8.1 Vortec questions?
 

Larry if your listening this is for you . Anyone else that knows is welcome to answer as well. I need to move my driver side knock sensor to clear my headers, can this be done? also in the interest of cleaning up the engine bay can I plug the oil cooler lines off or do I need to loop them. Im not going to be towing or hauling with it so I dont think the cooler is really necessary. Thanks for any help.

Re: 8.1 Vortec questions?
 

Yeah, I had to do the same thing on the driver’s side for exhaust manifold clearance. Use knock sensor 213-298 on the driver’s side as it has a different stud size and thread pitch that can be threaded into one of the other holes on the side of the block. Sorry, I don’t have a picture of that but you’ll figure it out quite easily once you have this sensor in hand. Outside of the thread, the sensor itself is the same and is compatible with everything else. Yes, you can just plug the oil cooler lines at the block with pipe plugs. Both my K10 and ’89 Suburban 8.1L’s oil cooler ports are plugged that way. No need for oil coolers unless you are pulling King Kong across Hong Kong

Re: 8.1 Vortec questions?
 

85 Super,
I talked to Raylar Marine about the cooler bypass, I had to remove the filter adapter and pull out a relief valve ?? I'm running about 40-45 psi at idle.
I think it was the center one but don't quote me on that..
Call Raylar and talk to a tech, it was real simple.

DirtyLarry,
Iv'e got a 02 8.1 from a GMC 1 ton, (lower ps a/c, upper ds alt ) it's in an 89 crew cab, cut down to 133" wb, with 42" Rockers.
This thing doesn't want to steer ! (D60, crossover steering).
Would a ZF p/s pump work with the bracket set I have ( Alt above the P/S)?
I'd like to go Hydro Assist steering and need to upgrade the p/s pump anyway.
Will the ZF pump work with Hydro Boost brakes ?
I'd really appreciate any advise you could offer ?
Thanks

Re: 8.1 Vortec questions?
 

I’ve heard that story too where a relief valve needs to be removed. While that may not hurt, I don’t feel it is necessary.

Oil pressure spec from the GM service manual:

Oil Pressure – Minimum 5 psi @ 1,000 RPM
Oil Pressure – Minimum 10 psi @ 2,000 RPM

The 8.1L has been in my K10 for 7 years and about 35,000 miles with the oil cooler ports plugged without removing any relief valve. It runs around 20 psi at idle (750 RPM) which is well above the GM minimum spec above. Normal highway driving it runs between 50 and 60 psi. With that, I just don’t see removing the pressure relief valve is really necessary. I didn’t remove the relief valve on the 8.1L I’m building for my ’89 Suburban either.

Not sure if the ZF pump will really help you much but it may not hurt. Yes, the ZF pump will run hydroboost. Have you priced a ZF pump?? They are well over $600! And if you can find a used one they will cost at least $300 unless you find a junk yard that doesn’t know what they have.

There were two different ways ZF pumps were mounted to 8.1L engines. Both require the accessory brackets that move the alternator to the passenger’s side and A/C compressor to the driver’s side. These brackets were used on G-vans, GM medium duty and Workhorse. From what I can tell, one bracket was a ZF exclusive piece used by GM medium duty then Workhorse used a bracket designed for a Saginaw pump with an adapter bracket to mount the ZF. From experience, I can assure you the Workhorse bracket with the ZF adapter does not provide enough clearance for the ZF pump to fit into our old truck frame rails.


Saginaw pump bracket 12558927 A/C P/S Bracket. This is how Workhorse mounted the ZF to the A/C bracket. For whatever reason, they used the Saginaw bracket with an adapter bracket to mount the ZF pump. This concoction will not fit our old trucks due to frame interference with the ZF pump. This bracket with a Saginaw pump is fine for fitment though.
https://farm4.staticflickr.com/3798/...6a68a704_c.jpg

Same bracket as above but with the ZF pump and adapter bracket
https://farm2.staticflickr.com/1028/...7be9fc9fa0.jpg

Close up of the ZF pump
https://farm2.staticflickr.com/1022/...4f137bc93e.jpg


ZF exclusive A/C and P/S bracket GM Pn 12563068. Notice how more square the P/S pump mounting is compared to the bracket in the first picture. I think there is one more small bracket that bolts the ZF pump to this bracket as GM used a few different versions of the ZF pump with different port locations which may have required small adapter brackets.
https://farm4.staticflickr.com/3759/...9ef4e451_c.jpg

This is how the ZF was plumbed on the Workhorse units
https://farm6.staticflickr.com/5123/...38807a5462.jpg


Here is an example of a GM medium duty truck 8.1L with a ZF pump
https://farm3.staticflickr.com/2827/...abfd571278.jpg

And another with a ZF pump. Notice the ports on the pump are different from the picture above.
https://farm8.staticflickr.com/7368/...9ea849c8a2.jpg

And a picture of the Saginaw pump. These are the brackets, A/C compressor and P/S pump I'm using on both the K10 and Suburban.
https://farm8.staticflickr.com/7332/...2050f6a97a.jpg


Here is a thread I put together on all things 8.1L related.. I put that together to help stop the overwhelming amount of PM's I was getting on 8.1L questions.

Re: 8.1 Vortec questions?
 

Larry,
Thank you.
I was hoping the used pumps were cheaper than that ?
Sounds like I'm better off buying a reworked factory pump.
Space is definitely an issue, along with cost.

