Help me give better advice. SBC content.

This is long winded, rambling and has no payoff. Proceed at your own risk.

First some background. A few years ago a friend of mine asked me how hard it would be to put a vortec supercharger on his truck. He is not a car guy and I am his only gearhead friend, so he came to me. The truck in question is a 1997 Chevy pickup regular cab long bed 2wd 305 automatic. It's not special in any way except it belonged to his late grandfather. 

My main advice was, don't do that. Then I set about finding out what he actually wanted. He told me he liked the truck but just wanted "a little more" I suggested a gear change to give him a but more acceleration as an easy way to wake it up a bit. He thanked me but never did swap the gears. 

Fast forward a couple years and the 305 is getting tired. He bought a running 350 4 bolt from my father, coincidentally, With the intention of rebuilding it and swapping it for the current 305. There are worse first projects.

Normally my advice would be sell your truck and buy one that already has the engine you want, but there is sentimental value in this truck.

So here is where we're at. we have a running but tired vortec 305 in the truck and a complete 87 4 bolt 350. To cut down on complexity the plan was to just use the complete induction system from the 305 on the 350. Stick a slightly lumpy cam in there (for the sound mostly) and a set of mid length headers and let him have his hot rod drivable truck.

The issue is the heads. The 305 is a vortec, the 87 is centrebolt. the existing manifold won't fit those heads. Kinda leaves us with a few paths forward each with their own pros and cons.

Option 1: Use the 305 heads.

Basically we'd just be swapping the short Blick. We really wouldn't be buying any big parts. The 305 heads have smaller chambers by about 10cc so there's a boost there, but that's offset by the smaller runners that flow worse. Probably a net loss.

Option 2: Buy a set of vortec compatible 350 heads.

Yeah. This would just work. but the newest used vortec heads are over 20 years old and are usually cracked. New heads will set you back like 800 fir cast iron ones. We're trying to not spend a ton of money.

Option 3: Just slap a holler on er.

A dual plane manifold. Holly 4bbl and HEI is as hot rod as it gets really. We're still buy stuff but that kind of stuff can be found second hand pretty simply. He'd need a good regulator to go from the electric pump to the carb. The downsides here is we're getting away from the plug and play first timer project into more custom stuff. Also... carbs are kind of crap, especially in a northern climate. Being able to hop in your car in 85 degree weather or 19 degree weather and have it crank first try is nice.

Option 4: Ditch the 305s fuel system for an 80's Tuned port or similar system.

Plus... everything will fit, and it'll look neat. Cons still have to buy stuff, have to start doing wiring and custom stuff to make it work. More in depth for a first timer and not necessarily better either.

You made it throught the rambling.

I have told him time and time again that there are better people than me to seek advice from and suggested he talks to everybody. 

Given that the project is less race truck and more essence of hot rod, how would you proceed?

Option 1.  Use the 350 short block and a little cam with the 305 heads and induction - and the gears you recommended, and a decent enough exhaust system that he can hear it all working.  That will get him turning wrenches and give him some exposure to the hobby.  If he doesn't catch the bug, he's not out much, and the truck isn't ruined.  If he does want more, he'll have enough experience to swap the new heads on himself, and can still drive it while he saves up for them.

Is there enough FMV in the center bolt 350 heads to help finance the project?

Return / sell the motor and get one that bolts in. How much is a basic long block vortec these days? 
 

Or put a used 5.3 or a 6.0 iron block in it out of another truck. Should be a direct bolt in. Get some education  on flywheels, starters and harmonic dampers as I think there are differences that you don't want to mix and match. Best to get a complete running used motor that is a drop in. 
 

For the time being forget about doing the cam swap. Just re gasket and replace all the seals on the replacement motor while it is out.  Do a water pump and basic tune up parts and stab the motor in. 

The fuel system might be what bites you. I don't remember what years but feel like around that used the "spider" injection. 

Easy would be just swapping bottom ends, used the 305 top end (even vortec 305 heads are better than the older non vortec heads), but the I have no idea if you'll be able to tune the fuel to get it to run right. But it might be close enough, maybe....

Yes, all 1996-1998 GMT400s have that spider injection setup. 

Does that '87 engine have provisions for hydraulic roller lifters? I can't remember when they changed over, but I think it was right around that time. 

