Bubbajones_ya

I've decided to entertain swapping my 305tbi for a 350tbi recently.

My current 305 runs great and has been very reliable, but I'm struggling with emissions now do to me needing to tune it better and probably the code 43 (something with the knock sensor system) showing up. I've had some great help from RBob and Street Lethal with this issue, but I started looking into this project now.


Upon reading the sticky thread 305 to 350 swap, I see the main different parts needed in the swap are:

350 injectors
350 specific knock sensor
350 ESC module
350 chip

I may need to replace my current knock sensor and ESC module on the 305 now due to my code 43 (which may be a big factor for me failing emissions), and I already have 350 injectors. I also have RBob's EBL system (which is a phenomenal product for tbi users with exceptional customer service), so I believe I should be able to tune my computer for the 350 motor using that setup. I figure, if I'll be buying the ESC module and Knock sensor, maybe I should just make the jump for a 350 now.


I just had a few specific questions on if I can/should use my current mods, and it people think it's really worth the hassle.

My current mods are:

Elgin 1136 camshaft
Hooker 2055 headers/y-pipe/3in exhasut
Edelbrock TBI intake (I believe it's a 350 intake so that should be good)
350 injectors
New stock rated fuel pump (not a mod I know but relevant)
EBL tuning system


==============================================

Some specific questions I have are:

I've read that most 305 parts are transferable to the 350, does that include my camshaft, pushrods/rocker arms, serpentine setup and flyhweel/headers/y pipe? Basically, if I get bare block (well assembled with the oil pan/crankshaft and pistons), can I reuse EVERYTHING except the knock sensor/module?

I've heard some people like to put 305 heads on to bump the compression. I had my 305 TBI heads (I know, not the greatest in existence) reworked recently with a valve job and some mild intake runner porting/gasket matching to the Edelbrock intake. Would it be a major bottleneck/bad idea to reuse my 305 tbi heads? I figure it would save me money if the block I buy doesn't include the cylinder heads. However, if 350 tbi heads are better (I'm assuming I'll come across more tbi 350s), then maybe I'll go for those.

If people generally do recommend I swap to a 350, what year/vehicles should I be looking at to get the block? I know some trucks were not equipped with roller setups in the late 80s early 90s, but the block was apparently setup as a roller block, so since I already have the roller setup in my 305, I was thinking I could just swap it on over.


Lastly, how much HP/TQ do you think I'd gain by swapping from my 305 to a 350?



I know this topic has been beaten to death, the topic's ghost found by TAPS, then captured and beaten to death AGAIN, but I wan't to make sure I'm making the right move before doing this. After I swapped the powerstroke turbo diesel into my Bronco, my Camaro seems so SLOW now, and I want to give it a little more love! I am quite tight on funds now too though, so I figured the 350 swap now might be a relatively inexpensive useful mod that would give my Camaro a little more power.


Thanks for any input and advice!

JoeMonte

Get some decent heads, maybe some 882's or some other generic casting that is cheap but not terrible. 305 heads on a 350 is like bandaging your foot and shooting the other one. The small valves don't flow nearly as well as you want for a well breathing 350. If you know the general concept of a carb, go with a carb, much simpler. I would get a generic summit grind camshaft and lifters, do not mix and match old cam and lifters. If you weren't in Arizona, I'd give you a steal on a 350 block. If you really want tbi heads go with vortec and just spend the little bit of cash on the intake. Honestly, I've been down that road that you're trying to go down with building an engine for dirt cheap, and it isn't possible to do it properly without spending cash. Search on craigslist and facebook for a block and then take it to a machine shop. Generally speaking they'll be able to tell you what your best course of action is. So, long story short, no you can't use everything off of your 305 to make a good, strong, healthy 350. Some bits should not be reused, such as oil pump, timing chain, and I definitely wouldn't bother with the 305 cam. Sorry if this seems like it makes no sense, but it's neigh midnight here. Where exactly in Arizona are you? I used to have family in Springerville.

Schurkey

Find a salvage yard that has a '91--'93 Caprice, RoadMaster, or Fleetwood Brougham 5.7L. A used engine in good condition will be a real bargain.

