I have a GenV 454 that is getting worked over. Aside from the usuall machining I'm replacing the heads. It is going into a 66 chevelle. Used for street application only. Only racing it should see should be some goof who thinks his Ford Focus GT is hot poop. Basically I want a quick car that won't be spinning much past 6000 rpm. It will be bolted to a Tremec TKO 600, 12 bolt with 3.73 gears. When we place new forged pistions in it a compression ratio of 9.5:1 will be the target. I haven't figured out cam selection yet but I'm sure a duel plane intake with an 850 carb will what I select based upon previous posts. I also don't know if that carb size is to big for my intentions considering many posts recommending that seems like a strip recommendation. I will have headers and MSD ignition as well. I've searched the forums alot and found recomendations for the Mark IV blocks but little on the after market heads for street application. Please help

Here is the heads I'm considering.

1. BB-Chevy Merlin III Cast Iron Cylinder Head
269cc Oval Intake Ports
119cc Combustion Chambers
2.300'' Int/1.880'' Exh Valves
1.550'' Valve Springs, .650'' Max Lift for Hydraulic Roller Cam
Assembled, Sold Individually

2. BB-Chevy Merlin III Cast Iron Cylinder Head
320cc Retangular Intake Ports
119cc Combustion Chambers
2.300'' Int/1.880'' Exh Valves
1.550'' Valve Springs, .650'' Max Lift for Hydraulic Roller Cam
Assembled, Sold Individually

3. BB-Chevy Dart Iron Eagle Cylinder Head
308cc Intake Ports
119cc Combustion Chambers
2.25'' Int/1.88'' Exh Valves
1.550'' Springs, 145lbs @ 1.900''
.660'' Max Lift
Assembled, Sold Individually

4. BB-Dart Chevy Iron Eagle Cylinder Head
345cc Intake Ports
119cc Combustion Chambers
2.30'' Int/1.88'' Exh Valves
1.550'' Springs, 195lbs @ 1.900''
.690'' Max Lift
Assembled, Sold Individually

So please offer any assistance
Thanks to everyone who helped me with the machine shop question last week, big help!!!

Mike Dettloff

Out of the heads you listed I like the 269 cc ports for your combo.

Just repeating what I have been told when building my 454. was told the Merlin 269 oval pots are decent heads but you can get just as much good flow for a street motor with a set of GM 781 oval port with larger 2.19/1.88 valves and some mild port work. This you can have for about $800 compared to the Merlins in the 1200-1400 range. Just a thought.

049/781 Heads. More than enuf potential to do what you want.
2.19/1.88 valve and bowl blend

Or if you need to buy aftermarket stuff...Oval port all the way. Brodix RR oval would make a great head in aluminum. Or the merlin in iron.

x3

049s or 781s will work well, cam in the 240/250 range on a 110, it should run 11s easy.
What ever you do, dont do option 4 - or the focus will drive right around you... your car would be a turd ;)

The 781 wont fit on that engine without adapter gaskets, and are easy for leeking.

I would consider new alumium heads instead.

What cam?

Yup, my car had a 9.5:1 454, 781's, 244@.050 cam, on a 110. ran 11.50's all day long on pump gas.
Now it's a little different :)

GEN V, Guess we missed that :(

If the aftermarket heads have raised ex. ports there may be header issues with sparkplugs

GEN V, Guess we missed that :(

Yeah I missed that V....thought it may be a typo and forgot to put the I before the V.

Not to steal the thread but what kind of converter/gear would be used to make a 9.5:1 454 with a cam like the one mentioned above run 11.50s?

Planning a similar build myself, I'll be using 781s.

go for the Merlin 269's and a 750. that other stuff is too big for what you want to do.

go for the Merlin 269's and a 750. that other stuff is too big for what you want to do.

Like he said.

Yeah I missed that V....thought it may be a typo and forgot to put the I before the V.

Its MARK IV and GEN V VI

;)

Be sure to check that the merlins isnt just a replacement MK4 head. It need to fit your newer block.

I would consider Ovalport Brodix heads instead. It will be lighter, more power. easier to port, better sell value. And you know that you did the right choice instead of changing them after a few years. ,)

I guess I'll play devils advocate a little. No doubt, that the 269 cc merlins or modded stock heads would be a better combo for right now. But, i don't buy into the absolute assumption that a little bigger head would be a bad thing.

Just look at the chevy crate motors like the 454ho and 502 ho. That's pretty much the worst combo....small cam, 8.75:1 compression and iron rec port heads. Yet still they make good power.

Now, take that Iron eagle 308 head that's been designed to have high velocity ports , not to mention a superior combustion chamber design, and put it on a more suitable 9.5:1 454 with good cam. I think you'd have a real ripper on your hands. Also, you'd have a better casting than the World Products merlin head. Lastly, you'd have a head at the end of the day that would "grow" with you if you wanted to make it a 496 or run some more compression/cam down the road.

