New water pump pulley holes don’t align?

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Sep 26, 2025 | 03:39 PM
  #1  
purchased new Gates 43099 water pump for my 87’ 305, upon getting old pump pulley off, new pump holes don’t align with old pulley.

New pulley needed? I thought this was the correct pump. Not sure what’s going on.



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Sep 26, 2025 | 04:18 PM
  #2  
Re: New water pump pulley holes don’t align?
You need to get the correct waterpump...
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Sep 26, 2025 | 04:23 PM
  #3  
Re: New water pump pulley holes don’t align?
Is that a Vbelt pully? Or did you switch to serpentine belt?
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Sep 26, 2025 | 04:36 PM
  #4  
Re: New water pump pulley holes don’t align?
Motor is a single serpentine belt pulley.
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Sep 26, 2025 | 04:41 PM
  #5  
Re: New water pump pulley holes don’t align?
87 doesn't have a "serpentine" (snake-like) belt.

It DOES have one flat ribbed belt, the same type of belt that's used in "serpentine" drive systems. However, it's not "serpentine"; only flat and ribbed.

AFAIK 87 uses the same WP as almost every SBC, except ones in the Vette, from about 69 up until the "serpentine" system was introduced.

That's simply the wrong WP. Might be the one for the "short" pump system from back in the 60s.
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Sep 26, 2025 | 04:50 PM
  #6  
Re: New water pump pulley holes don’t align?
Back to Rock Auto it goes I guess. That was the pump under the 87’ year so I guess I’m a bit confused.
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Sep 26, 2025 | 05:10 PM
  #7  
Re: New water pump pulley holes don’t align?
Quote: Back to Rock Auto it goes I guess. That was the pump under the 87’ year so I guess I’m a bit confused.
88 and later had a single belt. 87 had one flat ribbed belt and several v belts. Which one do you have on the car? If someone converted your car to the newer belts, that would explain your issue.
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Sep 26, 2025 | 05:37 PM
  #8  
Re: New water pump pulley holes don’t align?
Yup just one single belt.  So I need an 88’ up water pump.
Yup just one single belt. So I need an 88’ up water pump.
Reply 1
Sep 26, 2025 | 06:06 PM
  #9  
Re: New water pump pulley holes don’t align?
That's not the correct WP pulley for an 87. The pulley for an 87 should be part #14088685. It should have a V-groove on the front for a V-belt; 5 micro-grooves in the middle for a flat 5-rib Micro-V belt (same type as the 6-rib flat Micro-V belt used for serpentine drive systems, which, just like the 5-rib belt, is round; serpentine is a routing style, not a belt style, design or name); and there's a V-groove behind the 5-rib for a V-belt.

If your car is an 87, then it's been converted to the 88+ serpentine drive, so yes, you'd need an 88-92 WP.
Reply 1
Sep 26, 2025 | 09:28 PM
  #10  
Re: New water pump pulley holes don’t align?
Quote: Yup just one single belt.  So I need an 88’ up water pump.
Yup just one single belt. So I need an 88’ up water pump.

Looks like someone converted your 87 to an 88 up serp system. thise looke like the 87 fuel lines.
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Sep 27, 2025 | 01:23 AM
  #11  
Re: New water pump pulley holes don’t align?
Quote: Looks like someone converted your 87 to an 88 up serp system. thise looke like the 87 fuel lines.
Late 87 V8s had serpentine belts. I have run across 2 of them. One was a TPI 350 and the other a late production LG4 with a factory installed serpentine belt setup. I know it was factory because the vapor purge valve had a factory built mounting bracket.
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Sep 28, 2025 | 11:56 AM
  #12  
Re: New water pump pulley holes don’t align?
Yup, that's the "serpentine" (snake-like) system... I stand corrected. I've never come across that in a passenger car, only trucks in that year.

It needs NOT ONLY the different bolt pattern, BUT ALSO the opposite direction of rotation, since the back of the belt, not the front, goes over it and drives it the other way.
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Sep 30, 2025 | 01:37 PM
  #13  
Re: New water pump pulley holes don’t align?
Quote: Late 87 V8s had serpentine belts. I have run across 2 of them. One was a TPI 350 and the other a late production LG4 with a factory installed serpentine belt setup. I know it was factory because the vapor purge valve had a factory built mounting bracket.

I recall something about this.. but I think i heard 87 was only for Camaros? Then in 88 Birds got the serp system? My assumption always was because of the intake design etc... on the bird requiring more design but there was never enough info to verify . I always love learning new things about these cars.

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Oct 2, 2025 | 12:32 PM
  #14  
Re: New water pump pulley holes don’t align?
Quote: I recall something about this.. but I think i heard 87 was only for Camaros? Then in 88 Birds got the serp system? My assumption always was because of the intake design etc... on the bird requiring more design but there was never enough info to verify . I always love learning new things about these cars.
I looked up the crank pulley part number from GM and the 87 Camaro is listed for an application for the 6 rib pulley but not the Firebird.
Reply 1
Oct 2, 2025 | 01:25 PM
  #15  
Re: New water pump pulley holes don’t align?
Just FYI, I did end up switching out to an 88’ pump and everything lined up just fine.
Reply 2
Oct 2, 2025 | 05:28 PM
  #16  
Re: New water pump pulley holes don’t align?
Quote: Just FYI, I did end up switching out to an 88’ pump and everything lined up just fine.
Excellent...
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Oct 3, 2025 | 08:27 PM
  #17  
Re: New water pump pulley holes don’t align?
Anybody know why Felpro only lists the one gasket as being for this water pump. One side has 3 holes when the other has 4. Having trouble finding the 3 hole gasket. Most just say Felpro ES73030 as the gaskets which has 4.
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Oct 3, 2025 | 08:34 PM
  #18  
Re: New water pump pulley holes don’t align?
The 4th hole isn’t used on the drivers side. Same gasket both sides. Use liquid teflon on your mounting bolts.
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