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If i remember correctly that is a Trevits motor , so it is probably pieced together with different parts. If you would pull inj they probable ground the numbers off so no one can tell what they used.

He was a Mack engineer that worked with Curt Price from antrim's and JR Collins to develop high performance parts.

I'm also turbo stupid so don't worry u are not alone. But this is how u learn.

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If i remember correctly that is a Trevits motor , so it is probably pieced together with different parts. If you would pull inj they probable ground the numbers off so no one can tell what they used.

He was a Mack engineer that worked with Curt Price from antrim's and JR Collins to develop high performance parts.

Al,

Found Steve's notes on my engine. He was not into custom parts to much and used the military spec stuff. The injector tips are Bosch 0 433 171 341. Curt Price did my pump at Antrim, A stock motor runs best at 19 degrees timing as Steve states but I think I have around 25 degrees. What are you guys running on timing?

My old 866 in the B755 had 27 degrees on the valve cover tag as spec. It sort of clackes a bit, I think it sounds good with a little "hunting" going on, about 50-100 rpms at idle, just a slight rock if Ya Know what I mean. That pump, injectors were done at the old R&R Mack in Twinsburg Ohio.

Turbos.... All I know is bigger is not always better, more psi over a larger rpm range is for me. Pullers I think like it all at top rpm, is that right?I got two small turbo's on one of my cars and it is a rocketship beteewn 3500 to 7500 rpm's

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My timing is between 35-39 still playing with it, was always told not to go more then 1 degree over stock if working truck pulling a trailer with long hard pulls.

Guy around here had his advanced 3 degrees on working truck and eventually cracked all the heads.

You are right bigger turbo more top end.Made big difference when i went from 3.6 to 3.9 .

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My timing is between 35-39 still playing with it, was always told not to go more then 1 degree over stock if working truck pulling a trailer with long hard pulls.

Guy around here had his advanced 3 degrees on working truck and eventually cracked all the heads.

You are right bigger turbo more top end.Made big difference when i went from 3.6 to 3.9 .

That's funny... When I rebuilt the 866 with 27 degrees timing. I thought it was a lot. The engine I started with had 3 cracked heads!! I had to go through another 12 heads to find a good set. ALL 865/866 have at least one or two cracked heads no matter what. Maybe that is why Mack took a lot of timing out with the E9.

Thats another question for Dale when I see him,TIMING.

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ATAAC is Air To Air After Cooled.

Thanks, really did not know that. Intercooling would be much the same as an E9. Both engines have the same turbo and intake layout. There is a few inches differance in location but tubes could easily be bent up. I don't know if I would be turning up the pump and intercooling an 865/866 though. The heads are 2 valve and prone to cracking into the exhaust valve seat and dropping inserts. I had to go through a pile of heads to get a good set. Parts are a REAL issue, I have both engines and am just happy my 866 is as good as it is. It is rebuilt with less than 1000 miles on it. I did it back 20 years ago when Mack still had parts. Used standard main bearings and there were 3 differand standard bearing listed but only one set avalible at that time. Oil pressure is OK but runs 35-55 hot, almost 75 cold.

Intercooling would get you about 40-50 hp but probably at a cost in broken parts. Just my two cents worth.

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If you want to work the truck you might want to stay with Turbo you have. ant bigger and you will have to keep wound up to keep egt down.

I'm govn to 4000, Frances has two different size crossover tubes i have the smaller one now.

I have a valve on mine to lock back brakes so i can ride clutch to get boost up before i leave line. Ran Lipe clutch for years doing that.

Now i have 4 disk crower clutch.

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Hay Albert,

What did that clutch put you back? My twin disc is good for 4000 ft/lbs but after these mods maybe at its limits. Was that EZ to install? How's the pedal, a little stiff? Can it be driving daily? Cool looking unit!!

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5800 for clutch and flywheel

drove mine to all pulls and shows 2 years now

That's a chunk of change!! What is the torque rating?

I get that it is reliable but is it smooth like a metallic puck or is it like a NASCAR or drag clutch, in or out, no feathering unit. I have had many differant ones over the years. In the trucks it is smooth but my race car it's ether disengaged or all in and no in between. Can you inch up at a light with out chattering?

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I have to look into one of those when my setup starts giving me problems. Sounds like it is totally adjustable and can roll on the pressure with RPM. My leg gets a workout holding down the 4000lb one I got. Not something you want to drive everyday but it dose the job.

You running Rockwell lockers? I got them on air and is a nice setup.

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I made a air assist clutch control for mine.Easy to do.I used a air cylinder of 3" diameter and mounted in front of the clutch lever so it could pull the lever with a chain.A air pilot valve controls that and a fuller trans shifter stick clutch brake valve like the RT6613 trans used and mounted to my stick just below the shifter knob.Ever time I clutch my finger mash the small knob down and I am so used to it when I get in my dodge I look for that knob.A air regulator is in line of the air supply to the pilot valve and that you can adj it the way you want.I want it to only help but you can add air to it and it will mash the clutch buy its self if you want to adj for it.

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glenn akers

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