1991 V3500 Project Heavy Hauler

[MTCK]

My right manifold showed up right away, but just got the left one today. Go figure. I threw the right one on and torqued it down to 20 ft-lbs as specified and worked on getting the front accessory brackets on. The jack stand looked like it was going to quit so I put a jack stand under the front of the motor for a little insurance.

A buddy stopped by and was looking at my handwork and said, you know you have a cracked manifold? No f-ing way. Sure enough. I pulled it off and one ear about fell off. I put a straight edge on the head and it is perfectly true. OK, must have got a bad casting. Napa had one for about $80 bucks so I picked it up the next day.

It looked identical except it was in a Napa box instead of dorman. I put it on with no gasket and made sure it was perfectly true. Torqued it down using 4 passes and was doing final torque to 20 ft-lbs when I felt the same bolt get easier. Cracked that one too. My savings from ditching the header idea are rapidly going evaporating. The driver's side went on without incident, but I won't be buying any more Chinese exhaust manifolds. I'm going to the junk yard to see if I can find a straight, crack free passenger side manifold there.

[MTCK]

I've had a few more parts show up and have been plotting to stab this thing in now that our weather is improving. Harness and PCM arrived from Howell, and looks to be of good quality. There were a few quirks, but nothing terrible. The O2 sensors required are for a '96 1/2 ton 350. They are identical to the sensors you would buy for a 2000 1 ton 454, except female plug end instead of male. Returned those O2 sensors and picked up a pair a little motor.

One other point of interest is that the third VSS in the transfer case, the one that everybody pines after in a junk yard is not used. There is an input speed for the 4l80e, and output speed, and a switch for 4Lo which tells the PCM to adjust the speedo down. I've been reading and the output from the PCM is not the 4000 revolutions per mile that my speedo needs, so I'm going to try to retain the DRAC and VSS in the NP205. It is dead nuts on now and I don't want to screw with another side project.

I also ordered a Vintage Air HVAC system and am pretty excited to get that in. The folks in their tech support / sales were AWESOME. They made me a custom kit with the compressor that bolts in place of the factory unit and has cut to length lines to make sure it fits. Full disclosure - the kit only works up to '87 according to their catalog, so they were a little hesitant to send it for a '91. I'll document any customizations that need to happen.

[MTCK]

Alright enough talking, time to tear into this thing. During disassembly, I mocked up the auxiliary trans cooler and fan for the A/C condenser. I'm going to have to trim the brackets down slightly but I think they are going to fit great in the two openings in my core support.

Elected to remove the bumper and core support as my cherry picker can barely lift a 350 over it and the big block will hang quite a bit lower. Power washing, scrubbing and cleaning things up took a good chunk of time. Luckily weather has been great.

Real estate is getting to be scarce under the hood, and I'm having to relocate a few things. Washer fluid is being sent to the rear of the engine compartment on the driver's side. I'll make up a little bracket for it to live back there. My second battery, PCM, and pile of wiring trinkets will be residing where it was previously. The radiator overflow tank is also getting relocated to the rear on the passenger side. Once I remove the blower motor box (vintage air has all the components inside the cab), I think I can tuck it back there. This will make room for the factory air filter assembly. Induction noise and drone drives me nuts, so I want it to be as quiet as possible. Like most square body owners, the only sound I like is that of my wing windows howling as I go down the highway.

[watahyahknow]

maibe the flat spot where the nut pushes against isnt big enough and pushes the casting inward of the exhaustport breaking it in the process

maibe make youre own using steampipe pieces and thick flanges
https://www.youtube.com/watch?v=sskmMEekVlY
this stuff doesnt cost a lot compared to stainless and it stays together a whole lot better

[whitels1]

Looking good! bummer about the manifold.

[Greenlee]

Looking good Marcus! That's a bummer about the cracked manifolds. The mounting stud by the crack looks bent over just a bit in the picture? Maybe that's putting extra pressure when you tighten it up?

When I bought my Vintage Air, they said it would fit through 86'. I asked about that and they said it was because the under dash AC stuff might interfere with the location of the stock computer on the 87' and up TBI trucks. Probably no big deal for you since you are dumping the old TBI motor. I'm running the stock TBI, but my cab is an 83' and didn't have the mounting tabs for the computer anyway. After I got all the AC stuff in, there was barely enough space up top for the computer. I just zip tied it up there, but it fit tight and isn't going anywhere.