Could I bother you about one more issue ?
02 8.1, I had Howell build the harness.
I'm showing 400 RPM at idle on a Auto Meter Tach that's non adjustable, I've been racking my brain on google search's and it appears that the 8.1 puts out a 4cyl signal from the ecu.
Everything I'm finding on google is people with the opposite problem, their reading double the RPM.
Still waiting to hear back from Howell, but thought you had probably ran into this before ?
Any help would be greatly appreciated .
Thanks again.

Re: 8.1 Vortec questions?
 

I welded a pipe fitting onto a plug and made my knock sensor fit in one of the coolant drains IIRC. on the oil cooler I made a temporary/permanent loop out of 3/8" SS tubing, until/if I hook my oil cooler back up. Mine is my DD/towrig, but I haven't seen any need for the extra oil cooling yet. My biggest problem is getting my A/C hoses to hold. I guess Im going to have to buy an actual A/C crimper versus having the hydraulic style crimps on them.

Re: 8.1 Vortec questions?
 

I remember having some goofy problem with my aftermarket SunPro Tach after the Howell harness install as well but I don’t remember if it was reading too high or low. After quick call to Howell they told me to turn my tach to the 4 cylinder mode and it worked fine and reads RPM right on par with the Tech 2 scan tool. I'm sure my memory will be jogged shortly as I am very close to dropping an 8.1L into my '89 Suburban within a few weeks. Just need a few more parts. The radiator showed up today totally beat to hell.

Check out the hole in the box. I didn't even have to open it to see how fangled up the radiator is. My wife said, "The FedEx guy just left a box, rang the door bell then ran off real fast". After I saw the box I was furious! I hate FedEx Home Delivery and FedEx Ground contractors! :m6: They're hacks! What a chicken turd he is to leave a box like this knowing it as damaged. Errrr! To make it worse the Ebay store says it will take two more weeks to get a replacement. This is supposed to be a new 4 core '91 Suburban 454 radiator.

Re: 8.1 Vortec questions?
 

Larry,
That sucks, there's nothing worse than waiting on parts and they show up damaged.. wth ??
I'm sorry, I worked for FedEx 15 years ago.
We would get a set of triple's that were just stuffed to the gill's with, well ? stuff !!
We would have to sort through trailers looking for our local deliveries for the day, it wasn't pretty but customer service was #1, to me anyway..
If I had damaged freight you made the customer aware of it and did everything possible to help them make a claim.
98% of the time it showed up from the previous FedEx hub damaged.

Anyway, thanks for the info.
If how my tach is reading is my big concern after this swap, that's a good thing !!
This motor is heavy for a wheeler but what an animal !!
It's got 101K miles on it and still has cross hatch marks on the cylinders, really..?
Just curious ? I purchased a manual throttle body from Howell, if I remember correctly it was from a Camaro ?
Is there any throttle body upgrades that you know of ?
This motor is a 02 so I think it has the adjustable fuel pressure regulator ?
I haven't even played with it yet.

Re: 8.1 Vortec questions?
 

Love the big "do not crush" sticker. That sucks.

Re: 8.1 Vortec questions?
 

Errr, this radiator deal is really pissing me off. Pepboys was the Ebay store and they are being total idiots to deal with. The only parts I need are the radiator, two O2 sensors and the ECM to come in from Howell and I’m ready to go. I really didn’t want to tear the Burb down until I had EVERYTHING on hand. I just hate waiting on parts when something is totally ripped apart and killing a stall in the garage. I prefer to have every known needed widget on hand first.

Nah, an 8.1L isn’t heavy. A Cummins 5.9L is HEAVY for a wheeler. Not sure which TB Howell sold you but I use 96-00 L29 7.4L throttle bodies because they have the same bore diameter as the 8.1L, which is like 77 or 78 MM. The gen III small blocks used a smaller bore, including Vettes and Camaros, if I am not mistaking. About the only upgrade for the TB that I am aware of is to move the TPS and IAC sensors to an aftermarket 80MM TB. Those are stupid expensive!

Here is a pic of the L29 TB, albeit not a very good one
https://farm9.staticflickr.com/8067/...844bfa5f_c.jpg


Yeah, the Do Not Crush sticker is funny. Maybe the need to add a Do Not Drop and Do Not Poke sticker to the box too. I can tell you this for sure.....I will NEVER buy a single thing from Pepboys Ebay store ever again. Granted, the damaged part is not their fault but how they are handling this is totally lacking in customer service.

Re: 8.1 Vortec questions?
 

What is pep boys getting for a new radiator? Napa's is almost $550 here for the same application.

Re: 8.1 Vortec questions?
 

The cost was $303.54 including a free ride for the Spectra Premium Radiator PN CU774 through Pepboys via Ebay. It is the big dog 1991 square body 4 core radiator. My cost through Napa (jobber cost) was $604.00 with a List price of $834.44 so it was hugely cheaper to get it through Peterboys via Ebay even considering the hassle. The Napa Pn for the same radiator is NR 2071. And to find one of these in the salvage yard will be practically impossible.

3 days later I have still not heard a peep from Peterboys on my replacement or return of this one. They are total idiots on the phone too as they claim their internet sales Customer Assistance hotline does not include Ebay sales, only items sold through Pepboys . com. Total circle jerk if I ever heard of one. I’ll be sure to leave them honest feedback when this is all said and done :devil: