666 Questions

After looking for some time for a 60 to 80 hp tractor, I recently bought a 666 gas. The tractor will be used for tillage and other heavy work on the 40 acres that I've retired to. For lighter work, I have 2 smaller tractors, so the 666 won't be used a lot. Following are several questions regarding the 666.

1) IH used larger engines, both gas and diesel, in the 666 and later 686 models than in the earlier 656's. And the 666's and 686's had heavier front axles. Also I udnerstand that the diesel engines in late 686's had 310 cu. in. rather than 312 as used earlier. Aside from these consideratons, grilles and headlight placement, were there any differences in any of these models?

2) My tractor has 16.9-38 rear tires, but these are not mentioned in the operator's manual. Did IH offer this tire size or were they installed by the previous owner? My tractor came with fluid in the tires and 2 sets of weights. With the heavy soil I have, what size tire is likely to work best?

3) 656/666/686 tractors are often operated with the wheels dished in, which is usually not the case for other IH models. Is this for cultivating 30 in. rows or is there some other reason for this?

4) The throttle lever on my tractor is a 2 piece affair consisting of a chrome plated rod connected to a cast hub by a pin. Wear has occurred so that the connection between the rod and the casting is sloppy. Larger IH models, e.g. 706's, used a one-piece casting which seems to be a better design. Is there some reason for the different design used on the 666 and will the lever from the larger models fit a 666?

5) The manual says that tractors equipped with TA cannot be started by towing. Why is this?

6) The manual refers to "deluxe fenders". Was there more than 1 fender design? My tractor has flat top fenders. Are these the deluxe fenders?

7) I seem to recall reading somewhere that a deluxe seat was offered for the 666 tractors. Is this correct and if so, what were the differences in the deluxe seat?

8) Under optional features, the manual lists safety chains. What were these?

9) The manual lists a 3 pt. hitch as an option and also a "weight transfer hitch (3 pt. hitch)". What's the difference?

In the future you might not want to overwhelm people with so many questions at once... I'll answer what I can here.

1. The 312 diesel in the 666 is an American diesel. IH switched to the 310 German diesel in the 686 so the American engine plant could concentrate more on building the larger 414, 436, 466 engines.

2. 16.9x38 tires are a common replacement. The stock tires are too small. If the tires you have are good, use them. Otherwise replace them with the same size.

3. Wheels dished in, wheels dished out... Depends on the tread width you need to do the job.

4. Chrome is pretty. That's why they used it. Tractor's 30 years old. You gotta expect some wear.

5. Is it a manual for a 666? If it's the manual for a 766 or bigger, it's because the TA requires hydraulic pressure to connect the engine to the transmission. Otherwise it just free wheels. On the 666, it's a mechanical TA and the tractor can be pull started with the TA lever ahead.

6. I think deluxe was used as a marketing term. It was either deluxe fenders or no fenders.

7. Again, a marketing term. Deluxe seat, or no seat.

8. Safety chains to hook to the implement so if the drawpin breaks, it doesn't go rolling off out of control. Just like on your boat trailer, or snowmobile trailer.

9. I think this is what it's talking about: The weight transfer hitch is an arm that attaches to the 3pt, and a chain runs from the arm to the tongue of the implement. By lifting up on the 3pt, you put pressure on the tongue of the implement, which tries to lift the implement off the ground. The end result is that weight is transfered from the implement to the rear tires of the tractor for more traction. It has never been a popular option because the arm is in the way, it's a nuisance to hook up, and if the tongue isn't heavy enough, you end up with bent tongues on your implements. Not a difference, but two different things entirely.

I see someone else beat me to that comment - please, just one ? at a time :^) What else do you have for tractors?

My 666 has no seat suspension. I believe the deluxe was the same seat only with suspension.

As Farmall 57 said, the standard seat has no suspension vs suspension on the deluxe seat. The tractor could be ordered with standard clamshell fenders, deluxe flat top fenders, or no fender delete. Most we sold had 15.5 x 38 rear tires.

Harold H

Thanks to all for your input. I know more now than I did. And yes, the manual I referred to is the 666 manual. In fact it's the original manual that came with the tractor.