Prop Question
 

Guys - I have a 1988 Cig Bullet with 502 Mags. I picked the boat up late last season. Port engine has always run faster than the starboard and I assume that the slower engine is just getting tired. I have the drives now off in the garage and I notice that the prop on the slower engine is a 25P Mirage PLUS, while the faster engine has s 25P Mirage. I know the pitch is the same, but the props look slightly different in design. Could this be the problem? I would hate to buy new props to find that it is not even though they don't exactly match.

Thanks for your help, Don.

Re: Prop Question
 

How much RPM difference?

Re: Prop Question
 

There is about 400 RPM difference which is enough to have to run the throttles with one advanced about 1/2" in front of the other :(

Re: Prop Question
 

The same size prop shouln't have that much diff.
I would check the motor.
Check comp. first.
Then check timing, fuel, codes, ect.
Check leakdown if you have the tool.
I have worked on alot of these motors with clogged injectors, they will idle with no miss and pick up a miss under load.
If they are clogged try to take them to a local injector cleaning machine. You have to take them out to do this.

Re: Prop Question
 

Call your local Merc.dealer and ask or call Merc. Racing 1.920.921.5330 Don't start taking things apart until you get some answers about the props.They don't have different part numbers for nothing.You didn't mention anything about a miss so unless you're bored or need the practice be patient and ask questions.BOB

Re: Prop Question
 

In '88 where there EFI/MPI 502's? I thought they were carbed.

What is the difference in the props? I'd want to run them wiht identical props, if there is a difference in the Plus and standard.

Re: Prop Question
 

Sorry read right past that.
If it has bravo's you could switch the props around, run the drives in reverse and see if you have the same diff. If so then go back to orig. post - the efi part.

Re: Prop Question
 

The Mirage plus has more cup and blade area.

Re: Prop Question
 

Bingo, I think we just found your 400 RPM???? :evilb:

Re: Prop Question
 

Nobody - Good idea, swicthing the props and running the drives backward would tell right away.

SearayJim - the engines are 2000's 502 MAG MPI's - blew the 1988 454's a long while back. Of course, they were originally carb'd.

Thanks again for the help