5.3L GenIII /TH400 swap

[68fleetsidec20]

The 350 in my truck was on its last legs; the heads were cracked, valve seals leaking, cylinders heavily worn and pitted and it failed the emissions test misserably, so it was time for something new.
I picked up an almost complete 5.3L for around the cost of a low milage sbc. I decide to keep the TH400 as with my 30" tall tires and 3.08 gears I wouldn't be needing overdrive, although torque converter lockup would be nice.
Two days I pulled apart the front end of the truck and pulled out the tired 350

Yesterday I finished preping the engine and bolted it to the transmission using a spacer GM12563532 and new longer bolts GM12563533. The spacer and bolts are to make up for the shorter torque converter of the TH400. I had heard that the flexplate had bolt holes that would match up with the th400 torque converter, however I did not find this to be the case. Using the extra raised pads on the flexplate I carefully drilled holes to mount up with my torque converter. This seemed to work good.


I was then able to drop the engine in keeping the transmission in its stock location so that the shifter linkage and driveshaft would be uneffected. For the motor mounts I used common adaptor brackets and swaped the original trucks pedestle mounts side to side and 2 of the 3 bolt holes lined right up. The third one I will drill.
I test fitted the factor 5.3L exhaust manifolds and the drivers side fit with minor modification.

and the passanges side with a little more modification. The frame will need to be slightly clearanced as well. However If I not mistaken the 67's have wider frame rails around the engine then the 68-72s so it may not be an issue with other trucks.

The heat shields caused problems on both sides so I will leave them off for now, but the should fit with some modification.
I'll keep this thread updated with my progress, the plan is to have it finished by the end of the week.

[OLDIRON69]

Stupid Q maybe....Are you able to use the TBI or not?

[shifty]

What TBI? It's an EFI engine.

[OLDIRON69]

My bad, EFI. That's what I meant

[shifty]

Sure, just need to have the computer reprogrammed and modify the harness accordingly.

[gringoloco]

Sweet! Let's see some installed pics. Looks great so far.

[68fleetsidec20]

Today went a little slower then I was hoping for. I under estimated how much I needed to notch out of the frame to get the passengers side exhaust manifold to fit. but I did get it in eventually.

I then spent some time hooking up vaccum lines, linkages etc.

One item that didn't come with this engine was the starter, I went down to the parts store and they list at $450, I couldn't believe it. My cost was $275 but even that is like 3 times the cost of a sbc starter. And the starter bolts at $13 a piece, making me start to wonder if this Gen III thing is a good idea.

The rest of my day was spent on the fuel system. I converted the pickup for a return system.


and installed a low pressure pump.

I decided to run the fuel system on the out side of the frame rails as the inside is tight with the exhaust and brake lines.

Tomorrow I have to find a fuse/relay box get some adaptors for my fuel system and power steering and figure out the air intake. I guess I should have been more prepared, it might be tough to get this wrapped up this weekend.

[shifty]

I bought this setup, after seeing it installed in '68 short step's truck:

http://cgi.ebay.com/ebaymotors/1999-...9768QQtcZphoto

With that said:

Pros: It looks sweet and comes with everything you need.
Cons: You gotta move your battery to another location.

I am using a stock auxillary battery tray to move the battery to the passenger side of truck

Notes:

RE: your fuel line setup: Very creative. BE AWARE: you need to be able to put at least 50PSI to the fuel rail, make sure your pump can generate that. Your engine should have a regulator built into the rail if it's truck/newer.

Don't forget hose clamps be sure your fuel line can handle 50PSI pressure without blowing up

[shifty]

PS -

people ask "how much does this swap cost?!"

http://www.ls1tech.com/forums/showpo...&postcount=188

i went with a simple fuel system I knew would be adequate, one that would move the tank out of the cab. cost for a very modest kit (no frills) was over $1,000. this included the tank, pump, lines, fittings, filter/pressure regulator, pressure gauge, etc.

that post might be worth a read. Actually - that entire thread may be worth a read, i dunno.

[shifty]

PPS, then I quit posting.

The '98 Camaro/Transam stock manifolds fit without hacking the framerails - you used custom mount plates, so the hacking would simply be "less". using the ECE engine mounts ($250) with the 98 manifolds == no hacking the rails.

[68fleetsidec20]

Shifty; As I am using the stock unbaffled tank it is best to go with a low pressure pump, a small storage tank then a high pressure pump. This way even as the fuel sloshes around in the tank the engine will never lose fuel pressure. Hopefully tomorow you will see the rest of my fuel setup. As for hose clamps, they will be added I am just mocking everything up for now. Thanks for the link but I think I will just make my own system.

