Mike Ledbetter

Hi,

I got a Mac's tuned pipe for my OS .40 FSR. The header has no pressure outlet for a line to the fuel tank.

Am I supposed to run without one (it's a Viper 500) or install my own? If the latter, where can I get the part and does anybody know what size hole to drill and tap?

Thanks and regards.

RaceCity

Your local HS will be able to set you up with a pressure fitting, or...one could be culled from
an old muffler.

Refer to the MACS website for pressure tap placement.

www.macspro.com

'Race

jaka

Hi!
All you have to do is to drill/press a hole in the tuned pipe(at it's largest diameter) and silicon glue in a 3mm brass or aluminum tube......

Regards!
Jan K
Sweden

Ed_Moorman

My Feedback: (1)

Mac's carries several different types of pressure fittings, including one with a flange that can be installed in the thin wall of a pipe at the thickest part. I have used them several times.

Mike Ledbetter

Thanks for the replies. I'll check the LHS first. I'm a little new at this. Is there a reason why Mac's doesn't include the pressure fitting with a pipe and header package made for a specific motor?

Regards.

ml3456

Why can't you put the tap in the mounting flange? You just need a small amount of pressure. Is there any problems doing this?

Thanks. Mark

ChuckN

I have never had a problem with drilling and tapping the header flange for a pressure fitting. It sure beats running silicone tubing all the way out to the fattest part of the pipe. The difference is that you get MORE pressure at the header flange therefore you have to lean out your needle valve slightly more than you may be used to in order to avoid loading up in flight, especially at wide open throttle. The best pressure fitting for this is the 4-40 Fox fitting. It has a very small orifice.

Mike Ledbetter

Hi everyone and thanks for the input. I ordered and received a 6-32 pressure nipple made by Great Planes. $1.29. Gonna put it at the bend in the manifold.

Regards.