Go Back  Offshoreonly.com > Technical > General Q & A
Q-jet jetting question on modified  Mercruiser >

Q-jet jetting question on modified Mercruiser


Q-jet jetting question on modified Mercruiser

Old 07-27-2011, 12:01 PM
Thread Starter
Join Date: Sep 2007
Location: Belgium
Posts: 21
Likes: 0
Received 0 Likes on 0 Posts
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
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.
offshoreboat1 is offline  
Old 07-27-2011, 09:31 PM
Join Date: Dec 2009
Location: Grain Valley,Mo
Posts: 867
Likes: 0
Received 0 Likes on 0 Posts

Dont use carbs from a car engine a marine carb is different
firehawkcat is offline  
Old 07-28-2011, 08:40 PM
Join Date: Mar 2004
Location: Pa
Posts: 2,646
Received 74 Likes on 53 Posts

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.
GPM is offline  
Old 07-28-2011, 11:36 PM
Gold Member
Join Date: Apr 2010
Location: Daniels, WV
Posts: 895
Likes: 0
Received 10 Likes on 5 Posts

that cam is gonna more than likely revert water without the right exhaust setup, depending on a few other factors
87MagnumII is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.