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The GMC TORO-FLOW Diesel Engine, was basically the gas V6 engines converted to a Diesel.
I have heard alot of bad things about these engines, how they were under powered & broke down
a lot. Most ended up replaced by a Gas powered GMC V6 or V8 engines. They also built a 637 V8
Toro-Flow Diesel Engine. I have also heard a lot of good things about these eninges when they
got placed into pickups & 1-tons. they had plenty of power & got great fuel milage. It looks as if
GMC misssed the calling on these engines, instead of powering Large Trucks & Buses, maybe GMC
should have used them as an early Light Truck Diesel Engine. Below you will find some photos of
repowered trucks, engines & equipment the Toro-Flow was used in. They also Used these engines
in boats, I have heard from many owners looking for parts in recent years, so it would apear
that running in aboats was another job that was well suited for the Toro-Flow Diesel.

Toro-Flow Engine Specifications

Engine Model

Gross Horsepower

Net Horsepower

Gross Torque lbs. ft.

Net Torque lbs. ft.

Bore - Stroke




D351 V6

130 @ 3200 rpm

~ @ 3200 rpm

~ @ 2000 rpm

~ @ 2000 rpm

4.56" - 3.58"

351.2 cu. in.

17.5 to 1

D478 V6

150 @ 3200 rpm

135 @ 3200 rpm

275 @ 2000 rpm

266 @ 2000 rpm

5.125" - 3.86"

477.7 cu. in.

17.5 to 1

DH478 V6

170 @ 3200 rpm

155 @ 3200 rpm

310 @ 2000 rpm

298 @ 2000 rpm

5.125" - 3.86"

477.7 cu. in.

17.5 to 1

DT478 V6

220 @ 3200 rpm

5.125" - 3.86"

477.7 cu. in.

17.5 to 1


D637 V8

195 @ 2600 rpm

185 @ 2600 rpm

450 @ 1800 rpm

440 @ 1800 rpm

5.125" - 3.86"

637.0 cu. in.

17.5 to 1

DH637 V8

220 @ 2800 rpm

200 @ 2800 rpm

458 @ 2000 rpm

444 @ 2000 rpm

5.125" - 3.86"

637.0 cu. in.

17.5 to 1

Twin Turbo Setup.

GMC Toro-Flow V6 Diesels

Photos of GMC Toro-Flow Diesels

Jolly's DH478 Toro-Flow. This engine came from a 1964 GMC 4000. I paid Scrap price for it.

Photos sent to me with NO NAME D478

Seen at the in Antique Powerland Museums Complex, Brooks Oregon.

1967 GMC Pickup ~ Toro-Flow D478 V6

1967 GMC pick-up truck With GMC Toro-Flow D478, 170 hps, V6 engine. Matt Chipman's Father
also took the time to repaint the truck a nice marron, re-upolster the seats & install
a nice Pioneer Am/Fm Radio in it. He had this truck from late 1974 to fall of 1978. He
really liked this truck. I remember as a small toddler that this truck had a lot of power.
Also Associated Diesel Went out of business in 1985.

1967 GMC 1 Ton Dually ~ Toro-Flow D478 V6

This truck was purchased new in 67 brought home fitted with a new 67 GMC Toro Flow,
Air Compressor, Dual transmissions, Air Assist Brakes, Full Gauge Package, Dual Wheels and then
re-titled as a diesel truck. The truck is in original un restored condition and runs strong.
I purchased this truck a year ago just because is truly a one of a kind cool truck. I kept tabs
and insurance on it for a year and drove it very little. Two things that I have found wrong with
the truck are bendix on the start is going and a rear wheel cylinder is leaking.

Older GMC Truck ~ Toro-Flow D478 V6

Danny Shimizu Of the Rockey Mountain Chaper of the ATHS has a big collection of old truck
by his shop. this old GMC in part of that collection, and at some point in it's life it
was repowered with a GMC Toro-Flow Diesel engine. More of Danny's Trucks.

New Idea 702 Uni-system Power Unit

Back in the late '60s early '70s Avco built the New Idea No. 702 Uni-system Power unit. This unit
was used with different attachments to pick corn, wheat, & even had a snow blower. It came with
some three engine choices, the ones we're interested in on this page are the Toro-Flow Diesel Utins.
Here is one more place to find those Toro-Flow V6 engines, so keep your eyes open,
you may even find a HD478 Toro-Flow Diesel. The Unit shown below belongs to Marti Sacks.

Information About GMC Truck Drive Trains

1960-1974 GMC V6 & V12 Engine Data

GMC's Twin-Six V-12 Engine!

1960-1966 GMC's Inline 6 Engines

Powered by GMC V12 Engines

GMC Diesel Engine Data Page

GMC Twin-Six V12 Myths

Carburator Data Page

1965 Article GMC Irrigation Engines

GMC Toro-Flow Diesels

GMC Twin-Six V-12 Registry

GMC Transmission Data

Powered by GMC V6 Engines

GMC Drive Axle Data

Spicer 5831 Aux Transmission

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