L31 350 installation questions

[Quikshft]

Originally Posted by 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

My old engine actually had Vortec heads on it. Yes a couple of the plugs were real close but they worked ok.

The water neck on the intake actually has a tap I screwed the original temp sender into. Seems to work ok.

[Quikshft]

Well progress has been slow, been hammered with a chest cold since last Saturday and am just now feeling better. Here's what I've got on the front of my L31 now, I got a metal timing cover from the wrecking yard and ordered a water pump for my specific '71 application. I bought a harmonic balancer for a '71 350 as well but when I got it home and started measuring it appeared that if I used the reluctor wheel as a washer, the face of the balancer would press onto the crank and end up in about the same position the 'old' style balancer would. So, the picture shows the metal timing cover, ''71 water pump and the harmonic balancer that I received with the L31 crate. The crank pulleys and water pump pulley line up pretty much perfectly. I'm going to return the balancer that I bought and move ahead with this combo. Have to believe that the power steering and alternator brackets are going to install back onto the new block just as they worked on the original '71 block.

[dfosh]

Did you have to drill timing cover bolt holes or holes for alignment pins? Also what seal did you use for the seal on bottom of timing cover ? Keep us updated with what ever you did to make it work. thanks

[Quikshft]

Originally Posted by dfosh

Did you have to drill timing cover bolt holes or holes for alignment pins? Also what seal did you use for the seal on bottom of timing cover ? Keep us updated with what ever you did to make it work. thanks

All the holes for the metal timing cover were drilled and tapped in my block, and the holes for the dowel pin locaters also were drilled. Further, my block was also drilled/tapped for a mechanical clutch linkage/cross shaft ball stud. I don't think this is the typical experience concerning these items but I'm taking it.

[truckster]

Originally Posted by Quikshft

I bought a harmonic balancer for a '71 350 as well but when I got it home and started measuring it appeared that if I used the reluctor wheel as a washer, the face of the balancer would press onto the crank and end up in about the same position the 'old' style balancer would.

That's correct; the new-style balancer shipped with your crate motor has a shorter snout so it will fit in the same position with the reluctor in place as an older one will with the reluctor removed.

[Quikshft]

Originally Posted by truckster

That's correct; the new-style balancer shipped with your crate motor has a shorter snout so it will fit in the same position with the reluctor in place as an older one will with the reluctor removed.

Here's a pic to illustrate:

[rotten67]

Did you find out what the correct type of distributor gear is needed? I keep finding different answers for that.

[Quikshft]

Originally Posted by rotten67

Did you find out what the correct type of distributor gear is needed? I keep finding different answers for that.

I got a melonized gear for the HEI that I'm running. Didn't really find much that I can recall which was controversial on this subject, the material of which the roller camshaft in the L31 crate is made differs from the standard distributor drive gear and it will wear prematurely.

[dfosh]

How did you modify the reluctor for the metal timing cover to fit ?Anymore details ? Thanks

[Quikshft]

Originally Posted by dfosh

How did you modify the reluctor for the metal timing cover to fit ?Anymore details ? Thanks

I cut the outer portion away and used the inside like a washer. This seems to position the balancer that came with the crate end up in position to reuse the original pulleys and mounts for accessory drives - alternator, power steering pump.

[D.PASSMORE]

Originally Posted by Quikshft

I cut the outer portion away and used the inside like a washer. This seems to position the balancer that came with the crate end up in position to reuse the original pulleys and mounts for accessory drives - alternator, power steering pump.

Would you have anymore pictures of what your detailing above? I'm just about to start this same install, using my 1970 accessory brackets. Thanks

[D.PASSMORE]

Originally Posted by Quikshft

I cut the outer portion away and used the inside like a washer. This seems to position the balancer that came with the crate end up in position to reuse the original pulleys and mounts for accessory drives - alternator, power steering pump.

Would you have anymore pictures of what your detailing above? I'm just about to start this same install, using my 1970 accessory brackets. Thanks

[Quikshft]

I did not get pictures of my modified reluctor wheel. Here's a shot of one I grabbed off the net, I simply cut away the outer part of the wheel leaving the flat portion in the center. Pretty simple modification. Then if you look a couple posts above you can see a comparison of a harmonic balancer for the L31 application and for the stock 71 model year application. The reluctor wheel "washer" will make the two of them equal in height so when you install your original crank pulley it ends up in the original position line up with your driven accessories. You can use a metal timing cover like I did, you don't need the L31 plastic unit that fits over the reluctor wheel because its not there any longer. The plastic unit probably has a hole for the sensor anyhow, that would need to be plugged up at minimum.

[D.PASSMORE]

Did your the reluctor wheel come with the motor? I haven't uncrated mine yet.

[Quikshft]

Originally Posted by D.PASSMORE

Did your the reluctor wheel come with the motor? I haven't uncrated mine yet.

Yes it is already installed. Just pull the balancer and timing cover and you can retrieve it.

I think these are the timing cover options - there is actually a plastic cover available without the sensor hole in it. Then of course you can use the one that came with the crate and plug the hole. Or, you can use a metal timing cover which works fine once the reluctor wheel is cut down.

Since I used a metal cover from another engine I verified the balancer timing mark was at Zero on the timing tab at top dead center, something else to watch for so that you can time your engine accurately.

[jocko]

Quikshift, this is a very helpful thread, thanks for sharing what you're learning as you go. Quik question for you - is this the L31 or L31R engine?

[D.PASSMORE]

Originally Posted by jocko

quikshift, this is a very helpful thread, thanks for sharing what you're learning as you go.

x2

[toolboxchev]

Good thread. Maybe we could ask admin to make it a sticky in Engines and Drive train.


Thinking of the same route myself.

What I would really like to see is someone doing a 4 barrel carb setup with Auto Trans. I am wondering if I can reuse my stock Trans kick down bracket on a Vortec Manifold???

Anyone done this? Would be nice for the pics...

[dfosh]

I have an L31 in a 51 Chevy truck but I didn't change timing cover .I had to change out some of the stock timing cover bolts to get a stock short pump to work. I had a Tuff stuff chrome pump that still would not fit,that is why the stock pump.I have a Holley carb and three fifty trans that work and I used Locar throttle cable and hooked the trans as with any other sbc .I did have a cooling problem . The temp would go up and down as I drove . I had to use a water bypass to get this to stop . all the things about holes in thermostat and heater as a bypass did not work I had to run a hose from intake to the top of water pump. There was a good write up on one of the Camaro sites about this. I am changing to steel cover for this l31to use in a 68 GMC .Be careful as you remove the stock plastic cover so as not to damage the cover to oil pan gasket. Sorry but I can not post pic.

[Quikshft]

Originally Posted by jocko

Quikshift, this is a very helpful thread, thanks for sharing what you're learning as you go. Quik question for you - is this the L31 or L31R engine?

I did opt for the L31-R.

[jocko]

Originally Posted by Quikshft

I did opt for the L31-R.

Good call! I was just wondering. Kinda wondered if perhaps there was a difference between the two regarding whether or not the holes were all drilled and tapped for the timing cover. Seems like I've heard some folks say theirs weren't, so trying to see if there's any logic to whether they were or not. If I do this, it will also be the R version. Yet, for some reason, my search continues for a nearby 72 vintage 350 that hasn't been bored a few too many times.

[toolboxchev]

Originally Posted by jocko

Good call! I was just wondering. Kinda wondered if perhaps there was a difference between the two regarding whether or not the holes were all drilled and tapped for the timing cover. Seems like I've heard some folks say theirs weren't, so trying to see if there's any logic to whether they were or not. If I do this, it will also be the R version. Yet, for some reason, my search continues for a nearby 72 vintage 350 that hasn't been bored a few too many times.

Flat tops on your mind with a perfect .040 quench maybe. My Chevy friends like my old .010 over on the pistons better than the L31R.

Maybe its the 3 or 4 hundred and 80 thousand miles on a high nickel block.