Attn: TBI Gurus

[JCampbell]

After some consideration, I’ve decided to swap a TBI 5.7 into Shorty™. What do you guys recommend for building a daily driven 5.7? I commute 60 miles/day, so I’m not so much looking for big power as much as reliability and fuel economy.

The truck currently has a 700R4 and 3.08’s w/ 28” tires (275/60/15).

[GM-power]

Are you looking at a tbi motor, or wanting to completely build one block up?
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[JCampbell]

I'd rather just rebuild an existing "junkyard" TBI engine. Trying to keep costs to a practical minimum.

[Skunksmash]

In my personal experience, stacking up two throttle body spacers yields great results. Me and a buddy did one on his TBI truck and saw some mild improvements. Then at the advice of some old man where he works, we installed another one (for a total of 2.5") and he saw even further improvements. Long story short, TBI's love a higher throttle body. Get it up there a couple inches somehow.

[rfmaster]

JB

I had a few 'stray' JY dogs pass through my garage over the years. For a ultra low buck rebuild I would look for 90's and up short block (350) with 1 piece RMS. When local pull your part (50% off) have a sale they can be had for $100 (less heads)! Most of these blocks were cast with slightly higher nickel content and show virtually no bore ridge (EFI also keeps oil dilution to a minimum). After measuring bore taper and if found within spec, couple of passes with a bore hone tool will get cylinder into shape. With a set of new rings existing pistons can be used again. Same can not be said for main and con rod bearing - if the engine had regular oil changes crank may only need a polish job and with new 0.001 or 0.002 bearings can be put in. It is not a preferred way, but for a very tight budget it will have to do. Alternately, if crank bearing surface shows damage it will have to be turned down to next bearing size (0.010, 0.020, etc) A new 224-4146 pump (M55), pickup tube and HD oil pump shaft completes bottom end. Keep in mind that stock rod bolts are the weakest link. Do not go over 5000 RPM with stock rod bolts - they stretch and resulting spun rod bearings ruins the day (and your engine).
Heads will need a little bit of work - expect to replace stock valve springs, keepers, seals. This is based on the assumption that engine was never overheated. Before investing any money into existing head cores have them magnafluxed for cracks ~90 per pair. Valves may be salvaged and re-used to keep cost down, however exhaust valves take a beating and better be replaced. Expect to spend money on heads. Replace head bolts - they are inexpensive Elgin EHC99S.
For flat tappet cam CS1014r is hard to beat - price and performance wise. Expect to add ZDDP additive to your oil during break-in and follow the cam break-in procedure religiously!
If you get lucky and have a block with a roller cam this will open up whole bunch of possibilities, but do not go crazy with lift and duration.
A double roller timing chain will keep things nice a tight. A complete engine gasket kit KS2666, and another often forgotten item is a block plug kit ~$15 for brass plugs should round things up. Plenty towels, brake-cleen and a well lit garage. Beer helps, but not required.

//RF

[y5mgisi]

If your doing all the work anyway, why not go to a LS motor? A 5.3 out shines a TBI 350 in every way. More hp, tq, and mpg.

[JCampbell]

Thanks, RF. As far as roller cams go, I thought TBI never came factory w/ a roller?

[JCampbell]

Originally Posted by y5mgisi

If your doing all the work anyway, why not go to a LS motor? A 5.3 out shines a TBI 350 in every way. More hp, tq, and mpg.

I was wondering how long it would take for someone to bring up the “LS” engines.

I’ve looked at the pros and cons for both and have decided to go with TBI for this application.

[rfmaster]

Originally Posted by JCampbell

Thanks, RF. As far as roller cams go, I thought TBI never came factory w/ a roller?

The LO3 and LO5 (305 and 350) TBI were available with roller cam blocks. The LO3 roller were used in mass in third gen Camaros and roller LO5 were used in B-body cars (Caprice, Roadmasters and rear drive Cady's) between 87 and 93. In 94 cast iron headed version of LT1 made its appearance in the B-body car line.

In 96 a special RPO had TBI available in a handful of utility vans on top of L31 (vortec) engine. These are very rare, and from what I understand were sold as fleet vehicles.

