to you? Simple, with those motors that low, you will never get them to spin up without a 17" or 15" prop; they are simply too deep. You NEED to get those motors to the right height.

Hi Flabum,

Thanks for your input. I will try to get a welder to do the neccdesary adjustments so that the engines can be the correct height. All the aluplates are cut and ready to go on. I just don't get it. The midmotor spins up to 6000RPM no problems and drags the other two engines to a max of 4000RPM's??? By measurments, the outers are sitting about 4 inches too high for the water to pass underneath the plate. If you think this is it, I will try that first, before I start beating a dead horse.

Again, thanks a million for your input.

Kim !

[STV_Keith]

Flabum1017, in this configuration, Kim's boat has run before. The two outer motors used to run fine, up to 5500rpm, but the center motor had an electrical problem that wouldn't let it get over 3500rpm. He just fixed the center motor, which will now turn 6000, and now the outers won't go over 4000. Doesn't make a whole lot of sence.

[gotboostedvr6]

I'm gonna say lack of fuel to the outer motors nothing else would make sense.


What size is your primary fuel feed from the tank? You are using 850 hp worth of fuel.

[flabum1017]

We're talking props AND mids. FC, he's got all 25" motors...running 20" pitch on the outside and 22" in the middle.

With where his outer motors are mounted now, water hits the midsection - they are that low in respect to the bottom due to the deadrise in the hull. He wants to go to 20" mids on the outer two motors, but hasn't been able to locate two 20" mids yet.


This is the reason for my reply

[kimswang]

I'm gonna say lack of fuel to the outer motors nothing else would make sense.


What size is your primary fuel feed from the tank? You are using 850 hp worth of fuel.


New fuel tank from IMCO with 3/8" fuel hoses leading from the tank to three separate filters, then to three separate Holley Red Fuel pumps. Fuel pressure gauge sending unit located directly in front of the carbs and is showing 3-5PSI at WOT so flow should not be the problem. Besides, if fuel was a problem the engines would run hot, and by checking temp as well as spark plugs they don't. You might be right, it's just that all three engines have identical fuel delivery and one spools to 6000 in a second and the other two will only spin 4000RPM's, regardless of speed on the boat. I will do some filming of it next time out and post... I'm still lost.

[STV_Keith]

This is the reason for my reply

True, but with that config, the outers have run 5500rpm before.

[kimswang]

This is the height of the engines:

http://inlinethumb31.webshots.com/41310/2877969660103325923S600x600Q85.jpg (http://good-times.webshots.com/photo/2877969660103325923fLxcjy)

This is how it looks in the water:

http://inlinethumb04.webshots.com/35395/2769267120103325923S600x600Q85.jpg (http://good-times.webshots.com/photo/2769267120103325923vjDkCn)
I'm not saying it is not the reason, I'm just saying it is unlikely as they have spooled up with this setup before. Also, keep in mind that the mid motor idles fine and spools right up and it does sit the deepest while off plane and sits correct height while on plane. The outers are the ones that idles rough, spits and is hard to start while in the water but when on the hose starts right up and idles perfect. The problem motor so far has been the RH motor that had an electrical issue that is taken care of. They all run smooth at WOT, the two outers just don't spool up. The boat will do 53 - 54 MPH with the mid running 6000RPM's and the two outers at 4000RPM's with 20" props on the outers and a 22" prop on the mid. This suggests that the mid is doing ALL the work in addition to dragging the two outers since they will have negative slip with this RPM / speed. The outers are, as mentoned before, 4.0 powerheads with 275HP 3,6 ignition and big bore carbs. Theoretically they should spool to a higher amount of RPM's than the mid.

[flabum1017]

Are you sure the center motor doesn't have a spun prop hub?

[markt111]

just thought of one other thing,

what type of timing light are you using when you ste total timing???

[STV_Keith]

Spun hub could be one thing to check. It doesn't make sense that the middle motor could overrev the outers, unless it's got big prop slip. I know my twin engine rig would lug down one motor when I had to run home on one, not slip the one to higher rpm.

