I'm looking at Merlin II heads for my BB (454). There's 3 models. All three have 2.30/1.88 valves and 119 cc combustion chambers and are exactly the same price. The only difference is oval vs rectangular and the amount of CFM you're shooting for. The ovals are 269 and the two rec's are 320 and 345.

We're planning a street machine, primarily, 10.5:1 CR and about 500 hp, or so, with descent (but not perfect!!) street manners. The cam is a Lunati 50249 hydraulic roller 232/242 @.050, 578"/595" lift and 112 SEP. There's a Performer RPM intake (ports TBD) and a Holley 750 double pumper to top it off and a 3" exhaust w/ headers (2" primaries).

Since it's for street, the Ovals were recommended, but the rect's obvously flow alot better. I was thinking about the 320's, but have been advised that's too much for a street machine.

Anybody had any experience with the Merlin II's? Ovals or Rect's? Any thoughts/comments on the combo and which of the 3 heads would best meet our needs? Wish I could afford AFR's or some other good aluminum head, but I can't.

Thanks for your help!

Andy

I've heard the Brodix Race Rites are hard to beat but others here have ALOT more experience.

You are in for it now. The old rec port vs oval debate. Good luck. You will either get told to do a search or this thread will become 5 pages long and end up in an argument.

JMHO, I would go with the smaller of the rec ports. You have plenty of compression and the cam is not really that large so there should be no lack of bottum end.

One other decent option may be to get the Dart 308's. 310CC rec port head. These are pretty nice and have decent low lift flow.

Imho, go with a set of Merlin VR's!! Aren't the VR ovals 290 cc's or something like that??

OR are they still for sale IF they ever were??

pdq67

For a street motor, and a little bitty cam like that, I'd go with the ovals. It will never turn up enough RPMs with that small of a cam to where the square ports will become an advantage. You'll be forever in the RPM range where they're a liability, and it will never make it into the range where they're an asset.

I think that cam will give your car plenty good street manners. It'll almost work with a stock converter even. That just really isn't a whole lot of cam for a 454. It's an excellent size for a good hot street motor though.

What RB said Andy. Pulling to 7000 rpms and above, rects. Go oval. Remeber, flow is one thing velocity is another. You're not giving up peak flow, not with that cam, you are gaining velocity however, with the smaller port.

Go with the 320s. I wouldnt use oval port heads for anything.Yes there are some exceptions,the guys who put in lots of effort to make an oval port motor run, but having had rec. port heads on big blocks on the street before I can say from experience they were bad, as in fast,these were iron production heads too!You'd think Chevy might have had a reason for not using oval port heads on their best big blocks? Your combination is well suited for 320s,which is about what a factory rect. port head is.... :cool:

Stay with the ovals

In all honesty, I dont like the Merlin heads. They are very weak on the exhaust side for an aftermarket head. I personally would look at the Brodix Race Rights for an oval port head, or the Canfield 310s for the rectangular. If your budget and time allows it, you could get the AFR 305 or 315s, or wait for the AFR oval port series. Everyone has already commented about the RPM ranges for each head.

Joe,with all due resepct,they had crappy cams to work with. Modern bumpstick+ high velocity ports = torque terror. He's not spinning to the moon, which

I wholeheartedly concur,

Make the rat an entirely different animal...hehehe :D

I LIKE THE RAT!

Andy, why not source a set of stock heads and put $500-700 into them? To keep stock heads on it. Not an issue? Same $$$ as aftermarket

GRN

I'm beginning to see what you mean! lol!!

Thanks for all the replies, guys. I guess this is more a matter of opinion than it is something you could expect to get general agreement on.

I think I'm going to take the 049's that I have and see what would have to be done to them (in $$) to get them flowing and replace all of the parts with new. I don't know what size the valves are now, but if I need to go bigger, then you get into the cost of working the seats. A rough estimate of porting and seat work, along with new valves, guides, springs, etc. sounded like you were getting into the $$ range of just buying the Merlin II's ready to go - but I'm going to confirm that next week before I do anything else.

Gene - The 049's may not be available after all!

Anybody know what the combustion chambers are on 049's - 110 or 119 cc's?

Thanks again!

Andy

The ones I have look HUGE Andy,all of 119cc or more. BTW, I don't really think its a matter of opinion if you are asking preferred application ,not whether a rect will work.

Oh you have those 049s made into rect intake runners?

Beware of published combustion chamber volumes. Most guys report back larger chambers than listed. My 290's are listed at 101cc. but measured 104 by the time I got them done. If you do any valve relief work at all, the chamber volume opens up in a hurry.

Yes, cc any stock head b/c they vary all over...

Ttt.......

Again...

"Merlin VR's!! Aren't the VR ovals 290 cc's or something like that??

OR are they still for sale IF they ever were??"

Well, are they???????

pdq67

PS., and don't sell the E-brock, 100 cc heads short, the "ROVALs".. IF you are using flat-tops now and don't want to actually go up to 10.5 like you mentioned b/c of pump gas hassle..

Just a thought is all....

I just sold the iron Merlins Rec ports I had. These were the early design and very similiar to the current Dart Rec. The Dart 308 has a much smaller Rec Port, not much larger than the Ede 290 Roval, but noticible smaller than the Chevy and current Merlin Recs.

BB-1 rec port heads. 280cc intake ports. I like the rec port heads because the port is higher.