Replacement engine from Rapidomarine...

[FreeBeeTony]

Re: Replacement engine from Rapidomarine...

Just re-read some of this thread..........

I see you replaced the rocker arms w/ roller rockers from the previous engine........do the rollers use the same length push rods?

Just a thought.........

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

Just re-read some of this thread..........

I see you replaced the rocker arms w/ roller rockers from the previous engine........do the rollers use the same length push rods?

Just a thought.........

Yes, I double checked this prior to using them.....
.checked the lift on the cam and it is not the factory lift.....my engine came with a .273 lift on both intake and exhaust, the cam in it is not that...confirmed.....more on that later.....
Still having the same nightmare, engine will not make any rpm's past 2700 while on the water, boat still not on plane, new plugs check out fine after Monday's hour on the water.
I am waiting on an alignment bar to adjust the coupler/bearing, but it looks very close from the rear now, just to be sure and cross everything off the list.
I have the fuel pressure gauge plumbed up for installation my next trip out.
Checked engine compression with 2 separate gauges, still reads 210lbs sq in with both gauges and they are not the same brand and one is 20years old ad one is 2 years old.
Does anyone have any proof or knowledge that 210lbs of compression per cylinder may keep rpm's from happening?

I am dreaming about this non stop, nothing makes sense. I have asked many older mechanics and they are all stumped. Still making only 14 inches of vacuum at idle....We are due a freeze this week so each and every time I take her out, I have to immediately drain all the water from the engine....
The engine starts easily, runs fine to 2700rpm, no funny noises, no water in the oil, no fuel leaks, great oil pressure, no oil leaks and it is aging me rapidly......

I have been a chronic pain sufferer since 8/89 due to a spine/thorax crushing accident and have never once, until now, thought of suicide (not really, I know it's nothing to joke about, it is just REALLY getting to me!)
I really just don't know what else to do.....
thanks for all the help,
Kevo <clueless

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

Please report back on that. Also what ign module. It should be V6-14, and your total should be 22 (with 8 initial). According to the timing curve you should have full advance by 2700. If you have 30, thats way too much, contributing to why the higher octane ran better and maybe part of performance problem.


Check the advance, then the cam.

IMHO, measure cams before swapping. Just swapping will/can lead to more fustration.

The module is a V6 module, timing advances 22deg total by 2000rpm, double checked.

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

Ayuh,... Are the shutters where they belong,..??

I've seen 'em get burnt up, 'n fall into the lower y-pipe or farther...

Both the exhaust flaps are in the correct places, I repaired one of the pivot pins on one side last week with a stainless bolt that I cut to length, it is still noisy but now wont break and fall into the manifold. And I ran a wire from left to right, no rags in it...

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

Your compression test readings are high but I don't think that has anything to do with the low rpm you are getting at full throttle. The 14 inches of mercury at is low though..

My stock non-vortec 4.3 compression pressures vary from 165-185

One thing not discussed, is the boat propped correctly, does the outdrive have the correct final drive ratio?

My boat had a problem with the anti siphon valve, it was restricting fuel flow and the engine could not even plane out the boat...

Also it came with the wrong prop, it had a 14 1/2 x 19 which was correct for a V-8 Cobra on this boat, but the V-6 Cobras were supposed to have a 15 x 17 and when I put that one on my WOT rpm went from 4200 to 4600 which is in spec for a 4.3 4bbl Cobra V-6...

My next train of thought is to rebuild the fuel delivery system, new fuel pump and lines. Where would the anti siphon valve be? I am unfamiliar of its location...
Kevo

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

Each and every component of this project worked fine prior to replacing the long block.
I have spent several months along with everyone here who has helped me, restoring this boat this summer. It was completely gutted, no interior, no dash, no working wiring. I/we have basically brought it back from the dead, got it on the water just to find that the engine had cracks in it that were from bitter winters sitting in a driveway in Indianapolis, IN for several years. Neglected was not the word for this boat, now I would take it anywhere, although it would take a while to get there, lol...I am totally confident in your/my talents to see this project to completion, all is left to do is make it run past 2700rpm to plane and I will drag it home, put all the seats and engine cover in it and drag it to Indy and have this problem behind me as I have done with so many over the years....Thank you all for all your help....
cheers,
Kevo

 

[Lou C]

Re: Replacement engine from Rapidomarine...

My next train of thought is to rebuild the fuel delivery system, new fuel pump and lines. Where would the anti siphon valve be? I am unfamiliar of its location...
Kevo

its a fitting on top of the gas tank that the fuel line to the fuel pump would be connected to...

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

its a fitting on top of the gas tank that the fuel line to the fuel pump would be connected to...

