This concerned me as well. The 87' has the serpentine 6 rib, without the idler wheel, and 2 regular belts for A/C and PS in the rear of the pulley. I eliminated a/c. The lower pulley is very hard to find.
Most cheapo kits are crap or very expensive from Marsh. The PS fix brackets are not strong enough for off road, from fleabay... they flex badly and do not align...
This pulley set uses the long water pump. The water pump pulley has the 6 rib, for grabbing the alternator and 1 v-belt for the PS. I have not tried to add a/c to my system, and I'll bet it could be done with some mods... or adding a compressor for on board air... never tried it though.
Deleting the A/C caused a missing bracket with headers and the PS pump had no back brace and would squeal due to bending under load. My PS is press on... not the old threaded style. in 87' they went to the 14mm ps fittings at the pump...
Instead of buying a kit I made a plate that bolts on the head and used the POS bracket from an old Chevy... (Secret Sauce...) This allows headers and PS to line up correctly. AC Delete.
If you click my profile and find my welcome page, the pics of the plate and the style PS tensioner are there. You'll have to zoom into see the alt tensioner I make.
You'll see the alt has the wheel for the 6 rib, which is significantly better for turning the high amp alternator, and why GM wet 6 rib on only 1 pulley wheel section, in 1987. I had to pull my old 6 rib wheel for the alt with an impact wrench and re use it on my 200a alternator.
It's the adjustable voltage charge version, you'll need if you ever swap to AGM or Lithium batteries, because the stock alt will kill either of the new batteries by charging at the wrong voltage...
This is very important for anybody buying newer batteries^^^^^^^^^^^^^^^^^^^^
Make certain you tighten it up with an impact, or it will go flying... The alt wheels are different sizes, and why
fast99 said fix it right...^^^^
It has to be the correct diameter for charge ratio and proper current or **** will burn up...
You really have to get the correct size alt pulley... I can measure mine if you are going to ask one of the vendors for 87 pulleys... so they can find you the correct set.
Most people throw them out when they go serpentine, reverse water pump or buy the Marsh for a custom rod, so they are around...
Maybe one of the parts sellers here can locate you an 87 lower pulley, the h20 pulley and a six rib for your alternator, with the correct diameter and then you'll have enough ass to pull the amps your 140-200 amp alternator requires... no more squeal... stock looking pulleys and a lot cheaper than Marsh..?.
Ditching the old pulleys will solve your problem. Marsh makes a kit that actually works. Not all aluminum pulley kits can be trusted... Cheapest is $389 for what you need...
Post a wanted ad or find a parts stripper here for the one's I mentioned... if you can buy the OEM 1987 set, email me for the plate you'll need to fabricate.
Check out my mod:
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Willing to fabricate a set for you if you like. My post count is not high enough for selling yet, but after it is, Was thinking about fabricating the plate, tensioner and PS bracket as a kit and selling them here... If you have accessory holes, this will work. You can also use a thread post alternator, however it may require additional shims to line PS pulley up. Have not tested one out yet...
The gold plate requires special care when installing...
The pulleys line up perfect. Exact alignment for every belt. No BS.
The press on pulley for PS just needed a lil' extra using a socket to get that extra 1/8" on the PS shaft.
It came out very well. It took me months of anguish and research to come up with this... It saved me hundreds in aftermarket parts overall.
-Welder