peteslagel

Im not totally sure on the motors doing head gaskets, there arent many around here any more. The 865/6 had a bit of trouble if heads werent re-torqued periodically. I think a lot of blokes out here used to re-torque them around 50-60thousand Kms. Im not sure about the 864, but every block Ive seen has major shuffle marks on the deck surface, so I would say they were in the same boat. The 864s also cracked around the counter bores and between the counter bore and some head stud holes, as there is only about 3/16" surface area. They have fire rings. Ive just had a block repaired and we paid really close attention to these areas I mentioned. Do you have a T864? There were only ever 2 or 3 in Australia. The only one Ive seen is on ebay in an R719.

I am looking at buying a truck with a T864 in it. I had trouble with a 711 back in the late 70's and I went back to the 673. The 711 cracked between the two counterbores. I am concerned I might have the same problem with the 864. I need to use it for about 20k loaded miles a years, so I need it hold up, not just be a "show" truck.

Seems like I should look for an 866 for a backup.

On a related topic, did the 864 and 865/866 have a Mack single disk clutch? Can you replace the Mack clutch with a Spicer angle spring? Do you have to replace the rear housing and move the transmission mounting brackets?

How are ya mate? E9 injector wont fit into a 2 valve head. It goes in between the valves under the tappet covers whereas an 865/6 goes in on a slant outside the tappet cover, like a 6cyl 2 valve. E9 exhaust wont fit an 864/5/6. They have 4 ports per side whereas the old ones only had 2. And the 865/5 manifold wont go on an 864 either, as they have 4 bolt holes instead of 2. A pain in the arse.

I have never seen a T864 so I couldnt comment on compression ratio or piston type, but I would nearly be certain the pistons wont be interchangeable with an 865/6. The 864 series was always grouped with the 711 series. While the block and front cover looks similar between the 2 V8s there arent too many parts that are interchangeable. The Auxilliary drive was similar and you can put a Vee pump on an 864 but there was a different housing on some 865s just to make life complicated. Hope that rant wasnt too painful. Good onya mate. Skip

Thanks Skip,

Very informative. I did not appreciate the difference between the 864 and the 865/866.

Can you comment on the head gasket question? Was there a problem with blown head gaskets on these old motors? Do the 864 or 865/866 have fire rings?

Pete

Gday all. I dont think you would get 500 out of an 864. Ive heard of a few 866s being taken out to 450-500. The 865 was a Maxidyne engine with lower hp than the 866 but more torque. I have heard of blokes using an E9 pump on an 866 but not an 865. As for the T864 the rotary pump was a bit troublesome and the twin turbo setup was fairly complicated so they canned them both and went for the single turbo and vee pump. The T864 was 300hp as already mentioned and out here the 864A was rated at 280hp in the R models and a few F models. Cheers skip

So the ENDT864 was the twin turbo?

Did the 865 and 866 have the same compression ratio as the ENDT864, and the same piston?

Is it possible to install a an E9 injectors into the 866 head?

Will E9 exhaust manifolds work on the 866 head?

Pete

I think i've posted this on here not that long ago but here it is again august 1969 spec's from the Mack manual

bottom right last 3 row's gives 3 non turbo and 1 single turbo rating

Click to enlarge

if your sight is bad they read as follow's

END864 = 255 @ 2300 rpm

END864B = 270 @ 2300 rpm

ENDD864 = 237 @ 2000 rpm

ENDT864 = 300 @ 2300 rpm

Thanks for that. You guessed correctly, sight is bad. Is it possible to get a clearer picture of that sheet. Is the turbo compression ratio lower than the non-turbo?

Pete

Can someone tell me the factory horsepower rating for the turbocharged version of the 864 cu inch V8? Was there a twin turbo version as well as a single turbo?

Any additional info would be helpful, maximum boost pressure, etc.

Any problem with head gaskets on this motor?

Thanks,

Pete

Great, I found it on the old site under "Info" or else "Links" and then B "Model Info". Very interesting. Tom Gannaway did a great job collecting that list.

It looks like lo-lo is only usable in 1st and 2nd in the 72 series transmissions. The TRQ-72 looks like a direct main box with 15 speeds and two low holes.

The TRQ-720/7210/7220 all look like a 13 speed double over with 2 "useable" low holes.

I still can't work out the math for 14 and 18, but there must be some logic behind it.

Thanks for the help.

Pete

I have seen Mack shifting plates for Quadraplex transmission, in B model cabs, that have both 14 speed and 18 speed. Is there a difference in the transmission? Does anyone have a complete list of the Quadraplex gear ratios?

I am getting ready to swap out a 673 for a e-6 285 with a 5 speed. Will I have to change anything about the rad. other than clean it? Is it big enough to cool this engine. I will be using this truck as a big pickup mostly to just drive around and sometimes pull a gooseneck horse trailer.

I see you have no replies, so I will take a stab at it. The short answer is that you would only have a problem if you were pulling real loads (40 to 50k) in the mountains or the summer time. For your application, I doubt you will have a problem.

Some additional thoughts,

-be sure the horizontal fins are in good shape and do not pull away from the vertical water tubes. If the lower fins are rotten, replace the core.

-If you do have to replace the core, ask about using a core with an additional row of tubes. (check fan clearances and be prepared to use the water pump from the 673)

-I would add a pyrometer to be sure you limit exhaust heat to 1150 deg F. This will assure you that the air intake system is able to provide sufficient air

-I would consider keeping the original transmission, water temps are higher if you are pulling hard at 1200 rpm compared to 1700.

-Leave the original spec thermostat in the engine

I would like to see a picture of this when you are finished. peteslagel@earthlink.net

Pete