[outboards4life]

you could have some coils breaking down with the added pressure of being in the water. had that happen on a bass boat I worked on few years ago.

[kimswang]

Are you sure the center motor doesn't have a spun prop hub?

Yes, prop is fine. With a spun prop in the middle there is no way it would do more than 35MPH, it is doing 53MPH... Good thinking though, I like it!


just thought of one other thing,

what type of timing light are you using when you ste total timing???

Sears Professional. I have not set the timing under pressure yet (4500 - 5000RPM's as pr. the manual), hopefully today I will pull the boat to the lake and do it.

[kimswang]

you could have some coils breaking down with the added pressure of being in the water. had that happen on a bass boat I worked on few years ago.

That is very possible. Not very likely as the two outers are acting identical but if it was the case, how would I check without bying 16 new coils?

[markt111]

do not use a timing light with an adjustable advance!!!

go thru your steps to mark your O*, using a piston stop tool etc... then mark your 16* if that is what you want and use, use a basic timing light with no advance on it and set on your 16* mark at speed, found this out when I set mine up I went out and bought a new timing light with the advance so I didn't need to mark the flywheel for total timing, turns out it seemed to give exactly half the advance needed

[STV_Keith]

Hey Kim, if it was a prop issue, you could borrow my LH 20 pitch 4-blade Mach for your center motor (it is a LH right?) With more blade area than your 3-blades, it would probably act about the same pitch wise.

[BRH]

do not use a timing light with an adjustable advance!!!

go thru your steps to mark your O*, using a piston stop tool etc... then mark your 16* if that is what you want and use, use a basic timing light with no advance on it and set on your 16* mark at speed, found this out when I set mine up I went out and bought a new timing light with the advance so I didn't need to mark the flywheel for total timing, turns out it seemed to give exactly half the advance needed

Not sure how that happen to you. I use a adjustable advance timing
light and It works fine for me.

[kimswang]

do not use a timing light with an adjustable advance!!!

go thru your steps to mark your O*, using a piston stop tool etc... then mark your 16* if that is what you want and use, use a basic timing light with no advance on it and set on your 16* mark at speed, found this out when I set mine up I went out and bought a new timing light with the advance so I didn't need to mark the flywheel for total timing, turns out it seemed to give exactly half the advance needed

That is good advice and seem likely as they fire twice as many times compared to what they are intended for. I have marked my flywheels for all cyl / TDC and will set my mark on 16 degrees as well. My timing light does have the advance setting, but it can also be used with 0, and that I will use. Thanks.


Hey Kim, if it was a prop issue, you could borrow my LH 20 pitch 4-blade Mach for your center motor (it is a LH right?) With more blade area than your 3-blades, it would probably act about the same pitch wise.

Checked the prop, no issues there. I mounted a 26" prop on just to see if I could possibly rev the outers a bit more with more speed on the boat. The 22" that I took off will make the mid hit the rev limiter even with the outers at 4000RPM's. My neighbor also informed me about a guy down the street selling some big tanks today. Maybe I go and check it out and make my own test tank right here at home.. I was looking at them online yesterday and they want almost $2K for one of those test tanks. Should be easy enough to make one myself....

[kimswang]

Not sure how that happen to you. I use a adjustable advance timing
light and It works fine for me.


Once I get my engines in a tank or to the lake on the trailer, I will kill / verify this myth.

[markt111]

Not sure how that happen to you. I use a adjustable advance timing
light and It works fine for me.

after finding this I spoke to Gordon directly and he confirmed

I def trust him when it comes to any OMC question

[STV_Keith]

after finding this I spoke to Gordon directly and he confirmed

I def trust him when it comes to any OMC question

Me too. He is dynoing engine #1 today. :D

[markt111]

let us know Keith...

very curious, what do you expect? what did he say was the target?

