Hello! I'm ready to get started with my 350 build! I've done some research, including the 350 swap thread here on the forums and I'd like to lay out my core engine build with the hopes that some of you can help square me away. there's a few things I'm unsure about: compatibility, did I choose a weak link somewhere, should I consider better parts, etc..

Before anyone asks "why not a 383?" Well, I am hoping I can swap the 350 in and not have to upgrade my transmission, drivetrain, rear-end and brakes right away. I know that eventually I might have to do some or all of that, but I'm hoping the stock stuff will hold up a while. Am I wrong in that assumption? Should I just go with a 383 since the build would most likely be the same price and I'll have to upgrade all the stock stuff anyways?

Added:
My FB in case it matters: 1992 Firebird Base, 305, Automatic trans. Only mods I've done is open air filter, all aluminum radiator, true dual exhaust 2.5" (custom), ceramic coated shorty headers. First thing I did when I bought the car was new fuel pump, distributor, plugs & wires.
I should also include what I want out of the car: I don't plan on racing it, but I do want power from the 350 when I want it. I'm willing to spend a tad more for gains and quality if I'm already doing the work.

Sorry for the novel above.. Here's my 350 build plan:

Engine Internal:
350 core: Salvage: I am reading i should go with a recent '87+ block, 1 pc rear main to use a roller cam, ie: L31 (I know GD recommends this)
Camshaft: Cam/Lifters/Timing, Hydraulic Roller Tappet, Advertised Duration 258/264, Lift .480/.487 - https://www.summitracing.com/parts/cca-sk08-408-8
Pushrods: Not sure which rods to get, I know they must match Camshaft and Heads.. still reading up on this, but this is where I can use some advice.
Rockers: Not sure what rockers to get..
Crankshaft, Pistons, Kit: Speedmaster SuperStreet Series Engine Rotating Kits 1-290-003 - https://www.summitracing.com/parts/sdm-1-290-003

Engine Top:
Heads: Summit Racing® Vortec Cylinder Heads SUM-151124 - https://www.summitracing.com/parts/sum-151124 - Trying to find good aftermarket heads that will fit this build - that or should I pull '96 - '00 vortec heads from salvage? Do the heads determine the cam, pushrods, etc?
Intake Man: Edelbrock Performer T.B.I. Intake Manifolds 3704 - https://www.summitracing.com/parts/edl-3704
Throttle Body: CHEVROLET Holley OE Replacement Throttle Bodies 502-9 - https://www.summitracing.com/parts/h...make/chevrolet
Injectors: Chevrolet Caprice Fuel Injector SMP 34945TM 1990 1991 1992 5.7L V8 - (ebay)
ECM: Plan on getting the recommended from the 350 swap thread
Chip: tbichips..

As always, thanks in advance!

 

Yes. Least-expensive way to get into roller cam/lifters. Buy a roller-cam short- or long-block. The TBI swirl-port heads are junk. Vortec heads could work out well for you, depending on intake manifold and fueling system. Avoid LT1-style engines. Actual Vortec engines will need either the Vortec water pump, or the bypass holes drilled into the block. The Vortec timing cover, damper, and crank sensor/reluctor may need to be replaced. The TBI 5.7L engine from a Caprice, Roadmaster or Caddy is a better starting point. they're also somewhat rare. The TBI trucks usually don't have roller cams although the block may be set-up for one.

Beware of belt alignment problems from mixing TBI, Vortec, and other water pumps, accessory brackets, dampers, etc.

Camshaft will depend on your ability to tune/calibrate the computer. I can't help with that.


Pushrods are the LAST thing you buy to complete a long-block. Too many other things affect the proper pushrod length. You'll need to assemble the engine, then measure for proper pushrod length to get minimum sweep of the rocker tip across the valve tip. You'll probably want hardened pushrods; you MUST have hardened pushrods if your cylinder heads have pushrod guideplates.


Self-aligning, unless the heads you use have pushrod guideplates. New stock or stock-replacement rockers may be just fine; used ones will be worn-out at the tips. Roller-tip rockers are no big deal. Don't bother with them. Or buy REAL roller rockers that aren't made in China.