My personal suggestion? Buy a junkyard vortec 350 and swap that in. They are cheap and everywhere, and are durable enough and cheap enough to rebuild to have some confidence it wouldn't be too much work. It will already be hydraulic roller, you'll have a set of heads you can rebuild, you'll have the whole intake and fuel system, and you can grab the ECM to control it while you're in there if you don't want to buy EFILive or HPT. It's also already going to have the right timing stuff, sensors, distributor, etc. It won't be 4 bolt main most likely, but it doesn't sound like that is something he actually needs. Slide in a slightly lumpier cam if you want, do the MPFI injector conversion for $400 or whatever it costs these days, and put in an aluminum body distributor to get rid of the plastic one, and you've got a good solid engine with a lot more juice than the 305. 

If you don't go that route, I'd still try to find a set of vortec heads for the '87 engine so you can use the vortec fuel system for ease of tuning and electrical integration. The heads have different ports and the intake bolts are at a different angle if I remember right, so you either use all vortec stuff or no vortec stuff. If you're putting a cam in, you'll need to tune it no matter what you do. 

I would not swap a carb in, but that's just me. seems like this guy wants a "just drive it" vehicle and it's a little harder to get that with a carb and trying to integrate a modern automatic transmission with it. 

.....and another reason that a carb swap doesn't work too well is that he has an "e" transmission and when you start gutting the powertrain control stuff you lose the trans functionability. So then you either have to buy a very expensive stand alone transmission harness and computer or you have to convert the truck to an old mechanical control transmission. 

I would definitely go with a same year Vortec 350 vs messing with the 87 350.  Shouldnt be out more than a few hundred bucks and the whole project would be easier.

Switch it to MPFI (direct bolt in) at the same time to get rid of the spider (CPFI) that is likely tired anyway.  

https://www.motormanfuelinjection.com/Vortec_spider_fuel_injection_conversion.html

Read up on what cams are happy with 100% stock EFI, there are likely some mild ones but you will have to do some internet searching.  I would plan on taking it to a tuning shop when its all together to get it dialed in and running happy with the larger displacement and cam on the stock ECM.  

Definitely would not go carb swap, thats just a hack job and a headache.  

AClockworkGarage said:

Also... carbs are kind of crap, especially in a northern climate. Being able to hop in your car in 85 degree weather or 19 degree weather and have it crank first try is nice.

Big disagree. Carbs are only crap if you let them sit too long. I've had a Q-jet-style Edelbrock on my 350 El Camino for almost 20 years now, running nothing but regular ethanol gas, and I've never had a problem with it. Probably because I actually drive it all the time. 

But...I don't think carb is the answer here. Like gearheadE30, I would go all-out Vortec, or not at all. 350 Vortec heads (they're like $1000 for a brand new set from Jeg's), multi-port injection conversion, ECU, etc. Otherwise the power difference won't really be worth the effort over the stock 305. 

Depending on how tired the 305 is, doing the rear gears (3.08? -> 3.42 or 3.73) first plus exhaust and maybe a different governor/tune in the transmission (700r4 had a police version that raised the shift points) might be enough to not mess with the engine (other than tune up parts). A better exhaust may get you the sound aspect without doing a cam.

Agreed on the vortec heads being what you want over the 87 350 heads. That's said, tuning the fuel system is the big hurdle if you change comp ratio, cam, etc. 

If after the gears and exhaust, he still wants more, finding a tuner and determining a set of engine upgrades that can be supported within the desired budget is where I'd point him next.

edit: I also like the full 350 vortec package swap option as well. That plus headers and exhaust would give a good bump and keep things mostly factory.

Just a quick note, the 1996-up Vortec spider injection is actually multiport injection with 8 injectors, not the single injector CPFI setup like the 1995 and earlier Vortec had.  If it needs replacement, use the upgraded style with the injectors at the end of the lines, instead of the poppet valve ones.

I would hardcore pass on that 87 350.  No roller cam provisions.

I would also not put 305 heads on a 350.  305 Vortec heads are not really Vortec heads.  They're better than smoggers, but they will put compression near 10:1 and won't breathe enough.

I also take exception to the "for the sound mostly."  That's the most common reason, and also the worst.  Once you get lumpy with the idle, that means higher stall TC, lower rear gearing, and (sometimes) premium fuel.  It's a truck.  Keep that torque peak as low as possible.

