Merlin Heads

Wotland · Post by **Wotland** » Sat Dec 29, 2012 6:43 pm

There is something funny with these CNC heads.
In the late 1980s, NCK / TVR has developed the 4.45 for the Tuscan Challenge, they were as far as possible in the development of Rover heads.
It would have been impossible to go further in their development without weld heads. In practice, the heads were good for a 4.2, 4.45 brought just a little more torque but not really more than BHP.
The same heads were taken by Eales on his 4.5 engine for Paris-Dakar Halt-up Range Rover. Eales had the same opinion about the maximum displacement for these heads.
Eales CNC heads are based version of handported NCK/TVR heads developed almost 25 years ago....

minorv8 · Post by **minorv8** » Sat Dec 29, 2012 7:13 pm

Cost is such a major factor though;-) I think if we all had the money - we would order wildcats.

Thank God I am married, otherwise I would have a bunch of different heads to try out ! Seriously, sky is the limit but every once in a while you need to think what is reasonable and what is not. I believe that Merlins have a some unleashed potential. As std they flow about 180 cfm, Art Gertz´s heads flow 220+ cfm after porting. I don´t remember what they exhaust flowed but I have the numbers somewhere.

And please do remember, if the heads are not good enough you can always increase the capacity...

Spent 8 hours today machining a set of SBC 6 inch rods to fit my stroker crank, yeehaa ! (The Missus and kids are somewhere between Helsinki Finland and Stockholm Sweden on a ferry having quality time... I had quality time with my father in law´s lathe...)

P.S. It would be TA heads (if not married), not Wildcats.

DaviesDJ · Post by **DaviesDJ** » Sat Dec 29, 2012 9:10 pm

LOL !!well, you know what i meant;-) I am suprised that JE and co haven't done more with the 300 buickheads??? how much modification exactly does it take for them to fit a rover ? Can they use the same gasket? What capacity is your striker crank?

Robrover · Post by **Robrover** » Sun Dec 30, 2012 8:12 am

My Buick heads were developed, flowed and ported by the Head Stud Co in Melbourne who do a lot of the Holden/ Ford V8 comp heads here. I took 080 off the faces and welded the chambers to get a CR of 9.25:1 using std 4.6 dished pistons. That was with genuine Buick 300 metal head gaskets, you can use Rover gaskets but they are not ideal as there is a slight overlap of a combustion chamber.

These are 1964 vintage alloy heads, so nearly 50 years old now. You need to be careful selecting them to avoid problems with corrosion and tensile softness. They were used quite a lot here in the past on 5 litre P76 builds (using Holden pistons). And they are very popular in the States of course with the TR8 / MGB modifiers.

kokkolanpoika · Post by **kokkolanpoika** » Sun Dec 30, 2012 9:04 am

I dont see any point to port those heads if you dont use them. I understand that Art Gertz´s heads flow 220+ cfm after porting. But where is the dyno resutls that those heads are good?
Flow figures are some stupid numbers, nothinkg important at all. I have seen this too many times in dyno.
And 44mm/1.73" valves maxium flow is approx 410-420hp/210-220cfm with 100% efficiency..
Wild cat´s flows same amount with slightly bigger valves. So they are not good as merlin´s. Spending +1000£ more with cat´s and get slightly worse heads if you can do slightly porting job by yourself with merlins..

Make no sense to me.. Like Wotland say there is something funny with these heads.

Poor flowing wild cats, under 400hp and they flow approx 220-235cfm?
5.0 WILD CAT ENGINE 398 BHP @ 5950 RPM, 340FTLB @ 5600 RPM
http://www.automotivecomp.com/v8engines.htm
You get same amount of power race ported rover heads..

DaviesDJ · Post by **DaviesDJ** » Sun Dec 30, 2012 10:02 pm

Guys there are a set of Buick 63 heads on eBay- I have geared that these are as good as the 65 ish Buick 300 heads in terms of port sizes with the smaller combustion chambers? Then I read des Hamils chapter again and he says that they are more or less the same as stock rover heads? Is this true ? Do we have to go for the big combustion chamber heads to get the big ports?

Robrover · Post by **Robrover** » Mon Dec 31, 2012 2:27 am

The alloy 300 heads only appeared in 1964, and only for that year. 1963 would most probably be Buick 215 which are much the same as early Rover P6B heads with smaller chambers and ports (the Oldsmobile alloy heads were better but require work to fit). After '64 Buick 300 went cast iron heads, which are reputed to flow even better than the alloy ones, though of course they are much heavier.

sidecar · Post by **sidecar** » Mon Dec 31, 2012 8:54 am

If they are the ones that I found on ebay they look VERY 'ropey' to me!

DaviesDJ · Post by **DaviesDJ** » Mon Dec 31, 2012 12:29 pm

Yes, they are! Thought for some reason that they may have the same valves and ports as the 54cc chamber heads - but no.

mgbloke · Post by **mgbloke** » Mon Mar 25, 2013 1:05 pm

I have decided to do away with my Edelbrock 500 carb and fit EFI with Jenvey throttlebodies. As I have never been happy with the shape of the inlet ports I have decided to port match the heads to my new inlet manifolds.
So I have had the heads off and removed those stupid corner infills but for the time being the Huffaker/Edelbrock is back on until I am ready to fit the EFI.
Pics of standard v modified ports.

Will be interesting to see if there is an improvement.

minorv8 · Post by **minorv8** » Mon Mar 25, 2013 1:30 pm

Do you still have that weird fin in the intake port floor ?

Jukka

mgbloke · Post by **mgbloke** » Mon Mar 25, 2013 8:17 pm

Hi Jukka
No I removed that too and smoothed and blended everything.

kiwicar · Post by **kiwicar** » Tue Mar 26, 2013 8:59 am

Hi
Don't you think they might have been put there for a reason?

Best regards
Mike

mgbloke · Post by **mgbloke** » Tue Mar 26, 2013 4:39 pm

Mike
Probably but with the downdraught manifold the injector is pointing straight at that step in the corner which cant be right. So have port matched the manifolds to the heads.

Time will tell.

Mark

mgbloke · Post by **mgbloke** » Tue Mar 26, 2013 4:42 pm

Sureley those corners can only restrict flow at the top end? I can see they could be a benefit lower down the rev range.