Hit a milestone last night. I have a 95ish% complete longblock ready to come off the stand! RTV'd the valve cover gaskets to the covers, installed the intake manifold with a set of Fel-Pro 1204's, installed the dipstick (a nice piece from Lokar) and put a few pipe plugs in holes that I know I will not be using when the engine goes in. Still waiting for a breather, grommets, and some other small stuff, but it is ready to go onto the floor dollies and get its flywheel, crank bolt, and to dial in the bellhousing.

I need to nickname this engine. L46.2? I'll work on that...

 

I would say L47, but apparently that’s a version of a Northstar engine

Looks great though!

 

I settled on calling it the "L355" since every L## combo I came up with referred to another GM engine of some vintage or configuration.

I bagged the engine up back in September once my daughter's soccer season ramped up and we got 2 new puppies right after Thanksgiving, so I've had no free time to finish it up.
New "garage helpers" Stella and Sullivan (Sully):







Swap day is coming in the next 6-8 weeks (hopefully), so its time to button the L355 up and prepare for the day Shadow's LFortyGreat goes into a temporary retirement. I found its future home just a couple hours away in Arlington. Project "Darby". "Dirty Rat Bastard -> D.R.B. -> "Darby". 1980 C10 Silverado trim with the square eye option. Going to be a "patina rod" cruiser & street truck.





Probably going to get iced out of work on Thursday and Friday, so I'm hoping to get the flywheel installed, the crank bolt torqued, the bellhousing dialed in (for the TKX), the starter on, and hook a guage up to a port and prime it.

 

I've done everything I can to it except prime it and put the inspection cover on. I'll need to trim out the center of the inspection cover to fit around the 1 piece RMS housing, but otherwise, it will bolt up. Starter is bolted up and shimmed. Took a thick and a medium shim to get the proper alignment. Starter is a new Powermaster high-torque OEM style I got for a song the last time I visited the scratch & dent section of Summit Racing in Arlington. I fit the flywheel and pilot bearing in and got the bellhousing dialed in last week. Didn't have to use any new alignment dowels. With a GM 621 bellhousing and the stock alignment pins, total runout came to .004". Tremec's states that runout has to be .005" or less for your warranty. Done. Easy mode. To free up a bit of space in the garage, I put the transmission into the bellhousing and bolted it up. Now Shadow gets to look at its new engine and trans for a month before it gets swapped in. It will have to come off again to install the clutch and pivot fork. I also put in a stainless steel shut-off valve for the heater hose circuit to fix the "hot feet" issue. I'm off the last week of March to throw wrenches and invent new cuss words swapping out the LFortyGreat and 4 speed for the L355 and TKX. Time to order some new plug wires, boots, and an air cleaner top!


.004" with stock/factory parts. That will do.




Stainless steel shut-off for the heater hose circuit.

1 month to go...

 

And the excitement builds!

 

Well, after lots of prep and planning, researching, and assembly, it was swap time! My buddy and I took off the last week of March to complete the engine and transmission swap, as well as touch-up and improve a few things. For the most part, the swap went off without a hitch. The old engine came out with very little fuss. We didn't even have to take off the hood, radiator, or loosen the core support. It came right up and out easy with the transmission and bellhousing removed first. I did hit a bit of a snag when I discovered the new 880 roller block wasn't drilled and tapped for the clutch z-bar stud. Simple enough to fix as the boss was still there. Drill hole, tap, clean, install stud. Done. While the old engine was out, I gave the engine bay a bit of a detailing. Cleaned and painted the frame rails, engine mount horns, and the steering relay rod. Also repainted the lower half of the firewall around the transmission tunnel. We put some heat shielding material on the A/C box to help the A/C work a little better. The #8 cylinder primary tube runs awfully close to it.

