8.1L vortec to sm465 w/ mechanical clutch

[LuBlunt]

I have a 1979 Chevy k30 I’m wanting to swap the 350small block for an 8.1l vortec. I’m going to use the sm465/np205 thats already in the k30. After reading the forums it sounds like using the sm465 is pretty simple. Use the 8.1 flywheel and throw out bearing. Flywheel bolts are metric. Are the bellhousing bolts metric?

https://www.motortrend.com/how-to/gm-vortec-8100-the-454s-forgotten-big-brother/?utm_campaign=true_anthem&utm_medium=social&utm_source=facebook&utm_type=organic&fbclid=IwY2xjawE0PRlleHRuA2FlbQIxMQABHXY_t9gvHVBf6yBz8C9n1foCwFxpeqUaiGSCPalL-I9pCSD5lGv20VYDYA_aem_rurEfkgOQW9OaDV5XTsUmQ

Recently read this article and it says “Swapping 8100s into classic Chevys with manual transmissions requires a hydraulic clutch actuator. The 8100 block lacks the threaded receptacle for clutch pivot ball.”

Can anyone confirm if the mechanical clutch linkage does or doesn’t work with the 8.1l vortec? Thanks

 

[Wes Harden]

The block may not have a spot for the z bar pivot ball.
I would think a bracket could be fab'd to anchor the z bar pivot.
Have you seen our 8.1 resource thread, look in "The Engine Bay" section

Welcome to CK5

 

[Chickntrk]

It’s getting harder to find the hydraulic setups but imo it’s still way better than the old z bar setup especially if the truck sees any Flex Time off-road

 

[Capt Ron]

Are the bellhousing bolts metric?

yes

 

[tarussell]

While I would no doubt prefer a hydraulic clutch setup I feel that I should point out that there is no need for the bolt boss in the block that the 1972 on down truck Z-bar mounting point needs.

Take a look at the bell housing bolt location for the 1973 to 1984 mechanical clutch pivot bar linkage on our square trucks.
In other words - that mounting boss location was moved to the side of the bell housing in 1973 so that’s not an issue for your setup.

 

[LuBlunt]

Thanks for the info! Tarussell you are correct. I had time to look over a couple of my squarebodys and sure enough the z bar is mounted to the bellhousing not the block. Not sure how I missed that lol. I also confirmed my 2001 8.1L does not have the threaded receptacle for clutch pivot ball. I would prefer hydraulic over mechanical clutch but funds are limited for this project. Anyone have the part number for the bell housing bolts?

 

[tarussell]

Thanks for the info! Tarussell you are correct. I had time to look over a couple of my squarebodys and sure enough the z bar is mounted to the bellhousing not the block. Not sure how I missed that lol. I also confirmed my 2001 8.1L does not have the threaded receptacle for clutch pivot ball. I would prefer hydraulic over mechanical clutch but funds are limited for this project. Anyone have the part number for the bell housing bolts?

There might be different dimensions on the thickness of the bell holes for your 79 application versus the Allison ( or 4L80E if it came from a Avalanche ) or a ZF bell - might be best to verify the depth of threads of each hole individually plus each bell hole dimension and get some high quality hardware at your favorite nut-n-bolt place.
Don’t go blindly trusting that the only difference is SAE v/s metric diameter on that hardware.