I've been SLOWLY (lol) working on my 1973 for the last 15 years or so. I finally have a rebuilt chassis and I finally tore down the L48 engine. I brought the block to my local machine shop. They've gone as far as cleaning it up and magnafluxing it. All checked out. But he said the crank would need grinding and it's not worth doing that. He's pushing for a 383 conversion. His argument is if you're going to buy a new crank, why not get the extra ci? That wasn't in my original plans, but I'm not totally against it. I was just planning on a top end update to "wake it up" and delete the emissions stuff.

I know the conventional wisdom is to put the original engine aside and drop a crate engine in, but the goal has never been about the end car, but more about the experience building it. Here are my real goals of the project in order of importance:

1. Work with my kids on the car
2. Learn to tear down and build the engine
3. End with a "fun" street car, but nothing crazy in terms of HP
4. Be able to say it's still the original drive train even though I know that's not that big a deal with a L48 car

With those things in mind, would you lean into the 383 build? Or do something else? If you were to go towards an 383, any opinions on part selection?

 

Thutch,

Not sure I am buying the story about the crank can't be saved. Unless it has hairline cracks?
Cranks get turned undersize all the time. It's just a matter of using matching bearings.

Not sure about your population in your area, but there should be several used 350 cranks around.
Even FaceBook Market has cranks, blocks, heads on their web site once a month. Often less than 100 miles from my home.
I would keep looking.

 

I think this is what bothers me most. From the first meeting, he was talking 383 and that was never my goal. Seems like that's the only avenue he thinks is right. I have a hard time believe the crank is that bad as the block looked great. The cylinders don't have a scratch I can find. My only question was if the head surfaces were flat enough. The car had 93K miles on it, but it really seems like it wasn't driven hard.

 

Just like the doctor that wants to remove your heart, replace it for a bigger one:
I want a second opinion.

Any other shops in the area? The heads can be cleaned-up milled easy enough.
However, that easy task turns into a valve job, new spring$, seal$, sometimes guide$ and so on.

The purist / all original people say, ok, go for it.
The modifiers say, time for better heads.

Just for your peace of mind, perhaps glance over the BluePrint Engines web site.
You can get a rough idea what's involved and then figure out how to receive shipment.

 

I'm not really interested in a crate engine as it's about the experience for me, not the cheapest/easiest path. I do want to likely do different heads and cam. I think that's the only way to wake it up a bit. I don't think I can get too much more out of the stock heads. I'd like to just put those aside.

And yes, I'm looking for other shop options. My son works for a racing focused BMW shop and this was the one they use. I think they're good, but he seems to have a one track mind on approach. I'm sure I could push him to do something different, but I need good advice from the shop and if they're singularly focused, I don't feel like I'm getting the advice I need.

 

I think you need to backtrack and ask the machine shop: What Exactly Is the Issue with the Crank?
Then, regroup and go from there.

If it is cracked or journals cannot be safely turned any smaller, then its toast, look for another.

 

I am with you on the build it yourself thing. I pulled my L81 and put it on a stand. Had them bore and stroke a 4 bolt main block I found to a 383. Put some generic aluminum 64cc heads on it and put it together with my son in law. Nothing more satisfying ( also nerve racking) then starting that engine for the first time and hearing it run. The L81 is sitting on a stand complete in case I ever want to put it back in, which I won't That 383 is awfully fun! But this is in my 1981 that had CCC and more emissions crap than I wanted. Not exactly a sought after car, so I was fine with the upgrade.

 

Yes you can rebuild it on the cheap. And yes a performance oriented shop is always going to lean toward more performance, so you are absolutely correct to get a second opinion.

But. If your crank even just needs turned, and the block will need bored due to the miles, and the rods always need reconditioned.....

At that point you are only a couple dollars away from a stroker 383. And let me tell you, even in mild form, that extra TQ really wakes up the car!
It might seem like only 33 extra cu inches, but at 1500 rpm, just off idle, they can be 50-70-80 #s TQ stronger than a 350.
More TQ and at a lower rpm.
No more waiting a few hundred rpm for the TQ to build, it is just there, right now, all the time. Fun, fun.
You should drive one sometime. You have to drive one to believe the difference.

Many shops never recon rods anymore, it is a $ wash to just buy new better ones. Same with pistons, no one knurls old pistons to try and reuse. Heads, for just a few hundred extra over rebuilding the old ones, you get modern new ones, in AL, with modern fast flow swirl chambers, and 50 year newer port flow designs. Instant 50-70HP for a few hundred bucks. It is your best bang for the buck in engine building. Stroking the crank is a very close second, maybe even tied.

You will have to talk a performance shop into a mild cam. But even a mild cam 383, with modern heads, will annihilate the tires and that old L48 350.

 

A replacement cast 350 crank is about $200 brand new.
definitely not a forcing function to suddenly clearance the block and make it a 383.
sounds like the machine shop did a few 383’s and thinks they are the bees knees.

I fully agree with you, crate engines are boring, much more fun to build it yourself.

