Replacement engine from Rapidomarine...

[Bondo]

Re: Replacement engine from Rapidomarine...

I think I am making headway....

Ayuh,... That's always a Good thing...

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

Clean, freshly rebuilt carb going on as soon as my eyes are wide open and it warms up outside, valves readjusted just to be sure. All capped up with exception of carb, I will check for wet intake manifold interior after I get it started. Will take it to the lake tonight or tomorrow for a quick splash.
wish us luck,
Kevo

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

Everything but power, each and everything is just like it was with the bad engine which ran great until the oil and water spewed from the cracks. It idles great and never died once, no gas smell whatsoever, no water or oil leaks, where do I go from here? I have shot Rapidomarine an email. I guess I will check for a flat cam....ignition timing 8deg BTDC @700rpm. Had 210psi across the board compression test! Using pump gas 89octane....
cheers,
Kevo

 

[Evinrude Boater]

Re: Replacement engine from Rapidomarine...

Even with full throttle, it wont budge past this rpm

Have you verified that the throttle cable is actually opening the carburetor fully?

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

yes....verified....and rear butterflies are opening....water/fuel seperator is almost new....electric fuel pump....all ran good with cracked engine....

 

[kwoolard]

Re: Replacement engine from Rapidomarine...

I would check fuel pump pressure....could be too high and not letting the needle fully seat causing a flooded condition.

Check spark plug color...black sooty plugs will indicate excessive unburned fuel.

Possible exhaust restriction....broken flapper sitting in the bottom of the y-pipe.

If you've got an extra vacuum port on the intake manifold, hook up a vacuum gauge a go for a test run. Note the vacuum readings and needle movement at idle, during a throttle chop, during slow acceleration, etc. This will help Vacuum Testing

And last but not least check the full advance....should be close to all in at 3000 rpm's.

That's my 2 cents worth....hope you find the problem.

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

I thank you all for your replies, I am still at it.
I have checked the flaps in the "Y" pipe, both good.
I have contacted the builder and he suggests checking fuel pressures also along with advancing the timing to 10deg BTDC but to watch the heat.
My engine flooding has gone after I rebuilt the carb but it still runs the same.
I do not know how to check full advance without a degree wheel attached. My timing light does not have the advance features..

 

[FreeBeeTony]

Re: Replacement engine from Rapidomarine...

Possible the valves are adjusted too tight?

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

I first adjusted them one turn past zero lash, I have since 3/4 turn past zero lash and it runs just the same and still sounds like preignition @2600rpm..

 

[zbnutcase]

Re: Replacement engine from Rapidomarine...

Sounds like wrong cam in it

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

I agree, Bubba, I called the builder not to complain (210psi across all cylinders is unheard of, but I saw it with these eyes) I called him just to get someone to rock my brain as this forum has done. I have the carb off at the moment and just found that one of the pump activated jets seems to be clogged. I will surely check for an intake leak, but, it idled better than ever yesterday and it is firing correctly and I know the wires are in proper place and to be in good condition with no problems with the engine missing. I currently see a small issue with the carb and timing...and will report back when I have checked for an intake leak with spraying at the base of the carb and intake.
thanks for all the suggestions and help, I will not give up!
Kevo

p.s. if it comes to it, I will check the lift on the cam, just don't want to uncap it right now...kinda sick of the whole thing at the moment....and like I said, I have 210psi across the board!

 

[John_S]

Re: Replacement engine from Rapidomarine...

and still sounds like preignition @2600rpm..

You have allot of good advice already given. I'd follow it to try to diagnois it. In the meantime, if you don't already have it, would be good to know what rapido used in the rebuild, ie flat top or recessed pistons, heads, cam, etc.

Maybe what you think is preignition is a misfire, and suspect you swapped in the distributer and ignition from old motor.

210 psi on each cyclinder sounds a bit high, but might be just a gauge issue or new rebuild. My vortec head with recessed pistons 5.7L gets 165-175psi. Possibly run some 91 or 93 octane to see if the pre-ignition noise stops.

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

I used my newly purchased timing light yesterday and was getting random flashing from it, I decided to try another light, I bought a Craftsman with electronic advance built in that also has a digital tach and of course, it shows the timing is off a few degrees. I will start @ 8deg BTDC when on the water next time and go from there. I also checked for vacuum leaks @ the base of carb/to manifold and also manifold/heads, no leaks....Also checked idling vacuum and have 14" @ idle, so, these things all are looking better while at the same time getting a few more minutes each time on the muffs in my backyard going in the bank for the engines break in time. I am going to add another ground to my HEI ignition box just to make myself happy, I know it is advancing but am concerned that it might be going to high, I will check the total advance again and hope to get my head around the math one last time,(22degrees total advance @ 2500 rpm) lol..Just thinking out loud here and if someone spots a problem, you can hit me with a flame so I can get this devil boat back home....
cheers and thanks for all your good help,
Kevo

but, if the advance is going past 22degrees total advance @ 2500rpm, do I just set the high speed advance to 22 degrees total and readjust the idle speed to suit?

 

[redjmp]

Re: Replacement engine from Rapidomarine...

Personally I have never seen anything like 210psi on a gas engine before.

I remember some years ago, there was a case where Rapido installed heads with the wrong size combustion chamber on a sbc.

I would check casting #'s on the heads just to be sure...

Sometimes auto guys put the smaller heads on to bump up the compression to past 11 to 1

and if the rebuilder doesn't check to make sure the head/ piston combo is suitible for marine, then you can have some problems.

Or possibly you have flatop pistons instead of recessed.