The full-size car 5.7L engines have roller cams where the pickup engines have flat-tappets. The car engines have flat-top pistons where the pickups have dished pistons. You will need a plug for the oil pan because the cars have an oil-level sensor that goes into a threaded port in the pan.

I bought the crate-engine version, which has been discontinued for years. Used to be p/n 12513151. Dropped it into my 5.7L TBI pickup with ZERO tuning mods, and it runs FLAWLESSLY.

The 305 heads are no bonus.

Is that a roller-cam? If so...it transfers. There are two designs of camshaft thrust-plate, which depend on the block not the camshaft. Some blocks use the goofy thrust plate, some blocks use the same thrust plate that the big-block Chevy uses. Your serpentine setup, one-piece rear main seal flywheel, pushrods, rocker arms (except the rockers will be all worn-out) exhaust, small-cap HEI distributor, etc. are all compatible.

You'll have to be careful that the timing mark on the damper is compatible with the timing pointer on the timing cover.

A block with crank, rods, pistons, etc. is a "short-block". Add cylinder heads and valvegear, and you have a "long block". Some folks include the sheetmetal pan, timing cover, valve covers, etc., and others don't. In either case, the accessories, intake, distributor, carb, are not included in a long-block, or a short-block.

Ghettobird52

Heres the funny thing.... 6 years ago my L03 started leaking HEAVILY out the rear main. My dads friend worked at a machine shop and happened to have a L05 Block laying there.

The shop rebuilt the block .060 over, my friends dad, did my 187 heads up (1.94 intake valves, took swirl out , port polish) i had the Edelbrock TBI intake, and swapped over. I have Ebl flash like you and actually im still running off 5.0 injectors just with some prom work. I need to get my TPI fuel pump in as my car is STARVING for fuel above 45% throttle. So your most likely going to need to do the same. A bitch i know! Any who i think your on the right track. Especially already havin Ebl flash

Bubbajones_ya

Thanks for the responses!

For the cam yes it is a full roller setup. I did a major overhaul about a year ago (put in the new Elgin Cam, new waterpump/alternator/timing chain and sprockets/intake/injectors/oil pump) so pretty much the entire top end except for the pushrods and rocker arms and lifters are new or rebuilt.

My engine is currently running very well (except for the code 43 and my tune is a little off making it run a little rich), so I'm in no dire need to get a new engine, but I'd like a boost in performance!

I just figured if the knock sensor and ESC module were the only two things I'd need to get the swap running, then maybe I should do that now.


If I can get a good deal on a block with the heads, then I may just go ahead and use those (and save me time from scraping off head gasket material), but otherwise I probably will be stuck using my current heads if I do go this route for now.

My funds as of now are sorely lacking, so I have to be somewhat "cheap" initially on this swap, but thought I might have a lot of the important stuff taken care of (new timing chain/cam/waterpump etc). If I just need to buy the block and gaskets and the spark stuff, then I can afford to get this swap on its way.

If the 187 heads really are a huge performance killer, I may try and save up for some performance heads later on down the road.

I'll be leaving in roughly a year for the Air Force for my commitment to serve (waiting to see if I get accepted to OTS and if not, then seeing what my enlisted job allocation will be), so this swap has to be somewhat "simple" and not overly time consuming in order to get it done before then. I think too much machine shop work and parts hunting may put a stress on time!

JoeMonte

Thank you for your service. It shouldn't take a year to build an engine, so I think you should be fine. I'm expecting mine to take a few months simply because I'm working off of a student's salary, but I have the benefit of working for a shop with one of those old timers. Expect a grand or so, especially if you want to freshen it up a bit. Power costs money, how fast you go is dependent on how much you're able to spend.

Bubbajones_ya

Well I stopped by a yard today to grab the ESC module just to try and get code 43 off for now.

I ended up seeing a 98 lt Suburban with the motor. I believe it has the 5.7 in it.

Is this block compatible with the T5 transmission and my TBI stuff? I'm guessing it may have a different intake and potentially vortec heads but I didn't really get too good of a look at it. I don't know much about the truck motors and their compatibility, but the yard only charges 220 for a full motor so it seems like a good deal if it is a 5.7

Schurkey

Yeah, it'll have Vortec heads, intake, etc. You'll be screwed for EGR and for intake manifold exhaust crossover heat unless you find/fabricate an exhaust source from one of your headers. The manifold can be heated with coolant, but that doesn't work as well as exhaust--too slow to warm up.

