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frodin1 11-16-2011 06:22 PM

6.2 Diesel to 5.7 Conversion Information
1983 6.2 liter Diesel to 5.7 liter SB Conversion

I decided to write this all down since there have been such a variety of answers to the many questions I’ve had during this conversion project. I started out with a 1983 K20 “4X4” Chevy Silverado with the 6.2 liter “J”code diesel engine and TH400 automatic transmission. The engine in the truck was badly damaged, and I already had most of the components for the 350 engine in my garage so this is the reasoning behind the swap if you were wondering WHY go gas? I didn’t have the funds for a replacement used diesel, nor a newer complete roller Vortec motor, which would be the route I wanted to go with this. The used 5.7-liter Vortec motors I was finding in my area, were in the 500-700 dollar range and would still require a complete rebuild, seeing is they all had around 200,000 miles on them OUCH!. So I’m utilizing what I have!
OK, the 350ci engine I have is an older 2-piece rear main, 4 bolt. I also purchased a serpentine belt system, as well as a used set of “906” Vortec heads off of a 1996 Chevy truck for $300. There were many articles floating around out there about the hardened valve seats on certain 906 heads restricting flow. However, the newer information and testing has proved the opposite to be true. So if you can get a set of either, grab em’! My plan is to bore the cylinders .030” over and rebuild it, as well as use the stock crank and connecting rods “rebuilt of course”. I’m using a set of Keith Black 142-030 dish pistons, and a cylinder head improvement kit from Competition Products part #8511. I plan on running an HEI distributor, a Howards Cam and lifter kit part #CL112011-11 with an Edelbrock Performer intake manifold part# 2116, and a Quadrajet carburetor. This should provide me with good fuel economy, along with the power when I need it. As well as the option to do modifications later without needing a new bigger carb!
The serpentine system I purchased includes all the necessary brackets, the newer style A/C compressor “HT-6” that will be replacing the A-6 “Monster” Compressor that was in the truck originally, as well as the newer style alternator “CS130D”. However, I needed the pigtails/plugs for both the alternator and A/C. The A/C clutch plug is AC Delco PT209 and rear of the A/C is part# AC Delco PT1798. The Alternator is a 4 pin connector part # AC Delco PT368. All the connectors are readily available and can be found at: or As far as the wiring goes, on the A/C Clutch, the wires are not polarity sensitive. Which means you just hook one to ground, and the other to your positive source. On the rear of the compressor, this is the high-pressure cutout switch, and you can either run the hot wire or the ground through it. It automatically cuts the compressor off, if the pressure hits 427psi. With the alternator wiring, like I said there’s 4 pins. Pin A, is not used, Pin B needs a 12volt switched source, Pin C Not used, and Pin D 12 volt always hot. You can see the diagram at: as well as numerous other places on the web.
The power steering pump was another issue to contend with. Since the truck used a hydraulic brake booster, I needed to keep the original pump that was in the truck but still be able to use the newer serpentine belt and brackets, not the V belt it’s setup for. It turns out these pumps are interchangeable and you can swap the pulley over as well as the needed brackets for proper mounting to the serpentine brackets and motor.
A couple snags I’ve run into that I really couldn’t find mentioned, I’m running an aluminum timing cover, and a stock harmonic balancer. Finding the correct timing pointer has been a quest, but I ended up going with a Summit Part # 163800 as the cheap ones wouldn’t work for two reasons. One they wouldn’t bolt up to the aluminum cover made by RPC, however similar to the Summit G6300W. Two, being that it was to long and would cover over the entire balancer. The Summit #163800 pointer would require a slight shave to make it the correct distance from the block and I shortened the screws as well. Another snag I hit was the water pump. I purchased a reverse rotation, high volume pump off our favorite auction site “NOT”. However, these 97 serpentine systems use a different style pump that has a wider bolt pattern and a threaded stud that connects to the fan clutch. So I went with the pump for a 97 Chevy truck. The next issue was the 97-water pump, does not have the bypass port that is on the Gen 1 350 block, passenger side. I had to tap and plug this port on the block, and use the bypass system that was built into the Edelbrock 2116 intake manifold. The instructions for the 2116 manifold are quite vague on this “bypass” subject, however if you look up part number Edelbrock 7116 on it explains it in detail. So the engine build has gone straight forward, and with these few snags, everything has gone smoothly. In between building the motor and waiting on parts, I completely removed the interior and pretty much everything off the outside as well. Time for paint! I sanded everything down, fixed a few of the small rust holes that were behind the rear wheel wells, a couple dents hear and there. I painted the engine compartment and while I was there, I decided to remove the engine wire harness, and add a couple wires I needed for the electric choke, tachometer, oil pressure, and temp gauge, as I’m installing some real gauges. Not just the ones that came with the truck. I’m using an electric fuel pump as well, Summit Part# ATXE8012S, and I will be using the pink wire that was used for the injection pump on the original harness. The fuel pump is a lower pressure unit as I’m using a newly rebuilt Quadrajet carburetor and according to the instructions, they recommended only 5 PSI max to this carb. Because of this I also purchased a fuel pressure regulator and fluid filled gauge to go with it. I’m going to be utilizing the large canister style fuel filter unit that was used on the diesel setup as well since I still had a new filter for it. Overkill, yea. But why not? I’ll let you guys no more as I get closer to firing it up. Should be there eventually.