I know you can get over 400 out of these but we want driveability, torque and reliability

[STV_Keith]

Pump gas only, heavy boat setup. Shooting for 360-370. My dad has had it on his 25 Power Play for the last 10hrs. With a full load of fuel and people, it turns 600rpm more than his stock 275hp powerhead. With a light load, it was 900rpm more. It is still fat at this point. They are going to lean it down a bit today, then do 2 or 3 dyno tugs on it.

I told dad once he gets it leaned down and dynoed, that I'd like him to grab his GPS and go run the boat with the same 19 Tempest and 22 Bravo1 that he has used before, and see what the differences are in speed/rpm. Hopefully he will get it done for me before he puts his powerhead back on the boat.

[outboards4life]

That is very possible. Not very likely as the two outers are acting identical but if it was the case, how would I check without bying 16 new coils?


put em on a prv meter. they should put out like 25,000 volts.

[STV_Keith]

For those interested (and I will make a full post later), my first Monty motor is on the dyno now. They didn't jet it down - in fact Monty said "This thing is FAT FAT FAT!" :D

Still made 372hp/323tq! I'm happy already. I think they're gonna jet it down and do it again. I'll keep ya'll posted. :D

[STV_Keith]

Quick pull without the airbox, 391hp! We're getting there. :D

[kimswang]

put em on a prv meter. they should put out like 25,000 volts.

Will this one: http://www.maxrules.com/fixtools640.html work? If a coil is firing intermittently, this unit will still tell you the peak and not the intermittent firing, correct?

[kimswang]

Quick pull without the airbox, 391hp! We're getting there. :D

Looks like I better get mine fixed quickly or get blown away from a twin.... :D That is impressive numbers and I look forward to see them on your Scarab...

[outboards4life]

Will this one: http://www.maxrules.com/fixtools640.html work? If a coil is firing intermittently, this unit will still tell you the peak and not the intermittent firing, correct?

wow thats pretty sweet. the one I have is older than me.

[outboards4life]

that will work but the motors have to be in water not on a hose cdi makes a load bank tester for this. i'm not sure the price on it though. I'm sure it's not cheap.http://www.cdielectronics.com/Portals/0/Catalog/Tools%20and%20Test%20Equipment.pdf

[kimswang]

wow thats pretty sweet. the one I have is older than me.


But will yours tell you if you have an intermittent fireing? I think a scope might be the answer, but I am not sure.

[outboards4life]

mine does not tell me intermittent firing. mine just shows if you're getting enough voltage to the plug.

[flabum1017]

It's strange both outside motors started doing this at the same time. Do you have a single kill switch for those two motors? Back when they made those, they used to have a singe kill switch for twins that would screw up and cause that kind of a problem when the kill switch shorted across the engines.

[markt111]

hey Keith do you know what size jets Gordon is running during these runs? could let me know what the final size is too

also how much compression? 135ish?

probably going to send him my heads in the fall for a little milling to get my comp up once i get my setup complete this year, going down Sat and Sun to tighten up all the steering issues and will hopeully be in the water in a week or so

[kimswang]

It's strange both outside motors started doing this at the same time. Do you have a single kill switch for those two motors? Back when they made those, they used to have a singe kill switch for twins that would screw up and cause that kind of a problem when the kill switch shorted across the engines.


No, I have three separate killswitches from Livorsi (However, they are mounted lately and you might be on to something). Been on the boat most of the day today schratching my head and will head for the lake tomorrow armed with ideas and test procedures. The one thing that the two outers have that the middle doesn't is Sierra fuel filters. The middle one has OMC, despite the fact they where all installed new at the same time it will be one thing I will swap.

[STV_Keith]

Hey Mark, check out the other thread (don't want to sidetrack Kim's thread): http://forums.screamandfly.com/forums/showthread.php?t=158246

[markt111]

FYI Kim I have run Sierra filters without issues, I know they have a few different models as long as you run the larger I would think you should be fine there,

if it was a fuel starvation I would think you would surge more instead of just low performance (I think)

[STV_Keith]

Plus, your fuel pressure senders are AFTER the fuel filters, right? So you'd see it on the gauge.