Of course the block is compatible with the T5. SBC is SBC in terms of bellhousing bolt pattern. All the one-piece-seal crank flanges are the same, so the flywheel should bolt right up.

Bubbajones_ya

Okay I was thinking it was compatible but wasn't quite sure if the block was changed later on (I don't know much about the motor designation like lt1 ls2 etc, so I wasn't sure if 98 was a new classification or if it was still the same 5.7 block!)


I did end up pulling it today and dropping it off in my Bronco for now. I haven't had a chance to really check it over, but the back is stamped 5.7L6 SGI and 10243880.

I'm not sure what I'm going to do about the intake either. I believe I'm going to try and find an aftermarket vortec head compatible TBI manifold so I can keep my TBI and EBL stuff. I haven't checked the heads to see if they were swapped out with something else, but it does look like the drivers side head bolts are not new so I'll see when I pull the valve covers. Since the intake is made for full fuel injection, I don't think I'll be able to use the lower/upper at all unless I completely change wiring harnesses and computers (because I don't believe the EBL setup is designed for a full fuel injection system.)

I figured for 235 after tax, a full motor (that should be a roller) with heads/intake/brackets/pan etc would be the best deal I would find around here!


Just in case money is super tight or the current heads are no good, I may consider using my current swirl port 305 heads on the 350. Would I lose out on a lot of hp/tq if I go this way?

Schurkey

The swirl-port heads as installed on a 350, are down about 30 hp compared to Vortec heads as installed on a 350.

I'd expect 305 swirl-port heads to make less power than 350 swirl-port heads.

Yes, you'll be giving up power to go back to the swirl-port heads.

Again, you're screwed for EGR unless you modify something. GM used to sell a "kit" that included some metal tubing and an iron exhaust manifold that could supply exhaust gas to the manifold. There may have been other parts included--gaskets, small fittings, etc. I haven't seen a part number or a parts-list for that kit for the longest time. I'm sure that kit has been discontinued for years--and you probably don't want to go back to an iron manifold anyway.

Bubbajones_ya

Hmm I have some considerations to look into then.

I'm quite short on funds now so I can't afford to get the current vortec heads (I'm assuming they are vortec heads) reworked on top of buying a new intake manifold, especially if I want to keep EGR (because the EGR vortec TBI manifold is like 300-450 dollars).

I really want to throw on my 305 heads/eldbrock intake now because I think it would be a nice jump in performance with the 350 and those heads, compared to the 305 with those heads. I just recently had my 305 heads reworked with a 3 (or maybe 5 I don't remember) angle valve job, new bigger valves, and gasket matching at a good shope in Chandler AZ when I put the cam in (maybe a year ago or less) so those heads are in great shape.... they just aren't known to be the best.


I suppose it depends on if I should wait another 3 or so months to get the funds to get a new intake and have the vortec heads reworked, or if I put the new motor in now.

Schurkey

Why not TEST the cylinder sealing? If the valves aren't leaking...why replace the Vortec heads with swirl-ports?

Good luck with the EGR. Even with an EGR-capable intake manifold, you still have to supply exhaust gas to it--and it won't come from the exhaust-gas crossover in the heads, because they don't have one.

jmd

iTrader: (4)

For Vortec heads, There is a 4bbl intake with external exh. feed at the driver side front. I believe it was GMPP. Tap into a header primary and figure out what production heat pipe will thread into the intake. Oh, and use an adapter for TBI to 4bbl. I recommend this intake because the 355 I had in a car I parted pulled 26mpg. Yes, it's $$$.00 but it's probably the best choice for smog / TBI / egr.

jmd

iTrader: (4)

You heartily recommended that junk if it was on a Caprice engine.

external EGR feed is commonplace on OEM applications and it requires all of one primary tube to be tapped for it and welded. Not a big deal, and I have seen several swaps using it pass in CA and AZ. It's not a matter of luck; just gathering the parts.

Schurkey

I heartily recommended the Caprice engine--which has higher compression and a roller cam versus the dish-pistons and flat-tappet of my original LO5.

