Rise, Lazarus: Waking Up A Detroit Diesel 8V71 For A Dodge D900 Project


Rise, Lazarus: Waking Up A Detroit Diesel 8V71 For A Dodge D900 Project

I’ve become addicted to the Bus Grease Monkey channel on YouTube. We’ve shown you his handiwork before…this is the guy that wakes up old GM buses and gets them back on the road. The key to his success is his almost savant-like knowledge of old Detroit Diesel engines. While I’m pretty sure that video editing cuts out quite a bit of the work needed to make an old diesel cough into life without immediately going into runaway mode, there is still plenty of information shared and each and every time, as long as the engine turns over at all, that engine will cough it’s way back into life, usually with minimal drama. Reviving an old engine is one thing, but seeing someone who has procedural memory like this guy does is something that I could watch all day long.

The application for this one is a Detroit Diesel 8V71 that is slated to become the powerplant for a Dodge D900 LCF big rig. The Low Cab Forward series of trucks were built for both the medium and heavy-duty market and were built with pretty much no change from 1960 through 1978 worldwide. Using the cab from the 1956 Dodge truck and a front clip that had swing-open fenders that opened up the engine bay for great access to the bay, the LCF was designed to be basic and easy to keep up. The Detroit Diesel engine was one of many options this LCF could’ve had, among offerings from Cummins, Caterpillar and Perkins. This Detroit should give the LCF build plenty of power and even after a nice long slumber, it sounds pretty damn good for a diesel, especially after some ill-advised “tuning” gets sorted.


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2 thoughts on “Rise, Lazarus: Waking Up A Detroit Diesel 8V71 For A Dodge D900 Project

  1. phitter67

    My dad taught me years ago that a Detroit should not “hunt”. Years ago he was a Detroit expert. But, at 89 years of age he is starting to have trouble remembering things.

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  2. Brian Pilkington

    The cab they are going to install is a 1968 or older cab! In 1969 Dodge went to the single headlights! When he is finished he will have a CNT 900 Dodge! I owned about 9-10 of them back in the 60s-70s-80s, and 90s. He would have a much better truck with an “855” cu in 250 hp Cummins in this configuration! I never had any luck with either the 6-71, or the 8V-71 Detroit engines! Seemed the easier you were on them, the sooner the rings stuck, and she’d start smoking like crazy! Once that happens that engine is doomed! Neither engine was hard to work on. The inline models either Detroit or Cummins put 2 of the cylinders right inside the cab with you! I repowered 3 Dodges and 2 Ford’s with 855 cu in Cummins power! Another thing about this kind of a set up, you couldn’t get a RTO 9513 in one until late1972 or 1973. So almost all of my Dodges had Spicer 5&4 transmissions in them! 7352 main box, with a 70?? Auxillary! (Can’t recall the model number on the Auxillary) But that opened up a whole new can if worms, the Flanged driveshaft was often coming loose at the Flanges! Double nuts and locktite, was the best cure I ever came up with, and truely was a cure! Going to the overdrive Fuller 13 speeds was the best cure! But building the rear transmission mount was a pain in that Dodge chassis, set up as a trip axle dump truck! And without it, that 13 speed would explode sooner or later! Even using a RTO 12513, was better but still needed that rear mount! Another thing, that “71” series Detroit will end up leaking a lot of oil and kill the rear engine mounts! I shielded the mounts with sheet metal, until I could repower the unit! Another failing on the Dodge was the front cross member! They bolted to both frame rails top and bottom, and they would crack the bolt holes and the welded nuts underneath the alignment holes! Spent lots of hours, cutting those bolt holes out of each end and fabricate a piece to weld in, much heavier steel, with tall threaded 5/8″ nuts! The factory 1/2″ bolts and nuts just wouldn’t hold! In “73” when they went to the full 11 inch “Whiting Frame the whole length of the truck, was a whole different story! The other weak point on that Chassis was it being only 85,000 lb frame they wanted to twist bad right under the cab behind the dual fuel tanks! Chrysler tried to cure this with a double 2inch “X” cross member! This wasn’t the answer either! I built several different replacement frame drop cross members! The best one was 1/4 thick frane steel built in a horseshoe configuration, with gussets welded in each corner and a flat plate with the 4 holes to bolt up to the rear cab mount bracket, that bolted to the frame! But when the truck was used after 7-8 years, you had to fabricate the whole assembly, frame bracket, under frame horseshoe, and rear cab mount! The bottom line was for an every day dump truck, I would have been thousands of dollars ahead and thousands of hours saved, by buying a DM Mack! I like your project! It has brought back a lot of memories to this old man! I was listening to your 8V 71 running, and kept thinking “you better run that BUFFER screw in, to smooth that idle out! One of the Dodges I bought with an 8V 71 in it, was blown up! I mean the Crankshaft would not turn. The previous owner would start that Detroit in cold weather and let it idle surging badly! All it was doing was foaming the oil, and not lubricating the engine! Yup the bearings starved for lubricant and then seazed one morning! I bought the complete 1972 truck for $5,000. But had to repower it! So ended up with close to $10,000. In it! This was about 1978-79! Completely rebuilt that truck. I ran those trucks hauling limestone and asphalt! Tried to keep them out of the mud! They just weren’t built for that kind of work! Chrysler tried to market them in that market here in Indiana, they just weren’t not designed for that! The original design was marketed in 1961 with the”413” cu in gasoline engine in it, designated a “1000” series! Chrysler desperately needed a heavy duty truck, so they pulled some of these very same trucks off the assembly line in 1965 and pulled the power trains out of them. Most tandem axle trucks came with 38,000 LB SQHD Rockwell rearends under them! The smart guys later ordered these trucks with SSHD 44,000 LB Rockwell rearends under them. The ideal ratio was 4.88-1, but almost all of the SQHDs came geared 4.63-1! This let the truck run 73-74 mph at 2150 RPMs with the overdrive transmissions in them. The 4.88+1 ratios would run about 67-68 MPH, not loseing much, but being able to pick the load up to road speed much quicker, and easier on the driveline off-road! The best set up that I found came out of Atlanta, Ga. “855” cu in Cummins, or 8V-71 Detroit’s with RTO9513 Fuller transmissions, with the SSHD 44,000 lb Rockwell’s geared at 5.13-1 ratio! On 20 inch tires, (remember almost everything in the 60s and early 70s, was tube type tires) I got ahold of one of these trucks trucks, an early 1973 (probably built in 71-72) and yes had to rebuild front cross member can mount and decided to repower with Cummins, as it came with Detroit power! It would only run about 58mph! So I found a set of hubs and wheels and changed it over to 22 inch spoke wheels! Later went to 24.5 tubless! This ended up being the ideal set up for Central Indiana Construction work! But again, I would have been better off buying a DM600 Mack! When I sold out, we (my wife and I) had 46 dump trucks and 6 tractor trailers! We hauled raw materials into a glass bottle plant! (Our son still does that) but we still had 6 Dodges, 12 Ford’s, 3 GMCs, 8 internationals, and 14 Mack’s (DM600s) and 3 new Volvo’s! In 2007! So after 45 years had some experience with dump trucks! And Dodges!

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