The V8 Owners Forum -

I do not know if anyone has a pair of Merlin heads on hand?

How many valves have been moved to the center? And anyone knows the valve angle ? They keep same angle than rover heads ?

May be a good alternative for 3.5 and reduce valve shrouding problem with BV/small bore.

Nobody tried Merlin heads on (race) 3.5 ?

I am about to fit downdraught throttlebodies to the Merlin Heads and would like to port match the inlet manifolds.
This means I will remove the filled in corner of each inlet port.
Anyone done this after first running tham as standard and what was the effect?

Cheers
Mark

Dimitri, I believe that the valves will not physically fit in the 3,5 bore. I have the angle of the valves somewhere but around 20 degrees ? Valves are about 10-15 mm towards the centre of the bore, again have a pic somewhere to give you an idea.

Mark, I never bothered with the std intake ports and simply cut the silly corner away. If you need the corner in the first place them someone screwed up big time with the port design. I have also removed the fin inside the port.

minorv8 wrote:
Mark, I never bothered with the std intake ports and simply cut the silly corner away. If you need the corner in the first place them someone screwed up big time with the port design. I have also removed the fin inside the port.

Surely that little corner thingy is there for a reason ? ( i am a complete novice, so excuse my ignorance ). I was told, the guy who developed the Merlin heads has been developing some for an american race team and the deal is worth a few hundred K, surely he must know what he's doing ??

mgbloke wrote:I am about to fit downdraught throttlebodies to the Merlin Heads and would like to port match the inlet manifolds.
This means I will remove the filled in corner of each inlet port.
Anyone done this after first running tham as standard and what was the effect?

Cheers
Mark

Do you mean the cut out for the fuel injectors??

Perry if you go all the way back to the photos on page 3 you will see a pic of the inlet ports that are an odd shape.

Wotland There is a photo on page 2 of 2 sets of valve imprints one standard and one merlin. Merlins are about 10mm towards centre.

Mark

Sorry Mark!
I was talking Rover heads. I didnt read from day one.

If those corners are there for a reason i guess it must be to increase velocity through the narrow section??

If one wants to increase velocity one sizes the port accordingly. Not block one corner and create a huge amount of turbulence. Sorry but it simply does not make any sense whatsoever. Has anyone seen anything similar in any other head ? If such tricks would be beneficial what is the point of port matching ?

Jukka
I am sure you are right, I have never seen odd shape ports like this before. Will do some mild porting and probably take out the fin too.

Are you satisfied with your set of Merlins? seem to remember you did quite a few modifications to them.

Mark

I think to remember JP installed a set on his supercharged 3.5.

For ported Merlin heads you can contact Art Gertz on this forum http://forum.britishv8.org/read.php?6,18712, he has a set of heads ported by Todd McKenzie of McKenzie Racing in Oxnard, California.

I don't remember if Art had both heads ported or did he only have a couple of ports done as a pattern. He did increase the valve size a bit. I have some pics that Art sent me and the changes included a removed fillet from the intake port, fin removed and some changes to the chamber.

Art has since bought a pair of bare TA's and has discussed with David Vizard to have a pair of ports developed.

Mark, to be honest yes and no. The heads were new and reasonably priced. They werereally good on paper, nice chamber and bigger valves etc. But they did not produce that much more power compared my previous heads. I expected more. I plan to fit another cam to se if that unleashes the hidden potential

Knowing what I know now I might buy eales cnc heads since he claims that they are equal if not bettr than Merlins.

Some details about Merlins:

Valve size is limited even if the valves are moved towards e centre of the bore. Why not go to the centre, move the valves away from each other and fit really big valves, say 1,9 in and1,5 ex. This would provide basis for good breathing. Instead, RS chose to start from factory head and use all matching stuff like maniflods, rockers etc. This limits what you can do to the heads. Basically the Merlins are just a preformance upgrade, not really a hipo or comp pair of heads. They are good but not splemdid.

As for quality of machining, Timo had some opinions about lack of it when he built an engine for a friend. I do agree, there were some issues with seats. Mark has had some issues. Valve covers are quite stupid, you need to seal them with silicone, a hassle if you need to remove the covers. The bolt pattern and size is almost the same as ols SBC, why not use them and use literally hundreds of dfferent covers. Of vourse not, let's cast head specific covers ! Lots of time spent on secondary things, too little on primary things.

But nevertheless, I have them and will continue to fine tuning them. Feel free to comment or disagree !

But remember to have a very Merry Christmas. May your stockings be stuffed with V8 goodies !

Jukka

Jukka I think you have just about summed it up!
I went from self ported heads ( first time porting without any experience ) to the Merlins and saw quite an improvement (not surprising).
RS should have aimed a bit higher at the design stage.
Will probably change for TA heads in a couple of years if they become more available.

Seasons greetings to all.

Mark

minorv8 wrote:If one wants to increase velocity one sizes the port accordingly. Not block one corner and create a huge amount of turbulence. Sorry but it simply does not make any sense whatsoever. Has anyone seen anything similar in any other head ? If such tricks would be beneficial what is the point of port matching ?

I agree entirely!
I was just making a comment about why the obstruction may have been put there. It doesnt make sense to me

Who is the actual manufacturer. Are these made solely for Real Steel ?

The rocker covers do look a bit agricultural dont they.

Do you know if anyone has used these heads on a blown or turbo engine?

JP in Holland