Not trying to sound like a prick, but I suggest just getting a 350 Vortec.  It already has the good heads, 9:1 - ish compression, and has everything you need.  If your spider injectors fail, just find a boat junkyard and get a maine EFI intake.  They use traditional injectors.

In reply to Curtis73 (Forum Supporter) :

I just found out this year, that the 305 "vortec" was not an upgraded head like the 350 got. I also vote for selling the '87, and getting a '96 to 2000(?) 350 

Also, as Masch. said, carbs are fine, and would suit his " needs" for that truck. But l would not recommend that route for that owner. 

In reply to 03Panther :

Another thing is that Summit has Vortec copies using a better alloy that isn't a prone to cracking.  They're only about $600 each.

The big thing many people don't realize about the 305/350 debate is that the 305 might be 87% of the displacement, but it's far from 87% the performance potential because of the tiny bores.  So just going to a 350 stock Vortec is a much bigger change than most people think.  Pair it with a tune and a mild cam in the 200/210 range with a 113 LSA, and you're easily at better than 1hp/ci and your torque is almost double what the 305 made.

If you end up going carbed, the marine world has you covered there as well.  There were a ton of Vortec engines with Holleys and Qjets installed.  Volvo, OMC, and Mercruiser all had some version of a Vortec carb intake in the 90s.  Most are aluminum with a bronze-lined water passage, but that won't hurt a thing.  The ones used by Volvo/Penta were basically a copy of the Vortec Bowtie intake from the crate engine, and they are an excellent intake.

I used to hoard them and at one time I had a stack of about 20, but they've all been sold or used on a project.  I just called boat salvage yards and had them shipped to me.

In reply to Curtis73 (Forum Supporter) :

Yep. 305 is much less than a smaller 350!

With the description of the owners "wants" and "needs", he will never be satisfied with a carb, although it would fit his needs well. 
 

I thinking about that, I realized... although it would not be the "best" power, if he slid the 87 short block under the 305 "vortec" (in name only) heads / fuel / ignition, and at the same time went to a lower (higher numerically) rear gear, his butt dyno would LOVE all his "extra" power!

Not the correct solution for most - but I think it's the perfect (edit:, well, ok) answer here. 

How tired is the 305? Using oil? 200k+ miles? Low oil pressure?

You mentioned a gear swap discussion before, whats in it currently?

If the oil pressure and compression are good in the current motor, reman the heads 3.42 gears and a better exhaust for a little rumble. Maybe the MPI swap some of the other people have mentioned too.

My other is idea is to find a rough but running 350 truck for parts. You'll get everything you need for the swap once the 350 is freshened up. The 305 and 350 will have different ECUs, maybe injectors.

Trying to modify an modern injected engine is tough unless you are master at computer tuning. Not sure if that is even possible on this motor. Leave the 350 stock and save a ton of headaches. Otherwise just LS the thing and pay a good tuner to make it run right.

The L30 305 is 220hp and 285 lbs.

The L31 350 is 255hp and 330lbs.

Its a nice bump, but is it worth all the work?

I don't remember the different years of the "old" spider injectors (cpi?) and the upgraded "new" spider injectors (mpi?) that is a bolt in swap. But I did it on one my my 4.3 V6 Astro Vans. As 100% of the knowledgeable articles wil tell you, 0% difference in performance. Just more reliable. Mine did run better, after... but strictly because the old style spider was not quite firing correctly!

People that are not aware of the differences in gm's usage of the marketing word "Vortec" should not be advising "just throw money at it for Moor Powor."

Just my opinion. 
IIRC a stock 350 vortec can replace the same year 305, without overtaxing the stock computer. If it needs a touch of tweaking (and I doubt it) that range of GM is cheaper to tweak than ANY other option.

Or, throw money at it for power not needed in this description, just for the bragging rights. 
I may have mis read, but I got the impression this was a low budget case.

If it's not burning oil or giving others signs it's on its last legs, I'd do the following to improve seat of the pants performance on a budget:

- Acceleration: swap the rear for one with lower gears. It's amazing what making a jump from 2.73:1 to something in the 3.40- 3.73 range will do for seat of the pants performance and burnouts. 

- Sound: install a dual outlet chambered or flow through muffler and dual tailpipes. You could also go retro with a glass pack and Y to split to dual outlet. Leave the intermediate pipe factory sized to maintain velocity and not lose low end torque. 