When looking for a suitable JY core I try to locate L31 (96 to 00) - these have the best blocks (higher Ni content) 880, all provisions for OE roller cam and have powder forged connecting rods which are stronger by far than any OE rod. Original Vortec heads (906, 062) are notorious for cracking between the two adjacent exhaust ports - I tossed two set into a metal recycle bin (along with $$$) few years back. So I get just the short block and install earlier 64-68cc chamber heads for quick build. Vortec uses slightly dished pistons to keep compression around 9.5:1 with vortec style combustion chamber (which is excellent!). My only gripe about vortec is that OE castings are prone to cracking when engine is overheated.

//RF

[y5mgisi]

Fair enough. Before I got bit by the ls bug I liked tbi stuff too! I still like it actually, just every time I fantasize about putting one in something I quickly talk myself into an ls fantasy...

About the l31 stuff, I wish I could remember it, but there was a company making basically the l31 heads but with improved castings and for a good price. Another company, (might have even been the same company) was making vortec heads that looked just like old heads! So they had the original style intake pattern and perimeter style valve covers! I REALLY want to rebuild a l31 short block and stick those retro/vortec heads on it! Would be a sweet, durable, and daily cheap motor! Anyway, Cary on.
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[rfmaster]

Originally Posted by y5mgisi

Fair enough. Before I got bit by the ls bug I liked tbi stuff too! I still like it actually, just every time I fantasize about putting one in something I quickly talk myself into an ls fantasy...

About the l31 stuff, I wish I could remember it, but there was a company making basically the l31 heads but with improved castings and for a good price. Another company, (might have even been the same company) was making vortec heads that looked just like old heads! So they had the original style intake pattern and perimeter style valve covers! I REALLY want to rebuild a l31 short block and stick those retro/vortec heads on it! Would be a sweet, durable, and daily cheap motor! Anyway, Cary on.
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Definitive Vortec thread

http://www.nastyz28.com/forum/showthread.php?t=56505

[JCampbell]

I'm just really not looking to reinvent the wheel and do a bunch of retrofitting on this truck. A TBI engine (as you know) would be more or less a bolt in affair.

Simplicity is the name of the game on this one.

[JCampbell]

So RF, you're saying get a "Vortec" long block and top it with TBI heads/intake/etc?

How will that fly with the Eco-Nazis out here? Afterall, I'm still going to have to make an appointment w/ the Ref after it's all said and done.

[rfmaster]

Originally Posted by JCampbell

So RF, you're saying get a "Vortec" long block and top it with TBI heads/intake/etc?

How will that fly with the Eco-Nazis out here? Afterall, I'm still going to have to make an appointment w/ the Ref after it's all said and done.

JC - I must have been too fast on the keyboard. No it is not going to fly with Eco-Nazis. Why? The lack of exhaust cross-over port in Vortec heads will render conventional TBI intake EGR valve non-functioning even if you are able to bolt-on vortec heads. L31 engine uses a special exhaust tube to get exhaust gases to EGR valve. Furthermore vortec manifold uses 8 bolts vs conventional 12 to keep intake manifold in place - different flange angle and intake gasket all together. And this is where the problem lies - visual inspection failure. So, I am with you JC - for us, unfortunately, we have to stay away from L31 heads.

To keep it simple, I would just get the L31 short block (minus heads) and bolt on older swirl port heads 14102193 to L31 short block. Before hand I would go through some number crunching making sure that resulting compression is in check between 8.8 and 9.1:1 to burn our pucky gas. From my swap notes I see that the '193 head has 65.3cc combustion chamber while vortec 12258062 is between 64 to 68 cc - basically the same.

A side note. Last year me my friend were 'hunting' for a roller 350 block for 383 build at a local pick JY. We came across 94 burban with one head removed. It turned out that short block was replaced once in its life with a service '880 block (which was used in production L31) with 2000 production date. Engine was equipped with flat tappet lifters, but all mounting bosses were drilled and tapped for lifter retention spider. Heads were aforementioned swirl port heads. Pistons and rods were production L31 pieces. So it should work.

