L31 350 installation questions

[Quikshft]

I received my crate from Jegs - $1899 and free shipping to my door, not a hitch in the transaction and I can recommend them.

I'm putting this in my '71 4WD with an SM465. Staying pretty low tech, no fuel injection and in fact I had a Rochester two barrel on my previous engine that I'm planning to stick with. I have a new flywheel, a melonized distributor gear, a Holley Might Mite electric fuel pump, etc.

Question - I had assumed since this is just a small block Chevy engine that I could put an early timing cover and balancer on it, and then use the original brackets for the alternator and power steering. The new plastic timing cover doesn't have a timing mark and I'd like to put a timing light on it if I want. I believe the balancer is 8 inches diameter, the older balancers are 7 inches? Not opposed to getting a 7 inch balancer if that's what it takes. What experience is out there???

[B. W.]

You can install a steel cover on your L31.

You SHOULD be able to run an early style crank damper so you can use a short water pump & original brackets but I have not done this. If you don't mind, keep us posted on what part # damper you use.

https://www.crankshaftcoalition.com/...er_replacement

[Jrainman]

I am no expert but when I installed my L31 crate engine my timing cover did have a mark as well as my Damper ,I used 8 inch timing tape on the Damper , and went to my local junk yard and pulled a serp setup off a 98 model chevy truck for $80.00

being you got the weighted flex plate for the one piece seal and the rear of the crank is externly balanced you are ok ,but when you change over to a 7 inch stlye damper ,I dont think it will effect the balance of the crank because the front of the crank is internly balance but will this effect your warrenty on your new GM L31.

[Ol Blue K20]

I believe you'll have to change to a newer intake manifold though.

[6T7 C10]

Congrats on the new engine. The L31 does have a timing mark molded into the timing chain cover. Granted it is not all that but it will get you close enough to fine tune later. There is adding timing tape to the balancer route too. Check the cover to see if it has an open whole on the bottom for a sensor. If it does you will need to plug it or a stock OEM cover without the hole is part #12562818 which is what I did.

Other than using an adapter I am not aware of a two barrel carb intake manifold for vortec specific heads. A nice 0-5000 rpm dual plane intake and a 500-600 cfm carb will make a nice combo.

I went this route a year ago and am well pleased. Holler if you run across any more questions.

[truckster]

On my L31 I used a Cloyes double roller chain, stamped metal timing cover with a bolt-on timing tab, and a stock 8 inch harmonic damper for a 72 SBC 350. Everything went together easily. I did use a piston stop to verify TDC on the timing tab..

[dfosh]

67C10 , How did you do heater hoses ? I have heard about a water bypass ,could you post some pics? Thanks

[6T7 C10]

Here is an engine shot. Yes a bypass is needed. In my case the heater core acts as the bypass. Even a looped hose would work or a couple 1/8" holes in the thermostat would work. You just do not want to plug up all the outlets in the intake manifold and totally stop circulation while the thermostat is closed.

[Quikshft]

Here is my Vortec intake with a two barrel adapter I made from flat aluminum plate.

Some good info so far, with closer inspection I do see a timing mark on the plastic Vortec timing cover. But, I really don't want to go with the serpentine set up - I like the spartan look of the original brackets and all I am running is a power steering pump and alternator and water pump of course.

According to the link B.W. posted it LOOKS like I could use a steel timing cover with the balancer that came with my engine if I make the crank sensor/reluctor wheel into a spacer. I guess the question then is whether the drive pulley will then set in proper plane/position to meet up with all the accessories that are to be driven.

[Quikshft]

Originally Posted by truckster

On my L31 I used a Cloyes double roller chain, stamped metal timing cover with a bolt-on timing tab, and a stock 8 inch harmonic damper for a 72 SBC 350. Everything went together easily. I did use a piston stop to verify TDC on the timing tab..

Truckster did you run original accessory brackets with this set up??

[davischevy]

It will be a minor deal once you get to it, but the exhaust manifolds dump at a different angle. The down pipes will have to be redone.

[Mr_Rich]

Nice! Wouldn't you want to keep the heavy 8" balancer with a heavy flywheel on the back end of the engine? When you mentioned you were thinking about a 7" balancer I went looking in my spare parts. I have a timing tab that I used on an engine with a 6" balancer and it might work on a 7", but it would be close. I'm mentioning the part in case there's a need.

[Quikshft]

Originally Posted by Mr_Rich

Nice! Wouldn't you want to keep the heavy 8" balancer with a heavy flywheel on the back end of the engine? When you mentioned you were thinking about a 7" balancer I went looking in my spare parts. I have a timing tab that I used on an engine with a 6" balancer and it might work on a 7", but it would be close. I'm mentioning the part in case there's a need.

Yes, ideally there's a way to make the balancer I have work with a steel timing cover. I think I'm just going to have to get the engine on my stand and see if I can't add the parts to see what is actually going to be required.