The predetonation sound is probably just that because I'd bet you're running something like 12.5 to 1 with 210 showing on the dial...

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

The builder told me the block is .30 over(<which raises compression) with flat top pistons to lower the compression as opposed to dome topped pistons. He builds and sells a lot of engines...I asked him about the high compression and he was thrilled he built one with it, I was hesitant about it too, but I am sure it won't last....I can smell the valves leaking while I type....lol...
I have another question as per ignition timing, after checking the timing, idle and full advance, I think that the electronic advance may be going to far advance...The manual says that an added advance of 22deg's total advance with 8 @ idle and I think I am seeing a total of 30 advance @ 2500 rpm, can this be the problem? What if I set it to 22deg's total and then just adjust the idle, is that a workaround?
I am just a boatload of questions...
I have a fuel pressure gauge but not the plumbing to install it at the moment, I guess that will be next....if....
cheers,
Kevo

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

Personally I have never seen anything like 210psi on a gas engine before.

Nor have I....

 

[paultjohnson]

Re: Replacement engine from Rapidomarine...

Though 210 does sound high ... My stock 86 4.3 has 180 # which is 86% of 210# I believe... Don't ya just divide 180 by 210 ? IF my numbers are correct , thats only 14% over my 24 yr old stock 4.3 with 9.3 to 1 compression.

 

[John_S]

Re: Replacement engine from Rapidomarine...

What module do you have? Some have the full advance in by 3K, so 22 advance plus 8 intial, is 30 total. 30-32 total on sbc marine is a stock/conservative number.



OK, went back and read this is a 4.3L. : Too many long posts to remember!

Your advance is too much for a 4.3L. They are typically 14-15 advance with 8 initial for a 22-23 total.

 

[wca_tim]

Re: Replacement engine from Rapidomarine...

Rereading through the posts above, a few things come to mind?

1. There?s nothing to suggest that there is anything wrong with the cam or the valve lash ? compression would be inconsistent if that were the case.

2. The compression you?re seeing is high, but not ridiculous. It is too high to run 89 octane, you need 92 or 93. With a factory spec cam or close, 210 psi equates to somewhere around 10:1 or 10.5:1 I?m guessing off the top and is on the borderline of what you can get away with using iron heads and pump gas. Get the right fuel in it, run it just a little rich, run the cooler thermostat in it and be a little conservative with the timing, and it ought to run great once you get it dialed in! Be patient, you?ll get there.

3. Do all the plugs look the same or close? Have you tried carb cleaner or ether around the intake (if it?s leaking the rpm will change when it pulls a little ether through the leak?).

Finally, I?m betting that once you put better fuel (93 octane would be best) in it and set the timing right. (your v-6 module is I think 14 degree advance and so set initial at 8 gives 22 total advance as John above noted), it'll run great. Also assuming that your jetting is correct, etc... like I mentioned above, if you're on the bodreline for the fuel you're running, a little cooler thermostat, conservative on timing and a little fat are all good things...

Good luck with it!

 

[Kevoz]

Re: Replacement engine from Rapidomarine...

OK, Ladies and Gentlemen.....
Here are the updates:
I have yet to get the new plugs to check them after a run, had new irridiums in it, thought at the time unnecessary, will check them when I tear it apart next time, aack!
I have a pristine/clean carb with all bores opening and flowing fuel...
I have no vacuum leaks around intake/heads nor carb/intake....
14inches vacuum @ idle....
I put in 5gal of 93 octane fuel mixed with the little 89 octane left in tank, I also added one bottle of octane booster (with MMT) for the lower octane fuel....
I ran the boat all over the lake this afternoon and changed the ignition timing from 4 to 12 degrees and finally settled on 8 BTDC where the knocking stops @ WOT....(new electronic advance timing light works great here)
I roughly have 5hrs on the engine now and it has not once exceeded 2700rpm...on the water, will freewheeling on muffs I am sure but wont do this as a rule with new reman engine...
Idles great, pulls hard from idle to 2700 and then just stays there....
I did not check what thermostat it had in it, but it has yet to run hot....
There is a tiny amount of blow-by exiting the valve cover vent hoses which is to be expected....
I have the HEI IV Ignition Module....Advance seems to be working fine...
I just think, but am unsure, that this engine should rev up past 2700 in the water prior to having 10 hrs of breakin time on it.....
The boat was built with the same size engine in it so I am at a loss and have no idea what my next move might be other than put more hours in the water with it and we could have the first frost in about 2 weeks and will have to start winterizing it without knowing if it is right yet...And since it runs, the builder is of little help which is expected...
All the other water trips with this boat had 4 passengers, todays trip was with 2, myself and best friend (still made same rpm) who knows the lake, he lived on it and had a boat on it for several years, he is saving the prop from the mud, we are in a drought here, lake is low...and, they do not allow cuddy cabins on it, got special permission from the water lawman...lol...
I spoke with a retired marine mechanic last week who still builds drag car engines and he was at a total loss....AS AM I !!!!!
If someone can make me look like a dumbass and tell me what I have done wrong, PLEASE DO !
I am getting ready to pull out all my grey hair and that isnt much....
Also, concerning the cam, I can get 210psi in every cylinder without a cam....I think I will check the lift and ask the builder what I should find and compare it with the cracked motor's cam.....I just have no desire to do all this investigative crap at this point in my life....
Keep throwing out random bits for me to think about, I guess that is all there is left to do, I guess I could change the cam, just dont want to,,,or do you all think its rings still need to seat?
cheers,
Kevo