TroyBoy 11-26-2011 11:40 AM

Sounds like a fun build,lol. Does your existing trans have the same bolt pattern and the 350? Good luck :thumbup:

frodin1 11-26-2011 05:30 PM

yup, bolted right up to the TH400 I had rebuilt. I've run into a couple snags here and there, but nothing that can't be taken care of.

TroyBoy 11-27-2011 05:50 AM

Engine looks nice and you cant go wrong with a Qjet IMO. :thumbup:

frodin1 04-02-2016 03:09 PM

Need help with this build
Its been sometime now as I kind of gave up on this project. I'm having a cooling issue, as well as smoke when under high acceleration. Here's my question, since Im using an older block with the newer serpentine setup with vortec heads, should I be using a reverse rotation pump? I read that only some of the serpentine setups used a reverse rotation setup? Plus with the reverse setup, I have that funky water pump bypass setup that hooks into the intake manifold. When running , the radiator doesn't seem to have any flow, where as the normal water pumps you can see it moving. I'm trying to think of anything before I start ripping into this thing to see if there's a gasket issue. It runs fine, NO water in the oil, no milk anywhere in the system. If anyone has a clue as where to start, please let me know...... I'm lost. I'm going to pull the numbers off the block later just to see what i'm dealing with. Smoke is'nt oil more of a water vapor. Need someone experienced with this setup. HELP

joe_padavano 04-02-2016 04:33 PM


Originally Posted by frodin1 (Post 3629378)
Its been sometime now as I kind of gave up on this project. I'm having a cooling issue, as well as smoke when under high acceleration. Here's my question, since Im using an older block with the newer serpentine setup with vortec heads, should I be using a reverse rotation pump? I read that only some of the serpentine setups used a reverse rotation setup?

This is kinda common sense. Put the belt on the engine. If the water pump turns in the same direction as the crank, you need a conventional pump. If it turns opposite, you need a reverse rotation pump. From your photo (the belt isn't in place), it appears that you need a reverse rotation pump.

frodin1 04-02-2016 06:23 PM

Yea that's whats on it, as well as a reverse flex fan. I went with a flex fan because the stock clutch fan setup wasn't really inside the shroud, so I extended it and put the flex fan on. I'm just wondering if the by bass system is screwing me up? One thing for sure something isn't right. I figured if it was a head gasket I'd have water in my oil and or the plugs looking bad which everything looks normal. So I'm utterly confused. I guess I'm going to have to pull it back apart. It sucks because it runs perfect. I had the heads done at a local shop, so I'm wondering if I'm having a seat issue. I purchased a rebuild kit off flea bay with all stainless hardware and top notch parts, but they used stock components. I think I'll have a look and see whats going on.

jokerZ71 04-02-2016 06:34 PM

Fixing to do this swap as well in my sons truck, but, mine will be a little more complicated as it'a 93 GMC.I'm putting vortecs on an 89 tbi motor converted to roller cam & will be using EFI & the current 4L60e in the truck now.Glad to hear about the power steering pump.Still trying figure out what all I need to about the instrument cluster.

frodin1 05-19-2016 09:28 PM

Trouble and need some foresight,
Im still getting smoke, its most definitly water. No water in the dino oil with break in additive, plugs look ok, they supposedly went through the heads but who know anymore. I could use something to shoot for..... the drivers side smokes pretty bad where as the passenger barely smokes and thats only when reving up. I heard to check my intake gasket since theyre finiky, and possibly valve guides or head cracks? Any thoughs on this issue? Im assuming I have the bypass backward *** cooling is hooked up correctly. So? Im not sure where to start, Im half tempted to just pull the motor and put it back on the stand since its a 3/4 ton and sitting on new 35's. Tall! NEED HELP!!! PLEASE.

64nailhead 05-25-2016 04:37 PM

The water pump bypass isn't your issue. Is it building pressure in the colling system? If no, then I'd lean towards the intake gasket causing the issue. Or possbily some silliness going on with the intake itself. Have you pressure checked the cooling system when hot? Have you looked at the plugs? Is one spic and span clean? If yes, then that cylinder is the issue and the head is a very probable issue.

frodin1 05-25-2016 04:59 PM

Hey thanks for your reply, at least I have a direction to go now. I'll check it out and let you know whats happening
I just found it weird that theres no water in the oil on the cap or radiator? But will check it out. Thanks

64nailhead 05-26-2016 04:07 AM

There's no water in oil or oil in water because of where the leak is. Either of those things could be occurring with a leaking head or head gasket, but neither of them could be occurring as well, it's all a matter of where and what is leaking.

jokerZ71 05-26-2016 06:08 AM

What all was done to the heads during the rework? If the press in studs were replaced with screwin studs,were they properly sealed up?

frodin1 05-26-2016 09:34 AM

I have really no idea,.I got kinda pussed though because I bought the highflow kit off ebay and they ended up putting stock stuff back in. I have all new stainless valves, howard springs new comp locks, and they didnt use it. Its odd too, the hotter it gets the more steam or smoke im seeing. I ordered a new rad pressure test kit and a compression tester. I dont personally know what they did, if anything to the heads? Thats whats got me worried. I did buy them used.

frodin1 05-30-2016 01:51 PM

OK, I got the compression tester and checked the drivers side, starting from front to back, I got 100, 120, 120, &115. I did it twice to make sure. This was done on a cold motor because I actually have to pull the header off to reach the back 2 plugs. Its still 100 degrees out, but whatever. I'm still waiting on the coolant pressure tester to show up, but its looking like somethings wrong with that front cylinder? I've read a few different threads on this, but do I need to re torque the head gasket bolts after break in? Some say yes, some say no?

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