Where are the "breather holes" that need to be blocked when you turbo a 250?

[hethead]

I already spent over an hour searching the forum. Scrolling through 15 page threads etc., so I tried. I found mention of them, but that's it.

I paid my dues! Where are they!

 

[US6x4]

In the head it's here:


In the rocker box it's here:




Mine were already plugged from the factory, I believe (April 1981 engine). I guess if you insert a piece of wire into the rocker box hole and it goes in deeper than the rocker box height than yours are not plugged and the wire would keep going until it hits the bottom of the intake port.

 

[hethead]

In the head it's here:
View attachment 875341

In the rocker box it's here:
View attachment 875342

View attachment 875343

Mine were already plugged from the factory, I believe (April 1981 engine). I guess if you insert a piece of wire into the rocker box hole and it goes in deeper than the rocker box height than yours are not plugged and the wire would keep going until it hits the bottom of the intake port.

Thank you so much. I started installing the turbo today (mocking up the manifold and tubing and tacking things together) so I was really hoping someone could help me. Your timing couldn’t have been better. I appreciate that

 

[hethead]

Holes are plugged on mine too ‘71 M820.

 

[hethead]

Turbo installed. Setting the wastegate to 8 lbs of boost. It sounds pretty good! Quiets it down without a muffler.

 

[msgjd]

Turbo installed. Setting the wastegate to 8 lbs of boost. It sounds pretty good! Quiets it down without a muffler.

got a pyrometer installed? am interested how much the turbo affects the 3rd-4th tranny hole

 

[hethead]

got a pyrometer installed? am interested how much the turbo affects the 3rd-4th tranny hole

I do. I have a pyro and a rail pressure gauge since I turned the pump up. I keep it under 200 psi and I was able to get it above 1000 degrees before I installed the turbo. I don't like that.

With the turbo it does pull better from 16-1700 after I shift into 4th and I'm not able to get it above 900 degrees pre-turbo no matter what I do.

I pulled a decent grade in 4th.
Rpms: 2100
Pyro: 900
Rail pressure: 160
Boost: 8 psi.

That was what I was shooting for so I'm happy.

That was me controlling it with the pedal since it's capable of 230+ psi and 2400+ rpm. I have to turn things back down a little so it's not so "busy" to keep an eye on all the gauges.

It could make a lot of boost but I want to start out with 8 and maybe go as high as 10 psi, tops. I want this motor to last 200-300,000.

The turbo was a good step. I'll post pictures. It was a very quick and dirty (one day), very Mad Max and pretty ridiculous install, but I like it.

 

[hethead]

Here’s a few pics. I did this in a field with an acetylene torch and a generator so it’s not my finest work, but it was a quick way to go from zero to turbo.

 

[msgjd]

With the turbo it does pull better from 16-1700 after I shift into 4th and I'm not able to get it above 900 degrees pre-turbo no matter what I do.

I pulled a decent grade in 4th.
Rpms: 2100
Pyro: 900
Rail pressure: 160
Boost: 8 psi.

really good to hear .. I have some turbos from a 230, a 290 and larger 855's sitting around, and a M809-series custom turbo hump hood just waiting for something to go on to .. Know enough to know we can't turn the NHC250 up too much without having piston coolers, was wondering if there was enough difference with the dreaded 3-4 shift to be worth the effort