[MTCK]

Thanks guys. That makes sense about the tbi computer. The stud actually rolled over when the manifold cracked. I got a new one today and it bolted up without incident.

Got the last few pieces bolted up, cleaned and painted the rough spots in the engine bay.

[MTCK]

I had about three hours left to work and the engine was hanging on the hoist. Victory will be mine. Not so fast. These poly engine mounts are great when they are in but holy cow I could not get the motor to fall in to both at the same time. I'm a whipped puppy but I'll try some more things tomorrow. Anybody ever have luck swinging the motor in with the clamshells bolted to the mounts and set the whole assembly on the cross member? Am I missing some sort of bbc vs sbc trick? It's within 1/16" but just won't drop... PBR time.

[Greenlee]

That engine bay looks nice and clean! I wish I had some advice on getting that bad boy in there. 1/16th of an inch sounds awfully close, but close only counts in horseshoes and hand grenades.

[wildwilly4x4]

Are the mount buckets the ones that belong to the frame of your truck originally?

I had that problem using the big block one ton motor mount buckets from the one ton when trying to swap into my k5. I had to use the k5s original motor mount buckets. They were ever so slightly different.

[y5mgisi]

All good stuff!

[MTCK]

Thanks for the compliments. I'm using the buckets from the 454. I'll try swapping them. Thanks for the idea. Tend to get tunnel vision about three hours into a wrestling match like this. I decided it was bed time when I was standing in the garage, looking for a 9/16 wrench that was in my hand.

[COS399]

Looking good. Should be ready for those spring time chores. We had a mild winter.

[Dieselwrencher]

Nice project and your engine looks great! I've had that same dilemma with the wrench before! I've had a lot of big blocks with those clam shells and it seems like some are pinched closed more than others. Maybe spreading them out with a pry bar will help the engine drop down some?

[MTCK]

Thanks guys. Put the 350 mounts on and it dropped right in. Lots more to do...

[DirtyLarry]

Looking great Marcus! That is odd about the manifold cracking. Looks like those spark plug boot heat shields fit nicely for the manifolds. Not sure why they wouldn’t fit the manifolds for my FIL’s 454. Dieselwrencher nailed it with the engine mounts where the bracket that bolts to the engine sometimes needs to be opened. Another possibility is the mount portion that bolts to the frame could have been upside down.

Can’t wait to see her fire up!

[MTCK]

Thanks Larry, and thanks again for the heat shields and nuts. They took a little bit of massaging to get in there, and two of them I had to use bolts instead of studs in the adjacent hole.

I didn't take a picture, but there was definitely a difference between the 350 and 454 engine side mounts. Problem was the metal tabs on the poly inserts were too wide, even with clam shell to cross member bolts loose and spread all the way out. It literally fell right in once I switched them.

Mother nature gave a big middle finger this AM and it is snowing to beat the band, so I'm going to get the harness ready to go today, fab up my mounts for the radiator overflow and washer fluid tanks.

[MTCK]

So now I just hook up these wires and it works...

[DirtyLarry]

Yep, that's all. Just plug in the wires and fire it up. LOL If it was that easy any caveman could do this

[Greenlee]

Nice work. That new engine looks right at home in there.

[MTCK]

Thanks guys. I couldn't resist a little mock up last night. I think there is a good chance the factory L29 radiator hoses will work. Offsets and sizes are correct. To be seen.

[400/400]

Nice work!

[MTCK]

Thanks. Good looking pics on your build too.

I'm gaining a newfound respect for the engineers that package all this crap under the hood on new rigs.

[whitels1]

Looking good, keep it up and you will be done in no time!!

[MTCK]

Thanks Dave. I was shooting to get it to the exhaust shop this week and make a trip to anchorage with it this weekend but that isn't happening. One piece of advice if anyone ever does this swap: build your fuel lines and hook them up To the back of the intake before you drop the motor in! Took me two nights and cut a wrench in half to finally get the fittings tight. Fingers crossed for no leaks. It's finally starting to look like a truck again.