 

383 stroker kits from 1050.00 to 1600.00 , crank , bearings , rods , piston with pin , rings and balanced is hard to beat , modern stroker kits don't need all the machining like ten years ago

 

I have to agree with the machine shop. Once the crank needs turning (very possible) and you need a rebore....it makes it a perfect opportunity to go 383. Almost the same cost either way. The economics just work. You can buy a complete balanced rotating assembly. The shop can bore and clearance the block. If you work the numbers out, you will see what he is talking about. I just built one myself. Just examine the cost to turn the crank vs a brand new stroker crank = close to a wash. Pistons need to be new either way so nothing there. Rods can be reused but replacing the bolts and resizing costs as much as a new set so nobody does that.

bottom line - if you can not save the original bores because it's worn too much to just hone it, then replace the rotating assembly and the stroker is the way to go.

 

I ran a couple options for you thru Desktop Dyno to give you an idea of the power curves

Curve 1 - Stock1973 L48, as close as I could mimic it. Iron manifolds.
Curve 2: Rebuilt 355. Changes AFR 180 heads, 9.5 CR, Comp XR264 HR cam Iron Manifolds. Way more TQ but only from 3500 up. HP up significantly higher, 260 to 345 HP.. AFRs and a HR really help the power. 9.5 CR might still be OK on 87 octane pump gas. Could push to 10.5 CR if you want to run premium. 212/218*@ .050" HR cam. Nice mild & TQy street cam.
Curve 3: 383 same as above. Iron Manifolds. TQ @ 2000-2500 jumps 40-50# TQ. But HP not really up much. But look at the TQ jump.
Curve 4: 383 same as above with headers. TQ @ 2000-2500 jumps even more now 100# more than L48. Approaches 480# at 2500-3000.

383s like to breathe. This is still a kinda small street cam 212*/218* @.050. Going up one step on the 383 only to a XR270, 218/224*, gains 35HP up top, with virtually no TQ drop down low. That is a win-win. That would be around 435 HP @ 5500, and 480# TQ @ 2500. On 87 Octane regular pump gas no less.

Hopefully you can "see" the TQ difference at 2000-3000. That is where you drive it. You drive TQ not HP.
But the HP difference is also incredible when you floor it. From 260 to 435HP. You use HP when you race it.
With a 383 it will not feel like the same engine at either end of the power scale.
With a 355, it will feel better mostly when you rev it. It will be a lot stronger past 3000. But not too much change below that.

This program is not exact, it might be within 10 or 20 HP/TQ, but it sure makes it easy to compare engine combinations!

And if version 4/5 cost almost the same money????Why not?

 

Sounds like the machine shop is just stumping for more money. If you don't need more power than your 350 can provide, why spend big buck$ to make it into a 383. Put a decent cam and good aluminum heads and intake on the block and call it good.

 

To me the 383 is a no-brainer. Almost free TQ.

To me the Hydraulic Roller cam upgrade is a big decision.
~$1000 more vs more TQ & HP, vs much less likelihood of cam/lifter issues on a rebuild.

 

agree

 

Thutch,

As you can see its easy for others to spend someone elses money.
Expensive roller cam over $1100.
Big heads, carb, headers and on & on. You never asked what cam you should get or what heads. Or how to make 400 horse.

Going back to your original post, I think several people missed the point.
Here is what is very-very important to you:

#1. Will be a kids project, building it together at home.
#2. A learning experience for kids.
#3. Fun street car
#4. Still labeled (somewhat) original.

I think you already answered your quest of what to do.

 

Nothing beats cubic inches. Except still having some gas money, when your done.

The best bang for your buck, is probably still a pair of Vortec heads and a camshaft.

Find a good machine shop. Or buy a reman crankshaft at the parts store. While your there, grab a cheap engine stand... Then you can add number 5 to your list.
5.) That time me and my kid fixed up the original engine.

Eric

 

As mentioned...it depends on what it needs. If it needs bored and new pistons...and crank needs turned...I'd go 383 all day. If it's just a quicky rebuild with new rings and bearings and maybe a turned crank...then leave it a 350. It's the boring and pistons that change the game. Just the added cost of pressing your old pistons off and new ones on the old rods...will just about pay for half of a set of rods with floating pins so you can assemble them yourself.

I have a 383 in my '32 Ford coupe with old Twisted Wege heads and a 270H hydraulic flat tappet cam and an RPM performer intake. It uses a stock torque converter. The off idle and throttle response is fantastic, and it pulls hard to 6000+ RPM. It also gets over 20 MPG with the 4L60 O/D trans and FI Tech EFI.

JIM

 

I like that cam a lot for a fun street ride!
270* advertised duration, 224* @ .050, 110 LC.
Great overall street cam, kind of like an L46/L82 cam, but with modern improvements and quicker ramps.
Just a step bigger than a 268H.
Should run terrific as long as you have some compression.
Might be a little soggy and not so ideal if a guy only has 8:1 or 9:1 CR. Much crisper on a 10:1 motor.

If you build a lower CR L48, it would be crisper with a step smaller cam.
Do not make the mistake the very common mistake of going too big on cam duration.
Have fun building it your way!

 

A new stroker crank, new heads, and a roller cam are no brainer choices when you look at the cost of rebuilding the old junk stuff.

No one I know would touch a flat tappet cam in a new engine now days.

stroker crank $225
rods $300
pistons $250
cam/lifter $1100
heads $1100-$1500

why crate engines are popular.