300+ rebuild

[davehummell]

I haven't done timing on a mack in a long time but if I remember I set the engine on the timing mark and used air pressure and an adjustable pressure valve and you counted the drops on the clock if I remember correctly I did a lot more stuff on the 1693's for more power back in the day.

[BOBWhite]

12 minutes ago, davehummell said:

I haven't done timing on a mack in a long time but if I remember I set the engine on the timing mark and used air pressure and an adjustable pressure valve and you counted the drops on the clock if I remember correctly I did a lot more stuff on the 1693's for more power back in the day.

Was the air for pressurizing the fuel? Pressurizing the fuel tank then counting the drops when the pump gets into the right position? I've never spill timed anything but the process seems cool 

[Freightrain]

1 hour ago, terry said:

3400 ! Wonder how he keeps it together!  terry i once had a 285 turned up to 2300 and i thought that was pushing it!

He says never a problem.  Never had one come apart on him.  I was amazed.   I want to see it run this summer.  He is doing headwork, havig hard time finding someone to put fire ring back in heads.  I asked my motor shop and he just cringed.  They aren't set up for big truck stuff.

 

I did find the roll pin on the pump coupler.

[Mark T]

10 minutes ago, Freightrain said:

He says never a problem.  Never had one come apart on him.  I was amazed.   I want to see it run this summer.  He is doing headwork, havig hard time finding someone to put fire ring back in heads.  I asked my motor shop and he just cringed.  They aren't set up for big truck stuff.

🤔

[Mark T]

Some of those high performance diesel guys swap around valve components to achieve extra RPM s

I've heard of Cats that somehow have big block Chevy valve springs. My guess is that's the first area that would actually fail when using an engine like that. 3400??? I could see an 11  litre turning that high otherwise. 

[davehummell]

Back in the day there was a company I think called Lake city Diesel that advertised about getting 850 hp out of 3406 engines for trucks. The marine engines always seemed to get more power, but you could get rid of the heat out of the engine in a boat easier than a truck

[Freightrain]

They are turning the big CAT motors like 5000 rpm now.  Getting 2-3000 HP.

 

Valve float is a big deal.  Those huge valves need control.  I suppose the bottom end is not really an issue with staying bolted together.

 

Of course when they do break....it is spectacular!

[other dog]

The 300 I drove would turn 2400, and the pump had never been tampered with that I know of. I know it still had the seal on it. They put a pump on it one time, or had that pump rebuilt- by Mack- and when I got it back I was expecting it to turn 2100 but it still turned 24.

 

[mowerman]

yeah for years,,they were telling us,,dont take it over 2100,,