I did not specifically recommend the swirl-port heads, in fact I told him
However, it's a seamless package when it comes to dropping on his existing intake manifold, and does away with 4-barrel-to-TBI spacers. The swirl-port heads have the exhaust crossover ports that the Vortec heads don't. The Caprice engine gives up some power, but saves hundreds of dollars in aftermarket parts.

Another option would be aftermarket heads with improved port and combustion chamber, but with the exhaust crossover. Nice, but also expensive. Hard to justify when he already owns the Vortecs, and they're already installed on the engine. He doesn't even have to buy head gaskets!

The "Good luck" was in reference to him buying an EGR-capable manifold, and NOT SAYING ONE WORD about how he was going to route exhaust gas to it. I am entirely aware of the external exhaust gas supply, I was the one who mentioned the now-discontinued GM kit.

Bubbajones_ya

I suppose that is a good idea to test! I was thinking that it may be worth taking the heads off to have them checked to make sure nothing is wrong with them, but testing if they seal or not should indicate the major problems I would run into right?

I have never tested for cylinder sealing though. I assume this would be a leak down test and I would need to by a leak down tester for this correct? I see harbor freight sells one for about 45 dollars, should I go this route or should I try and see if I can rent one from a parts store?



As for the EGR setup. I WOULD like to keep it, but wouldn't be against not having it, at least for the time being. I will keep an eye out and see if I can get that GMPP thing on the cheap side though, but may waste some money up front getting a carb intake/TBI adapter and installing that first while I save up for the other intake. The economy can't support itself!

Schurkey

I wouldn't trust Harbor Junk any farther than I could throw it. The OTC offering is also Communist Chinese.

I have two leakdown testers: An ancient Snap-On MT324 single-gauge leakdown tester that I bought new back in the '80s; and a newer unit having a Master Orifice and the smaller main orifice, suitable for testing smaller Teledyne Continental aircraft engines. The point about using aircraft-style leakdown testers is that the tester orifice has as much effect on the indicated leakage as the actual leakage. There is no industry standard for the orifice size in automotive test equipment, but the FAA does set standards for the aircraft-suitable equipment. You want a .040 main orifice for engines with a bore smaller than 5", where engines with a bore larger than 5" use a .060 main orifice.

This is my newer unit:
http://www.aircraft-tool.com/shop/detail.aspx?id=2EM
It will come with an 18mm spark-plug hole adapter, unless you TELL THEM YOU NEED THE 14mm ADAPTER. As it turns out, all my Snap-On quick-change adapters also fit the newer tool, since they both use Industrial Interchange (Milton "M" style) quick-change couplers.

Remember that the tool makes as much difference as the actual leakage, so be sure to test several "Known-good" engines to get a feel for "normal" leakage.

Listen at the throttle body for intake valve leakage, listen at the tailpipe or exhaust port for exhaust valve leakage. Any valve leakage is not acceptable. There should be ZERO valve leakage. Same with leakage into the cooling system--watch for bubbles and listen for leakage at the radiator cap.

Leakage past the rings is completely normal. The quantity of leakage can be excessive, though. that's why you need to test "good" engines, so you know what's normal with your tester.

Cheapskate Method: Don't bother with the leakdown tester. Simply plug compressed air into the cylinder using a compression-tester quick-coupled adapter (remove the valve core), and "shop air" at ~100 psi having a Milton "M" style coupler body on the air hose. You'll never know what the percentage of leakage past the rings is, but you'll know whether the valves or head gaskets are leaking.

Bubbajones_ya

Thanks Schurkey for the info!

I've been quite busy lately so I haven't had much time at all to dig deeper into what I have.

I was finally able to put the engine up on my stands yesterday and start taking the intake and accessories off. The motor almost dropped when I was moving it into the garage..... one of the chains bent and came undone so it was left to swing on one chain.

Anyways, I verified that the motor does have the vortec 062 heads on it. I may try the cheapskate method by filling up the cylinder with compressed air, but I'm considering taking the heads off to get them cleaned up and rebuilt. I don't think I can afford any porting/polishing, but I may want the heads freshened up.

I think I may want to get a new fuel pump as well. I replaced it about a year ago, but I only put the stock tbi pump in there. I'm guessing I may need more PSI if I have this 350 in there with vortec heads and a cam (I think I'm going to reuse the elgin 1136 but may opt for something else if recommended)