10lbs per 1000 is more like it. He's not looking for 500 psi at 5000rpm. So how many miles is 100km? I think the 20/50 may be the only think helping make pressure now. How many miles are on the motor?

 

lol. craby said 1 lb for every 100 rpm, which works out the same mathematically as 10 per 1000 (all you gotta do is add a 0 to each number).
And I always thought it was 5 lbs for every 500 rpm. I'll give you a moment to figure that one out!!

 

100km is 62miles...its probably more like 300kms now....i'm not sure how many kms are on the motor because its not original, the odometer says 41xxx kms but i'm not sure how long it hasn't worked for im guessing its around 50-55000kms on the body...the guy i bought it from said that it was ported and polished (im really not sure what that means) new kb pistons and a cam, new intake, new carb, timing gears, msd ignition ect. so its not stock

 

WOW what a dope. I would blame it on not wearing my glasses, but I don't need them to read.

 

ported and polished is work done to you heads. You know those ports on the heads where your headers connect to...well when you put a header gasket on the head it doesnt sit quite flush right. So what they do is grind down the ports, making them larger than stock, so the port is exactly the same size as each little square cut out on the header gasket. and polishing is exactly what it means. they smooth out the insides of the newly ground exhaust ports for better airflow.

 

Thanks I always thought it was along those lines but was never quite sure

 

Proper porting and polishing will really add to the HP of a well built engine. When I assembled my 427 I did the porting and polishing with the help of a friend who had a shop and guided me through the process so I wouldn't screw things up.
I was surprised when he pointed out areas that should not be ground, as I just sort of figured the more you took out, the better they flowed. Some shrouded areas need to be left shrouded to give support to the valve stems, and flow properly.
Also the exhaust ports can be polished to a mirror finish, but he told me to leave the intakes just ground smooth, and not polished. He said it breaks up the air/fuel mixture better, and actually improves combustion when they are slightly irregular.
I've never regretted the 40 plus hours of grinding and matching I did on the heads and intake. The engine has always been a great performer.

 

The reason to not go to a high polish is very simple. Its easy to imagine if you think of it like this.

Say you haven't washed or waxed your car in a long while. Its dull with little reflection in the paint. You spray water on it and the water flattens out over the surface because microscopically there are tiny ridges and valleys the water is falling into.

Now you wash it and wax the snot out of it and shes glowing. The wax either filled in the valleys or removed enough material to make it flat. Then it rains. The water now doesn't have the small valley to fall in and it beads.

That is the same thing that fuel will do. The droplets will not stay atomized.

Think of this as a cross section of polished. ^^^^^^^^^^^^^^

And this is mirrior finished. ______________________