8070 ambac pump

Getting the pump and injectors redone on the 82 allis 8070. I read somewhere about the brass tee on the pump needing drilled out from .040 to .052. Is that a true allis update and recommended on my tractor?
Also had some guys talk about setting pop off pressure on injectors to 3600 vs the allis rated 4200. Is that recommended for my tractor?
Anything else I should know while I have the pump at the shop?

I appreciate you dr allis!

Got off the phone with the pump shop today. They said they had never heard of drilling out that orifice and wouldn't do it and stand behind the pump. Thought it was odd. I assume that would have been an allis only update?

He claimed it was still .040. I bought #55 drill bit and I'm going to drill it myself. I was just surprised that this wasn't listed in the updated foot notes for the pump rebuild. He did put a new head in the pump and claimed the introvance had too much backlash. He put new tips on all the injectors as well. My local gleaner dealer says they are the go to shop for these pumps so I'm not real concerned they don't know what their doing but the orifice thing makes me scratch my head a bit. I have read enough of dr allis posts to know you are very knowledgeable but also at the same time I remind myself I am listening to someone I don't know on the internet over the injection pump shop. I consider myself fairly smart and I can tell people who post with knowledge and people who don't know a 1/2 inch wrench from a 13mm. That is why I plan to drill the orifice out. It's kind of scary that without dr allis and his knowledge I don't think I would have ever heard of this! I thank you sir

I can distinctly remember that particular bulletin too. I may even have a copy myself. It doesn't seem possible that it's been 43 years ago.

Where is the T?  Is it on the back side of "head" which the return runs through? What is this "rattling" from? I bought an 8030 this spring for a planting tractor. At 1200rpm no load it sounds like a precup engine. Haven't taken time to check timing yet but way more rattle than my 8070's with A pumps @ 32deg.

So just curious - why did Allis go to Ambac at that time?? Wasnt Standyne/ Roosamaster still in business??

I gotcha- thanks!

The tee with the orifice built into it has to be removed to be able to drill it out. When you see where it is, there's no room. The engine sounds like absolute crap when you don't do this. Can't be good for things.

I think the first few I did there were some new cuss words created............

Ed says it's part of calibration. Does that mean that you can't just fix the tee without recalibrating the pump?

It is used when calibrating the pump, but the difference in hole sizes should not affect the calibration much, if any. It may lower transfer pump pressure slightly, as that is what the orifice is there to do, restrict return to build transfer pump pressure. Most shops just use the return fitting for an IH when they calibrate the Allis M100's. 

they vary, it just needs an orifice about that size range for calibration. The only thing it's various size affects is transfer pressure to some extent, actual fuel delivery won't change if transfer pressure changes 5 or 10 psi. Some pulling pumps we want to use a smaller orifice to get transfer pressure way up high to get the most output though. Stock applications not an issue. 

There was no update for the tee on ANY 8010.

I've never been a big fan of the ambac pumps on the Allis engines. There were several service bulletins on improving their performance from the beginning.The bosch injectors were an improvement as far as I'm concerned, but I'd rather have a snappy rossa pump myself. Maybe that style of pump on the 301 engines worked out better than on the 426 engines. The ambac style pump seemed to be a good fit for the IH products, so I'm not real sure why the Allis engines weren't a better fit. The IH certainly had a higher compression ratio, so maybe that played into it.