[kimswang]

FYI Kim I have run Sierra filters without issues, I know they have a few different models as long as you run the larger I would think you should be fine there,

if it was a fuel starvation I would think you would surge more instead of just low performance (I think)

One would think.. I am running the larger OMC type.


Plus, your fuel pressure senders are AFTER the fuel filters, right? So you'd see it on the gauge.

Yes they are, and I would expect so. Just running out of options...

[flabum1017]

The one thing that the two outers have that the middle doesn't is Sierra fuel filters. The middle one has OMC, despite the fact they where all installed new at the same time it will be one thing I will swap.


Ahhh.... the OMC's have a bigger thread on the filter = more flow.

You may be on to something there.

[kimswang]

Ahhh.... the OMC's have a bigger thread on the filter = more flow.

You may be on to something there.


Same thread, different brand filters. The mounting for the filters are all OMC, hence the big thread. I have asked Sierra about oil mix before and they claim it is OK, other filters will not work well with the two stroke oil. Got bumped from going to the lake today due to purchase of new truck to pull the beast. Heading out in the morning with a guy I buildt a car with... (All aluminum frame, Viper Engine mounted backwords in the back, fiberglass body...., hotrod kinda guy so we will see if we can solve it).

[markt111]

just bypass your filters for a quick test run, as long as you don't have a crappy tank

doubt it's the filters anyway but you never know chasing these little gremlins around, on my old boat i had an intermittent problem and chased the electrical side forever, turned out to be my vent line from the gas tank would hold fuel and vapor lock the fuel pump so it could not deliver adeqaute fuel under load, finally found it by running with no gas cap for 5 minutes

[kimswang]

just bypass your filters for a quick test run, as long as you don't have a crappy tank

doubt it's the filters anyway but you never know chasing these little gremlins around, on my old boat i had an intermittent problem and chased the electrical side forever, turned out to be my vent line from the gas tank would hold fuel and vapor lock the fuel pump so it could not deliver adeqaute fuel under load, finally found it by running with no gas cap for 5 minutes


It's kinda funny how one find these small gremlins... I took the boat out today for testing. I have made a test prop (with advice from the board here, thank you..) and had great success with it. My timing is dead on 16 degrees on all three motors, they run evenly all the way up to 5700RPM's for the outers and 6400RPM's for the mid. I ran into an old friend who is also an awesome engine builder and he was willing to bet money on that the X dimension is the main cause of the different output. I will now raise the outers to the correct height before I continue to beat a dead horse. Another fact is that the outer motors got all elctronics from 87 and the mid got the "new" stuff (single powepack), the outers got about 700 hours on them and the mid got less than 50 hours since new. The outers huff and puff a lot when started up at the lake while the mid is smooth from second one. This lead me to believe that the outers is due for some new reeds and maybe a little rebuilding. After reading STV Keith's Dyno sheet I have to admit I would like to send my motors to Monty and have them buildt like he did. This, however, will be a winterproject and for now the X dimension will be fixed and the summer enjoyed to the fullest while I can look forward to the winter to have all three tuned by Monty. Thanks again for all help and suggestions, should I find anything else I will post ASAP.

Kim !

[markt111]

so you got 5700 RPMs on the outers running the boat at speed or with the test prop?

[kimswang]

so you got 5700 RPMs on the outers running the boat at speed or with the test prop?

5700 was with the test prop on the outers as compared to 6400 with the test prop on the mid. I mounted a 26" prop on my mid and 20" on the outers for a seatrial and got about 4800 out of all three running at about 53 Mph. I can easily picture 65Mph after correcting my X dimension 8" on the outers.

[flabum1017]

65 with triple V-8's is way too doggy for that boat. Go wth the basics..... compression test, spark check, fuel quality and delivery (time for a vacuum guage on the fuel line), temps and setup.
If the test wheel shows that much descrepency, then something is going on with the motors.

