Diesels in '67-'72's.

[Bob B.]

Legend has it a very few '67 GMC pickups were built with the Toro-Flow diesel, a V-6 based on the big GMC V-6's. I don't know if I believe that, but I know some Toro-Flows were swapped in '67 3/4 tons by owners or maybe dealers. Anyway, I have been thinking about sticking a 6.2L or 6.5L G.M. diesel in one of these trucks. Those engine weigh about the same as a Big Block, they are about the same size, the bellhousing bolt pattern is the regular Chevy style, and I think the motor mounts are in the same place as a Chevy V-8. The turbocharged versions might present some plumbing problems, but one of the non-turbo 6.5L's might just about be a bolt-in.

[Longhorn Man]

But you'll pay Diesel dollars for limp V-6 performance... and it [/i]might[/i] out last a small block. (I'm not a fan of the pos 6.2/6.5... I see too many of them falling apart)

[special-K]

There are stories of good fortune and missfortune with the 6.2s & 6.5s.The bad stories are enough to discourage alot of folks.I`ve had good fortune and still like the motors.They do bolt-in and I`ve seen it done with great success.My daily driver is a`91 3/4t 4wd Suburban 6.2/4L80E and it roles along @75mph effortlessly getting 22 mpg,more than most downsized suvs.Better diesels have been developed since these that were introduced in`82.But none can be had for as cheap,run for so cheap,or bolt-in so easy.I have a Marine application 6.5TD that puts out 300+hp.It has a high-nickel alloy block with wider & beefier main journals.The compression is lowered to 18:1 to cut down on heat and allow more boost/fuel from the modified injector pump and medium-duty non-wastegate Switzer turbo.Not a cheap motor,but still cheaper and easier than the others with simular power.Check www.peninsularmarine.com to learn more on it.Here`s my economy wagon:

I want to reincarnate this drivetrain into a`72 sometime.Oh yeah,your original question about a few diesels sneaking into our beloved 67-72s.In the 10-30 series parts book I always noticed mention of diesel in some listings while peering at the book upsidedown at the parts counter.Like:Tachometer...w/diesel...

[special-K]

BTW,you can get about 180-195 hp out of a naturally aspired 6.2/6.5.The 6.5TDs are 195hp stock so, w/o the turbo lag,an N/A with that much power is ali`snappy(bottom-end torque).6.2s are 135 horse stock.

[shelby987]

if you still want to go the TD route, but are worried about the plumbing, there are a lot of kits popping up these days to run the turbo off the exhaust at the rear of the truck. This allows the exhaust gases to cool slightly before running the turbo, and the piping back to the intake acts as an intercooler....i would wager that you could fab up your own kit if you are handy enough and have a tubing bender.

[too much stuff]

special-K, you are correct about the diesel tachs. There is for sure 2 variations on the tach head also...

[Bob B.]

The Toroflow diesels used a mechanical tach.. Some of the larger 1970-72 C series medium duty trucks with the gas V-6 would have had a redline around 3250 though.

[too much stuff]

The tach pictured is mechanical drive, and my other is mechanical with a 2800 rpm redline. Interesting thing is the other one has no vacuum gauge, but a low vacuum idiot light in the gas gauge. Sorry i don't have the answer to your original question...

[barraza]

Why does that gauge cluster have a vacuum gauge if it is for a diesel? There shouldn't be any vacuum to measure.

[special-K]

Something to do with air brakes?Or,some auxilary unit?

The only problem with the 6.5 turbo set-up in earlier bodystyles is the heater/air conditioning unit being in the way.Going to a Vintage Air system eliminates that problem.

[Bob B.]

The vacuum gauge was for vacuum brakes. Many medium duty trucks in those days had the Bendix Hydro-vac, which was a large frame mounted vacuum booster. Good to know how much vacuum you had. Toro-Flow diesel trucks often had Hydro-vac's too, operated by a belt driven vacuum pump, much like the vacuum pumps you sometimes see on 6.2L diesel pickups. You are right, diesels do not have any manifold vacuum.

[special-K]

Hey Bob,I just noticed your truck in your signature.Sounds like a cool truck.I think those CamperCruisers are a cool model to find.

[72 CustomCamper]

Hey Bob B., when I got my 72 3/4 ton from my uncle he had installed a 6.2 diesel in it. I have since converted it back to a gas motor but the only thing he had to do was modify the engine stands. Youu would be able to use a set of factory big block stands to do the same thing...


Chuck

[texnician01]

I would if at all possible go with the 6.5 and not the 6.2, In the military most of the Hummvee's have 6.2's and they are always broken, underpowered.... Most of the 6.5's run really well. In my experience if you convoyed in Iraq and they asked what motor your Hummvee had, if you said 6.2 they laughed and then asked if it will do 50mph. most convoys over there range from 60 to 70 Mph. I do have to say though we had one truck with a 6.2 and it would do 70 with 1500 pounds of extra armor. Generally the 6.2's in my opinion are junk. But maybe that's just the military

Nathan

[bojoe]

I know around home the 6.2 has a good reputation and the 6.5 not so good. The 6.5 had more power, but the 6.2 lasted a lot longer. The biggest problem my friends have had with their 6.5's is the injection pump.

