Diesel to 350 gas conversion 1986 dually frankensteiner

She looks Innocent enough but at the heart of this truck is a 1986 c20 454 that has been worked over again and again and again. It's had a rat's life

When it formerly resided in El Cajon Ca. it was a 3/4 ton. someone sprung up the rear and possibly the front and added wheel adapters and dually rims.
It also had a factory dually box installed.
For an engine it had a 454 with a turbo400 and doug nash overdrive unit. I think the controller for the doug nash is still up under my dash.
It was originally blue and whoever changed it over to white did a really nice job it was long ago and still looks good most places.



A guy who has a tire shop in Phoenix bought it for the engine and tranny to put in a 36 hotrod then he threw it up on ebay

I'm blogging here!

I bought it and had it trailered near home. it sat on a friends farm for a couple years before I did anything with it
I had a couple other trucks same body style at the time.
My objective was to restore my dad's 82 gmc diesel
I was a teen when he bought it and learned to drive in it. I got to ride with him to bring it home for the first time.
Man it was a gorgeous truck. Old trusty was a black and chrome GMC 1500 with tan interior white letter tires and rally wheels.
It had 150k miles on it when he gave it up.
I ended up putting the GMC grill, hood, fuel tanks, 6.2 diesel engine, 700r4 tranny, fuel lines and engine harness from the 82 diesel in this 86 454 truck.

It was an adventure and required a manual to trace the circuits. I had to re-pin a few things at the firewall junction.
While I had it torn down, I bought a junk 83 4dr c30 dually.

It had the heavy duty front brakes which have rotors about 1/4 inch thicker than a 3/4 ton or standard 1 ton, and the large calipers.
Had an accident bringing it home.
Going about 50 mph the suspension broke on the trailer and it got squirrely.
I took it to the shoulder to avoid the trailer hitting an oncoming car and the crooked trailer axle dug the wheel into the soft shoulder and rolled the trailer
Just before the 1-ton van was about to go over the center of gravity the hitch twisted off.
The van released from the trailer shot up the shoulder jumping the lane I was in and it bounced once in the other lane and landed in the ditch opposite the trailer wreck.
I got it stopped before it jumped the rr tracks and wheeled it around to see the trailer.
A trucker stopped and we drug the trailer further off the shoulder.
The Sheriff gave me 2 days to get it cleaned up. I dreaded the idea of paying for a loader and flatbed...

I came out the next night and jacked it up and welded in new suspension


The Dana 70hd rear in the 4dr was shot. the pinion pin had wallered out the case.
I got lucky and bought a 1990-something 14 bolt true dually rear off Jack Alger out in Vegas. it only had 40k miles on it for $300 He does towing and junks cars. he loaded it up behind the cab on my semi and I took it home.

I got that 14 bolt in there and got her on the road. it ran just as good as dad's truck but after about a month the 700r4 pushed the front seal out and died.
I swapped in a th400 and got a year out of it. I don't think the old 6.2 liked the 4:11 gears. It started leaking antifreeze past the head gasket to the outside on the passenger side and began to use oil. sometimes a little almost nothing...and sometimes 4 quarts a day.
I nursed it through the winter and most of the summer.
My plan was to overhaul it this winter but she sucked the pan dry one day and threw a rod a few seconds after losing oil pressure.

I had a mean 4x4 van that I traded my brother for his old 85 chevy and an air compressor.

He had put an engine in the 85 I gave him a 350 steel crank 4 bolt main and he built it up pretty good. I took it to denver and it got 13 mpg running 70 with 3:73's

After the diesel died

Well I was looking around for another diesel after doing all that work switching it over and the more I thought about it the more I figured I would get the 86 c20 dually running again with what I already had.
First off pull the 6.2..
I got $150 for the injector pump and $50 for the starter off the dead mill.
got the 350 installed...
learned something new...

Now when I put the diesel in I couldn't get the diesel to bolt to my 86 454 stands.
I used the stands from the 1500 but a c20's frame is not as tall as a half tons here.
Rather than shimming the top flange off my frame an inch, I cut the flange from the stand and bolted it in place. Then I bolted in the stands bottom bolts.
I put the engine in, bolted it up and let gravity spread the stands then welded the flanges back to the stands.
all good.
Well now I'm jerking out the diesel and putting in a 350, I get on the internet and people say the smallblock and bigblock share the same mounts so I put the 454 stands back in and the 350 wont bolt up.
It turns out that... the 6.2 diesel and the chevy smallblock share the same mounts.
So I put them back. I'm out side and it's cold. I'm not happy but it's in there.

