Max rpm range for 1980 330 MIE Merc I/B: 3800-4200 (look in your manual dummy)

[1980Coronado]

I need some help confirming the max rpm range for my inboard. The engine is a model 1980 MIE 330-454 cid. I'm having trouble finding the information without making a trip to the barn where the boat is stored and getting it off the engine.

I looked in the Mercruiser #3 manual and it's not listed in there. I also tried looking it up on-line, but can't find it for my motor. I'm hoping someone may have access to the performance specs.

Also, I'm a bit confused about the serial number I wrote down off the engine, vs what I see on-line. The number I wrote down is s/n 56252430. This number is not in the serial number range for the Mercruiser information I see on-line....it has too many digits.??? I believe this is the original motor and has not been rebuilt or replaced.

Here is what I've found on-line regarding s/n:

Year 77-80 Model MIE 330-454 cid: s/n's 4623115 - 6083144

Does anyone have a clue about the discrepancy in the serial number?

 

[Bondo]

Re: Need max rpm range for Mercruiser inboard

Re: Need max rpm range for Mercruiser inboard

I need some help confirming the max rpm range for my inboard. The engine is a model 1980 MIE 330-454 cid.

Ayuh,.... It's a BBC,...
It'll make Globs of Horsepower, for thousands of hours in the 4400/ 4800 rpms at Wot range...

Donno why yer havin' the #s problem,...
Recheck the tags on the motor...

 

[1980Coronado]

Re: Need max rpm range for Mercruiser inboard

Re: Need max rpm range for Mercruiser inboard

Thanks Bond-o,

I've only had this boat since July and it's my first inboard. When I was winterizing, I remember seeing a tag on it that said 3800-4000..something like that...3900 sticks in my mind for some reason. My memory is a bit foggy, and I didn't write it down. Would there be any reason for it being that low, or is this just Mercruiser being ultra conservative? The motor has 1100+ hours on it currently, and in general runs very strong.

I need to get a different prop for this boat. The PO must have hit something bending the shaft.....I replaced it when I winterized the boat. The prop was reworked reducing both the diameter and the pitch by the PO as well....and as a result the RPM will quickly approach the 5000 mark such that I don't dare go over 3/4 throttle as it is. I'm starting to look for a prop, but needed the target rpm for the motor. Your recommendation is a bit higher than I expected. In your opinion I should be looking at a prop that lets the engine get to 4600 rpm with an average load?

I will have to take another look at the serial number to make sure I wrote it down correctly....actually dad was writing it as I read it to him and his hearing aint what it used to be...if it's wrong I'll just blame him

 

[Don S]

Re: Need max rpm range for Mercruiser inboard

Re: Need max rpm range for Mercruiser inboard

From THIS OEM Service Manual

.

 

[Bondo]

Re: Need max rpm range for Mercruiser inboard

Re: Need max rpm range for Mercruiser inboard

In your opinion I should be looking at a prop that lets the engine get to 4600 rpm with an average load?

Ayuh,... Rpms, at Wot....


edit; or go by the "Book" as Don says...

ya got me by Seconds, once again,...

 

[1980Coronado]

Re: Need max rpm range for Mercruiser inboard

Re: Need max rpm range for Mercruiser inboard

Thanks guys....I have this manual in PDF....I must have looked right at it! Couldn't find it to save my rear....I knew it had to be there! Ok...now I feel dumb:redface: