83' K1500 power plant build help needed.

[Dutch724]

Hi everyone, I’m new here and it looks like I will be here a lot.

83’ K1500 5.0 ltr. I don’t know what tranny it has in it. I don’t know too much about this truck except I was raised in the ones built in the 70’s. I had plenty of time under the hood of a 77’ 454 suburban and 75’ k1500 with a 350.

Now this 83’ that I have picked up for my son to drive when he gets home from boot camp and all his training schools that he has to go to. I have had the transfer case rebuilt. The engine is in bad shape and needs to be replaced with something that will get this truck moving down the road quickly. I would like to share my ideas of what I would like to do with the power plant but need some help since it’s been a long time since I have done this much work to a truck.

I would like to get 350 to 400hp out of the motor with a nice amount of torque for pulling a horse trailer if needed. I would like to keep it on 87 octane gas. With this much power I’m not sure if the tranny will be able to handle it or not. I have about $3000 to sink into a motor. I’m thinking something like a 383 or 350 would be able to do the trick. From what I have been reading LS or vortec heads are the way to go. Would it even be smart to add fuel injected carb or just fuel injection or am I getting into a mess of problems.

The bed is already removed and all the frame rails and metal will be sand blasted and por15 painted. I have new bilstein shocks to add all the way around. I know the fuel tank switch isn’t working so I understand I will be redoing that whole gas tank system so it can work like it did when it was new.

Any help or advice I could get would be a great help.

 

[1987 GMC Jimmy]

I think a performance long block is gonna be out of your budget so I think it’s safe to deem this a budget build. The way that this is probably gonna work is with a running motor or long block from Craigslist, preferably one that you can test compression on and hear run. Something with as low mileage as possible, or if not, one that you can tear down yourself and rebuild if the cost permits. Nothing on an engine is hard to do if it’s out of the vehicle. Another option I found is a bored forty over performance short block that Summit sells (I’ll attach). I think you can still work with that, but it’ll be cutting it much closer than the former approach, and it’s a late style block, which may or may not throw you for a loop with your mechanical pump depending on what they send you. Vortec heads are definitely an option, but if you buy those used, you’ll need to be wary of cracks and other defects that’ll screw you over down the line. Also, there’s a ceiling for the cam lift that you can use with those in their stock form. Consensus says .450, but I’m sure people run more and live. Personally, I wouldn’t play with those numbers. It maybe prudent to upgrade valve related components or even rebuild used heads from the get-go, but you’ll only know you plug and chug your figures whether new or used is right for you and also when you get an idea of how mean you want your camshaft to be. Me, I’d do an 87 or older motor that’s definitely got a place for a mechanical pump to run your carburetor. Every 86 and older will have that, but I don’t think every later block will so be mindful of that. I’ll get to the carb momentarily. Another option head wise is aftermarket, which may save you money on not having to buy a special intake, valve covers, upgrading valve components, and rebuilding in a worst case Vortec scenario. An example would be a set of World or Dart heads, for instance, and you have both cast iron and aluminum to choose from. That’s probably what I’d do look into so I could just run an Edelbrock or Holley/Weiand intake and standard issue SBC goodies instead of the expensive Vortec stuff. LS is strictly Gen III stuff so no compatibility there. You also have some good factory castings out there, but there’s variable consensus there, and a set of performance heads from the 70’s may not be accessory compatible or may need a ton of work. A mild, not so lopey cam will be preferable if you plan on having your cruise control and power brakes working normally, not to mention any emissions components that are mandated by your state/county or that you want to keep for your own sake (i.e. charcoal canister). A good mild flat tappet cam is a Comp 12-300-4. It’s the cam you want in order to keep it cheap and to have a lot of low end grunt, but if you want something more aggressive, they have a pretty comprehensive product line. Intake, I’d just go with an Edelbrock 2101 or equivalent if I was doing pre-swirl port factory heads or aftermarket heads. You’ll need a GMPP intake or a rather expensive equivalent if you go Vortec. For fuel delivery, I think carburetion is gonna be your cheapest, most effective route. Aftermarket EFI will more than likely put you in the red because an entry level FiTech system is gonna be $800+ dollars. If you can crunch the numbers and make it work, go for it. It’s a very reputable system. Otherwise, I vote Quadrajet. It can discretionarily bring in the air and fuel that no other carb can when it’s built right, and you probably already have one on your 305 so it’ll be a money saver just to rebuild/upgrade and throw a primary throttle shaft bushing in there. If you want, I can give you the contact for the guy who built my Quadrajet. It’s an excellent carb. Some others will probably recommend Holley, and those are good just not my personal preference. The only thing that I’m really tough on here to keep the build in the black is a carbureted setup, preferably Quadrajet since you already have one I’m assuming, and a block that can run a mechanical pump, which will almost certainly use a cheaper but still effective flat tappet cam. Feel free to get a higher lift and duration one, but I think a good springboard into cams is the model that I shared above. I think you should shop around for 1.94/1.5 or 2.02/1.6 heads, nothing lower, which are gonna be economy (crappy) factory castings and probably some economy aftermarket units. See what you can find Vortec wise, go see them in person if you find a deal, but don’t be afraid to go aftermarket if something doesn’t look right so you don’t have to pour a bunch of money into fixing heads. Going non-Vortec will save you $$$ on what’s above the heads, but make sure it still works out in overall cost.

You’re likely gonna have to dedicate some of that budget to the transmission. It’s either a TH350 three speed or a 700R4 four speed OD. The former can handle the power better in its stock form, but I’d still rebuild it and do some baseline upgrades. The latter won’t handle it well as is. You’ll either need to get it rebuilt and thoroughly upgrade it, or you’ll need to get a later model (87+) core and rebuild that and do some upgrades but considerably less than an early model 700R4. I don’t know if it can all be done for $3K, but if you sniff out a deal on every piece that you can without skimping on quality, I think it can be done.

https://www.summitracing.com/parts/...MIo_3g84j-2AIVxmV-Ch1LbgR_EAQYAiABEgImHfD_BwE

 

[Dutch724]

Thanks for all the advice I know it took some time to write it up and I appreciate it.

I do want to keep it on a close budget because I know how things can get away from you and before you know it you spent $6k in a motor. I should have explained this better, the $3k is just to get all the major components on the engine, I.E. the block and everything up to the intake. I’m sure there is going to more money spent on the motor than 3k. My son is going to be putting in some money as he gets paid to keep the project going.

I looked around on Craigslist yesterday and found a 1979 running 350 for $200. I’m sure something like that I can tear down and get the block looked over and made true and bore it out by a machine shop and then get a new 400 c.i. crank with all new internals and build it that way. Would that be the cheapest way to go or buy a 383 crate with all the internals without an intake and heads and then buy new vortec heads? I know you can’t quote me exact numbers but I’m looking for what would be the best way to go as far as cost. I understand what you’re saying as far as where I get the vortec heads from to be careful what I’m paying for. I’m sure I would go for a new set unless a machine shop sells me a set of rebuilt ones for a good price and have their guarantee on them.

I agree with keeping it carb and use the NEW quadrajet carb that I recently bought. I would like to get in touch with someone that knows how to build the quadrajet. Please send me that info.

I would like this motor be something you can drive every day and have some good torque for towing, so no mean cams or loping. That way the cruise control and power brakes work like normal. Of course if you get on the gas just goofying around the truck will “**** and get”.

With all the work we are doing to this truck the tranny will be sent in to be rebuilt at some point. Along with the axles and u-joints.

This was an old farm truck that had many years of neglect and its share of abuse.

Now here is a question that I’m not sure on the answer but it’s just a thought. The old 305 that is in the truck now, can’t I take that block and bore it out to a 350 and just use that block? I mean the 305 and 350 share the same block right?

Again, thank you!!

 

[Dutch724]

Here is a pic of the truck that is due to get all the work done on it.

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[4WDKC]

On such a tight budget LS is probably going to be the route to go. Here is why I say that, based on the numbers I have spent on various projects.

$600+ for heads (used aftermarket or new vortec)
75 -400 intake if vortec route (found mine on craigslist),
120 Cam with lifters
$30 timing set,
gaskets $50-100 if vortec,

that 1k-1300 right there and we havent touched the bottom end or transmission. For long trips to wherever he goes its going to need od,

700r4 to handle 400 hp is 700+ for rebuild or buy new.
$100-300 for carb rebuild.
$2k bore, new crank, rods, pistons, rings, gaskets, bearings
Even if yo buy a 6.0 4l80E for 1600 you now have an engine that is 360hp dont remember tq, tranny that holds 450 tq easily, efi.

I am far from a LS swap fanboy but my recent vortec heads/cam swap showed me this and if I had to do it over again I would not do the vortec swap. Id either put the money into a big block that I already have or a 6.0 swap.

 

[4WDKC]

Thanks for all the advice I know it took some time to write it up and I appreciate it.

I do want to keep it on a close budget because I know how things can get away from you and before you know it you spent $6k in a motor. I should have explained this better, the $3k is just to get all the major components on the engine, I.E. the block and everything up to the intake. I’m sure there is going to more money spent on the motor than 3k. My son is going to be putting in some money as he gets paid to keep the project going.

I looked around on Craigslist yesterday and found a 1979 running 350 for $200. I’m sure something like that I can tear down and get the block looked over and made true and bore it out by a machine shop and then get a new 400 c.i. crank with all new internals and build it that way. Would that be the cheapest way to go or buy a 383 crate with all the internals without an intake and heads and then buy new vortec heads? I know you can’t quote me exact numbers but I’m looking for what would be the best way to go as far as cost. I understand what you’re saying as far as where I get the vortec heads from to be careful what I’m paying for. I’m sure I would go for a new set unless a machine shop sells me a set of rebuilt ones for a good price and have their guarantee on them.

I agree with keeping it carb and use the NEW quadrajet carb that I recently bought. I would like to get in touch with someone that knows how to build the quadrajet. Please send me that info.

I would like this motor be something you can drive every day and have some good torque for towing, so no mean cams or loping. That way the cruise control and power brakes work like normal. Of course if you get on the gas just goofying around the truck will “**** and get”.

With all the work we are doing to this truck the tranny will be sent in to be rebuilt at some point. Along with the axles and u-joints.

This was an old farm truck that had many years of neglect and its share of abuse.

Now here is a question that I’m not sure on the answer but it’s just a thought. The old 305 that is in the truck now, can’t I take that block and bore it out to a 350 and just use that block? I mean the 305 and 350 share the same block right?

Again, thank you!!

no you cant bore the 305 while it is physically the same size the cylinders are based on a 3.76 bore spacing where as a 283,327,350,400 is based on 4" bore spacing and is the reason 305s can only use 305 heads.

 

[Dutch724]

Thank you for your input.
I'm not a fan of putting a big block in the truck. I see the point of putting vortec heads on the motor and staying old school no wiring changes to mess with and all that. I don't know much about the LS swap. Are they just LS heads? would they still be able to keep the truck old school and be cheaper than messing with vortec heads?
please help me clear up this mess in my head. Whats the advantage of LS over vortec?

 

[4WDKC]

Thank you for your input.
I'm not a fan of putting a big block in the truck. I see the point of putting vortec heads on the motor and staying old school no wiring changes to mess with and all that. I don't know much about the LS swap. Are they just LS heads? would they still be able to keep the truck old school and be cheaper than messing with vortec heads?
please help me clear up this mess in my head. Whats the advantage of LS over vortec?

No the LS swap is a completely different engine, with multiport fuel injection and a computer that also controls the shifting of the transmission.

 

[1987 GMC Jimmy]

I think the numbers provided for the Vortec setup are pretty accurate. Maybe even on the conservative side if you can’t find anything on Craigslist and have to buy new or used online. A head that was popular back in the day was the Camel Hump factory casting. Those can be worked if you find a good pair, but some didn’t come with accessory holes and the older ones that haven’t been serviced may not have hardened valve seats because they were initially designed to run leaded gas. They’re just an old school design, but they can do well if you find a good set. I don’t know if the economy type new heads (Summit, Jegs) are any good, but those will run you a little cheaper. That $600+ figure is pretty standard for the new “good” heads. If it were me, I’d look for deals and base it on that, but Vortec heads come with additional costs after the fact. Regular or aftermarket heads will keep open a lot of good deals so that route makes a little more sense to me. I’m not an LS guy so I won’t go into it, but I think you should keep and open mind. The people who built my carb are a husband and wife outfit, their names are Ted and Ardell, and they’re called Mountain Man Carb out of Hackett, AR. 479-639-2022

It shouldn’t be too bad if your rebuilt carb is good, but sweat shop rebuilds can be fishy sometimes. They’ll probably just recalibrate it for the engine specs you want, which is significantly cheaper. Quadrajet Power is another one, and he’s a member on here. I haven’t used them, but I think they’re held in good esteem. I think he charges $50 for a recalibration.