[Quikshft]

Originally Posted by davischevy

It will be a minor deal once you get to it, but the exhaust manifolds dump at a different angle. The down pipes will have to be redone.

One additional detail is a set of headers I've got, not running manifolds.

[Mr_Rich]

Originally Posted by Quikshft

Yes, ideally there's a way to make the balancer I have work with a steel timing cover. I think I'm just going to have to get the engine on my stand and see if I can't add the parts to see what is actually going to be required.

This was my truck project 5-6 years ago. I had the timing cover for a long time because I was storing this engine in my garage when I had time for my project. I was able to order the timing tab at the dealer during the project. I don't remember the part number unfortunately. There really isn't much physical difference between these engines except for the Vortec heads. My engine was early '90's TBI 350.

[truckster]

Originally Posted by Quikshft

Truckster did you run original accessory brackets with this set up??

I'm using a serpentine setup, but the difference is in the crank pulley, not the balancer. If you want to use a 72 balancer you need to remove the reluctor.

[Jrainman]

Also I wanted to add while researching the same conversion as you are looking to do. I found my L31 crate engine timing cover had 2 less holes then the old style metal timing cover, so it would have required to drill and tap .. and also I just wanted to add that they do sell a vortec plastic timing cover with out the sensor hole P/N 12562818 this cover was used on the zz4 engine if I remember rite .

[truckster]

Originally Posted by Jrainman

Also I wanted to add while researching the same conversion as you are looking to do. I found my L31 crate engine timing cover had 2 less holes then the old style metal timing cover, so it would have required to drill and tap .. and also I just wanted to add that they do sell a vortec plastic timing cover with out the sensor hole P/N 12562818 this cover was used on the zz4 engine if I remember rite .

Those two holes aren't drilled and tapped on the old blocks; they have locating pins. If you look the other (bolt) holes are evenly spaced. You don't need to worry about the timing cover gasket leaking without the pins.

[bhayes1]

Congrats on the new power plant Jeff. Keep us posted on parts and end results - as I am sure there are quite a few of us still wanting to do this to our trucks when time and money allow.

Merry Christmas

-Bryce

[dell72]

I have converted several L 31 350's to a steel front cover. I drilled and tapped the two missing timing cover holes and installed the dowel pins (pioneer brand) to locate the tin timing cover. I also used an older style balancer to get rid of the reluctor wheel.

[Quikshft]

Originally Posted by bhayes1

Congrats on the new power plant Jeff. Keep us posted on parts and end results - as I am sure there are quite a few of us still wanting to do this to our trucks when time and money allow.

Merry Christmas

-Bryce

Hi Bryce - And merry Christmas to you and your family as well.

Yes the plan is coming together, tomorrow looks like a trip to Fresno to one of the self help wrecking yards, going to grab a few things I'm missing like a dip stick tube and not least, a metal timing cover. Since it seems the front of the engine is "just" a small block Chevy I'm going to add back the same kind of pieces that came off my original block. Will take a vice grip to the yard with me so I can pull the timing cover locater pins. I suspect I will need to purchase a new harmonic balancer, but the trouble saved in lining up all the drive pulleys will be substantial. Could have gone with the serpentine system but I just like the old school look of multiple belts.

As I add back parts I'll keep everyone up to date on how things work out, that's the value of a good message board like this - you don't have to trial and error everything. I found a great thread on wiring up the electric fuel pump that is needed when converting to L31. I'll get this done right the first time with a relay and oil pressure safety switch.

Thanks to all who have offered insight here. Christmas is close, God bless.

[tdangle]

I like the idea of a oil pressure safety switch in line with the fuel pump. How are you going to tie this in assuming you have the mechanical oil pressure gauge?

Also did you already get rid of your original engine. Otherwise could you have used the timing chain cover and harmonic balancer from the old engine?

[truckster]

Originally Posted by tdangle

Also did you already get rid of your original engine. Otherwise could you have used the timing chain cover and harmonic balancer from the old engine?

I don't recommend reusing a harmonic balancer unless it's very recently been replaced. They are a wear item, and after many thousands of miles the rubber in them breaks down.

[weim55]

Bolt your headers to the engine and check clearance for spark plugs-plug wires. L31 spark plug location is slightly different and mighty close to a couple tubes. I modified a couple tubes on mine for proper clearance.
You will also need an adapter for different size hole if you are running a factory temp gauge-sender in the cylinder head.

Steve weim55 Colorado

[Quikshft]

Originally Posted by tdangle

I like the idea of a oil pressure safety switch in line with the fuel pump. How are you going to tie this in assuming you have the mechanical oil pressure gauge?

Also did you already get rid of your original engine. Otherwise could you have used the timing chain cover and harmonic balancer from the old engine?

There is a plug in the side of the block just above the oil filter. Planning to put the safety switch there.

Yes, my old engine already went away to a new home in a '72 4x4.