Wtf happened?? Help !
06-18-2025 | 06:48 AM
#32
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Joined: Jun 2021
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From: SW Ohio
Just to put it out there.... The carb in the pic is not a marine carb. Don't know if the carbs you are using are the same, but those overflow tubes should really be J-tubes. Or so I'm told....
Thanks. Brad.
06-18-2025 | 10:31 AM
#34
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Joined: Aug 2019
Posts: 1,223
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From: BC
USCG only requires that the excess fuel from the carb would drain into the carb and intake.
Pulling and twisting the bowl vents so the angled cut faces the carb bores, would meet the USCG requirements.
All throttle shafts are sealed...or you would have a vacuum leak.
Insurance providers may have other requirements. But we're talking safety and the legal requirements.
06-18-2025 | 10:47 AM
#35
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From: BC
Ok so the dual 750 carbs installed, I found out they are NOT Boost Referenced, ??? i was told this is not a problem, seems to be running good and I cant be certain that the lean condition on one bank is caused by this or the
problems I found and corrected, I will return with update in couple of days
problems I found and corrected, I will return with update in couple of days
Modern carbs have cone a long way, dumbing them down by removing power valves and jetting higher is a downgrade of sensitivity to the engine's needs.
It's not difficult to do, there's a few methods. Mine are all internal, but require drilling.
There are less invasive methods.
Either way...if you don't have an O2 sensor setup to tune, it's something that would really benefit you. Too rich means washing out the cylinders. Too lean...you get the picture.
I found the B&M book. I'll see what they say on Boost Ref.
06-18-2025 | 10:54 AM
#36
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Joined: Aug 2019
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From: BC
Ok Everyone; UPDATE; so , i appreciate everyone's feedback, seems we were chasing our tails, my apologies, so I had dual holley double pumper 750 carbs installed by my mechanics, upon recent inspection,I found;
1) a couple fuel inlet fittings loose-(leaking fuel)( re-tightened)
2) found loose linkage fittings(tightened) and adjusted.
3) when engine cover was completely closed, throttle cable was being restricted, Raised engine cover 4-5 inches-and it opened up beautifully, accelerated rapidly, confirming 30 pitch prop to low!
with the labbed 30 pitch Bravo 1, this engine revved freely to 6000rpm( rev limiter setting) so just swapped back to my labbed 32 pitch bravo 1. taking out within couple days- will update accordingly
QUESTION; anyone know what the difference is between a satin finish vs polished.
additionally; I checked x dimension, 1 " low- so will be looking for a -1" Imco lower. or relative lower, also recommended by Art Dnick at AO.
QUESTION; how much additional top-end, ya'all expect it would produce with the Imco lower ?
if after these discoveries AND eventually installing imco lower. if not surpassing 100mph i will be next looking for larger blower, thanks again,
any additional feedback or recommendations, i am open to suggestions.
Boat-On, Rock-on, and enjoy the summer !!!
1) a couple fuel inlet fittings loose-(leaking fuel)( re-tightened)
2) found loose linkage fittings(tightened) and adjusted.
3) when engine cover was completely closed, throttle cable was being restricted, Raised engine cover 4-5 inches-and it opened up beautifully, accelerated rapidly, confirming 30 pitch prop to low!
with the labbed 30 pitch Bravo 1, this engine revved freely to 6000rpm( rev limiter setting) so just swapped back to my labbed 32 pitch bravo 1. taking out within couple days- will update accordingly
QUESTION; anyone know what the difference is between a satin finish vs polished.
additionally; I checked x dimension, 1 " low- so will be looking for a -1" Imco lower. or relative lower, also recommended by Art Dnick at AO.
QUESTION; how much additional top-end, ya'all expect it would produce with the Imco lower ?
if after these discoveries AND eventually installing imco lower. if not surpassing 100mph i will be next looking for larger blower, thanks again,
any additional feedback or recommendations, i am open to suggestions.
Boat-On, Rock-on, and enjoy the summer !!!
The satin finish is faster. But people like the polished bling.
One thing you don't expect to have to check from a marine mechanic...is if the fuel fittings are loose and leaking.
One of the most common power losses is throttle not opening all the way.
Glad you tracked it down, amd before you had issues with leaking fuel.
Did you ever smell the weeping fuel from the connections?
