Exactly which heads do I have?
 

I have a `98 7.4 MPI (310 hp). I am in the planning stages for future upgrades. I am not sure what cylinder heads this engine came with. I have been told it has the 454 "Vortec" heads. I have also been told it has the infamous "peanut-port" heads. I know the peanut-port heads are only good for tow-trucks. If I have the Vortec heads, will they respond well to porting and larger valves? Or should I just save up and buy some Merlins? I`m not looking for huge horsepower, but would like about 425 at the prop. One more thing...Which is a better head? The Vortecs or the early 70`s large oval-port?

I know for a fact that Lingenfelter has ported and reworked the peanut heads for some absolutly incredible torque numbers.

Yes, I have seen that article in one of the hot rod magazines. He really woke them up.

I know that Valako (JimV) has done some peanut port heads with very good results. I guess you'd need to crunch the numbers to see which way is more cost-effective- having the heads modified or just buying aftermarket heads.

Man, that article must be 10 years old! Good to know that I'm not the only one to memorize a magazine! lol!

So, are you guys saying I have peanut port heads on this `98 7.4 MPI?
A reliable source thought it came with 454 Vortec heads.

???

I can do the bowl blending, I have ported several sets of heads. I wonder what size valves would work best in these heads. I have a very good relationship with a local machine shop. I am, without a doubt, on a budget!!!

DonMan reply
 

DonMan,
The heads you have are not the "peanut port heads" they are large oval port heads. The peanut port heads hold 200 cc's of volume and the BB Vortech heads hold 230 cc's of volume, the same as the early large oval port heads. The BB Vortech heads are superior to the early heads because they have a small vane in the intake port that induces swirl into the intake mixture as it enters the cylinder. The exhaust ports are improved D port designs that flow very well. The combustion chambers are high compression heart shaped that keep the fresh fuel mixture from exiting the exhaust valve on camshaft overlap. They are also good at adding swirl to the air fuel mixture. They tolerate high compression ratios with low octane fuel. The heads are an improved version of the old large oval port heads and are really something! They are the best engineered (not the highest flowing) big block cylinder heads available except for the new 496 engine.

You need to increase the camshaft lift and duration to improve the performance of your engine. This is a real can of worms with the EFI. Just for fun you should add a carb and cam and see how it goes. I bet you would be very pleased!

I wrote a very detailed article in the May 2002 FAMILY AND PERFORMANCE BOATING MAGAZINE on the big block Vortech heads.
See if you can find a copy, or order it from us at 805-986-0400.

By the way, Bob Carpenter, who writes for the magazine, is the same Bob Carpenter that used to write for Peterson Publishing/ CUSTOM CLASSIC TRUCKS he is really cool and laid back (typical of a native of southern caifornia) but gets a little uptight when I am driving the boat! (goes to show that race car drivers are wimps compared to us boat drivers!). Look for his daughter to be the next big tennis sensation from southern California!

Sincerely
Dennis Moore

Without casting numbers, you are guessing...

Thanks for the reply Dennis!
I realize how finicky the EFI is when installing go-fast parts...what a headache! I am just looking for a few more MPH out of the "little" 454 without going bankrupt. I have thought about swapping on a carb, but am afraid of killing my fuel consumption. It is really pretty respectable right now. When I get ready for the cam swap, I will get back to you on a recomendation.
I thought that was the same Bob Carpenter! Classic trucks are one of my other passions. Tell him to "lighten up", the white knuckles are a sure sign of a good time!
THANKS FOR THE INFO!

heads
 

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

TIMING WITH VORTECH HEADS
 

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.

Vortech Heads
 

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

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.! :p

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

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.

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.