Just my opinion,

Bill

I'd stay away from raised exhaust port heads if i were you. my heads have .625 raised ports,and it was murder trying to find a header that worked.I tryed three sets till i massaged a set to make them work. in the process i ruined a 200.00 set also. 66's with bbc"s are a tight fit when it comes to headers. Also the rpm ,rpm air gap is the the highest intake that will fit under a stock 66 hood. You will have to use a drop base air cleaner to make it work.

Not to steal the thread but what kind of converter/gear would be used to make a 9.5:1 454 with a cam like the one mentioned above run 11.50s?

Planning a similar build myself, I'll be using 781s.

im was running 11.51@117 with a 8.1 454 with a solid roller and 4.11. with a off the shelf holeshot 3000.


check these 781's out $500 OBO

http://www.maliburacing.com/forum/viewtopic.php?t=49818

i like the canfield head's. i do not know if they will fit gen6 or not. square port all the way. oval for truck's

Merlins and a smaller carb.

Not to steal the thread but what kind of converter/gear would be used to make a 9.5:1 454 with a cam like the one mentioned above run 11.50s?

Planning a similar build myself, I'll be using 781s.


3500 Coan converter, 4.56 gear, 30" tall tire. Shifted at 5800, went thru lights 6300

The oval port Merlins work O.K. but they weigh about 80 lbs. each (160 lbs. total). A set of 305 cc AFR's with the CNC chamber option or Brodix RR ovals would get better results and weigh less than half of that.

So far I am very happy with the stock GMPP 290CC heads from a ZZ502 motor. See these all the time for about $1500.00/set on Ebay (new take-offs), this is where I got mine. Have these on a 454 .030 motor with SpeedPro H693CP pistons for a stout 10.4/1CR. Low compression motors do make decent power, but getting the CR in the 10.5 range fortifies your throttle response.

Like he said.

Agreed. :thumbsup:

i like the canfield head's. i do not know if they will fit gen6 or not. square port all the way. oval for truck's

They fit a GEN 5/6 engine. Yes.

Anyone know about the old merlins? Will they?

How much is a set?

WOW I posted that I got one reply and thought it was dead. Guys I can't begin to thank everyone for the help they have offered to me. Yes It is a gen V that I scored complete from a 91 chevy pick up for 491 bucks (won the e-bay and it was local). After reviewing the information I wish I could use some of the heads listed but I have been told that even with gaskets some of the Mark IV heads are just not a good idea for my Gen V. I will admit that money was a bit of a factor (Iron vs Aluminum) but I found these heads from edelbrock. I might have found a few more dollars for the heads.

BB-Chevy Performer RPM Aluminum Cylinder Head
290cc Oval Intake Ports
110cc Combustion Chambers
2.190'' Int/1.880'' Exh Valves
1.550'' Valve Springs, .700'' Max Lift
7/16'' Rocker Studs
Assembled, Sold Individually

350-60459

Designed for big-block Chevy 396-502 c.i.d. engines, these oval port heads will support over 540 horsepower with 9.5:1 compression when used as part of the Performer RPM Power Package. A totally unique intake port design yields flow numbers traditionally associated with high performance rectangular port heads, but with the smaller runner size and velocity of an oval port for excellent seat-of-the-pants performance and crisp throttle response. The semi-open chamber design maximizes combustion efficiency with streetable compression ratios. The stainless steel 2.19'' intake and 1.88'' exhaust valves have smaller-than-stock 11/32'' valve stems to promote excellent flow and lighter valve weight. The deck surface and water jackets were specially designed to work with all big-block Chevrolet engine blocks. Heads include top-quality ARP rocker studs, bronze guides and hardened, ductile iron valve seats.

If a few of you don't mind chiming in and lending your opinion I would apprecaite it.

Mike Dettloff
mdettloff317@comcast.net

Usually the aftermarket head maunfactures make the heads so that they will fit all blocks (at least Eddy does).

If you have to buy new alum heads, I suggest going with a Brodix Race Rite. Were only talking about a couple of hundred dollars more, and there's probably ~20 more horse with those heads over the Eddy's. Look at it this way, what else can give you 20+ hp for ~200.00?

But, keep an eye on ebay. I, like Joe (GRN69CHV) scored new ZZ502 take off heads (Eddy RPM's) and new GMPP roller rockers for 1500.00 shipped to my door. I see used Eddy heads all the time on there for 1000-1200.00 with low miles.

I have the Brodix RR Rect port heads on my 496 and the absolutely kick a$$!! Great response on the low end as well.