Budman II

iTrader: (1)

I bought a Merlin intake that has the brass water passages. Unfortunately, the provisions for the rear water passage plugs are cast solid. I would like to drill and tap these passages so that I can install fittings and hoses to act as steam ports and prevent hot spots on the back cylinders, but I am not sure how to go about doing this. If it was aluminum I would just chuck it up in the drill press and have at it, but the little bit I have read about brass, it sounds like it has a tendency to try to suck the drill bit down and send the part spinning.

Anyone had any experience drilling and tapping one of these manifolds for NPT fittings? It is one like the one pictured in the link below:

http://www.offshoreonly.com/forums/s...ne-intake.html

30ftpanther

iTrader: (1)

I don't know about the intake. I do know about drilling, grind the helix angle flat so the drill bit doesn't try to screw itself into the brass. It doesn't take much see first pic. You can see the helix angle in second pic. Good luck with your project.

Google Image Result for http://i19.photobucket.com/albums/b159/deansofidaho/Machine/drilldone.jpg.


Google Image Result for http://www.emeraldinsight.com/content_images/fig/2170370201007.png.

US1 Fountain

iTrader: (1)

Drills will try to screw themselves in brass when you are step drilling. If you can drill it straight (drill press) in 1 shot with a good sharp drill, you'll be fine.

Budman II

iTrader: (1)

Thanks guys. I'll have to see if I can get this thing rigged up properly on my drill press. Doubt if it will fit in my vise.

What about tapping the brass insert? Any issues to worry about here? Standard thread cutting oil?

FIXX

iTrader: (2)

what head do you have? reason some of the older heads had a big azz plug in them,we use to take the plug out and with a reducer we use to blow off heat that way instead of drilling the intake.

Budman II

iTrader: (1)

Fixx, they are AFR 265 cc "rovals". Doubt if they have any plugs in them. Starting to look like it may be a moot point - I may have to run an oval port intake with these heads. They are kind of in between a rectangle port and a round port (hence the "roval reference") - larger than an oval port, but smaller than a rectangle port. Not sure which way to go - I really wanted to run this intake.

Budman II

iTrader: (1)

Another question - if I end up running an oval port manifold, many of the ones I am looking at do not have any kind of boss back near the rear water ports on the heads - they are either flat, or some even have a reinforcing rib in this location. Can this area still be drilled and tapped for a water port to relieve steam pockets and hot spots on the heads?

Cobra100+

iTrader: (3)

Dart 6200 or Brodix HVH are my choice, some are coming already drilled and tapped but if not there is a boss there to reference.

Budman II

iTrader: (1)

Yes, it would be my choice to run one that already at least has the bosses, but the ones I have available do not have them. That is why I am wondering if there is enough material there on a regular manifold to drill and tap this area. The Edelbrock Victor Jr was suggested as a good match for the heads, but most of them I have seen do not have the bosses. The Super Victor does, but I think it comes with a Dominator flange, and is a pretty high dollar piece.

The manifolds I have on hand that have the bosses are all rectangle point, and don't match up with the "roval" ports in the heads very well. Seems to be a lot of contention as to how much of a problem this would cause. Some suggest the airflow sets up a boundary layer on the "step" and that they still work well, others say that the turbulance will be a problem.

BenPerfected

We used the Merlin intake oval port intake, good choice that can be re-worked to flow best in class. We use (2) 1/8 NPT to -4 hoses teed into a -10 water dump line that bleeds off the air/water from the front of the intake to thru the transom. We also use a brass restriction in this line to manage the overall water pressure.