An 86 smallblock truck has radiator bungs about 1.5" on the bottom and 1.25" on the top. it's radiator is a 28" core
My diesel radiator is a 34" core and has 1.75" bungs top and bottom...
Solution... 1970 smallblock radiator hose on the bottom and I used a section from 2 different hoses and a section of 1.5" copper pipe with a coupler silver soldered to the radiator end to give me my 1.75".

I got everything hooked up and running normally.
I saved the engine harness from my brother's 85 which fit my 86 perfectly.; The esc was deleted on my brother's truck when he put that engine in so I didn't have to mess with that.

next job... the exhaust

Exhausted!

neighbor was throwing out this top rail from a swing set.

It had a couple nice mandrel bends and is about .010 thicker than exhaust tube
I have a mandrel tubing bender but it's missing some dies
first off I have a set of good used quicky header pipes from a beater.
I remove the collector flanges
clean them up
clean up the U bends from the swingset
got my gear on
and get ready to build Mufflerbearings!

Mufflerbearings

Who all hates leaky header collectors?
I do...
Gotta have Muffler Bearings!

I learned this trick from the guys at Exhaust Pros on 36th street South Omaha give them the props. It's not exactly how they do it...they use a smaller pipe for an insert and expand it.

I used the same size 2.5" pipe and removed a rip of 1/2" and clamshelled it back together so it will fit inside the 2.5" pipe and the donut.

My insert had a little tension on it to hold the donut in place. I could have tack welded it in place but chose a self tapper.

then I began to weld up the pipes.

I don't have a mig right now I lost it to hock getting some "looking for a job" money last year.
For this task I'm simply gas welding with copper coated steel rod

got to get over the tranny crossmember on the driver's side...

mock it up, tack it and test fit it on the truck...

and weld her up.

I'm sorry, I had some really nice pictures of the pipes for both sides both after fully welded and after I stripped them and painted them with black 2,000 degree ceramic header paint.
I put a new turbo on my 96 mack and used that stuff on the Iron manifold and turbo housing. It lasted 5 years and still looked good when I sold the truck

My next thread I'll show all y'all how I put 77f150 4x4 suspension into a 76 f250 2 wheel drive and made it look stock. that truck is a frankensteiner too

video of it running

I just put a video up on you tube of a cold start. well i started it an hour ago then I went back out to film....

lets see if I can get this to work...
nope no video...
You'll have to go there yourself...
Here's the link... http://www.youtube.com/watch?v=TvjLD06wZc0

what do all y'all think?

Should I post a thread on my conversion of a 76 f250 into a 4x4 or would that be more welcome over at ford truck enthusiasts?

Got a new ride! has 181k miles on a 4.6 need to do the timing chain slack-taker-uppers but it's getting about 50% better mileage than my dually with the 350.

The front end in my dually is getting pretty loose starting to death wobble on me
The 350 is still running great but ti has to work really hard towing.
The tranny has a gazillion miles on it and is shifting soft and slow when cold.

Picked up a rebuilt 700r4 for cheap a guy never got around to installing and a tci BOP to chevy adapter.
Sitting in the garage is a fully rebuilt 1967 389 with an edelbrock performer rpm cam and intake and 6x heads...

sounds like a little rough luck on the trailer there..... So what do the finished pipes look like?

Neverdone said:

sounds like a little rough luck on the trailer there..... So what do the finished pipes look like?

Click to expand...

it got dark and snowy I never thought to take pics>
I got them back the the back of the cab but didn't get the kick outs in>
i was going to have them turn out in front of the duallys with stainless tips

Behind the tires I'm going to hang mudflaps

And out in the garage is a shiney new 67 389 pontiac engine bored out to 400 with 6X heads and an Edelbrock performer rpm setup
I have an adapter to mate it to a chevy trans and can keep the th400.
I have a rebuilt 700r4 but I'm skeptical.
Should I try it?
I had one in there before behind the 6.2 diesel and it did give out but it had 150k miles on it.

Torchmann said:

it got dark and snowy I never thought to take pics>
I got them back the the back of the cab but didn't get the kick outs in>
i was going to have them turn out in front of the duallys with stainless tips

Behind the tires I'm going to hang mudflaps

And out in the garage is a shiney new 67 389 pontiac engine bored out to 400 with 6X heads and an Edelbrock performer rpm setup
I have an adapter to mate it to a chevy trans and can keep the th400.
I have a rebuilt 700r4 but I'm skeptical.
Should I try it?
I had one in there before behind the 6.2 diesel and it did give out but it had 150k miles on it.

Click to expand...

I say ditch the 700R4 never ran one, but most of my friends have had no luck with them. Of course we aren't all that gentle with our trucks either. I have a TH400 in my jeep and it has always treated me well.