Z22 power mods

[dat_sun720]

Looking to get more power out of my z22 but don’t really know what I can do. Was thinking on getting a Weber carb but want to know what else I could do to get a little more power 

[datzenmike]

Make sure tuned up to factory specs.

 

The 2wd differential gearing is a bit low, probably a 3.889. Good for mileage but acceleration is a bit slow. If you change to a 4.375 the engine will have more mechanical advantage turning the wheels and at the same speed will be revving higher and making more power than the lower revving 3.889 gears. Not exactly but similar to accelerating in 2nd gear compared to 3rd gear. The engine remains the same with the same power it just uses it more effectively. I would guess a 4.375 differential is worth maybe $100 from a wrecking yard. Your speedometer will now read fast and your mileage will not be as good. The speedometer can be corrected by changing the plastic drive gear in the transmission. I have a 710 car and it came with a 3.70 differential and I changed it for a 4.11. One of the best things I could have done, it really woke it up at all speeds.

 

Definitely look into a 32/36 Weber but there are a lot of counterfeit knock offs out there. Pierce Manifolds sell genuine made in Spain Webers. I think a complete conversion kit is about $300 with everything you need. The stock carburetor is a little small and a 32/36 is perfect. 

[dat_sun720]

Would it pick up more speed in a higher rpm just changing out the differential gear? Right now if I’m gunning it in 2nd gear and get it up to 4500, it stops accelerating as fast as it did like at 3000. And if I rev it out all the way to 5500, it just stops accelerating in general until I shift again.

[datzenmike]

The Z series engines don't breath well and above 4K and like you say by 5k it stops accelerating.

 

All gears will max out sooner and at lower speeds with a 4.375 vs. a 3.889. But they will get there faster.

[Madkaw]

Max torque is at 2800 rpm 

[banzai510(hainz)]

one can try a 38/38 weber but might be to much.  same as a 32/36 just 38s open both barrels at same time . Not to good if you live on hills starting out

Edited June 10, 2023 by banzai510(hainz)

[datzenmike]

That may be true but as I understand it 2,800 was the Z24 measurement. Not a lot of good dyno info on the Z series. I have the  '81 Z22 making 98 hp @ 4k and 117 ft lbs @ 1,800 RPMs (seems kind of low RPMs)

'84 Z24 making 103hp @ 4,800 and 134ft lbs @ 2,800