[68fleetsidec20]

Shifty; One recurring theme you might notice for this swap is cheap! My fuel system comes in under $200, new manifolds cost more money and fancy mouting kits are expensive. The end result my not look nearly as pretty as yours but should function just as well. When I finish I'll post a picture of the truck and you'll understand why "pretty" is not a big concern at the moment.

[ND_guy]

I want one! Maybe I should have two. Good work I hope it turns out ok.

[gringoloco]

One small suggestion on your sending unit. Either shorten your return line, or bend it away from the pickup. I did a set-up like this (in a '67 Mustang I dropped a 5.0 and T-5 in) the same way as you, by soldering the return in place. If the return is right next to the pickup, you may have problems with aerated fuel being sucked up directly from the return line.

Keep us updated on the progress. I'm like you- I'd rather build it and save a few bucks than buy it. Bites you in the a$$ sometimes though, when it would have been cheaper/easier just to buy it. Oh well, that's all part of the fun...

-Chris

[shifty]

"fun" lol, sounds masochistic to enjoy chasing frustrating bugs like sucking aerated fuel causing strange engine problems

anyway, i see cheap is the theme, i just want to make sure you know that you will need to produce an average of 50psi fuel pressure to the rail.

[68fleetsidec20]

Don't worry Shifty this isn't my first conversion. My current daily driver is a 1967 firebird powered by a megasquirted 454.

Gringoloco; The picture makes the pick up and return look closer then they actually are, plus the pickup is a little deeper in the tank then the return so as long as air continues to be lighter then gasoline it should be fine. Not to mention my system is designed to handle some intake air as you should see later today.

[shifty]

Sounds sweet

Not trying to bully you or shove info down your throat, just sharing the knowledge!!

[gringoloco]

Originally Posted by 68fleetsidec20

Not to mention my system is designed to handle some intake air as you should see later today.

Yeah, I forgot about the external sump. Shouldn't have to worry 'bout that at all.

[68fleetsidec20]

Today I finished my fuel system (minus hose clamps) with my reserve tank, high pressure pump, lines filter, etc.

To quickly explain the external sump;
the top left line is low pressure fuel comming in
the bottom right is fuel going to the high pressure pump.
the bottom left is the return form the engine
and the top right is back to the gas tank.



I used the Russell quick connects to mate to the fuel rail


Then I took some time to start the wiring

Earlier I made use of the ECU pinout and removed all unnecessary wires from the harness such as transmission, EGR, etc. I must have pulled a third of the wires out which makes things a lot simpler. I'm not to happy how the main junction of harness is located right in the middle of the intake, so I'll probably take some time to reroute the wires to make them more hidden.

I also put the radiator support back on as well as many other missalanious things.

[57T210]

Nice work. Excluding 'parts runs', how many hours do you figure you have in it to this point?

Regards.

[shifty]

I think I'm going to re-wrap my harness today ... and then punch it through the firewall about 3-4" in from the heater core so I can keep the ECU inside hte truck.

[68fleetsidec20]

57T210; Excluding parts runs, cleaning and painting the engine, and spending hours reading forums I probably only have less 35 hours into it and thats including the long day I put in today.

Today I went out looking for a fuse box and came up with this,

its out of a 1994 Grand Prix and seems to have everything I need and puts it in a nice package.

I tried to get some 4' aluminium bends for my intake but the local performance shop does't carry anything that size so Monady I'll get some 4" 304SS bends from work and fab up my intake. Untill then I bought a 90 degree plastic plumbing pipe and clamped it in.
The majority of my time today was spent on wiring. It was something I was looking forward to but once I got my game plan set up it went pretty smoothly. I managed to move the harness around so all the wires didn't sit right in the middle of the intake, instead tucking up around the backside. I got the majority of the wires soldered and heat shrunk into there respective locations and some just temporarily wired until I have more time tomorrow. I plugged in my ecu, which has been reprogramed by Wait4me Performance and primed the fuel system to check for leaks. Finding none I tried cranking it, to my disappointment it didn't fire. I confirmed spark and fuel pressure and I'm pretty sure that the injectors are firing so I'm not sure what the problem is. The guy I bought the engine off of had poured tranny fluid down the cylinders Earlier I had done my best to drain it but the spark plugs are fouled so I'm thinking that a fresh set might fix the problem. It was geting too late to keep working so I called it a night. Hopefully tomorow I will get this wrapped up.
Any suggestions on what might be wrong are apprecaited.

[killer71]

where did you get your air breather set up?

[Redaddiction]

Good looking swap. I can't wait to get mine underway.

[69Custom]

I had the same problem with mine. It ended up that my injectors were clogged. The only true way to make sure that they are not clogged is to pull one out at and hold a towel under it and have some one crank the engine. That is how I found out that mine were clogged. You just have to tap them till they work again. I know that it sounds weird, but it works.