L31 compatibility question

[tdangle]

I starting to gather the parts I will need for a swap from a Gen 1 350 to an L31. Does anyone know if a short water pump will work with the newer engine. I'm concerned with the pulley alignment. I would like to just plug the sensor in the L31 timing cover and keep the new harmonic balancer it comes with. Not sure if things will line up.

thanks in advance

Terry

[sweetk30]

the guys here popped a link in my L31 question thread for a 20.00 buck plug with bolt for the crank sensor .

i have a 88-95 style serp belt water pump on my L31 and no problems .

you do need to run a bypass hose from the water pump to the intake below the t-stat or near it . the hose will make it look like a bbc setup was with the bypass hose . as the L31 don't have the internal bypass port for cooling like a old gen 1 engine . also some say tap the bypass hole on the water pump and install the pipe thread plug just in-case your pump don't seal to the block face is all .

and the L31 takes a 1 piece rear style flexplate / flywheel so your old gen 1 2 piece rear wont fit up to the crank .

no mech fuel pump option at all so electric or efi with pump is only option .

my cooling thread figuring this info out . http://67-72chevytrucks.com/vboard/s...light=L31+plug

crank sensor plug . https://www.eficonnection.com/home/p...illet-aluminum

otherwise drop it in and have fun .

[garyd1961]

All your brackets off your old motor should work. I used the brackets off a newer model with the alternator on the passenger side.

[95 S_Trucker]

The L31 is also a gen 1 engine. 90-95 brackets will bolt on and work just fine(88-89 will work too, but the 90-95 are more popular). Buy a water pump for a 90-95. It will have a pipe plug in it. You can thread in a nipple for your bypass hose.

[Captainfab]

GM states that a short water pump will not bolt up with the stock plastic timing cover. I have checked and a stock short water pump as well as an Edelbrock aluminum short water pump will bolt up. But they are right up against the timing cover. You could likely grind down the bolt heads on the back cover a little for some clearance.

All of your original accessory brackets should bolt right up.

Also make sure you install a melonized drive gear onto your distributor.

[tdangle]

Originally Posted by Captainfab

GM states that a short water pump will not bolt up with the stock plastic timing cover. I have checked and a stock short water pump as well as an Edelbrock aluminum short water pump will bolt up. But they are right up against the timing cover. You could likely grind down the bolt heads on the back cover a little for some clearance.

All of your original accessory brackets should bolt right up.

Also make sure you install a melonized drive gear onto your distributor.

Perfect, that's what I was looking for. Trying to minimize the down time between removing my old engine and installing the new one.