I did a bit of netsearch and will check out this tomorrow, thanks heaps for the info, I truly hope it is something like this, let you all know soon...
cheers,
Kevo

 

[John_S]

Re: Replacement engine from Rapidomarine...

FWIW, I think 210 psi is still high but not sure if it is causing your problem, contributing to it, or nothing to do with it.

If it was high just from head/piston selection, and you are not detenating anymore since running the high octane, don't see that causing such a power loss. The high compression, high octane combo, probably wants to see more total ignition advance but don't see how it would cause that level of power loss.

If the cam timing is retarded, it will cause higher compression readings (intake valve closing sooner). I think that would also lower your idle vacuum, which you are seeing. But, don't know if it could cause that much of a power loss. This could be just a different cam that does have different timing, but performance cams usually go the other direction and have the intake valve open longer into the compression stroke.

Do you have a vacuum reading at your max sustained rpm of 2700? Did the other vacuum test checks reveal anything?

 

[kevs_gone]

Re: Replacement engine from Rapidomarine...

I'm no engine builder, but if it was me I think I would swap back to the original parts that rapido sent with the engine. You changed rockers, pushrods and maybe lifters without any information on the installed cam and that could very well be your issue. Not only could it explain your lack of RPM but also your low vacuum and your detonation problems. Not real hard to do and might just fix your problem.

IMO "another" Kevin

 

[choochooharley]

Re: Replacement engine from Rapidomarine...

Im just wondering have you had it over 2700 on the muffs....I read the entire thread a while ago and cant remember and its too long to read again.

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

Ok ladies and gentlemen, I took the boat out today and she still does the same things, but, she now reaches 2800-3000rpm's...
Things I have done since last posting:

Removed the anti-siphon valve.
Installed new fuel lines from elec fuel pump to carb with "T" and fuel pressure gauge.
Re-adjusted carb float to factory spec.
Trimmed all fuel lines and re-attached and re-installed clamps to avert air leaking issues.
Replaced fuel filter on separator side of fuel pump.
Acquired engine alignment tool and re-aligned engine/rear drive(minimal adjustment).
Acquired fuel pump pressure reading during WOT on the lake and was bouncing from 2-4psi, at idle would show 7psi..(does this look like a potential problem ?)

I am at my wits end and am just about to give up, this has been one huge problem for me....
cheers,
Kevo

I am going to try and look into a in tank obstruction, I dont know if I have access to a screen on the pickup tube or not and I am going to check the contents of the water/fuel separator too. I am just running out of ideas and the desire to drag this lump to the lake any more!

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

Im just wondering have you had it over 2700 on the muffs....I read the entire thread a while ago and cant remember and its too long to read again.

Yes, she will spin up fine on the muffs, certainly looks like a power issue to me, as in none....

 

[choochooharley]

Re: Replacement engine from Rapidomarine...

I dont have the book with me right now for the proper psi but im pretty sure it should stay pretty constant while under load...not drop 5 psi

 

[choochooharley]

Re: Replacement engine from Rapidomarine...

Ok I seem to remember it should be 8 to 10 psi and stay that way....did it come with a new fuel pump or did you reuse the old one...if it wasnt installed there is a specific procedure to put the fuel pump on I cant remember what it is but if you have a manual it would tell you...I seem to remember something about a timing mark so the cam hits the lever when its supposed to....

 

[redjmp]

Re: Replacement engine from Rapidomarine...

Well a quick down and dirty test to see if it is at all fuel related would be to use an old dish soap bottle to squirt some gas down the carb while running at wot. If suddenly you get power, them you know it is the fuel.
I wouldn't bet on it though.
If indeed your carb was starving your engine for gas, it would surely be in a very lean condition and would have quickly melted your pistons imho.

 

[choochooharley]

Re: Replacement engine from Rapidomarine...

IDK about the lean conditions to melt the pistons....I now recall a guy i know had to replace the engine in his boat and then he had all kinds of problems similar to this and he ended up replaceing the carb and fuel pump and the problems went away....it could be a seperate issue but sounds familiar

 

[John_S]

Re: Replacement engine from Rapidomarine...

7psi at idle is fine, and is within spec. Any higher and it will cause fuel to push past the needle. They don't list a wot spec. I can't say if 2psi is low or not. The pump would be providing more volume (needle open more often) and makes sense that psi would drop.

Boat Side Fuel System Tests: http://forums.iboats.com/showthread.php?t=283269

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

I also note that my secondary air valves are opening below 3000rpm's which from reading many posts here is a bad thing, this too could be a problem, but, ran fine prior to new longblock....I will get a new electric fuel pump if necessary, not a problem..
cheers,
Kevo

 

[choochooharley]

Re: Replacement engine from Rapidomarine...

Oh its an electric fuel pump so that rules out the timing issue but still I think it should be constant....