[150aintenuff]

5700-6400 with same prop l... you got problems.... thats about a 75 hp difference between the old versus new..... you have issues.. even burried that aint right

[kimswang]

Quote:
<TABLE cellSpacing=0 cellPadding=6 width="100%" border=0><TBODY><TR><TD class=alt2 style="BORDER-RIGHT: 1px inset; BORDER-TOP: 1px inset; BORDER-LEFT: 1px inset; BORDER-BOTTOM: 1px inset">Originally Posted by flabum1017 http://forums.screamandfly.com/forums/imagesSF/buttons/viewpost.gif (http://forums.screamandfly.com/forums/showthread.php?p=1360719#post1360719)
65 with triple V-8's is way too doggy for that boat. Go wth the basics..... compression test, spark check, fuel quality and delivery (time for a vacuum guage on the fuel line), temps and setup.
If the test wheel shows that much descrepency, then something is going on with the motors.
</TD></TR></TBODY></TABLE>
I could not agree more. I was expecting an honest 75mph out of the setup. I will continue checking / tinkering....

Quote:
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5700-6400 with same prop l... you got problems.... thats about a 75 hp difference between the old versus new..... you have issues.. even burried that aint right
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I have no doubt it is at least 75 HP difference between the old and the new. The test with the test prop clearly made me realize it. The issue is however, that the outers now run very smooth once they are warmed up. I have had two bad powerpacks and know what a bad ignition indication says. The fueltank is new from IMCO, the fuel lines are new USCG approved 3/8" lines, the fuel filters are new (middle is OMC, the outers got sierra but all on OMC platform), the fuelpumps are new Holley reds, all gauges (and there is a few...) are new from Livorsi and is telling me everything is A OK, the plugs are new, the plug wires are new Ford racing plug wires, the magnets are good (they where loose on the RH and I glued them back in), the plugs are all new stock Champion, one new stator, one new timerbase, compression is 105 -112 on all 24, the timing is dead on 16 degrees at 4500RPM on all three, the outers got the big bore carbs and the mid has mid bore, I am lost and about to give in.... (let me tell you that is NOT like me....). If ANYBODY got some idea, other than to tell me my outers are worn out (cause that what I think...), feel free to speak up....
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[kimswang]

Kim, you can delete your double...just click EDIT, then delete at the bottom of the edit screen. :)


What double?? U had a beer??? :D :D :D



Just kidding, thanks Keith. I will call u tomorrow....

[markt111]

are the motors 250s or 275s? all the same? stock? most people will run 18degrees with these motors with decent fuel for good performance even stock...

have you verified your timing tab location with a piston stop tool??????

also compression is a little on the low side but I guess as long as all is even your ok

why big bore carbs on the outers? were they like that when you got them? could be like putting a Holley 850 on a stock small block Chevy!!

[kimswang]

are the motors 250s or 275s? all the same? stock? most people will run 18degrees with these motors with decent fuel for good performance even stock...

have you verified your timing tab location with a piston stop tool??????

also compression is a little on the low side but I guess as long as all is even your ok

why big bore carbs on the outers? were they like that when you got them? could be like putting a Holley 850 on a stock small block Chevy!!

The outers are 1987 275HP with a 4.0 powerhead. The mid is a 1993 300 4.0. The 275 calls for 18 degrees while the 300 calls for 16. Big bore carbs was stock on the motor in 1987 (then a 3.6). Compression is also measured at 2200' MSL. Yeah, they should make a lot more than they are right now and I dunno...???

[STV_Keith]

Compression is also measured at 2200' MSL. Yeah, they should make a lot more than they are right now and I dunno...???

They could make more...you know where to send them. ;)

From my testing, cranking compression drops 2psi/500' elevation. FYI.

[flabum1017]

I still think you need to get your X-dimension right before you go chasing after your RPM problem. Right now you are lugging those motors by having them too deep, possibly carbing them up and damaging them.

[kimswang]

I still think you need to get your X-dimension right before you go chasing after your RPM problem. Right now you are lugging those motors by having them too deep, possibly carbing them up and damaging them.


I think you're right!