Mercruiser 5.0 Thunderbolt 5 ignition

[prestonhaywood]

i recently purchased a 99 crown line 182 18’ with mercruiser 5.0 alpha drive. has a newly installed remanned motor with roughly 50 hrs on it. motor runs great but will not go past or “revs out” at 3k in neutral. is this normal or a potential issue? also at WOT it will only get up to 4k rpm at 44 mph with trim set correctly. if i set trim almost all the way up before cut off at WOT it will jump up to 4100-4200 rpm. it has a solas 4 blade 20” pitch. i have a 3 blade 17” pitch ordered but im not sure prop is my issue. any input will be greatly appreciated, thanks.

 

[alldodge]

Welcome
Do you know the original motors serial number?

 

[Chris1956]

Gee, revving past 3K RPM in neutral is real bad for the engine. Do that a few times and the engine will likely blow, eliminating your question, at least for a while.

Has the engine/prop combo ever gotten above 4K in gear at WOT?

Where I would expect that motor/boat to get a few more RPM than you are seeing, redline on that motor is probably around 4400, so you are only about 2" in pitch too great, on the prop.

I would expect the engine to redline with the 17"P prop.

 

[Bondo]

i recently purchased a 99 crown line 182 18’ with mercruiser 5.0 alpha drive. has a newly installed remanned motor with roughly 50 hrs on it. motor runs great but will not go past or “revs out” at 3k in neutral. is this normal or a potential issue? also at WOT it will only get up to 4k rpm at 44 mph with trim set correctly. if i set trim almost all the way up before cut off at WOT it will jump up to 4100-4200 rpm. it has a solas 4 blade 20” pitch. i have a 3 blade 17” pitch ordered but im not sure prop is my issue. any input will be greatly appreciated, thanks.

Ayuh,.... Welcome Aboard,..... Cross check yer tach, with a known good shop tach to verify that it's accurate,....
I suspect it's not,....

 

[prestonhaywood]

Welcome
Do you know the original motors serial number?

no i don’t

 

[prestonhaywood]

Gee, revving past 3K RPM in neutral is real bad for the engine. Do that a few times and the engine will likely blow, eliminating your question, at least for a while.

Has the engine/prop combo ever gotten above 4K in gear at WOT?

Where I would expect that motor/boat to get a few more RPM than you are seeing, redline on that motor is probably around 4400, so you are only about 2" in pitch too great, on the prop.

I would expect the engine to redline with the 17"P prop.

it doesn’t revv past 3k in neutral. it hits revv limiter at 3k in neutral. no it will not go past 4k rpm at WOT in gear

 

[alldodge]

it doesn’t revv past 3k in neutral. it hits revv limiter at 3k in neutral. no it will not go past 4k rpm at WOT in gear

Is the motor TBI or Carb?
The 99 to 2000 was TBI with MEFI-3 ECM and TB5 distributor
Which ignition do you have?

If it's TB5 then the Rev limiter is closer to 5K

They did have a in gear switch on the motors yet

 

[Scott06]

it doesn’t revv past 3k in neutral. it hits revv limiter at 3k in neutral. no it will not go past 4k rpm at WOT in gear

if the rev limiter hits at 3 k rpm on the tach the tachometer is not accurate

 

[Chris1956]

OK, rev it up to 2999 RPMs in neutral and see what happens.

Just sarcasm. Don't rev an engine past 1500RPM in neutral. It is bad policy.