330 heads
 

There were some questions about the 330 heads. I finally had a chance to do some flow work on some Intake ports, here are the gains.

.Stock
.LIFT......................CFM..............Modifi ed.............Gain CFM

.200......................118..................118 ............................0
.300......................176..................181 ............................6
.400......................228..................245 ..........................17
.500......................240..................267 ..........................27
.550......................245..................280 ..........................35

I reworked these Intake ports looking for the most gain with the least amount of labor. After .550 the port stopped gaining airflow because of the small volume. The numbers are overall down from the larger ports but for what they are it is a subtantial gain. The flange was openend up to the larger oval port. With a cam and intake change I would guess 50 to 75 ft. lbs of torque increase. This would work great if your engines have the built in rev limiters. The heads will not want to turn many rpms, 5200 max.

Hm thanks for the info, so maybe the 3 sets of peanut port heads I have are useful after all. At 5000 rpm, how would your modified heads compare to the 781 or 049 stock oval ports? Oh, and did the head you tested have the 2.19, 1.88 valves or the smaller stock valves?

330 heads
 

Formula31,

They have the stock 2.07 intake valve. They will be down stightly from the rectangular port but because of the volume the motor wont rpm. My guess is they will a ton more torque than the rect. ports off Idle to 4000.

Do you think its worth the money to put the bigger valves in the peanut port heads or is the porting you do sufficient for 5000 rpm? My thoughts were by the time I had them ported and got bigger valves installed. Id be better off performance and money wise going up to the old large oval ports. ??

330 heads
 

Formula31

It will bring the numbers up but I dont think it's worth it. With what I did to the heads now is at $500.00 (that includes exhaust work too). Adding valves and a grind would push it beyond it's worth.

Thanks, Thats great info. It looks like the numbers you got are as good as, if not better than the large oval ports with large valves (unported) at reasonable lifts. I would think that for a 454 running at 5000, it would be a good upgrade.

Hey Jim, you ever flowed the later Vortec heads, just to see how well they flow over the old peanut ports? I would luv to see that kinda info....

You ever ported them? I've heard they can almost flow what merlins flow, and with the smaller valves.:confused:

Jim,

Great information ! Thanks ! It came at a good time as I'm considering 049 heads, Merlin 269 cc heads, or modifying my small 330 horsepower heads. If I keep my stock heads I would port them myself. Any chance of getting a run down of how you modified them ? Is the flange that was opened up to the larger oval port, the end of the runner that bolts up to the intake ? If so does this mean that there is a big mis match here ? I haven't had this motor apart yet so I dont know. Also due to hatch clearance problems I won't be able to install a taller intake. I've heard that if you smooth out the rough edges inside the intake and cut out the divider between the primary & secondary holes it will flow as good as the taller ones. Any input on this ?

Thanks for your help,
Bo

I was told that all the marine motors had large oval ports??? How can you tell large from small oval port heads????

Jon

I think every 7.4 or 330 merc engine since the late 80 has peanut port heads because the large oval port head were not made after like 79 or something. Thats why merc then used the rect port heads for the mags which are worse then the ovals but better than the peanuts. Is this right?

98 and later fuelie 330's have L-29 vortec heads. I slapped a set on my 97 carbed motor and picked up 3-4 mph, so they obviously work.! I would really like to see some flow #'s tho, so I could dial in the cam better.:D

how to tell large oval vs peanut
 

the peanut ports are about 1.6" wide x 1.5 " high ( 1 9/16 x 1 1/2)

the large oval ports are about 1.5 " wide x 1.9 " high (1 1/2 x 1 7/8)

Those are not exact measurments but close enuff to show you the difference

330 Heads
 

Here is a picture, the flange is openend to the larger Oval

JimV
It looks from the photo that you smoothed out the port. Did you change anything around the valve stem. It's hard to believe you could get that increase in flow from just opening up the intake side of the port.
Gary

Gary,

Your right, their is other work in the port but you dont want me to give away all my trade secrets do you?

Vortec Heads
 

Madmax

I did one set last year and yes they are great heads. The exhaust ports are like a mini Merlin. With the stock exhaust valve ported they flowed close to the Merlin up to .600 lift. With the small chamber volume these heads would be a good bolt on for a 330. They wont work on a 365 because of the chamber design/piston.

JimV
Just post all the deatails here. I promise not to tell anyone.
Gary

What , do you nibble away at the metal with a die grinder or something?
how do you get it so smooth?
Or do you extrude hone this thing?
Just trying to understand more about the process, im going to invest in 2 new intake manifolds and they are LARGE oval intakes and will have an abrupt lip where manifold meets head.

Just looking for a few ponies here and there thats all

Also, does this coincide with the post from last year about
"454 - 330 on steroids?"
Can someone post those tips., tricks and little HP bumps for the 330?
Simply because it is a very popular engine out there in marine land and im sure alot of us would like to be able to keep up with you guys at poker runs and ect that are running HP500's and mags ect
Thanks alot all
Jason

It would be impossible for me to explain the how to's(I am a terrible communicatior). It's taken me 25+ years and I'm still learning. You will need to spend some money on some long shank carbide cutters $45.00 ea and cartridge rolls.


Jay13,

I use a die grinder. Dont waste your money on extrude honing. By enlarging the flange only you wont see the gain. Be careful with cam choice, the retainer clearance is close.

Re: Vortec Heads
 

have you ever done any work to the intake manifold on the 7.4 mpi ?

JimV - Your picture brought back memories. I did the heads on a 7.4L in 1991. I had the pocket porting and valve job done professionally, but I wrecked a perfectly good electric drill enlarging the ports to large oval size at the gasket. I don't remember the flow numbers, but with an Edelbrock Performer intake and a 454 Magnum cam, the boat picked up 5 mph, so I figure those heads made just as much power as the rect ports on a 454 Magnum.

Tomcat

Man, your right on about the time/sweat to get those things into shape. A couple of years ago I started a set, they out flowed a set of rectangular ports to .550 with a 2.100 valve. I ended blowing a hole in the port trashing the head.

I really believe you could make a great 454 with these heads and the right cam intake combo.

Jim how much HP can I gain if we port my merlin ovals? and at about what price?

Dyno,

Bowl port intake, some chamber porting and full exhaust port $550.00 I would expect to see 40-50 hp gain depending on the camshaft

DYNO have JIM do it you won't be sorry. You will be happy with his work!!!