Speedmaster's entire product line is cheap crap. If this were me, given the relatively low-power output expected, I'd use a stock cast crank, stock powdered-metal rods, and new TBI Caprice or LT1 flat-top pistons at about $125, Use the special rings to fit the metric ring grooves. A GOOD used torsional damper, and a GOOD used flexplate would be fine. Check both to assure they're in usable condition. Stock flexplates are known to crack around the crankshaft bolt-hole area. Have a reputable machine shop balance the assembly. Enormously less expensive than buying Communist Chinese aftermarket crap.


If you intend to keep the TBI unit, your best bet is probably the Summit aluminum TBI replacement heads. Stock TBI manifold fits, EGR works, emissions-legal, all stock accessories bolt-up just like they did before.

Vortec heads will be a nightmare getting the EGR to function. It can be done, but it really sucks and it's expensive.

Other heads can work, but keep the intake manifold bolt pattern, and bolt angles in mind. There's several steel struts and accessories that bolt to the TBI intake manifold, the manifold you use is going to need bolt holes in the proper locations to mount it to the heads you choose, and also to mount the accessories. This gets complex, quick.

Won't fit Vortec heads. Won't fit non-TBI heads that have the "old" bolt angles. Beware bolt patterns and angles.


Consider the 502-6, depending on which connector your TPS uses. I'd at least try the standard injectors in the Holley throttle body before blowing money on eBay replacements. I think that throttle body comes with a tapered "adapter gasket", otherwise the throttle bore holes in the Edelbrock manifold are too small.


I can't help with that.

MAKE SURE YOUR MACHINIST VERIFIES:
Block, crank, rods, heads are in good condition. No cracks, good surface finishes, everything is straight and round as needed.
Block may or may not need to be bored. Some blocks have so little wear that all they need is a dingle-berry brush to restore some cross-hatch in the cylinder walls. IF you're going to have the block bored, pay extra for the torque-plate honing. TALK TO THE MACHINIST to make sure they can do this.
Block will almost certainly need to be decked. Amount of material removed depends on the head gasket you select. Thicker head gaskets require more material to be shaved off the block decks, to achieve proper quench/squish distance of .035--.040. You select a common, .040 head gasket, you'll probably need to take .025--.030 off the decks. Better to use a thinner gasket and remove less material from the block.
Block may/may not need to be align-honed. TALK TO THE MACHINIST.
A Vortec block probably won't be machined for the TBI water pump (coolant bypass hole.) SOME Vortec blocks have the hole, most don't. Be sure your water pump suits the block, and the accessory drive. TALK TO THE MACHINIST.
Rods may/may not need to be resized. TALK TO THE MACHINIST.
Crank may/may not need polishing or re-grinding. TALK TO THE MACHINIST.
Have the bottom-end balanced.

 

Schurkey, thanks for the reply! That's precisely the info I needed for the build. I'll address those parts in my build. It sounds like I need to just keep a lot of stock stuff with the 350 build and save money while at it.

Can you comment on whether a the stock 700r4 / 4l60, drivetrain, and rear will be driveable with a modern 350 build, at least for a little while while I budget in the rebuilds and replacements?

 

700/4L60 is fragile. The fairly-stock 350s in my TBI K1500 have shattered two of them in 20 years; although I don't think it's a matter of too much power, but poor lubrication at high speed in OD.

Anyway, you can spend a fortune to buy higher-strength aftermarket parts for a '700 or 4L60, or you can stuff in a 4L80E which is plenty strong but requires a computer to control automatic shifting. I say you should just change the filter, flush the fluid on your '60 and hope for the best. Be sure the TV cable is adjusted properly. Another reason to not use Vortec heads--the TV cable bracket will need modification to fit the Vortec bolt-pattern.

Rear-end gears can make a SIGNIFICANT difference in the performance of the vehicle. Whether you re-gear the axle you have, or find a replacement axle is a choice you'll have to look into. "I" would not put ten cents into an axle with a smaller ring gear than 8.5".

 

Just get an L31.

Main line hone, parallel deck, and new bearings. Don't bother with any "rotating kit" or changing the rods or pistons. Have the rods resized with ARP hardware.