//RF

[JCampbell]

So, pick up roller cam-equipped short block from like a 96+ Vortec truck, but use the "TBI" top-end?

Hmm. That's one way to retrofit a roller.

[rfmaster]

Originally Posted by JCampbell

So, pick up roller cam-equipped short block from like a 96+ Vortec truck, but use the "TBI" top-end?

Hmm. That's one way to retrofit a roller.

JC
Look for a Camaro LT1 cam, there are minor variations from year to year, but these are known for excellent performance with TBI (and cheap). Minor mod to a dowel pin is required.
Specs below
Duration: 203/207@.050,
Lift (I/E): .447/.459
LSA: 117deg

The LT1 cam offers power band from idle to 5500 RPM redline. The swirl heads could use intake side porting to improve flow (14102191 or 193 castings). Due to higher cam lift (assuming 1.5:1 rocker) all new springs+hardware will be required. In untouched form intake port flow stalls and cuts off around 4500 RPM. This flow constraint is inconsistent with the performance available from the LT-1 cam. So the swirl heads can be ported (swirl ramp shaped and intake port cleaned-up) or alternatively older cast iron L98 type head casting number 10125377 is another choice as they bolt on and accept TBI intake with no modifications. This cylinder head has 64cc chambers so that decent CR is maintained. Since these are Gen 1 pieces they should pass the visual and have exhaust cross over for EGR. The LT1 cam mods will shift torque band higher in RPM which may result in lost torque below 2000 RPM. If you want to keep low RPM torque I would find stock vortec roller cam.

Again - camshaft choices are many, it all depends on budget. Do a bit of research.

//RF

[BigBlocksRule]

As many vortec heads as I've removed, handled and checked, I've only had two that were cracked. Both off of the same waaay overheated block. There are TONS of 'em out there with no problems, keep 'em cool and they'll survive just like other thin wall castings. TBI heads make more torque on the bottom end, but Vortecs pass 'em at around 3000 - 3500rpms. However, they'll cost more to install since you'll either need the specific TBI-Vortec intake or a handful of adapters.
I built a 350 and my son built a 383 a couple of years ago. I used stock castings with bowls blended and short turns smoothed. My son used Pro Topline (now RHS) heads, both with an LT4 cam. I really like the RHS heads, they're a good bit thicker than stock and probably flow better. Both of these builds met our expectations, each is in a daily driver and has all the power we need plus some.
You can find the LT4 stock cam for sale many times on Corvette sites, I paid $50 apiece for mine when the original owners stepped up to GM's Hot Cam. Duration at .050 is 203/210, .476/.480 lift with 1.5's. Double check your particular heads, but these should be fine without mods for higher lift cams.

[rfmaster]

@BigBlockrules

Both of us reside in the eco-Nazi state of Kalifornia. Unfortunately, this simple fact precludes use of Vortec heads due to the absence of the exhaust crossover (requires external EGR plumbing) and unique Vortec intake manifold. Around here smog checks are worst then Gestapo or KGB searches (take your pick) - it has to look, function, and 'poop' like it was shipped from the factory and certified by master lord overseers CARB and EPA. Technically, in the official language if yo can read them, rules forbid using alternative internal components (which SEMA has fought against for years) unless there is EO number. The cut-off for this semi-annual insanity is 1975 and older model year vehicles. If your car or truck is newer - the pain goes on. What is worst air resource districts (another layers of fake do-gooders ) modify pass - fail limits making it even more difficult for older vehicles to pass based on faked data and science! So there you have it.

So this is why we have to be creative with what we can play with, which precludes known winning combinations used by many else where. But we have nice weather, occasional earthquakes and $4.50 cleaner burning gas (it is down to $4 now). Sorry guys for all the sarcasm and a small rant.

//RF

[BigBlocksRule]

Wow, lucky me, I live on the flat, dry, treeless, windy plains. Even if my old junker pollutes, I don't have to worry about it, just the folks northeast of me!
I spent a couple of years near LA, didn't lose anything I care to go back to get.
Seems like a lot of things CA does in the name of the environment end up biting them in the butt later...