When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have an 89 Formula 305 TPI with AC. I want to remove the smog pump and heard I will need to replace the serpentine belt with a different size. Does anyone know what size or have a part # for the right belt? Thanks!
I want to do it without using a bypass pulley. I did a search and 2 different people were giving 2 different answers on the size of the belt. I just want to make sure I get the right one.
Yes there are 2 different and it all depends on the Harmonic Balancer Pully size. Apparently GM used 2 different sizes through the years. I can't remember the belt sizes but IIRC its only 1" shorter than the original.
I have an 89 Formula 305 TPI with AC. I want to remove the smog pump and heard I will need to replace the serpentine belt with a different size. Does anyone know what size or have a part # for the right belt? Thanks!
Alright!
I'm going to try answering from memory and notes. Do your own due and diligence.
For an '89 LB9, the stock belt with A/C is 94.5in (example: Dayco 5060945). That is with OEM accessories with no underdrive pulleys or any other sort of hack.
The "by-pass" belt is 96.8" (example Dayco 5060968). It needs to be routed differently than OEM. Should not be to hard to find how with simple research on TGO... but see picture below.
FYI, with underdrive pulleys, Hypertech Power pulleys for example, you need 93.5in to by-pass.
1988 is different OEM set-up but same by pass belt
Good luck
Last edited by SbFormula; Feb 14, 2024 at 03:29 PM.
Hello, I am new to this forum and am looking for some info. I purchased a 1991 Z convertible last year and am in the process of eliminating the A.I.R. system. So far I've removed all the plumbing, just so I can access the sparkplugs. With the system being removed, what adjustments must I make in order to have the O2 sensor and ECM happy so as not to get a leaner signal to the injectors, now that the AIR tubes are removed from the exhaust manifolds and plugged?
Thanx
RJ
On a 1988 Iroc Z 5.7L TPI the belt size is Dayco part # 935K6, (I used a Continental Brand equivalent to that part #) that is a 96.8" 6 rib belt, that is with removing the A.I.R pump and not putting a delete pump/pulley in (why would you add another device with a potential bearing that could fail/cause noise/create drag/cost more).
Factory routing remains the same, its quick and easy.
Whatever was recommended here was a tad too short. I had to forced it on there with a screwdriver pry bar. Wish I had 1/4" longer.; But I am loving the way the car runs without the AIR pump, and I'm especially loving the spark plug access.
Engine bay is so much cleaner, and the computer doesn't know the difference.
Whatever was recommended here was a tad too short. I had to forced it on there with a screwdriver pry bar. Wish I had 1/4" longer.; But I am loving the way the car runs without the AIR pump, and I'm especially loving the spark plug access.
Engine bay is so much cleaner, and the computer doesn't know the difference.
when the air pump is commanded on the ecm adds to the o2 mv to compensate for the air going past the o2. The ecm does know
when the air pump is commanded on the ecm adds to the o2 mv to compensate for the air going past the o2. The ecm does know
My understanding is that the AIR is cold loop operation only. So it doesn't care what the o2mV says. and my car now runs great with the stock prom, no AIR.