[72 CustomCamper]

When my uncle had the truck he towed a 30 ton bull dozer with the 6.2...


Chuck

[TP from Cntl PA]

If you want a diesel, put a Cummins or Detroit in it..............IMO the rest are about useless.

[smokekiki]

The 93 6.5 still had a mechanical pump. The 94-96's had block and head cracking issues.97+had a thicker block.The 6.5s should never be ran hot.As special k stated,300 hp is possible.You can run a van manifold,it had a center mounted turbo.It gives more clearence.I am planning on putting a diesel in my 71 suburban.With the BB in it I am getting 8mpg.If I can double that,I will be happy.Besides,at work we have a diesel pump,I will be able to fill up as part of my pay package!

[special-K]

No problems with the Stanadyne DB2 mechanical injector pump used on all 6.2 & 6.5 NA and 92/93 6.5 TD.The Stanadyne DS4 electronic injector pump had problems with support components such as the PMD(pump mounted driver),TBS(turbo boost sensor),and the lift pump/oil pressure switch.Failures in these parts were greatly misdiagnosed as failed I/Ps.I is possible to change over to the mechanical,that`s what I did on my`95.The pump never failed in 130,000 miles.I sold it for $300.The`97-up blocks are actually weaker in the main journal webs due to being drilled for the oil-spray ports.The first year`82s,all military,and the new General Engine Products blocks are higher nickle and most desireable.The GEP blocks have beefier main journal webs.The 6.2 and the 6.5 are the same motor,different bore.The turbo set-up is what gives the 6.5TD 60 more hp than the 6.2.Put the turbo on a 6.2 and you wouldn`t know it wasn`t a 6.5.In`97 a higher-flow cooling system was used including a dual thermostat crossover and a 125gpm pump.American General will be supplying the military with Humvees powered by 6.5s through`07 when contract expires.I got 250,000 miles on original I/P,injectors,and glow plugs in my`92 K3500 w/6.5TD.Took the still runnin`strong(in need of those three things)motor out to install the 300hp motor out of my totalled`95.It`s fun pushing Powerstrokes,Duramaxes,and 5.9 Cummins` up the road in a truck running on a boat anchor.I know more can be made out of the three latest diesels when money is thrown at them.But in stock form they`re evenly matched to mine.
Oh yeah,these motors are Detroit/Allison.

[qksilver]

Back last summer I saw a 66 swb 4x4 with a V-6 diesel on ebay. He said it was a 68 drive train with the 66 body put on top. I went by and looked at it, it looked factory from what I could tell under all the mud.
I didn't buy it because the engine block looked like a gas one and didn't hear good things about reliablity.

[buildin72]

Originally Posted by TP from Cntl PA

If you want a diesel, put a Cummins or Detroit in it..............IMO the rest are about useless.

I agree 100% on the Cummins part!!!

If you are dead set on a GM diesel i would just go with a 6.2 (J-model only! for performance and reliability reasons...DO NOT use a C-model!!!) and add a Banks Sidewinder kit to it. I believe you would be happy with the performance.

A.Y.

[oteixeira]

I am in the process of converting my C-20 to a Cummins 4BT engine out of a P-30 Chevy Box Van. It bolts right up to a TH400, and lasts forever. That in my opinion is the best option we have for our trucks diesel wise.

Orlando

[cell]

oteixeira: Cool! I have been thinking about doing the exact same thing. I have a C10, and plan on taking the cross member off of a 73+ 3/4 ton for the front disc brakes, at which point I think my front suspension should be able to handle a cummins 4B.

I called up my local cummins distributor, and unfortunately a 4BTA reconditioned by cummins is over $6k, so I am definetly going to have to find one on my own.

Any tips on sources of old P-30 chevy box vans? Are there special junkyards for larger trucks like that?

[cypressbog]

Originally Posted by oteixeira

I am in the process of converting my C-20 to a Cummins 4BT engine out of a P-30 Chevy Box Van. It bolts right up to a TH400, and lasts forever. That in my opinion is the best option we have for our trucks diesel wise.

Orlando

I agree with oteixeira, the 4BT by Cummins is the way to go as long as it's mechanical fuel pump driven. One source of good used and rebuilt diesel engines is www.arsco.com or 1-800-621-4394. They are in Chicago IL.

I plan on using B100 (100% biodiesel), or produce my own biodiesel from WVO (waste vegitable oil) I can pick up for free at any fast food joint. Producing my own fuel for $0.70/gal is much more economical. Try www.biodieselnow.com. or www.greasecar.com for more info on frier oil driven vehicles. Yep, convert to run on pure veg oil!

[buildin72]

Originally Posted by oteixeira

I am in the process of converting my C-20 to a Cummins 4BT engine out of a P-30 Chevy Box Van. It bolts right up to a TH400, and lasts forever. That in my opinion is the best option we have for our trucks diesel wise.

Orlando

MAN..where have you guys been hiding??? My original plan was to build a 72 K/20 with a 6BT Cummins...but instead i am in the process restoring my grandpa's old 70 swb C/10. I was thinking about installing a 4bt in that truck. Can you throw me any tips on this conversion??? I would sure appreciate it.

Thanks,
Adam


P.S. Since there is more people than ME thinking and working on this maybe we should start a 4BT conversion thread. Think that is a good idea??? or not???