The TKX installation was very easy. Silver Sport Transmission's Perfect Fit Kit was exactly that: a perfect fit...nearly. The only snag we ran into was the exhaust setup. The new crossmember SST supplied with the kit was intended for a dual "one on each side of the transmission" exhaust setup, not the "duals on one side" Corvette Central setup that I had. There was interference between the top of the exhaust pipes and the extension on the transmission crossmember where the transmission mount bolts to. Instead of bashing and flattening out the exhaust pipes more (they are already flattened in this area from CC), we cut some small notches in the mount to provide clearance. So if anyone ever wonders if a Silver Sport Transmissions crossmember will work with with a Corvette Central "2 on the side" dual exhaust, the answer is YES! I retained the factory Z-Bar setup for my clutch and didn't convert, or more accurately, spend the money on a hydraulic setup. I have no complaints with the pedal effort and feel of the stock Z-bar linkage with the McLeod Super Street Pro clutch, so I decided to spend the money elsewhere.

After getting everything cleaned up, refreshed, refinished, and reinstalled, we fired the new engine for the first time. My machinist recommended to just "run it like you would a flat tappet cam engine". So we brought the idle up to around 2000 and varied it by few hundred rpm over the next 25ish minutes. When we were done, we were met with a healthy new idle, no smoke, and 40psi of oil pressure with a 225* oil temperature at idle. I took a S.W.A.G. at the clutch linkage setup and was on the money. The thinner, lighter weight flywheel means my clutch catch point is a bit closer to the floor than I normally like, but the throw-out bearing air gap is dead on the money. I'll just get used to it.

My Borg Warner Super T10 gearbox was a great transmission. But nothing, I mean NOTHING shifts like a Tremec! The nex TKX with the SST shifter is lightyears beyond the Super T10. The finishing touches to the project were putting in the new 5-speed plate in the center console, and doing a muffler change to let the new engine sound-off more at idle. I paid for 231* of intake duration @ .050" lift, and I want to HEAR those 231* of intake duration! Black Widow Race Venom mufflers with their "straight through w/ baffles on the side" and no packing design fit the bill perfectly.

Now, its on to an easy 500 mile break-in period with 10w-30 conventional VR1 in the crankcase and conventional Dex3/Merc ATF in the TKX. After 500 miles, change both fluids and give it hell!


"What have I got myself into?"

Going up!



I'll be dipped!

The LFortyGreat will live on. It will get a refresh, some L98/ZZ4 aluminum heads, and a roller cam conversion and go into a squarebody pickup.

A/C shielding

Cleaned up the lower firewall & transmission tunnel.

TKX in its new home.

Putting it back together.

Ready to run!

Ready to run!

The final touch...

New Black Widow with 2.5" tip on the left, old Flowmaster 44 with 2" tip on the right.

Done!

Buying 93 octane hits ya different when you HAVE to do it vs. when you do it just because you can!

 

Some video clips for your enjoyment:

Original L48 with a Summit 1065 Cam and the Flowmasters:

Comparison of the new 355 with the old Flowmasters vs. the new Black Widows:

Short Driving Clip:

 

Looks and sounds great! Should be a fun and reliable powertrain for many years to come.

Coming from the L48 and Borg Warner to the extra HP and overdrive how could you compare the two?

 

Your Vette looks awesome! Can you tell me what antenna you used? Sorry if it was already mentioned and I missed it.

 

Thank you!

I wish I could tell you, but I don't know. It was on the car when I bought it. I wish it still had its power antenna though.

 

Thanks for the response. My power antenna was replaced a couple of times, so I just thought I'd ask.
One more question. Do you have part numbers for the mufflers?

Thanks

 

Now that I CAN help you with! Black Widow Race Venom Mufflers BWOOR-22.

https://www.summitracing.com/parts/bwe-bwoor-22

Ignore Summit’s photo. It’s wrong. The Race Venoms are much shorter than what is pictured.

 

I'm late to the party. Very nice L31 build.
I have a question/suggestion about Your L31 oil galley plugs behind Cam sprocket.
I note you've replaced the OE cup plugs with threaded internal hex; I see them clearly in a pic.
Perhaps I've missed it, but I don't resolve a small hole in either of the two outboard plugs. If there, please disregard following.
FWIW, OE L31 has small OE air bleed holes (about 0.025") in both outboard OE cup plugs. Only outboard, Not center plug.
It's my understanding those holes aren't to aid chain lube; but are there to assist valvetrain via purging entrained air upon startup.