cheap air compressor head porting

[corax]

Today's cheap project is to port a cheap air compressor cylinder head.

I'm pretty sure this isn't anything new, but it's so simple and does make a difference. Total time spent was ~ 30 minutes including the time it took for me to walk out to the truck.

This is our patient - a Harbor Freight cheapie air compressor, it's lasted nearly 1.5 years so far and has some good design features such as: big motor, no separate cylinder sleeve (better heat disipation) and cheap . . . did I mention that already? I think I paid $20 for it on sale

I took the head off, which was just 4 allen bolts (no pics 'cause it was simple) - the "head gasket" is just a recessed o-ring (cylinder has a ridge which goes into the recess to sandwich everything) and was reused. Here's the inlet side of the cylinder head - the air gets pulled through dual reed valves on the piston and pushed through the reed valve in the cylinder head. BTW, the gunk you see on it is dried up anti-seize.
From the cylinder, air has to pass though this 1/8" hole

here's the actual reed valve (covered by measuring tape) where air comes into the chamber on top of the head before going to the air fitting, note the little ring seal - the reed valve side of the air hole is 3/16"

here's the Dremel bit I used

cylinder side of the head plate after opening it up - about 1/4" diameter in 30 seconds - I also tried to "radius" the hole a bit so the air wouldn't have to flow past a sharp edge (think of the air horns on ITB's or side draft carbs)

discharge side of the head - just under 1/4" diameter - I didn't want to get too close to the reed vavle seal and as passage diameter decreases the air velocity will increase, so it shouldn't matter anyway


I didn't bother timing how long it took to fill a tire from x psi before and after this mod, but I can tell it's moving a higher volume of air now - and with the easier flow should come lower operating temps.

[Tankota]

Wow thats pretty cool. I never thought about porting an air compressor head. I always like your write ups.

[4runnerchevy]

Hey Keith, it sounds like your polishing a turd.

[Tankota]

Well I'd rather have a polished turd than a regular ol' unpolished one!

[corax]

Hey Keith, it sounds like your polishing a turd.

Nah, it came plated like that . . . don't ya know "chrome will get you home"

[Brunoski]

Would this apply to any compact air compressors? I have an ARB under the hood, i think its the bigger of the two available. I always welcome cheap improvements.

[corax]

Would this apply to any compact air compressors? I have an ARB under the hood, i think its the bigger of the two available. I always welcome cheap improvements.

the only way to tell is to take it apart . . . should apply though

[Tankota]

Just dont screw up a good expensive compressor.

[corax]

Hey Keith, it sounds like your polishing a turd.

a more in-depth look at the quality and mods available is in this thread

At this point the differences between the 1050 and the HF really started to add up. Although from a distance things like the castings look identical, they are not. The HF motor makes the 1050 look like a toy. It has stronger magnets, better ball bearings, the armature had nice tight windings, there were the proper high dielectric insulators on the armature polls, a .1uf capacitor accross the motor leads (cuts down arcing of the brushes) and the can was some kind of seamless tube that had been finished up on a lathe.
I really think that both units are attempts to "use up" not to spec electric motor parts purchased at pennies on the $.
The bore and stroke are the same and the pistons are interchangeable.
In both units the crank throw was not inline with the cylinder.

Finally, the HF heat sink was a sung interference fit with the cylinder sleeve while the 1050 had 4 little bosses only allowing minimal contact. The 1050 heat sink is mostly to hold the head up.

[Robinhood4x4]

Keith, which model is that? HF has 3 different ones that look the same and range in price from $27-$70.