DO NOT touch the cylinder walls WITH ANY abrasive unless they are WRECKED. Very light scuffing is fine - pretty normal. Most L31's aren't going to show any significant bore wear - most are going to show cross-hatch. And if they do it must be bored and plateau honed to about a 600 grit finish. Don't unless you can't avoid it. And if you do only remove as little material as you need to. Remember - removed material is reduced strength and one less time it can be rebuilt in the future.

You will blow the trans. Probably the rear end as well at some point. I just ordered my 4th 700R4 in 5 years. This time I went with the 900 HP unit with a warranty. It's torque that breaks them very likely I stripped the teeth between the drum and input shaft.

GD

 

I put an L31 short-block in my truck. It's not a bolt-in operation if you're using the TBI water pump and accessories.

The intake manifold is hatefully expensive, and the EGR is a mess. So is bolting-on the bracket for the TV cable.

I used old-style aluminum heads with the original intake manifold bolt pattern, and a ZZ4-style intake with a TBI adapter on top. Even that has problems with fabrication needed.

The Summit heads for TBI would have saved me a shitload of work 'cause I could have re-used the TBI intake.

 

Could re-pin to TPI and get a FIRST manifold in Vortec pattern...... Solves many of those problems. Delete the EGR......... Depends on where you live, your budget and goals, etc I suppose. It's a good option and certainly the parts exist to make it work. The TBI manifold might be kinda spendy but you can often find L31's for like $200 to $300 now since everyone wants LS's.

He's going to blow his trans. And his rear end. The factory stuff was barely adequate for L98 power. Sometimes not even. So there's that to consider also.

GD

 

This discussion is making my rethink the order of upgrades. Since whether I go 350 or 383 I'll need to upgrade my trans/drive/rear, would it make sense to start at the rear? Get a 3.73 or 4.10 geared posi rear that'll handle HP. That'll keep me on the road with a slight difference in feel. (someone suggested this above already). Then maybe a lighter, stronger driveshaft (shave some weight), then onto the trans. I called locally and was quoted that a rebuild would cost $1900 for 500hp rebuild w/ warranty. That included a shift kit, might make the car fun until I can eventually do the engine swap. This way, I get to keep it on the road. I can afford a swap right now, but that's about it. The rest would come piecemeal throughout the year. Thoughts? Afterthought, I know GD you also said brakes would need upgrade as well. (on a different thread)..

 

Brakes would be a good idea once it's considerably faster.

The rear end swap would be a great idea first - it would give you a boost in off the line performance and will be needed later.

The trans..... I've had enough experience to know not to trust ANY local builders. Get one from Dana at Probuilt or talk to Allen at Performabuilt. The cost is not that much greater.

GD

 

I did not have to modify a throttle cable bracket. Bought the edelbrock one for vortec heads. On my G20 van with vacuum cruise the edelbrock bracket bolted to the stock vacuum cruise control bracket on the back of the head, might have had to drill two holes and use bolts and nuts, been so long I forget.. If there was modification needed it was solely to maintain the old vacuum cruise on the van. The edelbrock bracket bolts to the vortec intake and is slotted for both height and distance adjustment. Slide the bracket up to get the throttle cable level with the TBI then slide it back enough to give full throttle when the pedal is to the carpet. Then let the TV cable self adjust. IIRC the edelbrock bracket also had the cutout for the remote mounted cruise control cable.

Edit...Just looked it up. Definately has the hole for the cruise as well.

https://www.summitracing.com/parts/edl-8032?rrec=true

Honestly not sure why so many people are having issues with fitment. Worked perfectly for me with both a carb and TBI on an adapter. Had it on my Van with TBI on a performer rpm and a victor jr, then pulled it out of my spare parts bucket and put it on my Vette with a Q-Jet fed Vortec 305. Fit the Holley I had on the Vette too.

I was also running a marine TBI unit. The edelbrock cruise control kit they make for the performer carb bolts directly to the 2 holes the marine TBI throttle lever had and gave me a TV stud with the correct geometry for a 700r4 as well and a provision to add a return spring.

 

Getting everything else built up first is probably a better plan of attack. You can put 98-02 fbody "ls1" brakes on the front fairly inexpensively. Install some subframe connectors as well if you don't have them.