JimV

iTrader: (1)

The vortech heads are a better casting. With some port work they can be made better. The chambers need material removed around and in between the valves for airflow. The exhaust ports have nice radiused seats from the factory. A fully ported exhaust port will yield an extra 15% increase in airflow. Be carefull in the exhaust port there is water close. The combustion chamber will end up around 105 cc's. Not much increase in the intake side.


I am working on a set of peanut ports now I can post airflow numbers and pictures in a couple of days. Their going on a 454 with a hydraulic roller cam. Should be a stump puller

HARRISONMIRAGE

I WAS WONDERING IF ANY MEMBERS HAVE EXPERIANCE WITH THESE HEADS ON A CARBURATED ENGINE.I HAD A BAD DETONATION PROBLEM WITH THESE HEADS TRYING TOO LARGE OF PROP WITH MID GRADE FUEL.AS THE BOAT ACCELERATED UP TO SPEED IT DECELERATED JUST AS FAST.IT ONLY HAD ABOUT 1 MINUTE RUN TIME BEFORE I SHUT IT DOWN AND IDLED BACK TO THE DOCK.THE DETONATION MELTED SOME OF THE GROUND STRAPS ON THE PLUGS.AFTER ABOUT 100 HOURS I HAD TO PULL THE MOTOR DOWN DUE TO AN OIL PUMP PICKUP TUBE FAILURE.UPON DISSASEMBLY THE INTAKE VALVES WERE TULIPING.I DON'T KNOW IF THIS WAS FROM MY ONE OVER LOADING INCIDENT OR DO THESE HEADS NEED AN ELECTRONIC FUEL MANAGEMENT SYSTEM.MY ENGINE SETUP IS AS FOLLOWS.454 .030 OVER,KB FLAT TOPS,VORTECH HEADS,CAST CRANK,FORGED RODS,COMP XE 268-280 CAM,EDELBROCK AIR GAP INTAKE,EDELBROCK 750 CFM CARB,STAINLESS MARINE MANIFOLDS,& SILENT CHOICE DIVERTERS.I AM RUNNING ONLY 4 DEGREES INITIAL AND 28 TOTAL TIMING.THE ENGINE DOES NOT SEEM TO RESPOND WELL TO MORE TIMING.THE JETTING IS 110 PRIM,107 SEC,&65/42 NEEDLE.I HAVE TRIED DIFFERENT PLUGS.THE MR43LTS RUN A BIT HOT,THE R42LTSM SEEMED TO MISFIRE A BIT,AND THE R42LTS RUN GOOD ONCE THE ENGINE IS WARM BUT IT IS A DOG GETTING IT STARTED AND KEEPING IT RUNNING AT THE START OF THE DAY(LEAVING DOCK).THE ENGINE IS IN A 25'7''MIRAGE DEEP V (24 DEGREE NON STEPPED) BOAT.IT WEIGHS 4000LBS.DRY AND ABOUT 5000 LOADED.LIGHT ON FUEL WITH ONE PERSON IN THE BOAT I CAN GET 62 MPH ON THE GPS.I RUN A 23 ''MIRAGE PLUS AND TACH ABOUT 5000.WITH A 21'' PROP I GET BETTER SPEED LOADED BUT I'M SPINNING 5400 RPM SO I GENERALLY RUN THE 23 FOR CRUISING ECONOMY.I ALWAYS RUN 91 OCTANE MINUMUM.I HAVE 90 HOURS ON THIS ENGINE NOW WITH NO MAJOR PROBLEMS BUT AM VERY NERVOUS OF PROPING ENGINE FOR LESS THAN 5000 RPM AND OF OVER TIMING IT.

Dennis Moore

Harrisonmirage
It sounds to me like you have to much compression. Have you tested it with a compression tester. It shouldn't be any higher than 175-180 for premium fuel. The heads and the pistons should give you about a 9.0:1 compression ratio but I am concerned about the camshaft timing. It may be advanced to far. The multiple keyway timing chain sets are sometimes confusing on which marks to line up and many mechanics get it wrong (I did this on a 383 sb engine and the engine ran hot, detonated and had over 210 psi cranking compression).
Hope this helps someone!
Sincerely
Dennis Moore
Family and Performance Boating Magazine

Madmax

I've been running these heads on a carbed motor with a Edelbrock Performer RPM intake, GM454HO crate motor cam with matching springs, and Gil exhaust. Jetting at 107 primary, 107 secondary with a 68/47 rod. 6 degrees intial, 30 degrees total at 3200rpm. 145 hours with no problems, but I do run 92 octane. They did ping with 87 octane, I also melted off the electrodes on the plugs on #7 and #2. Never tried a mid-grade fuel. Compression was right at 180lbs with these heads. Runs the same mph as a guy with a 502 in the same boat. Get rid of the MPI, it's junk on these motors. Sell it for a grand on e-bay to some street rod guy, and buy all your parts and have enough left over for gas money for the summer.!

JIM V, i'm looking to have these heads ported. How much $$ are we talking to wake them up?

turbo2256

If these vortec heads have swirl like the older small block ones. The swirl washed down the cylinder walls and rings and caused the most excessive bore wear I have ever seen.

JimV

iTrader: (1)

Mad Max

If you will e-mail me your number or call me I can go into more detail. For some reason I feel kina cheesie posting prices.