The available H2O pumps for the 144/170/200 come in two lengths. The shorter of the two is usually on cars with the early single groove small damper paired with a large diameter single groove H2O pump pulley (or the extremely rare early short double pulley). The longer pump is from later years and is used with a double or triple groove smaller diameter H2O pulley. Just by looking at the dampers and H2O pulleys you wouldn't think there was enough difference in diameter to matter. As it turns out, the large late damper is just big enough to interfere with -most- early H2O pump pulleys. If you are trying to install the early short pump and matching big H2O pulley in an effort to get some fan space between the front of the fan and thicker (3 core) radiator, and, are also using a late two groove damper, there will be issues.
The two pump heights, mounting surface to face: long = 4.75", short = 4.0".
Below is the late, dual groove, "big" damper. The dual groove unit is needed if you plan on running A/C. It's 6-3/16" dia.
Below is the early single groove "small" damper. There was a fairly rare add-a-pulley for these dampers. It's 5-7/8" dia.
You can always have a smaller diameter custom "overdriven" short pump pulley made. It will turn the water pump and fan faster at idle, and let you run double belts. Great for A/C equipped cars.
Link to plans.
Any halfway competent machinist should be able to turn one out of aluminum in a couple hours from those plans.
This pulley is around 10% overdriven
I've been using one for a few years now, and I'll have another one made when it is time (soon). If you can get the pulley hard anodized, do so. Otherwise expect a lifespan of 30k miles, or so, before the grooves wear completely out.
Worn grooves after about 25,000 miles.
Rick(wrench)