- Feel: install a Transgo shift improver kit. Follow steps to produce firm shifts and maintain lockup. The lack of slip when in 3rd or 4th will give the feeling of more performance because of the direct relationship between pressing the gas pedal, engine sound, and acceleration when done in conjunction with the gears and exhaust. 

If he's set on swapping the engine, finding a 350 vortex will be the most straightforward and least frustrating option. 

Well, arse. Totally forgot about  the roller cam aspect. Apparently I know damn near less than nothing about small block Chivverlays. Please disregard anything I said above as I probably didn't mean it and surely Dunning-Krugered myself into a laughably deep hole.

Ain't it funny how much we can not know about something so ostensibly universal as an SBC?

for the V8s, there isn't a different year of injector thing. That's unique to the 4.3. All of the V8s were spider injectors, and the mpfi injector kit was only introduced as an aftermarket part. They were never sold with the mpfi kit originally, at least not in a GMT400 chassis. Correct that it isn't a performance upgrade, just a reliability upgrade.

ECM tuning is possible on the 1997+ GMT400s with the "black box" pcm. At least, EFIlive supports it. Not nearly as fully mapped as later ECMs, but it still gets the job done. 0411 PCM swaps are straightforward as well, but not really in scope for the original question.

I have done some mild tuning on my 1998 K1500. The transmission benefits dramatically from some tune attention and really wakes things up. Stock shift timing is slooooow, the 4L60 can crack off some fairly quick shifts if you're appropriately aggressive with torque reduction. for exhaust, I built my own cat back after the flange, so still using the stock cats. X pipe, dual giant magnaflow mufflers one for each bank, and dual pipes out the back. Very happy with how it turned out, even with unequal length pipes leading into the X pipe. Even otherwise all stock, it sounds good enough, especially with the snappy shifts, to encourage using a bit more pedal than is really necessary. And it is still very quiet.

If it is any consolation, your initial advice was spot on the best offered so far.

He is not a motor-head so he should keep his paws off the engine because he is going to fail. No engine mod comes without some post-debug and tune effort. If your friend can't motivate himself to do a gear change, he is going to be lo$t in the forest if he has to refine an engine mod.

On the other hand, if ever there was a cry for a bone-stock junkyard 5.3 Vortec with a 4L60 autobox, this is the answer that will make him the most happy.

In reply to gearheadE30 :

The 96-up is CSfI system (Central Sequential Fuel Injection), and it does have 8 injectors, all in the main body, with the poppet valves at the ends.  This was done to meet emission requirements of OBD2, so it is not an aftermarket only item.  The improved version with the injectors at the ports was first done on 2001-up 4.3L V6, then a version was made by the aftermarket as an inproved replacement for the V8 models.

It sounds like your friend doesn't have the right combination of drive/skills to do this work himself, so who will be doing the work? None of the options presented above are what I could categorize as "plug and play", so he's going to need some help.

Your dad's 350 bottom end doesn't have a crank reluctor wheel, so you can't put the 305 heads/EFI on it (and even if you could, stock for stock 305 vs 350 in a full size truck is not going to make a big seat of the pants difference).

IMO, people that don't have the knowledge to plan a series of supporting mods and a realistic understanding of engine building compromises (I'm assuming your friend is in this category) will often make the vehicle worse by trying to change stuff (especially if you go cam swapping for "the sound").  

If he's dead set on keeping the truck and dead set on doing something to the engine, he needs to swap in a 5.3 or 6.0 LS variant. He already has a high pressure fuel system in the truck, all the truck accessory drive parts will fit in the engine bay of his GMT400, the LS computers can basically be run as standalone systems, and you can buy a cheap flexplate spacer and bolt the LS to his current 4L60e. He won't need a tune if he leaves the 5.3 stock, he'll just need to pay someone $100 to remove the VATS security system.

In reply to budget_bandit :

The bone-stock Ls would be the way to go. And for the love of god leave it stock running the stock wiring harness and stock tune. 

This is a standalone running just such a combo on my test rig. It is running a stock tune with the factory harness thinned out and a relay board added. You can buy china harnesses for cheap, but only do so if you are able to go over them pin-by-pin as most have at least one mistake in the wiring.

Removing VATS, setting fan control ON/Off and removing rear O2 sensors and EGR was free with on-line tools. But yeah, $100 will get it done quicker.

Interesting that you guys are saying "get a junk yard 350". I see more 4.8 and 5.3 engines in the yard than I see old 350 sbc engines.