Pulley set

[FlyingToaster]

My alternator pulley doesn't lineup at all with my h2o pump or crank (off by 3/4" easily). I'm about to replace water pump and timing belt, anyone sell a (3) piece lightweight pulley set? Is it worth it or just fix the alt pulley and move on? Thanks, -John

[RRoller123]

culprit may be the crank pulley? Mine has multiple belt positions, I assume for use with an AC pump, or for a prior pollution air pump or whatever. 3/4" sounds exactly like the pitch. Thus, if the Alt and WP line up visually, that would support this possibility.

[klweimer]

While the aluminum pulleys look cool, I can't imagine they would do anything for performance. I would try to figure out what's mis-aligned first, or you could end up with cool looking pulleys that still don't line up.
Kirk

[RRoller123]

That double pulley on the front of the crank is surprisingly heavy! I bet there is some not insignificant power loss spinning that thing up and down? I wonder if anyone has done some actual data on it. Same with the cam wheels, (although they spin at half speed). The aluminum adjustable ones save quite a few pounds.

[klweimer]

True enough about the crank pulley, but because it's diameter is not very big, it's flywheel effect would be pretty limited. Maybe someone with experience will chime in.
Kirk

[RRoller123]

It is an interesting topic! I am a little surprised that there is not more that comes up with a quick web search. I will keep looking.

Here is a reference that gives probably more than one would ever want to know about this, although this fellow approaches it from a purely racing perspective:

http://www.w8ji.com/rotating_mass_acceleration.htm

This one claims 3-5 rwhp gain with an aluminum crank pulley on a Mustang, but it involves geometry changes, not just material/weight changes, so it's not really apples to apples:

http://www.angelfire.com/my/fan/Mustang ... sites.html

Pete

[FlyingToaster]

I have the single pulley on the crank using one belt to drive the water pump and alternator. You can see in the pic my alternator does not line up. I have since taken the pulley off and there is a spacer behind it. Perhaps the wrong thickness spacer? Wrong pulley?
I asked about the lightweight pulleys as I have experience on my old water cooled vw's urilizing all aluminum pulleys along with a lightened flywheel. Significant improvement in throttle response and could certainly "feel" an improvement.

[RRoller123]

I am not aware of any spacers being installed behind the alt pulley, but I haven't taken one apart. That may be it. Looks like the crank and WP are lined up ok. Is the alt properly mounted in it's bottom cradle? If so, then the alt pulley is clearly the culprit.

[So Cal Mark]

the fan/pulley set up on your alternator doesn't look right. Usually the fan is closer to the alternator body

[carl]

I agree, that alternator does not look right. I just checked three 124 alternators an one X alternator in my parts stash and they all have large cooling fans that are the same diameter as the alternator. Also the 124 alternators have the upper bolt ear flush with the front of the alternator.

[FlyingToaster]

Here's a shot on the bench of pulley and the spacer that was behind it. Spacer is 3/8" thick and pulley appears to be ~1.5"
I could ditch the spacer and modify the blades on the pulley to keep them from hitting the alt housing.

[klweimer]

That whole set-up looks funky. Maybe someone here has an extra alternator you could tidy up and put on?
Kirk

[RRoller123]

I bet someone replaced the alt some time back with an improper one. An upgraded alt or a replacement stock one are quite plentiful, used, here on the forum and new from the various vendors.

[Sparky]

Are there any guides to compatible pulley & part combos?
eg. I've got some late 1.8L engines and I'm looking for a crank pulley that I can easily adapt a trigger wheel to, but the only suitable candidates are for the 2L engines. I also need a new alternator and I wouldn't mind replacing the water pump for some peace of mind so switching around parts is fair game... There's a lot of posting about the alternator being on the right or left side of the engine and I have no idea what perspective people are using, fwiw, on the 1800's I have, the alternator is on the passenger/exhaust side.
Being a '78 it should have the same 30mm crank-nose as the 2L...