Freightrain

I think the 285/300 were 676(maxidyne). The 300+ isn't the same.

Thanks Steve. What I need to know is the serial number after the Etaz673c, does that correlate with anything? 7S8762 ??

Ford had similar coding for clearances so they could put correct parts together without having assembler measure anything.

Not sure of year. Only thing I have is serial on motor. EtAZ673C 7S8762. If that means anything. I looked on Agkits and they want truck serial number. I hope we can work around that.

Shop I use can cut rings. No issue there. Using fingernail, I'm guessing +.020 deep currently. Pretty solid groove. I did get #6 piston out. Was able to wiggle past oiler. Rod bearing was 12-7 112 62GB33-P1 Crank and bearings look fine.

Was hesitant to pull injectors, but going to have heads cleaned up. Should I zip the two bolts out of clamp and do they pop out easily? Will there be a seal ring in hole?

They are at least that. The deck has 020 hand stamped at each cylinder? Protrusion is more then that? Fire ring may be that by feel?

They are there, #4 had some crud in the area where gasket was blown. It was going to get worse had I try to just install and run it.

Got the heads off. Yup, took a 5ft cheater to get them to SNAP loose. Looks like I had a head gasket on its way out on #4? Rest looks ok. Cylinders ok, no damage. Noticable wear on top of liner. Not huge ridge, but very detectable. Not a " fresh" rebuild.

I wondered what "low flow cooling" was. Terms passed around and never knew what it was about. Thanks for clarifying.

I got it up on legs and the pan dropped. Looks like someone has been in it before. Orange silicone on the back and the main bolts look like the paint is chipped off like it has been apart. Rolled new brgs? It has signs that things have been apart other places(orange silicone). When I looked at truck originally I tried to find the serial number on frame but severe mud and crap kept me from getting in too close. I wonder if this is a transplant? Truck had straight 5 spd, did it originally have a 285 and this was put in? Never know now. Has new air compressor and lots of other pieces that don't match paint. It was definitely tinkered with. No idea on mileage (or hours) either. One bigass pan. Noticable marks from previous fingers in the bottom end. Will work on getting heads off next.

I welded a 1/16" thick lip on my cab and bolted boot to it with thin aluminum backer on the rubber side. The new opening for the bunk I made a similar lip to bolt boot to. Sounds like the up fitter just kinda cobbled it and hoped it would last past any warranty. 🙄 My trailer has similar luan(thin 1/8" plywood)with vinyl covering. You could replace that yourself. I just painted mine white to match.

CH looking good. The Windfall Wimmen model really add to the class!!! 😉 Bummer about the GMC bunk. I've been fighting leakage on my trailer for years. Had to replace the ceiling in the front(bed area)along with the three walls and part of the plywood flooring. Went from "eh" to rotted and mold in short order. I have the leak fixed so it should be good for awhile. I forget what the bunk looks like? Alum ext. with luan panel inside?

I was going to try to add one to my 237, but got a whole motor. I hear they are quiet noisy at full song? Guess I will find out. Seeing they are 40+ yrs old, it is likely harder to find one? Mine does work, as I had motor running and if I jabbed the throttle it would send a touch of wind into it and it would spin easily. They were popular before CAC was mounted in front of radiator.

The difference is, the 237 and 285 were made for only 5 gears. The 300+ isn't, so I bet it was slow to recover on a shift.

That Mack 10 spd must have similar OD as my Triplex. I want more though. A quiet, get home gear. Even if I only used OD on level or downhill. Not sure a 12 spd would fit under the cab in a B model? I would love to have one.

That would be a cool set up. Seen a few for sale but a bit pricey and not sure about rebuilding cost? Availability?

My 300+ has the flip flop linkage going to the pump so it can push instead of pull. A new local FB friend pulls using a 285/300 and removes the intercooler in an R model. Apparently this pump is " the pump" to run . He turns it like 3000+ rpm, all stock bottom end. Says it is no problem.

The 300+ needs more gearing. Like a Thermodyne. The truck had a 5 spd, but I bet it was a real PITA around town. But it was a fleet truck, so I assume that is why they used a 5 spd.

I'm not overly worried about a deep low. Like my deep under 6041 just for the slow truck race. Beyond that I don't "need" it. I know I am dealing odd pieces and trying to get something that works well together. Decent splits and something like the double OD I have using my Triplex and 6041. Gets me 65 mph at 1500ish. Much quieter then 1800! I don't like lugging it much with that 6041 and the 300 will be harder on it. I wouldn't kick a 18 to the curb if I found one reasonable, even it it means paying full core for it? If there is a DO version that would be a plus. I have the Eaton chart saved, need to look around. I need at least a single OD, period. I will remove the 6041no matter. As for clutch housing, Geoff and I were already poking around at those before I rebuilt the Triplex. Using the Triplex? I could, but I don't want to have to "baby it". If I feel the need to let it rip, I want a transmission that will not flinch. Just a note, I purchased a new $10k transmission for my race car. It is the top of the line, badass, never have to worry kind of transmission. I have no problem with doing that for the Mack. I only want to do this once. Thanks for all the input guys. It will come together somehow.

I want to cruise at 14-1500 rpm @ 65 mph. Not 1800 I am now. Those 3.55s or a double OD like I basically have using that 6041 box. I'm not worried about going fast, just fast enough without all the noise.

My initial thought is NO. Everyone says to but I don't want to worry about something going wrong. These transmissions arent on every block anymore. My next thought is get rid of the 4.10s for a set of 3.55s if I can find a set for a Rockwell. Then I can run a 13 spd. If changing rear gears becomes a hassle, I want a true double over 13. Not a homemade version. I want more road speed at lower rpm(noise level). I will be removing the little 6041 box I have hanging in there. Much to fragile.(I'm a gearhead, I want something I don't have to drive like I have an egg under my foot). I had thought of using the 5 spd that came with engine and find a 1241 and use it for splits, plus if I get a 1241C it has deep under like my 6041. Lots of "maybes" and "ifs".

The 237 is a huge upgrade from the 673. Can't wait to see it with new motor! I found out last winter that my throttle was not quite wide open at WOT. I adjusted the arm just a touch and WOW what a difference. It really pulls the hills now. It was good but that last little touch of fuel made a big difference in keeping speed with my trailer on steeper hills. Always had to drop a gear, now I can almost not have to. Can't imagine another 100hp?

Ok, it makes sense. It uses an adjustable rocker cup to apply extra lift to open the valve instead of a Jake housing. Normal setting it has lash, once pressure applies it pushes rocker further opening the valve. Kinda ingenious actually.

I've run valves, so I understand the procedure. On my hot rods, I always do one cyl at a time. They have cheat sheets on how to do multiple cylinders at a time but I never do it that way. Ever. Even after getting grief for it. "Oh, you're taking too long". Whatever. This having so much lash surprised me. Why does it require so much for a "dynatard" cam? What is special about it? I'm just glad it isn't a cam lobe problem. I did the valves on my 237 and the Jakes without issues. I know Jakes are different but I followed the sequence and they work fine. I want to transfer the Jakes over to this engine, if possible.