 

[4WDKC]

The problem with double hump heads is those that have them think they are made of gold and in reality require the above work to be used along with alot of port work to even be compared to the TPI heads of the 80s. By the time you buy the double hump heads, have the necessary work done its the same or more than the vortecs. I would and have used TPI heads over double hump just because they flow about as well can be had for alot cheaper and dont need the amount of work. These came in two forms stock cast iron on the camaros and firebirds with 64 cc chamber and the alum. corvette/zz3 crate engine heads with 58 cc chambers

 

[QBuff02]

Based off a little of what I've read, it might be of interest to you to find a local engine machine shop to you and see what the prices are for a ready to go rebuilt engine.. I say this because for example, the one local machine shop to me offers what's basically a reliable .030 over 355 in the 300-325 hp range for about $1,800, and they offer it with a warranty. For a few hundred $ more, they offer a few upgrades to like the cam, timing chain and gears and better pistons, etc. depending on application. I don't know what the "going rate" is in your area but you might find something that's appealing to you by making a few phone calls. If a 383 is truly the route you want to take, The rotating assemblies have gotten way cheaper in the last few years and a complete new rotating assembly ready to install can be had for $700ish dollars, but then you've also got to figure in machine work and prep before assembly, because putting a stroker bottom end in will require modifications to the block and possibly the connecting rods for clearance. It can be done somewhat "budget friendly" but will cost more for the obvious reasons, and then you've still got to decide on the direction to go with the top end. Which could cost a couple hundred to as much as a grand or more. We know the 355 won't have the torque of the 383, but pretty much anything you do will be light years over the worn out engine it sounds like the truck currently has.. Just some food for thought.

 

[Dutch724]

If the difference between the LS and vortec I understand is the top end selection for the motor and cost of that. I do like staying old school that way I'm not taking this truck too far off from where it started from, as far as wiring and certain components. It looks like I will be contacting some of my local machine shops and seeing what they might be able to offer me.
At least I have a place to start from now. thanks for the help, if you think of anything else please let me know.

 

[4WDKC]

If the difference between the LS and vortec I understand is the top end selection for the motor and cost of that. I do like staying old school that way I'm not taking this truck too far off from where it started from, as far as wiring and certain components. It looks like I will be contacting some of my local machine shops and seeing what they might be able to offer me.
At least I have a place to start from now. thanks for the help, if you think of anything else please let me know.

The LS is a completely different engine from oil pan to map sensor nothing will fit a sbc.

 

[Dutch724]

Ok, but LS requires fuel injection and electric fuel pump or can you adapt that to old school setup?
Once you put vortec heads on you have to have a vortec intake, but you could adapt that for mechanical fuel pump and carb?

 

[1987 GMC Jimmy]

Ok, but LS requires fuel injection and electric fuel pump or can you adapt that to old school setup?
Once you put vortec heads on you have to have a vortec intake, but you could adapt that for mechanical fuel pump and carb?

Gen III (LS):

You’ll have to have an electric fuel pump and a regulator to run a carb using a decent in-tank pump that’ll have some longevity to it. If you did that, you’d need to convert to a 1987 fuel tank because that one has the baffling for an in-tank pump. There’s no cam eccentric for a mech. pump, and your only option that I know of would be to do a belt driven pump which would take away your A/C compressor. You can run your Quadrajet on an LS, but you’d need an ignition control box since there’s no distributor on those. You could get a distributor kit, but I think you’d still need the control box. The only thing that you’d gain with that is having one ignition coil instead of 8. I’m not 100% on the last part, but someone can check me. I don’t say this to stand against the people who love these motors, but this stuff is why I don’t like them. You can do a somewhat old school setup with those, but it’s gonna cost you more money to do that than the factory setup.

Gen I Vortec:

Vortec is just called that because of the heads. The Edelbrock 2116 is an a Vortec spread bore intake. The GMPP intake I mentioned in my initial post is for TBI Vortec conversions. That one is crazy expensive, but the Edelbrock one is not bad. If you run an 86 or older block, you’ll have your mechanical pump. If you find an M Code 350 or just an M block, those were carbureted until 1988, but I doubt there’s an SBC newer that will have a spot for your pump.

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