"New member here
Great look
"New member here
Great looking forum, and thanks to all who reply in advance.
I tried this yesterday, but somehow cant seem to find the thread so if I dupe it sorry.
I have a rebuilt 7.4 454 that has been a horror for the entire 2 years I have owned it. I wont bore everyone with all the wonderfull horror stories that I have from the builder, dealer, and marina who were involved with this engine swap from hell that has less than 2 hours running time and more thousands of dollars invested than I can care to recount.
The specs are as follows. replaced a 89 7.4 330 merc with a four bolt main perf block, oval port heads, rochester rebuilt carb (rebuilt twice), replacment std low rise manifold, most stuff is new in 07 including the starter, alt, water pumps, thermostat and housing, belts, most hoses, oil and temp senders, and a whole bunch of bolts and brackets. The rest was replaced in 05 and has less than 2 hours time incl exh manifolds, ign amplifier, cap and rotor, wires, coil, etc etc.
The only thing on the engine that isnt new is the risers, and there on the way. So basically except for the fact that there wasnt any way to know what actually went into the rebuild everything should be new or darn near new.
Anyhow the two main problems are a valve tap (sounds like every cylinder) and a loss of power that involves the engine not reving above 2900 rpm/
The tap has been present from the original delivery from the marina who did the orig install. After an 18 month delay the engine was removed, inspected, and there was found to be 16 very loose rockers. It appeared that this was the cause of the loud valvetrain, they were adjusted cold, and the engine assembly continued.
After replacing every accessory due to the marina partially sinking the boat (it sunk well above the starter and alt. but somehow didnt cause water to get into the oil pan thank God)and installing the engine the problem still existed though not as loud as before.
The engine is getting oil to the heads, and after another adjustment they are improved, but not right, and there still is noise. oil pressure reads from 65 to full above 80 psi.
The power loss or lack of power may or may not be associated with the valvetrain noise. It is hard starting when cold, and will not rev above 3000 rpm without breaking up and backfiring thru the carb. This is both with and without a load.
Due to this the boat will not get onto plane. IT will run from idle up to the point it breaks up, but when you call for real power it just laughs and coughs.
Even though the carb was a rebuild and the marina rebuilt it again for no reason the secondaries were frozen when checking the carb and needed to disassembled and the butterflies and shaft freed up.
There is a an obvious smell of unburned fuel, and the small amount of run time which was mostly at the dock has consumed well over a 1/4 tank of fuel (100gal tank).
If I left anything out please ask, and thanks in advance for any input.
Also I have been thru engines before (been some time for auto stuff though)and am thinking that all the bs and frustration from this disaster is effecting my thinking and I am missing something simple.
The carb problems sound like a lean issue, but the smell and fuel use seems like its running rich.
Could the problem be unrelated to the noisy valvetrain?
Also any help on setting up this carb would be appreciated since I dont know much about them as they were normally replaced with hollys when I messed with cars etc."
Great look
"New member here
Great looking forum, and thanks to all who reply in advance.
I tried this yesterday, but somehow cant seem to find the thread so if I dupe it sorry.
I have a rebuilt 7.4 454 that has been a horror for the entire 2 years I have owned it. I wont bore everyone with all the wonderfull horror stories that I have from the builder, dealer, and marina who were involved with this engine swap from hell that has less than 2 hours running time and more thousands of dollars invested than I can care to recount.
The specs are as follows. replaced a 89 7.4 330 merc with a four bolt main perf block, oval port heads, rochester rebuilt carb (rebuilt twice), replacment std low rise manifold, most stuff is new in 07 including the starter, alt, water pumps, thermostat and housing, belts, most hoses, oil and temp senders, and a whole bunch of bolts and brackets. The rest was replaced in 05 and has less than 2 hours time incl exh manifolds, ign amplifier, cap and rotor, wires, coil, etc etc.
The only thing on the engine that isnt new is the risers, and there on the way. So basically except for the fact that there wasnt any way to know what actually went into the rebuild everything should be new or darn near new.
Anyhow the two main problems are a valve tap (sounds like every cylinder) and a loss of power that involves the engine not reving above 2900 rpm/
The tap has been present from the original delivery from the marina who did the orig install. After an 18 month delay the engine was removed, inspected, and there was found to be 16 very loose rockers. It appeared that this was the cause of the loud valvetrain, they were adjusted cold, and the engine assembly continued.
After replacing every accessory due to the marina partially sinking the boat (it sunk well above the starter and alt. but somehow didnt cause water to get into the oil pan thank God)and installing the engine the problem still existed though not as loud as before.
The engine is getting oil to the heads, and after another adjustment they are improved, but not right, and there still is noise. oil pressure reads from 65 to full above 80 psi.
The power loss or lack of power may or may not be associated with the valvetrain noise. It is hard starting when cold, and will not rev above 3000 rpm without breaking up and backfiring thru the carb. This is both with and without a load.
Due to this the boat will not get onto plane. IT will run from idle up to the point it breaks up, but when you call for real power it just laughs and coughs.
Even though the carb was a rebuild and the marina rebuilt it again for no reason the secondaries were frozen when checking the carb and needed to disassembled and the butterflies and shaft freed up.
There is a an obvious smell of unburned fuel, and the small amount of run time which was mostly at the dock has consumed well over a 1/4 tank of fuel (100gal tank).
If I left anything out please ask, and thanks in advance for any input.
Also I have been thru engines before (been some time for auto stuff though)and am thinking that all the bs and frustration from this disaster is effecting my thinking and I am missing something simple.
The carb problems sound like a lean issue, but the smell and fuel use seems like its running rich.
Could the problem be unrelated to the noisy valvetrain?
Also any help on setting up this carb would be appreciated since I dont know much about them as they were normally replaced with hollys when I messed with cars etc."