gumbya55

Just purchased a 22' 1990 scarab with a 454 (supposed to be 400hp) and a Bravo One. Previous owner said that it ran 72 GPS with a 24pitch 4 blade so I went out and bought a brand new one.

Well took it out today and it only ran 58 (low fuel and only 2 people) on GPS. Also ran that at 4100 RPMS.

Timing is set to 8 degrees, new 750 marine carb, MSD distributor. Runs perfect, no pings misses etc.

Is there something else I should check? It seems even a stock 454 would push that to 65mph?

Any suggestions on what to check would be appreciated. Thanks

tinman565

Sounds like your low on HP. Meaning, the 400 he told you was off by about 75 or so. How many hours are on the motors ?

frankenstein

That's a big difference, but try fresh fuel

pluguglyinhere

If it helps I have a 97 22 with the 454 injected stock and I have the 24P 4 blade. It is new to me so I maybe low due to inexperience in many areas but for reference I got 58mph GPS with 4 adults, 4 kids (under 12) and 1/2 tank of fuel.

gumbya55

The 454 is a rebuild, with less than 50hrs on it. 750 holley marine carb and a brand new distributor. I mean it runs good, but just not getting the power I expected. And only 4100 rpms at WOT. Is that what you were running pluguglyinhere? Do you know what your timing is set at?

I do run higher octane fuel (always fuel up on land) and always add an additive (octane boost, etc).

Never pings or runs rough. I was just wondering about what kind of power it would need to be up around 65mph. I mean I thought stock 454's in those boats ran around that...

HTRDLNCN

new dist?
timing is probably off, you need to check total timing, most 454s like something like 36deg by 3000rpm

trc2

what are you trimming your outdrive to and does the boat have trim tabs

gumbya55

Ive only been able to time it at about 700 rpms, and it's set at 8 degrees. Not sure how to time it that high with just a timing light and the marks on the tab over the damper.

Trim gauge doesnt work but I trim it to the point where the outdrive comes out of the water, then bring it back. I do have trim tabs, boat seems to chime walk just a bit with the 4 blade...but at 58mph it doesnt feel out-of-control.

HTRDLNCN

you need to check it at higher rpm to make sure dist is advancing correctly or you will be down on power.

here is a post on procedure:
http://www.offshoreonly.com/forums/d...procedure.html

gumbya55

Ok thanks. Any suggestions on a timing light for advance? It has no vacuum advance. I've attached a pic!