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Q-jet jetting question on modified Mercruiser

Old 07-27-2011, 12:01 PM
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Q-jet jetting question on modified Mercruiser

Hi from Belgium ,after almost 2 years my engines are finaly almost ready,so now i have some more questions for You all
Would be happy if I can get help.
This is the story...
My 2 Mercruiser 350 Cu.in SBC engines in my Chris Crfaft Stinger 260 needed
rebuilt.
So from stock I have changed following.
Heads are now Patriot aluminium Freedom heads
2.02 intake/1.60 exh.
64cc chambers
flat top pistons
compression ratio 10/1
Running 98 premium gas
camshaft:CompCams Xtreme marine 278 H/valve lift intake .498 exh..500
duration @.050 intake 234 exhaust 244
RPM range 2000/6200
Alumium aftermarket dual plane intake manifold
IMCO Thumper alu exhaust manifolds
Alpha1 to Bravo 1 conversion
rated HP is ......You guys have any suggestion?
Boat weight is approx 6200 Lbs.
OK now for the carbs....the original carbs on the engines where some car
carbs fitted by the former US owner.
So I want to use 2 Mercruiser Q-Jets from my friends 454 Magnum engines
Specs are: Primary jets .68
Primary rods .41
Secondary rods DA
Power valve spring colour Purple.
Do You have any suggestions if this combination would work on my engines?
Thanks so much for advice.
Brgrds
Roland
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Old 07-27-2011, 09:31 PM
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Dont use carbs from a car engine a marine carb is different
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Old 07-28-2011, 08:40 PM
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I think you have to much cam for a 350 in a heavy boat, you'll never see the power band. 218/226 maybe. If the 454 carbs are stock I would just bolt them on and see what happens. At least it would give you a starting point.
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Old 07-28-2011, 11:36 PM
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that cam is gonna more than likely revert water without the right exhaust setup, depending on a few other factors
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